JP6854531B2 - electrode - Google Patents

Description

The present invention relates to electrodes. More specifically, the present invention relates to a Co ₃ O ₄ electrode. The present invention also relates to a method of synthesizing a _{Co 3} O _{4 electrode.} The electrodes of the present invention can be used directly in an ethanol fuel cell.

A fuel cell is a device that converts chemical energy from a fuel into electricity through a controlled chemical reaction between an oxidant and the fuel. Typical fuels commonly used in fuel cells include hydrogen, alcohols such as methanol or ethanol, or hydrocarbons. The oxidant is typically oxygen.

Fuel cells are a promising means of converting chemical energy into electrical energy in many applications. One of the most important applications is the use of fuel cells to power electric vehicles because they can provide high output densities at low cost with zero emissions. (Stambouli, AB, "Renew. Sustain. Energy Rev.", 2011, pp. 15,4507-4520). Direct ethanol fuel cells have several advantages over other types of fuel cells because they have high power density, high efficiency and are considered to be relatively environmentally friendly.

Adjusted nano-object design and surface morphology may provide an electrode catalyst with improved accessibility to electrically active sites. This leads to preferential surface coating of ethanol molecules, shorter ion / electron diffusion pathways, better mass transfer of reactants through nanoscale structures, and faster or reversible kinetics in ethanol electrolytic oxidation reactions. obtain. However, the effect of catalytic morphology on anisotropy, the density of exposed active sites, and the density of multidiffusive voids in the longitudinal direction on the electrolytic oxidation reaction of ethanol remains unclear.

Current methods of forming electrodes result in the formation of structures with randomly oriented morphology. In addition, typical methods require a small, multi-step process due to the cost of current electrode materials such as platinum. The drawbacks of current industrial catalytic electrodes are the high cost of materials such as platinum and the finite cycle life of the electrodes. In addition, the platinum catalyst can easily bind to carbon monoxide, thereby causing the ethanol redox reaction to be "poisoned". Therefore, it is necessary to provide improved electrodes, for example electrodes for direct use in ethanol fuel cells.

The present invention provides electrode structures that benefit from low- and high-refractive index single and interfacial planes with multi-diffusive meso-cage cavities and windows. The present disclosure provides a simple one-pot hydrothermal method for synthesizing various electrode structures along the longitudinal axis by using a multi-component carbon / Co ₃ O _{4 / substrate layer.} The method of the present invention is versatile for the production of _{various anisotropic forms of Co 3} O ₄ structures having low and high index single planes and interface planes with multiple diffusible meso-cage cavities and windows. Provides control.

The present invention provides a significant cost advantage over current electrode systems due to the use of low cost materials including porous nickel substrates and Co ₃ O _{4 mesocrystals.} In addition, the present invention provides electrodes with improved electron transport and diffusion as compared to electrodes in the art. The metal oxide catalyst of the present invention, such as Co ₃ O _4, can be produced at low cost, and in embodiments, it has a hierarchical form (eg, a nanoforest structure disclosed herein), a high surface area coverage. It has unique features such as, and a single crystal having a high refractive index exposed active site plane surface. These parameters provide highly efficient performance of electrochemical catalysis of oxygen reduction reaction (ORR) or alcohol oxidation reaction (AOR).

The electrodes of the present invention offer many advantages. The electrode has improved catalytic efficiency of ethanol electrolytic oxidation as compared to conventional platinum / carbon (Pt / C) electrodes.

An object of the present invention is to provide a low cost electrode having high catalytic efficiency. Therefore, a further object is to provide a method of manufacturing the electrode. Applicants believe that these objects are achieved by embodiments of the present invention.

In one aspect, the present invention provides an electrode comprising a support and a metal oxide catalyst, wherein the metal oxide catalyst comprises a nanoforest structure.

In one embodiment, the metal oxide catalyst is a transition metal oxide. In one embodiment, the transition metal oxide catalyst is cobalt oxide (eg Co ₃ O ₄ and / or CoO), nickel oxide (eg NiO), manganese oxide (eg MnO ₂ ), or cadmium oxide. In one embodiment, the metal oxide catalyst is cobalt oxide. In one embodiment, the cobalt oxide comprises Co ₃ O ₄ , CoO, or a mixture of _{Co 3} O _{4 and CoO.} In one embodiment, cobalt oxide comprises Co ₃ O ₄ . In one embodiment, the cobalt oxide is Co ₃ O ₄ . Cobalt oxide typically comprises a mixture of cobalt atoms in the form of ^{Co 2+} and Co ^3+. Although not bound by any theory, this is believed to result in improved catalytic activity, especially in combination with the nanoforest structure in embodiments of the present invention.

In one embodiment, the nanoforest structure is oriented perpendicular to the surface of the support. In one embodiment, the nanoforest structure comprises a mesocrystal structure. In one embodiment, the nanoforest structure is composed of corn nodule pellets (CPs), banana clusters (BCs: banana clusters), thin sheets (LSs: lamina sheets) and multiple cantilever sheets (MCSs: multi-cells). , Or a morphological structure selected from a combination thereof. In one embodiment, the nanoforest structure comprises a morphological structure containing corn nodule pellets (CPs), optionally said CPs in the nanorod (NR) domain perpendicular to the longitudinal plane of the surface of the support. Oriented. In one embodiment, the nanoforest structure comprises a morphological structure containing banana clusters (BCs), optionally said BCs oriented perpendicular to the longitudinal plane of the surface of the support in the nanorod (NR) domain. doing. In one embodiment, the nanoforest structure comprises a morphological structure that includes thin sheets (LSs). In one embodiment, the nanoforest structure comprises a morphological structure that includes a plurality of cantilever sheets (MCSs). In one embodiment, CPs and / or BCs, and / or LSs, and / or MCSs are oriented perpendicular to the surface of the support. In one embodiment, the CPs are oriented perpendicular to the surface of the support. In one embodiment, the BCs are oriented perpendicular to the surface of the support. In one embodiment, the LSs are oriented perpendicular to the surface of the support. In one embodiment, the MCSs are oriented perpendicular to the surface of the support.

In one embodiment, the metal oxide catalyst has a Miller index of {111} / {112} and / or {112} / {111} and / or {110} / {001} and / or {001} / {110}. And / or includes crystals having an interface with {112}. In one embodiment, the metal oxide catalyst comprises a crystal having an interface having Miller indexes {111} / {112} and / or {112} / {111}. In one embodiment, the metal oxide catalyst comprises a crystal having an interface having Miller indexes {110} / {001} and / or {001} / {110}. In one embodiment, the metal oxide catalyst comprises crystals with facets having a Miller index of {112}. In one embodiment, the nanoforest structure comprises crystals. Although not bound by any theory, the provision of interfaces, such as {111} / {112} or {110} / {001}, has advantages over materials with only high index single crystal facets. It is thought to bring. For example, it is believed that interfacial facets produce better adsorption, binding and surface energy due to typical reactions in catalysts, as compared to similar materials with only high refractive index single crystal facets.

In one embodiment, the support comprises a carbon-containing substrate. In one embodiment, the carbon comprises graphite, graphene sheets (g—C), or carbon nanotubes (C-NTs). In one embodiment, carbon comprises g-C or C-NTs. In one embodiment, the carbon comprises g—C. In one embodiment, carbon comprises C-NTs. In one embodiment, the C-NTs are multi-walled carbon nanotubes (MWCNTs). In one embodiment, the metal oxide catalyst is deposited on the substrate.

In one embodiment, the support comprises a base comprising a metal foam, glassy carbon (GC), or a ceramic film (eg, alumina or titania film). In one embodiment, the support comprises a base containing metal foam or glassy carbon (GC). In one embodiment, the support comprises a base containing glassy carbon (GC). In one embodiment, the support comprises a base containing a foamed metal. In one embodiment, the foam metal comprises or consists of nickel foam or aluminum foam. In one embodiment, the foam metal comprises nickel foam. In one embodiment, the nickel foam is a 3D porous nickel foam (3D-PNi).

In one embodiment, the support comprises a substrate as defined herein deposited on a base as defined herein.

In one embodiment, the nanoforest structure is on the exposed surface of the electrode.

In one embodiment, the electrode has a surface area of more than ^{50 m 2 / g.} In one embodiment, the electrode has a surface area of more than ^{75 m 2} / g, eg, a surface area of more than ^{100 m 2 / g.}

In one aspect, the present invention provides a composition comprising a support and a metal oxide catalyst precursor, wherein the metal oxide catalyst precursor comprises a nanoforest structure. The composition may be a composition for use as an electrode precursor. For example, after the metal oxide catalyst precursor has been converted to a catalyst, the converted composition may be for use with electrodes.

In one embodiment, the metal oxide catalyst precursor is or comprises a hydrated metal oxide precursor. In one embodiment, the metal oxide catalyst precursor is a hydration transition metal oxide catalyst precursor. In one embodiment, the hydration transition metal oxide precursor is cobalt oxide (eg Co ₃ O ₄ and / or CoO), nickel oxide (eg NiO), manganese oxide (eg MnO ₂ ), or cadmium oxide. In one embodiment, the metal oxide catalyst precursor is a hydrated cobalt oxide. In one embodiment, the metal oxide catalyst precursor is of formula CoO (OH) _x (CO ₃ ) _0.5. It has 0.11H ₂ O (where x is selected from 1, 2 or 3 in the formula), or a mixture thereof.

In one embodiment, the nanoforest structure is oriented perpendicular to the surface of the support. In one embodiment, the nanoforest structure comprises a mesocrystal structure. In one embodiment, the nanoforest structure is composed of corn nodule pellets (CPs), banana clusters (BCs: banana clusters), thin sheets (LSs: lamina sheets) and multiple cantilever sheets (MCSs: multi-cells). , Or a morphological structure selected from a combination thereof. In one embodiment, the nanoforest structure comprises a morphological structure containing corn nodule pellets (CPs), optionally said CPs in the nanorod (NR) domain perpendicular to the longitudinal plane of the surface of the support. Oriented. In one embodiment, the nanoforest structure comprises a morphological structure containing banana clusters (BCs), optionally said BCs oriented perpendicular to the longitudinal plane of the surface of the support in the nanorod (NR) domain. doing. In one embodiment, the nanoforest structure comprises a morphological structure containing corn nodule pellets (CPs). In one embodiment, the nanoforest structure comprises a morphological structure that includes a plurality of cantilever sheets (MCSs). In one embodiment, CPs and / or BCs, and / or LSs, and / or MCSs are oriented perpendicular to the surface of the support. In one embodiment, the CPs are oriented perpendicular to the surface of the support. In one embodiment, the BCs are oriented perpendicular to the surface of the support. In one embodiment, the LSs are oriented perpendicular to the surface of the support. In one embodiment, the MCSs are oriented perpendicular to the surface of the support.

In one embodiment, the support comprises a carbon-containing substrate. In one embodiment, the carbon comprises graphene sheets (g—C), carbon nanotubes (C-NTs), graphite, carbon fibers, mesoporous carbon, or carbon nitride. In one embodiment, the carbon comprises graphene sheets (g—C), carbon nanotubes (C-NTs), graphite, carbon fibers, or mesoporous carbon. In one embodiment, the carbon comprises graphene sheets (g—C), carbon nanotubes (C-NTs), graphite, or carbon fibers. In one embodiment, the carbon comprises graphite, graphene sheets (g—C) or carbon nanotubes (C-NTs). In one embodiment, carbon comprises g-C or C-NTs. In one embodiment, the carbon comprises g—C. In one embodiment, carbon comprises C-NTs. In one embodiment, the C-NTs are multi-walled carbon nanotubes (MWCNTs). In one embodiment, the metal oxide catalyst is deposited on the substrate.

In one embodiment, the support comprises a base comprising a metal foam, glassy carbon (GC), or a ceramic film (eg, alumina or titania film). In one embodiment, the support comprises a base containing metal foam or glassy carbon (GC). In one embodiment, the support comprises a base containing glassy carbon (GC). In one embodiment, the support comprises a base containing a foamed metal. In one embodiment, the foam metal comprises or consists of nickel foam or aluminum foam. In one embodiment, the foam metal comprises nickel foam. In one embodiment, the nickel foam is a 3D porous nickel foam (3D-PNi).

