CN112194818A

CN112194818A - Copper/silver-based electrode with conductive bacterial cellulose composite membrane as substrate

Info

Publication number: CN112194818A
Application number: CN202011032013.9A
Authority: CN
Inventors: 洪枫; 高璐; 陈琳; 聂子琪; 李宣江; 乔锦丽
Original assignee: Donghua University
Current assignee: Donghua University; National Dong Hwa University
Priority date: 2020-09-27
Filing date: 2020-09-27
Publication date: 2021-01-08
Anticipated expiration: 2040-09-27
Also published as: CN112194818B

Abstract

The invention relates to a copper/silver-based electrode with a conductive bacterial cellulose composite membrane as a substrate, which takes the composite membrane as the substrate and obtains the electrode by in-situ chemical reduction, catalytic reduction or hydrothermal synthesis of Cu/Ag ions. Compared with the traditional electrode taking carbon cloth as a substrate, the catalytic electrode prepared by the method has a three-dimensional nanofiber network structure, a high specific surface and high conductivity, and has higher catalytic efficiency and longer electrode life. The preparation method is green and environment-friendly, simple in process and short in preparation time. The electrode has good application prospect in the fields of carbon dioxide electro-catalytic reduction, fuel cells, photocatalysis, biocatalysis and the like, and has important significance for environmental protection, energy recycling and the like.

Description

Copper/silver-based electrode with conductive bacterial cellulose composite membrane as substrate

Technical Field

The invention belongs to the field of electrode materials, and particularly relates to a copper/silver-based electrode with a conductive bacterial cellulose composite membrane as a substrate.

Background

Bacterial nanocellulose (BC) is cellulose produced by microorganisms, has excellent mechanical properties, low density and a perfect 3D network structure, is widely applied to the aspects of textiles, medical use, food, conductive materials and the like as a novel material, and has good mechanical properties and reproducible properties compared with synthetic polymers.

The explosion of the industrial revolution, the demand and utilization of fossil fuels by humans are increasing, resulting in resource shortage on the global scale and greenhouse effect caused by carbon dioxide, thereby causing a series of environmental problems such as rise in sea level, melting of glaciers, and the like. Therefore, how to find a new method which can reduce the emission of carbon dioxide and effectively utilize the carbon dioxide as resources becomes a current research hotspot. The technology for converting carbon dioxide into value-added chemicals and fuels attracts wide attention, and the technology for electrochemically reducing carbon dioxide has the advantages of environmental protection, simple device, stable catalytic efficiency, easiness in industrial production and the like. The method can reduce carbon dioxide into high value-added products such as formic acid, methane, methanol, ethylene and the like. Copper is used as a cheap metal, the reserves are abundant, the metal is nontoxic and environment-friendly, carbon dioxide can be effectively reduced into important fossil fuels such as methane, ethylene and the like, and the metal silver has good catalytic activity.

The prior electrode substrate material for electrochemical catalytic reduction of carbon dioxide is carbon paper, carbon cloth, carbon sheet, carbon felt and other materials with certain conductive performance, and the carbon-based materials do not have a nano network structure, so that a catalyst cannot enter the substrate material to be efficiently compounded with the substrate material; the existing preparation method for the carbon dioxide electrochemical catalytic reduction electrode is a coating method, namely a catalyst is coated on a substrate material, the method cannot enable the catalyst and the substrate material to be tightly compounded, and the catalyst is easy to fall into an electrolyte solution in application, so that the efficiency is reduced.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a copper/silver-based electrode with a conductive bacterial cellulose composite membrane as a substrate, and a copper/silver catalyst is subjected to in-situ reduction synthesis in the interior and on the surface of the conductive bacterial cellulose composite membrane by adopting an in-situ compounding method to obtain the copper/silver-based electrode with the conductive bacterial cellulose composite membrane as the substrate and a nanofiber network structure.

The invention relates to a composite electrode material, which is a bacterial cellulose/conductive material composite film with silver or copper nanoparticles loaded on the surface.

The electrode material is of a porous structure, the bacterial cellulose is used as a natural biological material, the electrode material has a 3D nano-fiber network structure, and the porous conductive composite membrane with the 3D nano-network structure can be obtained after the electrode material is compounded with a low-dimensional carbon material LDC, polypyrrole PPy and polyaniline PANI.