In one embodiment, the support comprises a substrate as defined herein deposited on a substrate as defined herein.

In one embodiment, the nanoforest structure is on the exposed surface of the electrode.

In one embodiment, the composition has a surface area of greater than ^{50 m 2 / g.} In one embodiment, the electrode has a surface area of more than ^{75 m 2} / g, eg, a surface area of more than ^{100 m 2 / g.}

In one aspect, the invention provides a method of making an electrode. The method is a step of forming an aqueous solution containing cobalt (II) cation, urea or cyclic amide and carbon in the presence of an electrode base; a step of activating the solution; cobalt and carbon deposited on the electrode base. A step of advancing the reaction so that a composition containing and is formed; a step of isolating the composition from the solution; a step of calcining the composition to form an electrode containing a cobalt oxide catalyst.

In one embodiment, the cobalt (II) cation is provided by a salt. In one embodiment, the salt comprises cobalt chloride, cobalt nitrate, or a combination thereof. In one embodiment, the salt comprises cobalt chloride. In one embodiment, the salt comprises cobalt nitrate.

In one embodiment, the urea or cyclic amide is urea. In one embodiment, the urea or cyclic amide is a cyclic amide. In one embodiment, the cyclic amide is hexamethylenetetramine (HMT).

In one embodiment, carbon comprises graphene sheets (g—C), carbon nanotubes (C-NTs), graphite, carbon fibers, mesoporous carbon or carbon nitride. In one embodiment, the carbon comprises graphene sheets (g—C), carbon nanotubes (C-NTs), graphite, carbon fibers, or mesoporous carbon. In one embodiment, the carbon comprises graphite, graphene sheets (g—C) or carbon nanotubes (C-NTs). In one embodiment, the carbon comprises g-C or carbon nanotubes C-NTs. In one embodiment, the carbon comprises g—C. In one embodiment, the carbon comprises carbon nanotubes C-NTs. The C-NTs may be multi-walled carbon nanotubes (MWCNTs).

In one embodiment, the electrode base is, or comprises a metal foam, glassy carbon (GC), or ceramic film (eg, alumina or titania film). In one embodiment, the electrode base is, or comprises, metal foam or glassy carbon (GC). In one embodiment, the base is or comprises glassy carbon (GC). In one embodiment, the support is or comprises foamed metal. In one embodiment, the foam metal comprises or consists of nickel foam or aluminum foam. In one embodiment, the foam metal comprises or consists of nickel foam. In one embodiment, the nickel foam is a 3D porous nickel foam (3D-PNi).

In one embodiment, carbon provides a substrate for the deposition of cobalt (II) cations during the process of advancing the reaction. In one embodiment, the substrate is deposited on the electrode base during the process of advancing the reaction.

In one embodiment, the step of advancing the reaction comprises activating the solution.

In one embodiment, the steps of activating the solution and advancing the reaction are performed in a pressure vessel. In one embodiment, the steps of activating the solution and advancing the reaction are performed at a pressure higher than 1 atm (eg, at least 2 atm, 5 atm or 10 atm).

In one embodiment, the step of activating the solution comprises heating the solution, irradiating it with electromagnetic radiation (eg, UV, infrared, or microwave radiation), or sonicating it. In one embodiment, the step of activating the solution comprises heating the solution to a temperature selected from at least 80 ° C, at least 100 ° C, at least 120 ° C and at least 140 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range of 100-200 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range of 120-180 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range 130-170 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range 140-160 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range of 150 ° C. (eg, 145-155 ° C.).

In one embodiment, the step of advancing the reaction comprises a time of at least 1 hour. In one embodiment, the step of advancing the reaction comprises a time of at least 4 hours. In one embodiment, the step of advancing the reaction comprises a time of at least 8 hours. In one embodiment, the step of advancing the reaction comprises a time of 1 to 36 hours. In one embodiment, the step of advancing the reaction comprises a time of 4 to 36 hours. In one embodiment, the step of advancing the reaction comprises a time of 8 to 24 hours.

In one embodiment, the composition comprises a hydrated cobalt oxide. In one embodiment, the hydrated cobalt oxide is of formula Co (OH) _x (CO ₃ ) _0.5. It has 0.11H ₂ O (where x is selected from 1, 2 or 3 in the formula), or a mixture thereof.

In one embodiment, the hydrated cobalt oxide comprises a nanoforest structure. In one embodiment, the nanoforest structure is oriented perpendicular to the surface of the support. In one embodiment, the nanoforest structure comprises a mesocrystal structure. In one embodiment, the nanoforest structure is composed of corn nodule pellets (CPs), banana clusters (BCs: banana clusters), thin sheets (LSs: lamina sheets) and multiple cantilever sheets (MCSs: multi-cells). , Or a morphological structure selected from a combination thereof. In one embodiment, the nanoforest structure comprises a morphological structure containing corn nodule pellets (CPs), optionally said CPs in the nanorod (NR) domain perpendicular to the longitudinal plane of the surface of the electrode base. Oriented. In one embodiment, the nanoforest structure comprises a morphological structure containing banana clusters (BCs), optionally said that the BCs are perpendicular to the longitudinal plane of the surface of the electrode base in the nanorod (NR) domain. Oriented. In one embodiment, the nanoforest structure comprises a morphological structure containing corn nodule pellets (CPs). In one embodiment, the nanoforest structure comprises a morphological structure that includes a plurality of cantilever sheets (MCSs). In one embodiment, CPs and / or BCs, and / or LSs, and / or MCSs are oriented perpendicular to the surface of the electrode base. In one embodiment, the CPs are oriented perpendicular to the surface of the electrode base. In one embodiment, the BCs are oriented perpendicular to the surface of the electrode base. In one embodiment, the LSs are oriented perpendicular to the surface of the electrode base. In one embodiment, the MCSs are oriented perpendicular to the surface of the electrode base.

In one embodiment, the composition is washed with at least one solvent between the isolation step and the calcination step. In one embodiment, washing involves washing sequentially with at least two solvents. In one embodiment, one solvent or multiple solvents (eg, two, three or four solvents) are selected from water and water miscible solvents. In one embodiment, the water-miscible solvent comprises water and a water-miscible organic solvent. In one embodiment, the water-miscible solvent comprises less than 5% water, eg, less than 2% water. In one embodiment, the water-miscible solvent is selected from methanol, ethanol and isopropanol, or mixtures thereof. In one embodiment, the water-miscible solvent is ethanol (eg, absolute ethanol).

In one embodiment, the isolated composition is dried prior to the firing step.

In one embodiment, the firing step involves heating the composition to at least 200 ° C. In one embodiment, the firing step comprises heating the composition to at least 300 ° C. In one embodiment, the firing step comprises heating the composition to at least 350 ° C. In one embodiment, the firing step comprises heating the composition to a temperature of 500 ° C. or lower. In one embodiment, the firing step involves heating the composition to a temperature of 200-500 ° C. In one embodiment, the firing step comprises heating the composition to a temperature of 300-500 ° C. (eg, a temperature of 350-450 ° C.).

Another aspect of the invention provides a method of making an electrode precursor. The method is a step of forming an aqueous solution containing a cobalt (II) cation, urea or a cyclic amide and carbon in the presence of an electrode base; a step of activating the solution; cobalt and carbon deposited on the electrode base. Including a step of advancing the reaction so that a composition containing and is formed. The method comprises optionally isolating the composition from the solution.

In one embodiment, the cobalt (II) cation is provided by a salt. In one embodiment, the salt comprises cobalt chloride, cobalt nitrate, or a combination thereof. In one embodiment, the salt comprises cobalt chloride. In one embodiment, the salt comprises cobalt nitrate.

In one embodiment, the urea or cyclic amide is urea. In one embodiment, the urea or cyclic amide is a cyclic amide. In one embodiment, the cyclic amide is hexamethylenetetramine (HMT).

In one embodiment, carbon comprises graphene sheets (g—C), carbon nanotubes (C-NTs), graphite, carbon fibers, mesoporous carbon or carbon nitride. In one embodiment, the carbon comprises graphite, graphene sheets (g—C) or carbon nanotubes (C-NTs). In one embodiment, the carbon comprises g-C or carbon nanotubes C-NTs. In one embodiment, the carbon comprises g—C. In one embodiment, the carbon comprises carbon nanotubes C-NTs. The C-NTs may be multi-walled carbon nanotubes (MWCNTs).

In one embodiment, the electrode base is, or comprises a metal foam, glassy carbon (GC), or ceramic film (eg, alumina or titania film). In one embodiment, the electrode base is, or comprises, metal foam or glassy carbon (GC). In one embodiment, the base is or comprises glassy carbon (GC). In one embodiment, the support is or comprises foamed metal. In one embodiment, the foam metal comprises or consists of nickel foam or aluminum foam. In one embodiment, the foam metal comprises or consists of nickel foam. In one embodiment, the nickel foam is a 3D porous nickel foam (3D-PNi).

In one embodiment, carbon provides a substrate for the deposition of cobalt (II) cations during the process of advancing the reaction. In one embodiment, the substrate is deposited on the electrode base during the process of advancing the reaction.

In one embodiment, the step of advancing the reaction comprises activating the solution.

In one embodiment, the steps of activating the solution and advancing the reaction are performed in a pressure vessel. In one embodiment, the steps of activating the solution and advancing the reaction are performed at a pressure higher than 1 atm (eg, at least 2 atm, 5 atm or 10 atm).

In one embodiment, the step of activating the solution comprises heating the solution, irradiating it with electromagnetic radiation (eg, UV, infrared, or microwave radiation), or sonicating it. In one embodiment, the step of activating the solution comprises heating the solution to a temperature selected from at least 80 ° C, at least 100 ° C, at least 120 ° C and at least 140 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range of 100-200 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range of 120-180 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range 130-170 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range 140-160 ° C. In one embodiment, the step of activating the solution comprises heating the solution to a temperature in the range of 150 ° C. (eg, 145-155 ° C.).

In one embodiment, the step of advancing the reaction comprises a time of at least 1 hour. In one embodiment, the step of advancing the reaction comprises a time of at least 4 hours. In one embodiment, the step of advancing the reaction comprises a time of at least 8 hours. In one embodiment, the step of advancing the reaction comprises a time of 1 to 36 hours. In one embodiment, the step of advancing the reaction comprises a time of 4 to 36 hours. In one embodiment, the step of advancing the reaction comprises a time of 8 to 24 hours.

In one embodiment, the composition comprises a hydrated cobalt oxide. In one embodiment, the hydrated cobalt oxide is of formula Co (OH) _x (CO ₃ ) _0.5. It has 0.11H ₂ O (where x is selected from 1, 2 or 3 in the formula), or a mixture thereof.

In one embodiment, the hydrated cobalt oxide comprises a nanoforest structure. In one embodiment, the nanoforest structure is oriented perpendicular to the surface of the support. In one embodiment, the nanoforest structure comprises a mesocrystal structure. In one embodiment, the nanoforest structure is composed of corn nodule pellets (CPs), banana clusters (BCs: banana clusters), thin sheets (LSs: lamina sheets) and multiple cantilever sheets (MCSs: multi-cells). , Or a morphological structure selected from a combination thereof. In one embodiment, the nanoforest structure comprises a morphological structure containing corn nodule pellets (CPs), optionally said CPs in the nanorod (NR) domain perpendicular to the longitudinal plane of the surface of the electrode base. Oriented. In one embodiment, the nanoforest structure comprises a morphological structure containing banana clusters (BCs), optionally said that the BCs are perpendicular to the longitudinal plane of the surface of the electrode base in the nanorod (NR) domain. Oriented. In one embodiment, the nanoforest structure comprises a morphological structure containing corn nodule pellets (CPs). In one embodiment, the nanoforest structure comprises a morphological structure that includes a plurality of cantilever sheets (MCSs). In one embodiment, CPs and / or BCs, and / or LSs, and / or MCSs are oriented perpendicular to the surface of the electrode base. In one embodiment, the CPs are oriented perpendicular to the surface of the electrode base. In one embodiment, the BCs are oriented perpendicular to the surface of the electrode base. In one embodiment, the LSs are oriented perpendicular to the surface of the electrode base. In one embodiment, the MCSs are oriented perpendicular to the surface of the electrode base.

In one embodiment, the composition is washed with at least one solvent between the isolation step and the calcination step. In one embodiment, washing involves washing sequentially with at least two solvents. In one embodiment, one solvent or multiple solvents (eg, two, three or four solvents) are selected from water and water miscible solvents. In one embodiment, the water-miscible solvent comprises water and a water-miscible organic solvent. In one embodiment, the water-miscible solvent comprises less than 5% water, eg, less than 2% water. In one embodiment, the water-miscible solvent is selected from methanol, ethanol and isopropanol, or mixtures thereof. In one embodiment, the water-miscible solvent is ethanol (eg, absolute ethanol).

One aspect of the present invention provides an electrode precursor obtained by the method of the present invention. Another aspect of the invention provides an electrode precursor obtained by the method of the invention.

One aspect of the present invention provides an electrode obtained by the method of the present invention. Another aspect of the invention provides an electrode obtained by the method of the invention.

One aspect of the present invention provides a fuel cell comprising the electrodes of the present invention. In one embodiment, the fuel cell anode comprises the electrodes of the present invention.

Another aspect of the invention provides a vehicle comprising the fuel cell or electrodes of the invention.

One aspect of the invention provides the use of the electrodes of the invention in fuel cells. In one embodiment, the present use comprises using the electrode as an anode electrode. In one embodiment, the present use includes the use of the electrode as an anode electrode of the electrode in an ethanol electrolytic oxidation reaction.

Embodiments of the present invention will be further described below with reference to the accompanying drawings.

FIG. 1 shows a schematic flow chart illustrating the formation of corn nodule pellets or banana clusters. The carbon nanotubes (300) undergo surface activation (301) to become functionalized CNTs (302) having hydroxyl functional groups on the surface. Further reaction of (303) the result of CoCl ₂ · 6H ₂ O and urea, H. T. It results in crystals (304) of longitudinal axis growth. The reaction of (304) with high-concentration urea (305) or the reaction with low-concentration urea (306) gives C / Co ₃ O ₄ nanorods (307). When (307) obtained via the pathway (305) is heated to 400 ° C. (308), corn nodule pellets (310) are obtained. When (307) obtained via the route (306) is heated to 400 ° C. (309), banana clusters (311) are obtained.

FIG. 2 shows a more detailed flow chart of the procedure, and the right side of the figure includes micrographs showing CPs, BCs, LSs and MCSs (from top to bottom).

3 (AG) are low and high magnification top views of the _{hierarchically controlled original Co 3} O ₄ nanostructures vertically aligned on the 3D-PNi foam along the longitudinal axis. The SEM image is shown. (A-C) is a _Co 3 _O 4 4 CPs SEM image showing the internal structure of the _Co 3 _{O 4} high-density particulate unit blocks meso crystals forming the CP nanorod structure. _{(D, E) are SEM micrographs of Co 3} O ₄ BCs that resemble giant bamboos that exist throughout the NR column, and the inset shows the construction of a sharp edge NR structure along a longitudinal scale. Shown. (F, D) is _{an SEM image of Co 3} O ₄ MCSs, and shows a multi-peripheral sheet assembly of MCSs preferentially arranged in the axial direction with respect to the PNi substrate.

FIGS. 4 (A to H) show _{the dense aggregation of particle unit blocks of Co 3} O ₄ or CoO mesocrystals and the attachment of components to the c-axis functional core along the longitudinal direction. _{This aggregation produces a unique molecular carbon / Co 3} O ₄ or CoO structure of CPs synthesized perpendicular to the underlying 3D-PNi substrate. (AE) is an SEM image of C-NT or g-C / Co ₃ O ₄ CPs / 3D-PNi, constructed with a core diameter slightly reduced from the upper root along the C-axis arch. The cylindrical roller size of the NR obtained is shown. (FI) is an SEM image of C-NT / CoO CPs / 3D-PNi, which is a specific arrangement of pellets with continuous ribs and vertically protruding while creating a hierarchical assembly within the NR structure. Is shown. Importantly, the addition of C-NT and g-C counterpart supports _{did not affect the stable molecular level morphology of Co 3} O ₄ or CoO, but reduced the thickness of NR and NS sizes. I let you.

FIG. 5 (A-a-A-c, B-a-B-c, C-a, D-a-D-b) shows a hierarchy prepared along the longitudinal axis via a one-pot hydrothermal method. The low-magnification and high-magnification FE-SEM micrographs of the top view of the C-NT or gC / Co ₃ O _{4 / 3D-PNi electrode are shown.} The image shows the scalability of the composite route. (A-a to AC) are _{low-magnification and high-magnification scanning electron microscope (SEM) magnifications of the C-NT / Co 3} O ₄ BCs / 3D-PNi electrode, which are perpendicular to the 3D-PNi substrate. Shows the dense formation of nanoforests with multiple bamboos placed in. The low magnification FE-SEM image (A-c) clearly shows that the tip of BC-NR has a sharp edged ridge. (B-a to B-c) show SEM images in which _{C-NT / Co 3} O ₄ is incorporated into the NR structure by adhesion of _{Co 3} O _{4 NP along the longitudinal axis.} (Ca) is a low-magnification FE-SEM image of g-C / Co ₃ O ₄ LS / 3D-PNi and a low-magnification FE-SEM image of C-NT / Co ₃ O ₄ MCs / 3D-PNi. Each is shown. The image shows efficient surface control of the sheet structure along the longitudinal axis. The low magnification FE-SEM image of (CA) shows a thin sheet in which the curvature of each edge is in the direction of two concave shapes. In (D-a, D-b), MCSs induce a double helix flattened band in the opposite direction. The micrograph pattern shows a controlled structural form along the longitudinal axis of the NR and multiple cantilever and thin sheets oriented perpendicular to the 3D-PNi substrate.

6 (A to C, D a to D b, and E a to E b) show discrete surface points along the longitudinal axis in the C-NT direction synthesized by the one-pot hydrothermal method. Shows the evolution of the geometric features of _{the hierarchical C / Co 3} O ₄ MCS arranged axially around the axial stacking center in. (A to D) are _{SEM images of C-NT / Co 3} O ₄ MCSs / 3D-PNi electrodes, and a composite MCS structure having an inverse opal multilayer on a longitudinal scale oriented perpendicular to the 3D-PNi substrate. Shows the structural integration of the sheet into.

_{FIGS. 7 (A to E) show N 2} absorption / desorption isotherms of the calcined sample showing texture properties including specific surface area and pore size distribution measured at 77K. (A) C-NT / Co ₃ O ₄ CPs, (B) C-NT / Co ₃ O ₄ MCSs, (C) gC / Co ₃ O ₄ LSs, (D) C-NT / Co ₃ O ₄ BCs ( E) C-NT / CoO CPs, and (F) the original Co ₃ O ₄ CPs. _{The specific surface area (S, BET} ) of the sample in the liner portion of the relevant absorption loop was collected. Inserted (a to f) represent the corresponding pore size distribution analyzed using the NLDFT theory from _{N 2 adsorption / desorption hysteresis.}

8A-8C show data showing the vertical orientation of CP-NR, BC-NR, LSs or MCS mesocrystal structures.

FIG. 9 (A-ad, B-B-B-d, C-a-C-d) shows a FIB setup showing sample preparation by FIB survey prior to characterization by HAADF-STEM. (A-A-D) are low-magnification cross-sectional FESEM images showing the stages of sample manipulation by the FIB system with different electron beams. (B-a to B-d, C-a to C-d) are microtomed g-C / Co ₃ O ₄ LSs and C-NT / Co by etching the sample in the direction parallel to the longitudinal axis. It is a schematic diagram of each SEM of ₃ O _{4 BCs and the corresponding schematic.} The lower image is a related HAADF-STEM (bright / dark) image of _{the microtomed Co 3} O ₄ / g-C LSs sample and the C-NT / Co ₃ O _{4 BCs sample.}

FIG. 10 shows scanning / transmission electron micrographs of CPs, LSs, MCSs and BCs and the corresponding energy dispersive X-ray spectroscopy mappings.

FIG. 11 shows low-resolution and high-resolution HAADF-STEM micrographs of _{the hierarchical C-NT / Co 3} O ₄ BCs / 3D-PNi substrate observed along the {001} plane in (A to D). The corresponding electron diffraction is shown. (A, B) are low resolution HAADF-STEM micrographs at different locations showing the geometry of NR and its surface structure, and insets (B-a, B-b) were designed. Represents a high magnification at the tip of the NR. (C to E) are HR-HAADF STEMs along {001}, showing multi-step terrace topography and anisotropic projections with numerous ridges and cavities on the surface edge.

FIG. 12 shows the results obtained for the electrodes of the present disclosure _{having a C-NT or g-C / Co 3} O ₄ or CoO / 3D-PNi or glassy carbon structure used as an anode electrode in the ethanol electrolytic oxidation reaction. Is shown.

FIG. 13 (A, B) shows the CV of an exemplary electrode recorded in 0.5 M NaOH at a scanning rate of ^{50 mV · sec-1 at room temperature.} (A) CV response of a bare 3D-PNi electrode in the absence and presence of ethanol. (B) _{CV profile of the Co 3} O ₄ / 3D-PNi electrode in the absence of ethanol.

14 (A to C) show the effect of scanning speed on the behavior of _{exemplary C-NT / Co 3} O _{4 CPs / 3D-PNi electrodes. (A) CV response of C-NT / Co 3} O ₄ CPs / 3D-PNi electrodes recorded in 0.5 M NaOH at different scan rates of 20-200 mV · sec- ^{1 at room temperature.} (B) Plot of peak current for scanning speed (B) applied at 20-50 mV · sec- ¹ ; (C) Plot of peak current for scanning speed (C) applied at ^{70-200 mV · sec-1.}

FIGS. 15 (A to D) show exemplary carbon / Co ₃ O _{4 in 0.5 M NaOH and N 2} saturated electrolyte in the absence or presence of ethanol at a scanning rate of ^{50 mV · sec-1.} Alternatively, the electrochemical evaluation of the CoO / GC electrode is shown. CV profiles were recorded in the absence (A) and presence (B) of 0.5 M ethanol. (C) Current-time relationship of 18,000 seconds for _{carbon / Co 3} O _{4 or CoO / GC electrodes in 0.5 M ethanol. (D) Relative current of the g-C or C / Co 3} O ₄ or CoO / GC electrode as a function of the initial current at the start of the CA test. In addition, a, b, c, d, e and f are C-NT / Co ₃ O ₄ CPs / GC, g-C / Co ₃ O ₄ LSs / GC, C-NT / Co ₃ O ₄ MCSs / GC. , Commercially available Pt / C electrodes, C-NT / Co ₃ O ₄ BCs / GC, and C-NT / CoO CPs / GC electrodes.

FIGS. 16 (A to D) show exemplary C-NT / Co ₃ O ₄ CPs / GC electrodes and C-NT / Co ₃ O ₄ CPs / 3D-PNi recorded in 0.5 M NaOH at room temperature. The CV curve of the electrode is shown. _{(A) CV of the C-NT / Co 3} O ₄ CPs / GC electrode and the C-NT / Co ₃ O ₄ CPs / 3D-PNi electrode in the absence of ethanol at a scanning rate of 50 mV · sec- ^1. _{(B) Expanded CV spectrum of C-NT / Co 3} O ₄ CPs / GC in the absence of ethanol at a scanning rate of 50 mV · sec- ^1. (C) C-NT / Co ₃ O ₄ CPs / GC electrodes and C-NT / Co ₃ O ₄ CPs / _{in the presence of 0.5 M C 2} H ₅ OH at a scanning rate of ^{50 mV · -1.} CV of 3D-PNi electrode. (D) High resolution CV spectrum of C-NT / Co ₃ O4 CPs / GC electrodes _{in the presence of 0.5 M C 2} H _{5 OH.}

FIGS. 17 (A to E) _{show the CVs of exemplary C-NT / Co 3} O ₄ CPs / GC modified electrodes recorded in 0.5 M NaOH at room temperature. _{(A) C-NT / Co 3} O ₄ CPs and bare Co ₃ O ₄ CPs / GC-based electrodes collected in 0.5 M NaOH solution after sweeping 100 times at a scanning speed of 50 mV · sec- ^1. CV. _{(B) CV plots of C-NT / Co 3} O ₄ CPs / GC electrodes recorded in 0.5 M NaOH at various scan rates. (C) Effect of ethanol concentration on the CV response of the C-NT / Co ₃ O ₄ CPs / GC electrode at a scanning speed of 50 mV · sec- ^1. (D) CV behavior at different scanning speeds measured in 0.5 M NaOH.