The electrode material is as follows: preparing a conductive composite membrane from the bacterial nano-cellulose, LDC, PPy and PANI by an in-situ culture method, an impregnation method, a homogenate suction filtration method and an in-situ chemical polymerization method; the obtained composite membrane is used as a substrate to carry out in-situ catalytic reduction or hydrothermal synthesis on Cu and/or Ag ions, and the preparation method comprises the following steps: Cu/C @ BC, Ag/C @ BC, Cu/PPy @ BC, Ag/PPy @ BC, Cu/PANI @ BC, Ag/PANI/C @ BC or Cu/PANI/C @ BC electrodes, namely copper/silver-based and other metal catalyst electrodes.

Further, the concentrations of CNT, PPy and PANI were 0.1M.

The size of the Cu/C @ BC, Ag/C @ BC, Cu/PPy @ BC, Ag/PPy @ BC, Cu/PANI @ BC, Ag/PANI/C @ BC or Cu/PANI/C @ BC electrode is 1 multiplied by 1 to 3cm²。

The conductive material is one or more of a low-dimensional carbon material LDC, polypyrrole PPy and polyaniline PANI; the bacterial nano cellulose comprises various different forms such as a bacterial nano cellulose film, a bacterial nano cellulose homogenate, a bacterial nano cellulose flocculent fiber, a spongy bacterial nano cellulose obtained by freeze drying and the like.

The low-dimensional carbon material LDC comprises zero-dimensional, one-dimensional and two-dimensional materials, and specifically comprises the following components: one or more of carbon nano tube CNT, graphene and nano carbon powder.

Further, the carbon nanotubes include various carbon nanotubes such as single-walled carbon nanotubes, multi-walled carbon nanotubes, and carboxylated multi-walled carbon nanotubes, and the graphene includes various graphenes such as single-layer graphene, double-layer graphene, few-layer graphene, and multi-layer graphene.

The preparation method of the composite electrode material comprises the following steps:

(1) immersing the bacterial cellulose/conductive material composite membrane into a copper-containing or silver ion water solution, and carrying out oscillation impregnation in a constant-temperature water bath oscillator at the temperature of 30-90 ℃;

(2) and (2) under the ice-water bath condition, uniformly mixing sodium hydroxide, a stabilizer and a reducing agent to obtain a mixed solution, then adding the mixed solution into the copper or silver ion aqueous solution containing the composite membrane in the step (1), then placing the mixed solution into a water bath constant temperature oscillator to oscillate at the temperature of 30-90 ℃, and drying to obtain the electrochemical catalytic electrode.

The preferred mode of the above preparation method is as follows:

the bacterial cellulose/conductive material composite membrane in the step (1) is as follows: by taking bacterial nano-cellulose as a substrate, one or more conductive materials of low-dimensional carbon material (LDC), polypyrrole (PPy) and Polyaniline (PANI) are compounded. Such as forming C @ BC, PPy @ BC, PANI @ BC, PPy/C @ BC, PANI/C @ BC conductive composite films.

The bacterial cellulose/conductive material composite membrane in the step (1) is of a 3D nano network structure; the copper ion-containing aqueous solution is a copper sulfate aqueous solution, a copper chloride aqueous solution or a copper nitrate solution; the silver ion-containing aqueous solution is silver nitrate aqueous solution; the concentration of the copper or silver ion-containing aqueous solution is 0.1-0.4M.

The shaking and dipping time in the step (1) is 8-48 h.

The stabilizer in the step (2) is one or more of L-ascorbic acid, ethanol and citric acid; the reducing agent is one or two of sodium borohydride and potassium borohydride; the concentration of the reducing agent in the mixed solution is 0.2-0.4M, the concentration of the sodium hydroxide is 1M, and the concentration of the stabilizing agent is 0.2-0.8M.

The oscillation time in the step (2) is 30-90 min; the drying is carried out in a vacuum drying oven at 50-90 deg.C for 30-90 min.

The molar concentration ratio of the copper or silver ions to the reducing agent is 4: 2-4: 4; the molar concentration ratio of the copper/silver ions to the stabilizer is 2: 1-2: 4.

The rotating speed of the water bath oscillator in the steps (1) and (2) is 70-80 r/min.