_{FIG. 18 shows the CV of an exemplary C-NT / Co 3} O ₄ CPs / 3D-PNi electrode recorded in 0.5 M NaOH at room temperature. (A) CV recorded at various concentrations of ethanol (0.05-0.5 M) and ^{scanning speeds of 50 mV · sec-1.} (B) Relationship between ethanol concentration and corresponding current density measured at the end of anode scanning. (C) C-NT / Co ₃ O ₄ CPs / 3D-PNi electrodes ^{at different scanning rates of 10 to 200 mV · sec-1} obtained in 0.5 M NaOH containing 0.5 M ethanol. CV response. (D) Plot of catalytic currents (Ia, Ic measured at the end of forward scan and at the peak of the cathode) against the square root of the applied scan rate. (E) Ia / Ic plot for the applied scan rate. _{(F) C-NT / Co 3} O ₄ CPs / 3D-PNi electrodes collected in 0.5 M NaOH and 0.5 M ethanol after a continuous potential cycle at a sweep rate of 50 mV · sec- ^1. CV curve.

FIGS. 19 (A to D) _{show a CA analysis of exemplary C-NT / Co 3} O ₄ CPs / 3D-PNi electrodes evaluated in 0.5 M NaOH solution. _{(A) Current-time spectrum of C-NT / Co 3} O ₄ CPs / 3D-PNi electrodes collected in the absence of ethanol with a constant applied potential of 0.67 V vs. Hg / HgO for 1800 seconds. (B) The relationship between (IC / IL) and the square root is measured from the date of CA (Fig. 3C-a). (C) Dependence of catalytic current (IC current in the presence of ethanol) on the reciprocal of the square root of time measured from the date of CA (FIG. 3C-a). (D) Dependence of critical current (IL current in the absence of ethanol) on the reciprocal of the square root of time measured from CA data (A).

FIG. 20 (AD) shows the dependence of the catalytic current (IC) of the exemplarily applied electrode on the reciprocal of the square root of time measured from the CA data (FIGS. 10C, curves b-e). (A) g-C / Co ₃ O ₄ LSs / 3D-PNi electrode, (B) C-NT / Co ₃ O ₄ MCSs / 3D-PNi electrode, (C) C-NT / Co ₃ O ₄ BCs / 3D -PNi electrode and (D) C-NT / Co ₃ O ₄ CPs / 3D-PNi electrode.

FIG. 21 (AH) shows the HAADF-STEM of the C-NT / Co ₃ O ₄ BCs / 3D-PNi electrode and the C-NT / Co ₃ O _{4 CPs / 3D-PNi electrode after multiple reuse cycles.} The image is shown. This image shows that the designed morphology of both self-supporting electrodes is well preserved. In (A to C), _{HAADF-STEM micrographs of C-NT / Co 3} O ₄ BCs / 3D-PNi measured along the {001} plane show the structure after the stability test for 18,000 seconds. There is. In (A, B), STEM micrographs show the surface morphology of NR at different locations. In (C), the HR-HAADF-STEM image shows that the atomic structure is {001}. (DG) shows HAADF-STEM of a single NR of C-NT / Co ₃ O ₄ CPs / 3D-PNi electrode, and (D) shows the middle part after a long-term stability test of 5000 cycles. The obtained one (E) shows the one obtained at the top after a long-term stability test of 5000 cycles. (F, G) are HR-HAADF-STEM obtained after the stability test, and (F) is obtained along {112}, {112}, and {111} / {112}. The one (G) obtained in the interface plane is shown. Inset (D) shows a single low-orientation polyhedron with a low index of refraction surface and a high index of refraction surface of the C-NT / Co ₃ O _{4 CPs / 3D-PNi electrode.} These single crystal polyhedral CPs are predominantly low index single crystals (ie, eight hexagonal {111} planes, and six and twelve octagonal {100} and {110} planes) and high. It contained different orientation types: single crystals of refractive index (ie, 24 squares) and interface {111} / {112} planes.

FIG. 22 shows a simulation of the hierarchical nanoforest catalyst structure of the present disclosure.

FIG. 23 shows additional simulation data for the catalyst structure of the present disclosure.

FIG. 24 (A to F) show a schematic view of _{the C-NT / Co 3} O _{4 CP crystal plane.} (A) shows a simulation model of _{C-Co 3} O _{4 CPs.} (B to E) show parallel projections along the crystal planes, and the crystal planes are {111} (B), {110} (C), {112} (D), {112} (E), { 001} (F).

FIG. 25 reveals the thermal events that have occurred, Co (OH) _x (CO ₃ ) _{0 . 5} 0.11H _{2 The} TG-DTA curve measured for the OCP hierarchical structure is shown. These curves show the total weight loss of the target sample during the heat treatment.

FIG. 26 (A, B) shows WA-XRD of synthesized and calcined samples assigned according to the database of the International Center for Diffraction Data provided by Bruker. (A) is _{an XRD pattern of Co (OH) x} (CO ₃ ) _0.5 0.11H ₂ O / carbon orthorhombic cobalt basic carbonate phase of the designed surface structure, and is the surface structure. Are CPs (a), BCs (b), MCSs (c), and LSs (d). (E) is a linear cobalt basic carbonate phase of bare Co (OH) _x (CO ₃ ) _0.5 0.11H _{2 O CPs.} (B) is a morphological structure, a XRD spectrum of the final product Fd3mC-NT or _gC-Co 3 _{O 4} and Fm3mC-NT / CoO face-centered cubic phase of the morphological structure, CPs ( a), BCs (b), MCSs (c), and LSs (d). (E) is _{a spectrum of bare Co 3} O ₄ CPs, and (f) is a spectrum of C-NT / CoO CPs.

27 (A to E) show the chemical composition and composition of the survey sample measured by XPS and Raman analysis. (A) is a complete examination of the XPS spectra of C-NT / Co ₃ O ₄ CPs, indicating the presence of peaks specific to O1s, C1s, and Co2p. (B) is a high resolution of the Co2p peak and is decomposed into two characteristic peaks having an energy difference of 15.0 eV. (C) is a high resolution C1s scan, which is decomposed into three promising peaks. (D) is a high-resolution O1s peak, which is decomposed into three peaks. (E) is a Raman spectroscopy survey of the sample measured with a laser beam of 633 nm.

Applicants simply have their own nanoscale shapes (sheets, cubes, rods, belts, etc.) and surfaces that are predominantly exposed in {111}, {100}, {110}, and {112} planes. We have endeavored to develop crystalline cobalt (II, III) structure and oxidized Co ₃ O _{4 structure.} For example, a cubic, dense structure of spinel Co ₃ O ₄ ^{mesocrystals consisting of Co 3+} and Co ²⁺ ions that occupy octahedral and tetrahedral coordination sites plays an important role in the high catalytic performance of the material. In particular, the exposed {110} plane of _{Co 3} O ₄ NCs oxidizes carbon monoxide more than the {100} plane and {111} plane due to the presence ^{of abundant Co 3+ active sites in the {110} plane.} It is more catalytically active against. The exposed surface of Co ₃ O ₄ NCs has oxygen reducing activity in the order of {111}> {100} >> {110}, which is consistent with the density ^{of highly exposed Co 2+ active sites in each plane.} Furthermore, _{the high surface energy {112} facets of Co 3} O ₄ NCs have been shown to function better during methane combustion than the {001} and {011} planes.

Throughout the description and claims of the present specification, the terms "comprise" and "contain" and their variations are meant to mean "including but not limited to". , Other parts, additives, ingredients, integers or steps are not meant to be excluded (not excluded). Throughout the description and claims of the present specification, the singular form includes the plural form unless the context requires otherwise. In particular, when indefinite articles are used, the specification should be understood to consider plurals and unity, unless otherwise required in the context.

Features, integers, properties, compounds, chemical parts or groups described in connection with a particular aspect, embodiment or embodiment of the invention are other described herein unless incompatible with them. It is understood that it is applicable to aspects, embodiments or examples. All features disclosed herein, including the appended claims, abstracts and drawings, and / or all steps of such disclosed methods or processes are such features and /. Alternatively, any combination can be combined, except for combinations in which at least some of the steps are mutually exclusive. The present invention is not limited to the details of the embodiments described above. The present invention spans or discloses any novel or any novel combination of features disclosed herein, including the appended claims, abstracts and drawings. It extends to any novel or any novel combination of steps of any method or process made.

The reader's interest is directed to all treatises and documents submitted at the same time as or prior to this specification in connection with this application and made publicly available herein, all such. The contents of these treatises and documents are incorporated herein by reference.

<Definition>
As used herein, the term "C-NT" refers to carbon nanotubes. The carbon nanotubes may be single-walled carbon nanotubes or multi-walled carbon nanotubes (MWCNTs), for example, MWCNTs. C-NT may be oxidized, for example, C-NT may be oxidized MWCNT. C-NT represents a suitable substrate material for the electrode support material of the present disclosure.

As used herein, the term "exposed surface" refers to the surface of a solid or similar material that can be used to interact with a gas or solution. For example, in the electrodes of the present disclosure, the exposed surface represents a portion of the electrode having a surface capable of interacting with a redox reaction reactant. It can include pores accessible to the reactants.

As used herein, the term "g-C" refers to a graphene sheet. The graphene sheet may be in the form of graphene oxide. g—C represents a suitable substrate material for the electrode support material of the present disclosure.

As used herein, the term "HMT" means the compound hexamethylenetetramine.

The following terms are used herein with respect to electron microscopy: "High Angle Annular Dark Field Scanning Electron Microscopy System (HAADF-STEM)", "STEM Energy Dispersive X-ray Spectroscopy" (STEM-EDS) Mapping Analysis. system.

As used herein, the term "Miller index" refers to a standard system of notation used to define planes within a crystal lattice. The Miller index of the equivalent plane of the crystal form is represented by the {hkl} plane. An exemplary Miller index includes {110}, {001}, {111} and {112} planes. If the crystal contains surface features that include interfaces or boundaries between planes with different Miller index {h ₁ k ₁ l ₁ } planes and {h ₂ k ₂ l _{2} planes, the interface planes are as follows: , {H 1} k ₁ l ₁ } / {h ₂ k ₂ l ₂ } may be indicated by using the slash “/” as follows. An exemplary interface plane (also called an interface) includes {111} / {112}, {112} / {111}, {110} / {001} and {001} / {100}.

As used herein, the term "PNi" refers to porous nickel foam. PNi is typically represented as a three-dimensional material, 3D-PNi. PNi (and 3D-PNi) represents a suitable substrate for the electrode support material of the present disclosure.

As used herein, the terms corn nodule pellets (CP or CPs), banana clusters (BC or BCs), thin sheets (LS or LSs) and multiple cantilever sheets (MCS or MCSs) are for metal oxide catalysts. Refers to surface morphology or morphological structure. CPs may be oriented in the nanorod (NR) domain called CP-NR. BCs may be oriented in the NR domain called BC-NR. The surface morphology or morphological structure may have a surface morphology oriented vertically from the support or the substrate below it. The CP (eg CP-NR), BC (eg BC-NR), LS or MCS surface morphology may be mesocrystalline morphology.

The term "mesocrystal" refers to nanostructured materials with long-range order defined on the atomic scale. This can be inferred, for example, from the presence of an essentially sharp wide-angle diffraction pattern (with sharp Bragg peaks) and clear evidence that the material consists of individual nanoparticle building blocks (eg, by electron microscopy). Can be done. Mesocrystals have high porosity and can provide a high surface area. Mesocrystals may represent more stable analogs of similar nanoparticle materials. This high surface area and / or better stability can provide advantageous catalytic properties when mesocrystals or mesocrystal structures are used to form the catalytic portion of the electrode (eg, used in fuel cells). For electrodes). For example, the high surface area of the mesocrystal structure can provide a reaction region with relatively high current and / or lower resistance. For example, the better stability provided by the mesocrystal structure can lead to longer electrode life.

<Catalyst mesocrystal structure and electrodes>
The electrodes of the present invention can include _{Co 3} O _{4 mesocrystals.}

To assess the surface-dependent properties of _{Co 3} O ₄ mesocrystals with respect to high-energy surfaces and the density of exposed facets associated with low- and high-refractive-index single planes and interface planes is ethanol electrolytic oxidation. It is important when considering their use in. The scalable and low-cost direct growth of uniform nanostructures containing multi-component complexes along the longitudinal axis of the conductive substrate provides improved conductivity, better structural stability and flexibility, excellent electrons. It may provide synergistic and competitive advantages over currently used electrodes in terms of collection efficiency and abundance of electrically active sites.

One embodiment of the present invention provides a method of making the electrodes of the present invention.

An object of the present invention is _{to provide Co 3} O ₄ mesocrystals having the following structural features: (1) Dense aggregation and composition of _{Co 3} O ₄ CP-NRs and Co ₃ O _{4 BC-NRs.} An attachment of elements that has a dense CP-NRs or BC-NRs axis band along the longitudinal axis around the central focal point, thereby containing a giant bamboo tree-like structure in the nano. A forest is formed; (2) the size of CP-NRs and BC-NRs in the bamboo decreases as the distance from the central focal point increases and becomes arched along the c-axis. , Forming a sharp, pointed, convex, needle-like NR structure with nanoscale windows running inward along the c-axis. This influential needle-shaped end top surface allowed rapid electron transport by maximizing the diffusion of trigger pulsed electrons during the catalytic reaction.

1 and 2 show Applicant's simple one-pot hydrothermal method for synthesizing self-supporting electrodes with novel morphological structures. The overall structure of the electrode was [carbon support / Co ₃ O ₄ or cobalt oxide (II) (CoO) / substrate]. Here, the carbon support was either a functionalized multi-walled carbon nanotube (C-NTs) or a graphene sheet (gC), and the substrate was a 3D porous Ni foam (3D-PNi). The technical advantages of the proposed method are its simplicity, scalability, and low cost operation. In addition, the proposed method is vertical from the substrate in the form of corn nodule pellets (CPs) or banana clusters (BCs), thin sheets (LSs), or multiple cantilever sheets (MCSs) oriented in the nanorod (NR) domain. _{It allows the synthesis of Co 3} O ₄ or CoO mesocrystal structures along a longitudinal plane with a directionally oriented surface morphology (FIGS. 3-6).

_{Co 3} O ₄ mesocrystals in the form of CP-NR, BC-NR, LS, or MCS were well dispersed internally and oriented vertically from the 3D-PNi support. Monodisperse particles were attached to a c-axis functional core on which new and smart CP, BC, LS, and MCS intermediate crystal morphologies were formed. Field emission scanning electron microscopy has revealed that the disclosed method provides mesocrystalline morphology with the following important structural features, as shown in FIGS. 3-6.
(1) _{Dense aggregation of Co 3} O ₄ CP-NRs and Co ₃ O ₄ BC-NRs and adhesion of components, CP-NRs or BCs densely packed around the central focal point along the longitudinal axis. It has a shaft band of −NRs, which forms a nanoforest containing a structure resembling a giant bamboo tree.
(2) The sizes of CP-NRs and BC-NRs in the "bamboo" decrease as the distance from the central focal point increases and become arched along the c-axis, thereby becoming the c-axis. It forms a sharp, pointed, convex, needle-like NR structure with nanoscale windows running along it. This influential needle-shaped end top surface allowed rapid electron transport by maximizing the diffusion of trigger pulsed electrons during the catalytic reaction.
(3) as indicated by the N ₂ isothermal profiling (see FIG. 7), the addition of a surfactant hexamethylenetetramine in the catalyst synthesis, facilitate the formation of a dense vertical thin layer assembly of LSs and MCSs, They have terminal non-laminated layers bounded by the micro, meso and macroscopic pores of the spacers. Therefore, the growth along the vertical axis of LSs and MCSs resulted from the directional growth along the longitudinal axis.
(4) By using g—C as the carbon support, LSs were discretely stacked at regular intervals (100 nm) or not stacked at all. This multi-layer LS structure along the longitudinal axis can contribute to the observed efficient catalytic activity as compared to that of a composite MCS structure with an inverse opal multi-layer.
(5) The use of C-NTs, cobalt (II) chloride (CoCl ₂ ), and hexamethylenetetramine favors the axial arrangement of flat double helix bands running in opposite directions and the longitudinal direction of the C-NT domain. It resulted in the fabrication of multiple cantilever sheets along the axis. Each individual flattened sheet exhibited dynamic flexibility in directional curvature in two concave directions along each edge (FIGS. 5 and 6).

The vertical orientation of CP-NR, BC-NR, LS or MCS mesocrystal structures along the longitudinal plane is an interesting topic for ethanol oxidation reactions. In order to investigate the internal concentric arrangement and orientation of the structural units of these structural forms, an experiment was conducted in which a sample was etched to a thickness of 100 nm parallel to the longitudinal axis using a focused ion beam milling device (FIGS. 8A to 8A). FIG. 8B). Focused ion beam systems for making thin samples include High Angle Annular Dark Field (HAADF) -Scanning / Transmission Electron Microscopy System (STEM) (FIGS. 8 and 9) and STEM Energy Dispersive X-ray Spectroscopy (EDS). It was integrated with the mapping analysis system (Fig. 8C).

8B-a-8B-d show the internal structure _{of the Co 3} O ₄ CP form at a depth of 100 nm and at different positions along the longitudinal axis of the NRs. The specific placement and surface heterogeneity of the pellets protruding on the surface of these maize nodules is readily located at the apex of the C-NT covered by a large number of oriented small nodules. The internal atomic arrangement of the nanoforest was also well dispersed in the longitudinal direction (STEM-EDS mapping, FIG. 8C). CPs on the Co ₃ O ₄ NR surface are ribbed and configured perpendicular to the grooves on the longitudinal axis (aligned parallel to the main direction of the NR mesocrystalline process) and are tubes for electron diffusion and transport. And created window space (ie, upward and downward movements; see FIGS. 8 and 9).

HAADF-STEM microscopy revealed morphology along the longitudinal axis of _{NRs (ie, C / Co 3} O ₄ CPs and C / Co ₃ O ₄ BCs) and morphology along the longitudinal axis of nanosheets (ie, C / Co ₃ O ₄ MCSs and g-C / Co ₃ O ₄ LSs) have been clarified (Fig. 3A). The individual CP domains showed prominent symmetrical variants with well-distributed atomic surface active sites (Fig. 10A-a). High-resolution HAADF-STEM microscopy of 50 nm particles revealed a proposal for a mesocrystal model of 50 faceted polyhedra (Fig. 10A-a, inset). The 50 faceted Co ₃ O ₄ CPs, like other poorly defined polyhedral mesocrystals, have several high indices, mainly along the low index {100} and {111} planes. It grew along the {112} plane and other bad facets of. Twenty-four exposed high-refractive index {112} planes grew axially around each of the {100} and {111} planes of the 50 faceted polyhedron. Increasing the number of high index planes with high surface energy and the number of longitudinally oriented polyhedron CPs within the NR form is important for improving the performance of the electrodes for ethanol oxidation.

Side view of Co ₃ O ₄ MCSs HAADF-STEM microscopy revealed a thin sheet that was flattened during reassembly and had a rough surface with pores aligned perpendicular to the longitudinal axis (Figure). 10A-b, c). HAADF-STEM microscopic examination of the top surface of Co ₃ O ₄ LSs revealed a series of unlaminated, well-aligned vertical thin sheets. The nanoscale (40-60 nm) edges of the thin sheet were located laterally along the longitudinal axis (FIGS. 10A-d, e). In fact _{, by HAADF-STEM microscopy of Co 3} O ₄ BCs, they have a structure constructed as a nanopattern of tunnel lines, dense particles, and a smooth surface on the surface of the one-dimensional NR and control boundary layer. It was revealed that it represents the visual structure of the banana clusters in (Fig. 10A-f, g).

{111} / {112} planes (FIGS. 10B-a, b) and influential {112} planes (FIG. 10B-c), {111} planes (FIGS. 10B-a, d), {112} planes (FIG. 10B). -E), with high-resolution HAADF-STEM micrographs (FIG. 10B) taken along the {110} / {001} planes (FIG. 10B-f) and {001} planes (FIG. 10B-f, g). Corresponding EDS patterns (FIG. 10B, inset) further revealed the structure of single crystals of _{Co 3} O _{4 CPs, LSs, MCSs, BCs. Preparation of Co (OH) x} (CO ₃ ) _{0.5 / 0.11H 2} O in the form of CP-NR, BC-NR, LS, or MCS Due to the growth of mesocrystals in the sample, mainly {001} Produced longitudinally aligned facets exposed along the surface. High temperature treatment of CP-NRs, BC-NRs, MCSs, and LSs can have a strong effect on atomic configuration and renuucleation in the structure, which is the persistence of atoms around the predominant {001} facets. Allowing relaxation, high surface energy {112}, {111} / {112} planes of CPs, MCSs, and LSs (FIGS. 10B-a-e) and {110} / {001} planes of BCs (FIGS. 10B-a-e). FIG. 10B-f, g) and can be produced.

Axial changes in the crystal planes along the {001} direction during processing _{are significant between the {112} and {111} planes of the Co 3} O ₄ CPs on the {111} / {112} interface plane. Brought about formation. Multi-step terrace topography on the ridges of the nanosheets formed {111} / {112} interface planes on the _{Co 3} O _{4 LSs and MCSs.} The dense structure of BCs was then generated on a smooth, flat, lamellar surface with tightly coupled and tightly packed basal edges (ie, adjacent boundaries) (FIG. 11). Protruding surfaces with multi-stage terrace topography forming hedge-saw islands with numerous ridges and cavities along their edges at a depth of 10 nm were also observed (FIGS. 10B-f, g). Such interfacial topography can create an open surface for the diffusion ^{of Co 3+} atoms into the pores of the crystal surface. ^{As a result, the Co 3+} -rich {111} / {112} interface surfaces and {110} / associated with the main topographic facet islands aligned along the {111}, {112}, and {001} planes. {001}) An interface plane can be formed. A continuous electron stream can then be generated parallel to the longitudinal axis of the nanoforest.

Using the catalytic electrochemical assay described herein, Applicants investigated the effect of the following parameters on ethanol electrolytic oxidation: (i) heterogeneous Co ²⁺ / Co ³⁺ site atom arrangement and orientation, (Ii) type of nanoforest form (CP-NR, BC-NR, LS, or MCS), (iii) mesocrystalline orientation with exposed high refractive electrode {112} planes, (iv) internal atomic scale {111 } / {112} Degree of exposure of interfacial block, (v) ^{growth along longitudinal axis to achieve high surface energy and high density Co 3+} site surface, (vi) presence of multidiffusive pore phase , (Vii) Electrode nanopattern design resulting from a combination of a conductive support (C-NT or g-C) and a substrate (4D-PNi or glass carbon, GC) (FIGS. 12-20).

In the ethanol electrolytic oxidation reaction, an electrode having a C-NT or g-C / Co ₃ O ₄ or CoO / 3D-PNi or a glassy carbon structure was used as an anode electrode (FIG. 12). In non-alcoholic assay, generated from a reversible reaction between all of the electrodes are produced from a reversible reaction between _Co 3 _{O 4} and cobalt hydroxide (CoOOH) (peak I and IV), and the CoOOH and CoO ₂ (Peak III and / II), two pairs of redox pairs were shown (Fig. 12A).

In the ethanol electrochemical assay, no anode peak was observed at any of the electrodes, indicating that oxygen generation overlapped with ethanol oxidation and oxygen was generated at a very positive potential of 0.6-0.9 V. (Fig. 12B). In the reverse scan, a cathode peak of 0.3-0.5 V was observed. This is primarily for the removal of carbonaceous species that are not completely oxidized by reverse scanning (carbon monoxide, carbon dioxide, mechanic acid, hydroxymethylene, methylmethanolate, etc.) and the chemical adsorption of unknown species on the electrodes. It was related (Fig. 12B).