The zero-valent elemental metal copper/silver has a nanoscale. (i.e., the copper/silver catalyst is reduced to the zero-valent copper/silver catalyst with nanometer size in situ in the bacterial cellulose/conductive material composite membrane)

The C @ BC, PPy @ BC and PANI @ BC composite membrane obtained by the method is of a 3D nano-mesh structure, and the porous junction is obtained by effectively adjusting the proportion of reactants, the impregnation time, the reaction temperature and the like of the composite membraneThe conductive composite film of the structure loads the nano copper/silver electrode, reduces the occurrence of hydrogen evolution reaction, reduces higher overpotential in the reaction process, and improves CO₂Utilization and conversion.

The invention provides an application of the composite electrode material in carbon dioxide electrocatalysis, fuel cells, photocatalysis or biocatalysis.

Furthermore, the Cu/C @ BC, Ag/C @ BC, Cu/PPy @ BC, Ag/PPy @ BC, Cu/PANI @ BC, Ag/PANI/C @ BC or Cu/PANI/C @ BC electrode prepared by the method is used for carbon dioxide electrochemical reduction, the production process is green and environment-friendly, and the electrode can be produced in large quantity, the 3D nano-network structure and the hydrophilicity thereof can well load the copper/silver nano-particles with C @ BC, PPy @ BC, PANI/C @ BC, and the PANI/C @ BC composite membrane to synthesize the Cu/C @ BC, Ag/C @ BC, Cu/PPy @ BC, Cu/PANI @ BC, Ag/PANI/C @ BC or Cu/PANI/C @ nanometer electrode, and can greatly improve the electrochemical specific surface area, more catalytic active sites are provided, thereby improving the Faraday efficiency of the product.

The electrode is prepared by a simple chemical in-situ reduction, ultraviolet irradiation reduction, catalytic reduction or hydrothermal synthesis method, the C @ BC, PPy @ BC, PANI @ BC, PPy/C @ BC, PANI/C @ BC composite membrane is soaked in a copper/silver ion-containing solution, and a Cu/C @ BC, Ag/C @ BC, Cu/PPy @ BC, Ag/PPy @ BC, Cu/PANI @ BC, Ag/PANI/C @ BC or Cu/PANI/C @ BC electrode with a large specific surface area and loaded with nano copper/silver is obtained by changing the soaking time, so that the contact specific surface area of carbon dioxide and a catalyst is increased, more catalytic active sites are provided, and the hydrogen evolution process in the reaction process can be effectively inhibited; and simultaneously, the Cu/C @ BC, Ag/C @ BC, Cu/PPy @ BC, Ag/PPy @ BC, Cu/PANI @ BC, Ag/PANI/C @ BC or Cu/PANI/C @ BC electrode with the nano structure is obtained by effectively regulating and controlling the preparation conditions (time, temperature, reducing agent ratio and stabilizing agent ratio) of the catalyst electrode copper/silver-based electrode.

Advantageous effects

(1) Compared with the traditional electrode taking carbon cloth as a substrate, the catalytic electrode prepared by the method has a three-dimensional nanofiber network structure and a high specific surface, so that the catalytic efficiency is higher, and the service life of the electrode is longer.

(2) The patent proposes that copper/silver nanoparticles are loaded on a bacterial cellulose composite membrane with electroconductivity in situ to carry out CO₂Electrochemical reduction is carried out, and more CO is obtained by effectively regulating and controlling the preparation conditions of the electrode₂The active sites are catalyzed and reduced, thereby improving the catalytic activity of the catalyst and the selectivity of catalytic products and improving the Faraday efficiency of the products.

(3) The conductive composite membrane related by the invention is a 3D nano-mesh structure, and the porous composite membrane loaded nano-copper/silver electrode with the porous structure such as C @ BC, PPy @ BC, PANI @ BC and the like is obtained by effectively adjusting the proportion among reactants, the dipping time, the reaction temperature and the like of the composite membrane, so that the occurrence of hydrogen evolution reaction is reduced, higher overpotential in the reaction process is reduced, and CO is improved₂The utilization rate and conversion rate of the Cu/CNT @ BC can be seen from FIG. 17, wherein the CO of the Cu/CNT @ BC is obtained by using the CNT @ BC as a substrate material₂The hydrogen evolution reaction decreases with increasing potential in the Faraday efficiency diagram of the electrochemical reduction product, and CO₂The utilization rate and the conversion rate are increased.

(2) The preparation method is green and environment-friendly, has simple process, short preparation time, low energy consumption, easy operation and easy large-scale production.

(3) The catalytic electrode of the invention effectively improves CO₂Ethylene selectivity during reduction.

(4) The electrode has good application prospect in the fields of carbon dioxide electro-catalytic reduction, fuel cells, photocatalysis, biocatalysis and the like, and has important significance in environmental protection, energy recycling and the like.

Drawings

FIG. 1 is a LSV curve comparing a Cu/CNT @ BC electrode with a pure carbon cloth, a Cu @ carbon cloth, a pure BC, a CNT @ BC, a Cu @ BC of example 1;

FIG. 2 is a macroscopic view of CNT @ BC composite membranes in example 1 cultured in situ statically at different concentrations;

FIG. 3 is a macroscopic view of a dynamic in situ cultured CNT @ BC composite membrane according to example 2; wherein A1 is a visual diagram; a2 is an expanded view;

FIG. 4 is a microscopic SEM image of different concentrations of CNT @ BC composite membrane statically cultured in situ in example 1;

FIG. 5 is a microscopic SEM image of the dynamically in situ cultured CNT @ BC composite membrane of example 2; wherein the magnification of B1, B2 and B3 is 10K, 5K or 2K;

FIG. 6 shows flexibility of the PPy/CNT @ BC composite film of example 12; wherein A is the flexibility of the PPy/CNT @ BC composite film, and B is the flexibility of the PPy @ BC composite film;

FIG. 7 is a microscopic SEM image of a PPy @ BC composite membrane obtained by in-situ polymerization in example 5; wherein the magnification of B1 and B2 is 10K and 2K;

FIG. 8 is a graph of the conductivity versus water content for different concentrations of CNT @ BC composite films of example 1;

FIG. 9 shows the reduction of CO by reducing agent with different ratios of Cu/CNT/@ BC electrode in example 1₂Graph of CV of (a); the numerical ratio in the figure is the molar concentration ratio of the copper ions to the reducing agent; the Cu/CNT/@ BC electrode is prepared only by different molar concentration ratios of copper ions and a reducing agent, and the other conditions are the same;

FIG. 10 shows the catalytic reduction of CO by Cu/CNT/@ BC electrode in example 1 at different soaking times₂The LSV graph of (a); the preparation process of the Cu/CNT/@ BC electrode is different only in the soaking time, and the other conditions are the same;

FIG. 11 is the catalytic reduction of CO by Cu/CNT/@ BC electrode in example 1 under different reaction times₂The electrical conductivity of (a); wherein the preparation process of the Cu/CNT/@ BC electrode is only different in reaction time, and the rest conditions are the same;

FIG. 12 is the catalytic reduction of CO by Cu/CNT/@ BC electrode in example 1 at different reaction temperatures₂The LSV graph of (a); the preparation process of the Cu/CNT/@ BC electrode is different only in that the reaction temperature is different, and the rest conditions are the same;

FIG. 13 shows the ratio of ascorbic acid to carbon monoxide for the catalytic reduction of CO by Cu/CNT/@ BC electrode in example 1₂Graph of CV of (a); wherein the numerical ratio in the figure is the molar concentration ratio of the copper ions to the stabilizer; wherein the Cu/CNT/@ BC electrode is prepared by a process which is different only in the molar ratio of the copper ions to the stabilizerThe concentration ratio is different, and the other conditions are the same;

FIG. 14 is a microscopic SEM photograph of whether the Cu/CNT/@ BC electrode is added with ascorbic acid or not in example 3;

FIG. 15 shows Cu/CNT/@ BC in example 10_NaBH4It diagram of electrodes under different voltages;

FIG. 16 shows Cu/CNT/@ BC in example 4_KBH4The unit of the electrode in a long time and the Faraday efficiency are combined;

FIG. 17 shows Cu/CNT/@ BC in example 10_NaBH4Faraday efficiency plots of the electrodes at different voltages;

FIG. 18 shows Cu/CNT @ BC in examples 4 and 10_KBH4And Cu/CNT @ BC_NaBH4The double layer capacitance fit plot of (1);

FIG. 19 is a graph of a double layer capacitance fit of the Cu @ carbon cloth, Cu @ BC and Cu/CNT @ BC composite electrode of example 1;

FIG. 20 is a LSV diagram of composite films of Cu/CNT @ BC, Cu/PPy @ BC, Cu/PANI/CNT @ BC, Ag/PPy @ BC, Ag/PANI/CNT @ BC in accordance with various embodiments;

FIG. 21 is a LSV plot of the nickel copper @ carbon cloth (8:2) versus Cu/PPy @ BC electrodes of comparative example 1;

FIG. 22 is a CV diagram of the nickel copper @ carbon cloth (1:9) and Ag/PPy @ BC electrodes of comparative example 2;

FIG. 23 shows Cu/CNT @ BC in examples 4 and 10_KBH4And Cu/CNT @ BC_NaBH4Microscopic SEM image of (a).