Each electrode used in the assay has been proposed to promote absorption and electron transport of ethanol molecules to form an electrically active mediator CoOOH layer that forms the highly active species Co (IV). As shown in FIG. 12B, the increase in current density at 0.9V is C-NT / Co ₃ O ₄ CPs> g-C / Co ₃ O ₄ LSs> C-NT / Co ₃ O ₄ MCSs> C- Follow the order of NT / Co ₃ O ₄ BCs> C-NT / CoO CPs. The current density increased significantly with the addition of ethanol, indicating that the electrodes catalyzed the electrolytic oxidation of ethanol (FIGS. 12A, B and 15A, B). _{Further, a Co 3} O ₄ ^{mesocrystal having a tetrahedral Co 2+} site and an octahedral Co ³⁺ site that are catalytically active on the exposed high and low index planes is a catalytically active Co ^2+. It showed higher catalytic ethanol electrolytic oxidation activity than CoO mesocrystals with only moieties. Without being bound by any theory, surfaces containing both ^{Co 2+} and Co ³⁺ sites are believed to have higher catalytic activity than surfaces having only ^{Co 2+ sites.}

To further illustrate the superior electrochemical activity imparted by growing the C-NT or g-C / Co ₃ O _{4 catalyst directly on the 3D-PNi along the longitudinal axis, the C-NT or} An ethanol electrolytic oxidation reaction was carried out using a g-C / Co ₃ O ₄ 4 / GC electrode and a commercially available Pt / C electrode for comparison (FIGS. 15C and D). And commercial Pt / C electrode, C-NT or when compared with _{g-C / Co 3 O 4} / GC electrode performance, C-NT or g-C / _Co 3 _{O 4} having any form having CP form The performance of the / 3D-PNi or GC electrodes was also comparable to, or perhaps even better than, that of commercially available Pt / C electrodes in terms of current density and electrode stability (FIGS. 12C, D and 15C, D).

In order to evaluate the current density and stability of the developed electrode, the relationship between current and time was _{measured in 0.5 M ethanol using carbon / Co 3} O ₄ or CoO / 3D-PNi and Pt / C electrodes. It was evaluated by a 18,000 second chronoamperometry test (Fig. 12C). Slight attenuation of the current in C-NT or _{g-C / Co 3 O 4} / 3D-PNi electrode, compared with excellent current stability and poisoning C-NT / CoO / 3D- PNi and Pt / C electrode It showed resistance (FIGS. 4C, D and 15C, D). The relative current% at the end of the evaluation time (that is, t = 18,000 seconds) is C-NT / Co ₃ O ₄ CP> g-C / Co ₃ O ₄ LS> C-NT / Co ₃ O ₄ MCS. > C-NT / Co ₃ O ₄ BC> C-NT / CoO CP> Pt / C. This is consistent with changes in the electrode reaction rate (catalytic rate constant) and diffusion coefficient (Table 1). Different C-NT or g-C / _Co 3 _{O 4} electrodes, which from having C-NT or g-C / CoO electrode and Pt / C excellent catalytic activity than the electrode, along the longitudinal direction of the c-axis It was suggested that manipulation of the anisotropic C-NT or g-C / Co ₃ O ₄ morphology could allow the creation of improved catalytic structural features. Compared to the other electrodes examined, the exposed surfaces and interfaces of the high index of C-NT or g-C / Co ₃ O ₄ are oxygenated grooves through upstream vortices and multiple diffusion windows. It is believed to generate more efficient electron transfer to the attached electrode surface and the Co ^{3+ site.}

Measured energy of exposed facets and interface surfaces obtained by DFT modeling.

Optimizing the long-term stability, efficiency, and recyclability of electrodes used in direct ethanol fuel cells remains a challenge. In order to further evaluate the durability of the developed electrode, a series of experimental ethanol electrolytic oxidation reactions were _{carried out using C-NT / Co 3} O ₄ CP electrodes under a continuous potential cycle of 5000 cycles (Fig. 12E). .. The electrode retains about 68.7% of the original current density after multiple reuse cycles at 0.9V (≧ 5000 cycles), which is superior to other recently reported electrodes (Table 2). ). In particular, after more than 5000 cycles, the reusable electrodes of the present disclosure retain a highly reactive surface (FIG. 21) and retain 71.9% of the current density in the fresh electrolyte of the electrochemical assay. It is shown (Fig. 18). This result suggests that the electrodes of the present disclosure have significantly improved dead-end workability and recyclability as compared with other electrodes (see Table 2).

Oxidation current retained as a percentage of the original value after long-term stability evaluation for various electrode materials as compared to C-NT / Co ₃ O _{4 CPs / 3D-PNi electrodes.}

(Reference)
36. Li, G. , Lei, Q. , Ying, L. et al. , Yanyan, W. et al. , Jing, L. , Hongyan, Y. et al. , & Dan, X, "Microwave-assisted synthesis of nanosheet-like NiCo ₂ O ₄ cousing of for
37. Wei, W. et al. , "Nickel foam supported mesoporous NiCo ₂ O ₄ arrays with excelent mesoporous performance", New J. et al. Chem. (2015).
38. Ashok, K. , D. , Rama, K. et al. L. , Nam, H. et al. K. , Daeseng, J. et al. , & Joong, H.M. L. , "Redox graphene oxide (RGO) -supported NiCo ₂ O ₄ nanoparticles: an electrocatalyst for matrix oxide", Nanoscale 6,10657-10665 (2014).
39. Rui, D. , Li, Q. , Mingjun, J. et al. , & Hongyu, W. , "Sodium dodecyl sulphate-assisted hydrothermal synthesis of mesoporous nickel cobaltite nanoparticles with twenty-enhanced catalytic
40. Xin, Y. Y. et al. , "Facile synthesis of urchin-like NiCo ₂ O ₄ hello microspheres with enhanced electrochemical properties in energy and environmental synthesis. Mater. Interfaces 6,3689-3695 (2014).

The present specification includes a quantitative study of the number of ^{Co 3+} site-rich surfaces in anisotropic morphology and charge transfer (ie, conductivity) within the developed electrode. Electrodes with C-NT / Co ₃ O ₄ CP, C-NT / Co ₃ O ₄ BC, C-NT / Co ₃ O ₄ MCS, gC / Co ₃ O ₄ LS, and C-NT / CoO CP structures Was evaluated by electrochemical impedance spectroscopy. For evaluation, an open circuit potential was used in 0.5 M sodium hydroxide containing 0.5 M ethanol at a frequency of 100 kHz to 0.01 Hz with an amplitude of 5 mV (FIGS. 12F-a-e). Impedance of all electrodes Nyquist plots have a semicircular shape at high frequencies, which represents the Rct of the electrode design. Furthermore, they have a linear shape at low frequencies, this is a solution resistance of CoO or _Co 3 _{O 4} (Rs), represents the charge transfer resistance (Rct) and redox capacitance behavior (C) (FIG. 12F- Inset). The diameter of the semicircle in the plot is C-NT / Co ₃ O ₄ CP <g-C / Co ₃ O ₄ LS <C-NT / Co ₃ O ₄ MCS <C-NT / Co ₃ O ₄ BC <C. It increased in the order of -NT / CoO CP.

Importantly, hierarchical nanoforest structures include longitudinal single windows and mesocylindrical open pore structures (CPs and BCs) (FIG. 22A), vertical interlayer spaces and interfaces (LSs and MCSs (FIG. 22C)). It is also believed to generate multiple diffusion phases of molecular and electron transport along the catalytic form through catalytically active surfaces and exposed sites (FIG. 22B). In such multiple diffusion phases, intermediate species. "Surface blocking" due to the accumulation of "poison" can "poison" the electrode surface. In addition, vertical grooves across the longitudinal axis correspond to changes in internal and external structures, resulting in electron flow. Permanently readjusted (Fig. 22A). Therefore, a longitudinally oriented surface with catalytically exposed sites can play an important role in improving electron kinetics and diffusion (Fig. 22A). 22B). The proposed model (FIG. 22B) ^{considers an electrode surface consisting of Co 2+} , Co ³⁺ , and O ^2- atoms stacked alternately along the c-axis, which is the {111} plane. It becomes dense in the upper region of the coating surface of the {111} / {112} plane. The plane created by the interface (ie, {111} / {112}) is more thermodynamically stable and chemically active. ^{It provides a binding site, which allows ethanol molecules to be adsorbed on abundant O2-} atoms rather than adsorbing a high refractive index {112} plane (FIG. 23 and Table 1). Discontinuous jumps in are expected with the curvature of the stacking points of the MCS double spiral layer (Fig. 22C). The movement of electrons in the curvature of the intricately connected MCS is vertical, continuous, or non-stacked. With respect to the axial movement of the LS structure to the outer interface, it may provide angular motion transmission (ie, immediate torque block) that limits the degree of freedom of electron movement, which is the diffusion coefficient value and current of the electrodes of the LS and MCS systems. It is clear from the density (Fig. 24C).

The catalytic efficiency of the electrodes developed for ethanol electrolytic oxidation was substantially influenced by the structural properties of the electrode catalysts in terms of current density, stability, surface electron transfer, and molecular diffusivity. Factors with significant effects included morphological structures oriented along the longitudinal axis, the presence of multidiffusive pores with fractal binding windows, and the presence of facet-dependent surface sites (ie, high). Energy exposure facets, high electron densities along nanoscale structures, and interface planes). In the catalytic activity of electrodes in the form of CP, BC, LS, and MCS, the effect of tightly coupled, closely located high index interface planes throughout the mesocrystal was evident. Models of the atomic arrangements and active sites of the leading {111}, {112}, {001}, and {110} planes and their interface planes were simulated using density functional theory (FIG. 24). ).

^{The density of catalytically active Co 3+} sites placed vertically on the meso crystal plane and catalyst surface was an important parameter of surface reactivity, which significantly affected the catalytic performance of the developed electrode. The density of Co ³⁺ decreased in the order of {112} / {111}> {110} ≧ {001}> {110} / {001} ≧ {112}> {111}. The exposed surface of the {112} / {111} interface plane had more unsaturated bonds (dangling bonds) and higher surface stabilization energies than other facets and interface facets. This finding is consistent with the order of catalytic reactivity of the tested forms (ie CP>LS>MCS> BC). The ethanol molecule was adsorbed on its surface perpendicular to the O2 ^{- atom near the active Co 3+ site.} Similarly, the adsorption energy increased in the same order as the increase in ^{Co 3+ density on the crystal plane.}

The high index {112} / {111} interface plane in the 50-sided polyhedron catalyst has a large number of exposed C / Co ₃ O ₄ ^{CP surfaces enriched with Co 3+} active sites, which are effective. It was important for active adsorption, molecular emission, and electron transport (Table 1). Reactive facets containing multiple Co ³⁺ sites (ie, {112} planes of {112} / {111} planes) formed stronger bonds with ethanol molecules at smaller bond distances. Therefore, ethanol adsorption was dependent on the active site on the active adsorption surface on the exposed interface surfaces of the {112} / {111} and {110} / {001} surfaces (interface-site-dependent adsorption energy) ( FIG. 24). Negative adsorption energy indicates that ethanol adsorption on the crystal surface with a high refractive index and a low refractive index is an exothermic and energetically dominant behavior in an effective ethanol oxidation reaction. The change in adsorption energy may be due to a change in the atomic charge of the active adsorption surface sites of the crystal {110}, {001}, {111}, and {112} planes and their interfaces (Table 1).

The electrostatic potential map was investigated using density functional theory. As a result, Co present on equal surfaces and unsaturated coordination bonds (ie, dangling bonds) at the exposed {110}, {001}, {111}, and {112} planes and interface CO ^{3+ sites.} Gradients on the surface were shown with respect to the charge densities of ²⁺ , Co ³⁺ , and O ^{2-atoms (Fig. 23).} The active site was emphasized using changes in the electrostatic potential distribution on the low and high index planes. The maximum anomaly of the electrostatic potential was found at the surface active center due to the formation of oxygen vacancies at that location. Electrostatic potential mapping of the exposed ^planes, strongly suggest having ^{O 2-} surface oxygen atoms in the vicinity of pores sites greater negative charge than that away from the O ^2- vacancies site (electron-rich surface) did.