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Example 1

The copper-based electrode for electrochemical catalysis in the embodiment is composed of a CNT @ BC composite membrane loaded nano-copper electrode which is statically cultured in situ, the electrode is synthesized by an in situ catalytic reduction method, and the preparation method comprises the following steps:

(1) acetobacter xylinum strain (Komagataeibacter xylinus ATCC23770, the same below) was added with carbon nanotubes (industrial multi-walled carbon nanotubes,>90%, inner diameter of 5-15nm, outer diameter:>50nm, length 10-20 μm, 50g, Allantin reagent (Shanghai) Co., Ltd., other examples are the same) and fermentation medium (50g/L glucose, C)₆H₁₂O₆AR, national drug group reagents ltd; 5g/L tryptone, BR, national pharmaceutical group reagents, Inc.; 3g/L yeast powder, BR, the national drug group reagent company, the same below) mixed solution (in-situ standing and constant temperature culture for 2-3 days, taking out the CNT @ BC composite membrane, placing the CNT @ BC composite membrane in a sodium hydroxide (NaOH, analytical reagent, the national drug group Shanghai chemical reagent company, the same below) solution, treating the CNT @ BC composite membrane for 2-4 hours at 80 ℃, taking out the CNT @ BC composite membrane, and rinsing the CNT @ BC composite membrane to be neutral by using deionized water to obtain the CNT @ BC composite membrane.

(2) The membrane was analyzed by CV (cyclic voltammetry, scan range was set to-1.36-0.43V (vs. RHE), respectively), and scan rate was set to 50mV^-1，0.5M K₂HCO₃And (3) solution. ) LSV (Linear sweep voltammetry, Linear sweep range was set to coincide with the range of cyclic voltammetric sweep at a 5 mV. um^-1，0.5M K₂HCO₃And (3) solution. ) Conductivity (AC impedance method, its scanning frequency is 0.1Hz-100KHz, and its voltage amplitude is 100 mA. Conductivity δ (S/cm) ═ L/RTW L ═ 0.5cm, W ═ 1cm, R ═ impedance, and T ═ film thickness. ) Equal performance characterization, the CNT @ BC composite film with the carbon nanotube concentration of 0.1M was preferably selected for the experiments of the following steps (see fig. 2, 4 and 8).

(3) 0.1M of CuSO was weighed₄·5H₂Dissolving O (AR, national medicine group reagent Co., Ltd., the same below) in 50mL of deionized water, stirring thoroughly, mixing well, placing in a 1X 2cm container²The CNT @ BC composite membrane is soaked for 24 hours in a water bath constant temperature oscillator under the condition of 30 ℃.

(4) 0.5g NaOH was mixed with 1.76g L-ascorbic acid (C)₆H₈O₆AR, national drug group reagent Co., Ltd., the same below) was dissolved in 12.5mL of deionized water, and the mixture was stirred sufficiently in an ice bath and added0.09g of NaBH₄(98 wt%, national drug group reagents Co., Ltd., the same below) were thoroughly mixed, and the mixture was added dropwise to a CNT @ BC composite membrane immersed in a copper sulfate solution by a constant flow pump at 70rpm, and shaken in a 30 ℃ water bath constant temperature shaker for 60min, and then deionized water and ethanol (CH) were used₃CH₂OH, AR, Hongsheng fine chemical industry Co., Ltd., Hemo city, the same below) washing the membrane, and drying at 60 ℃ for 2h to obtain a Cu/CNT @ BC electrode (the concentration of CNT is 0.1M, and the molar concentration ratio of copper ions to the reducing agent is 4: 2; the dipping time is 24 hours; the reaction time is 60 min; the reaction temperature is 30 ℃; the molar concentration ratio of the copper ions to the stabilizer is 1: 2).