Electrostatic potential map of Co ³⁺ atoms is compared with the charge density of the ^{Co 2+} atom, a more pronounced charge density, which is ^{Co 3+} atom, particularly ^{Co 3+} of ^{O 2-} vacancies near the site of the outer surface It shows that the atom is the site with the highest electrical activity (Fig. 23). Therefore, more electron-rich O ^2- vacancy sites were created on the interface facets. As a result, the surface active center exhibits high electron density and large-scale electron motion across surface atoms. The hierarchical structure in the surface structure of the longitudinally oriented C / Co ₃ O ₄ ^{CP electrode is an O 2-} vacancy site ^{rich in many Co 3+} atoms and more electrons on both the main crystal surface and the top crystal surface. It is possible to form a significantly complex {111} / {112} plane with. High adsorption and surface stabilization energies, as well as abundant unsaturated bonds, can be achieved in the reaction, thereby more efficient and elastic electron transport and intermolecular diffusion along these interface planes. Causes.

<References>
The disclosure also includes the following references, the entire contents of which are incorporated herein by reference.
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<Material>
All chemicals and materials investigated were analytical grade and used without further purification. Cobalt chloride hexahydrate _{(CoCl 2 · 6H 2 O,} 99%), graphite powder (98%), urea _{(CO (NH 2) 2,} 99%), HMT (C 6 H 12 N 4) and hydroxide Sodium (NaOH, 98%) was supplied by Wako (Osaka, Japan). Cobalt nitrate hexahydrate _{(Co (NO 3) 2 ·} 6H 2 O, 98%), ammonium nitrate _{(NH 4 NO 3, 99%} ), absolute ethanol _{(C 2 H 5 OH, 99.5} %), nitric acid ( HNO ₃ , 61%), sulfuric acid (H ₂ SO ₄ , 95%), hydrochloric acid (HCl, 36%) and hydrogen peroxide (H ₂ O ₂ , 30%) were purchased from Nakalai Tesque (Japan). MWCNT (98%) was purchased from Sigma-Aldrich, Inc. of the United States, and potassium permanganate (KMnO ₄ , 99.5%) was purchased from Tokyo Chemical Industry (TCI). A three-dimensional porous Ni foam (3D-PNi) (1 cm x 1 cm) was produced by TCI as a conductive base on which nanocomposites were grown. Prior to synthesis, the 3D HCl substrate was repeatedly rinsed by continuous sonication with concentrated HCl solution, ethanol and Milli-Q water, then dried at 60 ° C. for 12 hours.

[Example 1]
<Purification and functionalization of multi-walled carbon nanotubes (MWCNTs)>

The untreated MWCNT was first _{mixed with the HNO 3} / H ₂ SO ₄ solution in a ratio of 1: 3. The mixture was then sonicated at 50 ° C. for 5 hours and then refluxed at 110 ° C. for 3 hours. The resulting mixture was then diluted with deionized water at pH 7. The solids (ie, oxidized MWCNTs) were collected by centrifugation and dried overnight at 65 ° C. for later use.

<Preparation of graphene oxide>
Graphene oxide was synthesized from graphite powder according to the slightly modified Hummers method. Typically, a 2g of graphite powder (approximately 40 [mu] m), by stirring vigorously for 1 hour at 25 ° C., concentrated _H 2 SO ₄ and _HNO 3: and (100 mL, 1 1 v / v) strong solution of the reaction I let you. Then, the solution was placed in an ice-water bath, and 7 g of KMnO ₄ was slowly added to the solution with stirring for 2 hours. The mixture was then sonicated at 40 ° C. for 6 hours to avoid obtaining a homogeneous reaction solution. Deionized water (350 mL) was then mixed with the formed gel and the entire mixture was stirred at 80 ° C. for 1 hour. Subsequently, the addition of 15% HCl solution _30% H _{2 O} 2 and 50mL of 120mL the mixture which was then stirred for 10 minutes. The gel mixture was allowed to stand until a brown precipitate formed. The solid material was washed twice with distilled water and dried overnight at 60 ° C. before the next investigation.

<Preparation of C-NT / CoO CPs / 3D-PNi nanostructures>
A simple one-pot method for the synthesis of C-NT / CoO CPs / 3D-PNi electrodes has been achieved by microwave assist technology. In this method, 0.1 M cobalt nitrate hexahydrate and 0.35 M HMT were mixed with 37 mL deionized water with stirring for 10 minutes. Then, 80 mg of oxidized C-NT was immersed in the above solution and stirred vigorously for 3 hours. The mixture was then transferred to a Teflon-lined autoclave containing a 3D-PNi sheet (Scheme 1) and microwave-irradiated at 160 ° C. for 1 hour (600 W). The recovered samples were carefully washed with ethanol and deionized water, dried overnight at 60 ° C. and finally calcined in air at 400 ° C. for 4 hours.

<Preparation of C-NT or g-C / Co ₃ O ₄ or CoO / GC>
Several electrochemical experiments were performed to investigate the effect of carrier substrates on EOR efficiency using longitudinal electrode designs. In these experiments, C-NT or g-C / under the same electrochemical conditions as those applied to _{the C-NT or g-C / Co 3} O _{4 or CoO / 3D-PNi electrode assay.} Co ₃ O ₄ or Co O / GC electrodes were used. A thin film laminated C-NT or g-C / Co ₃ O ₄ or CoO / GC electrode was prepared by dispersing the active catalyst powder on a GC substrate by a non-uniform assist ink deposition method at 25 ° C. A uniform catalyst ink was prepared by mixing 5 mg of active catalyst into 50 μL of 5 wt% Nafion solution used as a binder in 2 mL Milli-Q water for at least 30 minutes under sonication. Then, the catalyst ink (4 μL) was filled in the three active regions (φ = 3 mm) of GC at about 0.143 mg / cm ^2. The catalyst ink-filled GC electrode was dried in a sealed oven at 50 ° C. to form a uniform catalyst layer on the GC substrate region.

[Example 2]
<Characteristics>
The morphology of the annealed sample was examined by FE-SEM (JEOL Model 6500) at 15 kV. Prior to insertion into the FE-SEM chamber, a C-NT or g-C / Co ₃ O ₄ or CoO / 3D-PNi electrode was fixed onto the FE-SEM stage using carbon tape. A thin Pt film was deposited on the electrodes at 25 ° C. using an ion sputtering apparatus (Hitachi E-1030). The Focused Ion Beam (FIB) system (JEM-9320FIB) was operated with an acceleration voltage of 5 to 30 kV in 5 kV variable steps and a magnification of 150 to 300,000 times. The orientation axes (X and Y) of the powder sample containing the C-NT or g-C / Co ₃ O ₄ or CoO catalyst can be changed within ± 1.2 mm with an inclination angle of ± 60 °. The sample was deposited in a carbon protective layer and then inserted into the FIB device using a ^{bulk sample holder (8 x 8 mm 2).} Prior to the FIB survey, a powder sample of C-NT or gC / Co ₃ O ₄ or CoO catalyst was mixed with a small amount of epoxy (Gatan) on a small silicon wafer using a fine eyelash probe and on a silicon substrate. A very thin film was formed in (FIGS. 2 and S7). Each thin film was baked on a hot plate at 130 ° C. for 10 minutes and subsequently coated with a uniformly thin carbon layer of about 30 nm. The sample was inserted into a FIB microscope operated at 30 kV and then coarsely ground on both sides using −1.5 ° and + 1.5 ° tilts to a final thickness of 2 μm. The C-NT or g-C / Co ₃ O ₄ or CoO samples were then cleaved and removed from the FIB system for subsequent HAADF-STEM microscopy.

HAADF-STEM was used to perform (i) TEM and (ii) STEM, (iii) EDS for element mapping, and (iv) electron diffraction (ED). HAADF-STEM micrographs were recorded using a JEMARM200F-G apparatus equipped with an aberration corrector in the illumination and imaging lens system to observe TEM / STEM images with high resolution. The HAADF-STEM microscope was also equipped with a monochromatic electron gun, which was supported by electron energy loss spectroscopy with high energy resolution. Specifically, a cross-sectional sample of HAADF-STEM was prepared by FIB system milling. The finely confined probe typically sharpened the sample parallel to the longitudinal c-axis. Well-prepared FIB samples were attached to the silver grid with epoxy material using a pickup system. C-NT or g-C / Co ₃ O ₄ or CoO attached to the silver grid was reinserted into the FIB system to create a 100 nm thick layer. Samples were thinned from both sides by using an alternative beam with variable intensity until a final thickness of 4 at 100 nm. A 100 nm sample was observed under a HAADF-STEM microscope and a cross-sectional image was recorded.

BELSORP36 analyzed using apparatus (BEL Japan Inc.), _{N 2} adsorption at 77K - by desorption isotherms were evaluated the surface properties of the material containing a pore structure distribution and surface area. Samples, _{N 2} atmosphere, was at least 6 hours heat treatment at 200 ° C.. The specific surface area (SBET), was calculated using the Brunauer-Emmett-Teller (BET) method using a multi-point adsorption data from the linear portion of the _{N 2} adsorption isotherm. The pore size distribution was determined using nonlocal DFT (NLDFT). The structural shape of the catalyst was further investigated by WA-XRD. WA-XRD patterns were recorded on a monochromatic CuKα-X-ray (λ = 1.54178 Å) using an 18 kW diffractometer (Bruker D8 Advance) at a scanning speed of 10 ° / min. Diffraction and structural analysis Diffraction data was analyzed using DIFRAC plus Evaluation Package (EVA) software with the PDF-2 Release 2009 database provided by Bruker AXS. A TOPAS package program was applied to integrate various types of X-ray diffraction (XRD) analysis. XPS analysis was performed with a PHI Quantera SXM (ULVAC-PHI) device (Perkin-Elmer, USA) equipped with AlKα as an excitation X-ray source (1.5 mm × 0.1 mm, 15 kV, 50 W), 4 × ^10-8. It was performed under the pressure of Pa. Prior to the start of the analysis, a thin film of sample was deposited on a Si slide.

Raman spectroscopy (HR Micro Raman spectrometer, Horiba, Jobin Yvon) was performed using an Ar ion laser at 633 nm. A CCD (charge-coupled device) camera detection system and a LabSpec-3.01C software package were used for data collection and analysis, respectively. To ensure the accuracy and precision of the Raman spectrum from 300 cm ^-1 to 1,600Cm ^-1, it was recorded 10 scans of 5 seconds. TG and DTA were simultaneously achieved using the DTA-TG device TG-60 (Shimadzu, Japan).

[Example 3]
<Electrochemical measurement>
Mercury / mercury oxide (Hg / HgO, 1M NaOH) and platinum wire (φ = 0.1 mm) were used as reference electrodes and counter electrodes, respectively, and electrochemical measurements were performed in a home-made electrochemical cell. _{An active catalyst C-NT or g-C / Co 3} O ₄ or CoO grown on a 3D-PNi having a surface structure of CPs, LSs, MCSs and BCs and having 1.5 mg of active loading. , Used as a working electrode for electrochemical investigation. Data were recorded using a Zennium / ZAHNER electrochemical workstation (Electrik Co., Ltd.) controlled by Thales Z 2.0 software. First, all working electrodes were cycled at least 10 times at a scanning rate of ^{50 mV seconds-1 until the signal was stable.} Next, CV data was collected. The current density 5 refers to the geometric surface area (1 cm ^{2) of the working electrode investigated.} The measured potentials were reported for the Hg / HgO reference electrode. The freshly prepared electrolyte solution (NaOH in 0.5M), was degassed by bubbling a slow stream of N ₂ was purified on a electrolyte in electrochemical glass cell. To ensure a N ₂ saturated electrolyte was maintained N ₂ flow in the electrochemical measurements. A freshly prepared electrolyte was used for each electrochemical measurement to ensure the reproducibility of the recorded results. A chronoamperometry test (CA) was performed to evaluate the electrode stability during the ethanol electrolytic oxidation reaction. The CA measurement was obtained by applying a constant potential of 0.7 V to Hg / HgO in the presence of 0.5 M ethanol. The EIS measurement was performed in the frequency range where the amplitude was 5 mV and the open circuit potential was 100 kHz to 0.01 Hz.

[Example 4]
<Manufacturing of C-NT / Co ₃ O ₄ CP or BC / 3D-PNi electrode>
The BC electrode, CoCl ₂ · _{6H 2} O in 1.5g, urea _{0.5g (CO (NH 2) 2} ), and were prepared from _{H 2} O solution of 60 mL. The CP electrodes were prepared from CoCl ₂ · _{6H 2} O, urea 3.6g and 60mL of _{H 2} O solution, the 1.43 g. C-NT (80 mg) was added to the solution, which was stirred for 3 hours ^{and then deposited on 1 cm 2} of 3D-PNi in a 100 mL Teflon-lined stainless steel autoclave. The mixture was heat treated at 150 ° C. for 12 hours and then naturally cooled to 25 ° C. Products grown on 3D-PNi, C / Co (OH) _x (CO ₃ ) _0.5 / 0.11H ₂ O were washed sequentially with anhydrous ethanol and deionized water, then dried overnight at 60 ° C. I let you. Next, the prepared C / Co (OH) _x (CO ₃ ) _0.5 / 0.11H ₂ O / CP or BC electrode was placed at a heating rate of 400 ° C. and 5 ° C./min for 4 hours, N ₂ It was fired under a gas flow.

[Example 5]
<Manufacturing of C-NT / Co ₃ O ₄ MCS / 3D-PNi electrode and g-C / Co ₃ O ₄ LS / 3D-PNi electrode>
The addition of the C-NT or g-C conductive substrate to the composition was essential to achieve the MCS and LS structures. CoCl ₂ · _{6H 2} O in 1.43 g, hexamethylenetetramine _{2.94g (C 6 H 12 N 4} ), and was a mixture of _{H 2} O in 60mL was stirred for 10 minutes. Then 80 mg of C-NT or g-C was added to the solution, the mixture was stirred for 3 hours ^{and then deposited on 1 cm 2} of 3D-PNi in a 100 mL Teflon-lined stainless steel autoclave. The mixture was heat treated at 150 ° C. for 12 hours and then naturally cooled to 25 ° C. The product grown on 3D-PNi, C-NT or g-C / Co (OH) _x (CO ₃ ) _0.5 / 0.11H ₂ O was washed successively with absolute ethanol and deionized water, 60. Allowed to dry overnight at ° C. Next, the prepared C / Co (OH) _x (CO ₃ ) _0.5 / 0.11H ₂ O / MCS electrode and g-C / Co (OH) _x (CO ₃ ) _0.5 / 0.11H ₂ the O / LS electrodes, 400 ° C., 4 hours at a heating rate of 5 ° C. / min, and calcined under _{N 2} gas flow.

[Example 6]
<Mathematical modeling>
DFT is a promising method for effectively explaining the electron correlation effect. In this study, all calculations examined by the DFT were performed according to DMol3 of the BIOVIA Dassault System (2,3). The exchange correlation energy function was expressed by Perdew-Burke-Ernzerhof (PBE) formalism (4). The Kohn-Sham equation was extended with a dual numerical quality basis set (DNP) using polarization functions. To consider the relativistic effect, the DFT semi-core pseudopotential (Reference 5) was used to process the core electrons of the doped cluster. The orbital cutoff range and Fermi smearing were selected as 5.0 Å and 0.001 Ha, respectively. A self-aligned field (SCF) procedure was performed to obtain a well-converged geometric and electronic structure with a convergence criterion of ^{10-6 arbitrary units.} The energy, maximum force, and maximum displacement convergence were ^{set to 10-6} Ha, 0.002 Ha / Å, and 0.005 Å, respectively. On the other hand, the potential of the electrostatic site is a measure of Coulomb interaction per unit charge that an ion receives at a given position in space. A DFT was also used to calculate the electrostatic potential (EP) distribution. Modeling was performed to show a physical quantitative study at each point on the equisurface using the features of the surface charge map. Typically, the electron density equisurface is colored based on EP intensity (EPI) using lattice representation, and this charge is mapped onto a cubic lattice in the so-called contour from which EP is calculated. The slab model was composed of 9 atomic layers of each catalyst (Fig. 23). To compare the active centers in the structure, oxygen atoms in the surface and subsurface layers were involved in the stoichiometric mode. EP was investigated over the range of -0.06 eV to +0.6 eV, as shown in the optimized model.

[Example 7]
< _{Hydraulic Co 3} O ₄ nanocomposite hydro-assisted formation>
FIG. 2 shows an outline of the morphological evolution of an exemplary electrode. _{A C-NT or g-C / Co 3} O ₄ nanohybrid structure derived from a layered metal skeleton grown directly on a 3D-PNi substrate with strong mechanical adhesion was obtained. This was a suitable thermal decomposition of the synthesized C-NT or g-C / Co (OH) _x (CO ₃ ) _0.5 / 0.11H ₂ O / 3D-PNi electrode at 400 ° C. for 4 hours. Obtained later (additional details can be found in the experimental section). A scalable and flexible method has been adopted to produce morphologically controlled nanohybrid along the longitudinal direction perpendicular to the 3D-PNi backbone. In these processes, the surface morphology of CPs and BCs was predominant in the NR structure, and the surface morphology of MCSs and LSs was predominant in the nanosheets. The GO sheet (g-C) or functionalized multi-walled carbon nanotube (C-NT) counterpart acted as a carbon support. Basically, the unique structure of the produced electrodes was provided by directional basic salts (urea and HMT) and cobalt precursors.

Under the hydrothermal conditions described herein, self-supporting (ie, C-NT or gC / Co ₃ O ₄ or CoO / substrate) electrodes, Co ₃ O ₄ or CoO and C-NT or gC / Co. _{The production of 3} O ₄ or CoO hybrids is of BC-NR, CP-NR, LS and MCS structures with uniformly spaced inner pores of micro and mesoscale size (0.5-65.8 nm). It can be hierarchically controlled to produce morphological features similar to those of morphological features. This includes field emission scanning electron microscope (FE-SEM) micrographs (FIGS. 3-6), thermogravimetric analysis (TG) -differential thermal analysis (DTA), wide-angle powder X-ray diffraction (WA-XRD) and It is clear from the N2 isotherm (see FIGS. 7, 25 and 26). Chemical bond, from the viewpoint of structural environment, and elemental, in order to examine the geometric C / _Co 3 _{O 4} of meso crystal hybrid atomic core levels of the _{organization, C / Co 3 O 4 CPs} X -ray photoelectron spectroscopy Method (XPS) analysis and Raman spectroscopy were performed (Fig. 27).

FE-SEM and HAADF-STEM micrographs (FIGS. 1-6, 8, 9 and 11) show that reaction times and growth temperatures are sufficient for immobilization and nucleation of free-standing nanostructures. Shown. In addition, the metal particles were attached to the surface functional groups of the counterpart by electrostatic interaction during the hot water treatment (FIGS. 2A-a, 2B-a, and 2B-b). These oxygen functional groups provide a reliable mediator that completely disperses the counterpart in the reaction solution _{and ensures the growth of Co 3} O _{4 mesocrystals on the backbone of the counterpart.} The porosity of the formed nanostructures improved significantly after decomposition at relatively high temperatures from the release of gas, adsorbed water and organic molecules. This result shows an improvement in the utilization rate of the active material. Therefore, a significant improvement in its electrochemical performance was expected. In addition, such a unique structure provides a clear path for the electrolyte to pass through the graphene layer and along the carbon tubing, resulting in high electron transport. Interestingly, the controlled longitudinal growth of the C-NT or g-C / Co ₃ O ₄ or CoO / 3D-PNi electrodes is a more preferred exposed surface and interface that includes a broad region of the ^{Co 3+ active site.} To generate. This effect improves the dynamics of EOR, as evidenced by HR-HAAF-STEM micrographs (Fig. 11).

Claims (20)

An electrode containing a support, a metal oxide catalyst located on the surface of the support , and a substrate.
The support is made of carbon nanotubes or graphene sheets.
The metal oxide catalyst is a Co ₃ O ₄ crystal.
The substrate is made of foamed metal or glassy carbon.
When the support is a carbon nanotube, the longitudinal direction of the carbon nanotube is positioned so as to be perpendicular to the plane of the substrate.
When the support is a graphene sheet, the plane of the graphene sheet is positioned so as to be perpendicular to the plane of the substrate.
The Co ₃ O ₄ crystal is an electrode having a Miller index {111} / {112} interface plane and a {110} / {001} interface plane. The support is made of carbon nanotubes
The Co ₃ O ₄ The electrode according to claim 1, wherein the carbon nanotubes having crystals located on the surface have a morphological structure similar to corn nodule pellets (CPs) with respect to the substrate. The support is made of carbon nanotubes
The Co ₃ O ₄ The electrode according to claim 1, wherein the carbon nanotubes having crystals located on the surface have a banana cluster (BCs: banana clusters) -like morphological structure with respect to the substrate. The support is made of carbon nanotubes
The Co ₃ O ₄ The electrode according to claim 1, wherein the carbon nanotubes having crystals located on the surface have a morphological structure like a plurality of cantilever sheets (MCSs) with respect to the substrate. The support consists of a graphene sheet
The Co ₃ O ₄ The electrode according to claim 1, wherein the graphene sheet on which the crystal is located has a morphological structure similar to that of a thin sheet (LSs: lamina sheets) with respect to the substrate. The metal foam is foamed nickel or foamed aluminum or Ranaru electrode according to any one of claims 1 to 5. The method for manufacturing the electrode according to any one of claims 1 to 6.
A step of forming an aqueous solution containing a cobalt (II) salt , urea or hexamethylenetetramine, a support made of carbon nanotubes or a graphene sheet, and water in the presence of a substrate made of metal foam or glassy carbon;
Step of the water solution to a hydrothermal treatment;
A step of washing and drying the product on the substrate obtained by the step of hydrothermal treatment ;
Step that forms baked product on the substrate,
The above method, including. The cobalt (II) salt, cobalt chloride, cobalt nitrate, or including a combination thereof, The method of claim 7. Said step of hydrothermal treatment is in the presence of the substrate, the water solution, a step of heating the temperature range of 100 to 200 ° C., The method according to claim 7 or 8. The method according to any one of claims 7 to 9, wherein the hydroheat treatment step is a step of heating the aqueous solution in the presence of the substrate for 1 hour to 36 hours. The method according to any one of claims 7 to 10, wherein the washing and drying step comprises washing with absolute ethanol and deionized water. The product comprises a support and a composition located on the surface of the support.
When the support is a carbon nanotube, the longitudinal direction of the carbon nanotube is positioned so as to be perpendicular to the plane of the substrate.
The method according to any one of claims 7 to 11, wherein when the support is a graphene sheet, the plane of the graphene sheet is located so as to be in a direction perpendicular to the plane of the substrate. The composition is a hydrated cobalt oxide represented by the formula Co (OH) _x (CO ₃ ) _0.5 / 0.11H ₂ O (where x is selected from 1, 2 or 3). there the method of claim 12. The firing to step is a step of heating the product on the substrate to a temperature of 200 to 500 ° C., the method according to any one of claims 7-13. The firing step produces N on the substrate. ₂ The method according to any one of claims 7 to 14, which is a step of firing under a gas flow. The aqueous solution contains a cobalt (II) salt, urea, and a support made of carbon nanotubes.
The mass of the urea in the aqueous solution is smaller than the mass of the cobalt (II) salt.
The method according to any one of claims 7 to 15, wherein the product has a corn tubercle pellets-like morphological structure with respect to the substrate. The aqueous solution contains a cobalt (II) salt, urea, and a support made of carbon nanotubes.
The mass of the urea in the aqueous solution is larger than the mass of the cobalt (II) salt.
The method according to any one of claims 7 to 15, wherein the product has a banana cluster (BCs: banana clusters) -like morphological structure with respect to the substrate. The aqueous solution contains a cobalt (II) salt, hexamethylenetetramine, and a support composed of carbon nanotubes.
The method according to any one of claims 7 to 15, wherein the product has a plurality of cantilever sheets (MCSs) -like morphological structures with respect to the substrate. The aqueous solution contains a cobalt (II) salt, hexamethylenetetramine, and a support composed of a graphene sheet.
The method according to any one of claims 7 to 15, wherein the product has a thin sheet (LSs: lamina sheets) -like morphological structure with respect to the substrate. A fuel cell comprising the electrode according to any one of claims 1 to 6.

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