(5) Using acetobacter xylinum as a strain, performing static culture for 2-4 days to prepare a bacterial cellulose pure film, taking out the pure film, placing the pure film into a sodium hydroxide solution, treating the pure film at 80 ℃ for 2-4 hours, taking out the pure film, and rinsing the pure film with deionized water to be neutral to obtain the pure BC film. 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL deionized water, stirring, mixing, adding into 1 × 2cm²And oscillating the mixture for 24 hours at the temperature of 30 ℃ in a water bath constant temperature oscillator. 0.5g NaOH and 1.76g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.09g NaBH₄Fully mixing, dropwise adding the mixture into BC soaked in a copper sulfate solution through a constant flow pump at 70rpm, oscillating in a water bath constant temperature oscillator at 30 ℃ for 60min, washing the membrane with deionized water and ethanol, and drying at 60 ℃ for 2h to obtain the Cu @ BC electrode.

(6) 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL deionized water, stirring, mixing, adding into 1 × 2cm²Was shaken for 24 hours in a water bath constant temperature shaker at 30 ℃ in a carbon cloth (WOS1009, Taiwan carbon energy Co., Ltd., the same below). 0.5g NaOH and 1.76g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.09g NaBH₄Fully mixing, dropwise adding the mixture into carbon cloth soaked in a copper sulfate solution through a constant flow pump at 70rpm, oscillating the mixture in a water bath constant temperature oscillator at 30 ℃ for 60min, washing the membrane with deionized water and ethanol, and drying the membrane at 60 ℃ for 2h to obtain the Cu @ carbon cloth electrode.

FIG. 1 is a LSV plot of pure BC, CNT @ BC, pure carbon cloth, Cu @ BC, and Cu/CNT @ BC, showing the conductive properties of the BC after the addition of CNT; the composite electrode is also compounded with Cu, and the current density of the Cu @ BC composite electrode taking BC as a substrate is higher than that of the Cu @ carbon cloth electrode taking carbon cloth as a substrate; the Cu/CNT @ BC composite electrode has the highest current density and excellent electrochemical reduction performance.

Fig. 2 shows the macroscopic morphologies of the CNT @ BC composite film and the pure BC at the concentrations of 0.2M, 0.1M, and 0.05M, respectively, and it can be observed that the CNT and BC are more uniformly composited.

FIG. 4 is a SEM image of a static-state-cultured CNT @ BC composite membrane with the concentrations of 0.2M, 0.1M and 0.05M, respectively, showing that the fibers are wound with agglomerated CNT spheres, and the more CNT spheres are loaded on the surface of the fibers, the more CNT spheres are stacked. It can be obviously observed that more BC fibers are on CNT spheres on the 0.05M CNT @ BC composite film, and the BC fibers on the CNT spheres are obviously reduced along with the increase of the concentration of the CNT, because the addition of the CNT has a certain inhibition effect on the growth of the BC fibers, which indicates that the CNT and BC are cultured in situ, but the CNT with proper concentration is selected to be compounded with the BC fibers, and the composite film grows better when the concentration of the CNT is higher.

As shown in fig. 8, the water contents and conductivities of the CNT @ BC composite film and the pure BC at concentrations of 0.2M, 0.1M and 0.05M respectively are shown in a combined graph, which shows that the water contents of the pure BC and the CNT @ BC composite film are not greatly changed; as the loading concentration of the CNT increases, the conductivity of the CNT @ BC composite film also increases.

As shown in fig. 9, fig. 10, fig. 11, fig. 12, and fig. 13, the process optimization of the Cu/CNT @ BC nanocomposite electrode preparation process includes optimization of the molar concentration ratio of copper ions to the reducing agent (CV diagram), the immersion time (LSV diagram), the reaction temperature (LSV diagram), the reaction time (conductivity bar diagram), and the molar concentration ratio of copper ions to the stabilizer (CV diagram). From the figure, the current density with the molar concentration ratio of copper ions to the reducing agent of 4:3 is the maximum; the current density is maximum when the dipping time is 48h, and the peak potential is maximum; the reaction time is 90min, and the conductivity is maximum; the current densities at the reaction temperature of 60 ℃ and 90 ℃ are basically the same; the current density with the molar concentration ratio of copper ions to the stabilizer being 1:1 is the maximum; note: wherein the dipping time is the oscillation dipping time in the step (3); the reaction temperature is the temperature of the water bath in the step (4); the reaction time is the water bath reaction time in the step (4).

As shown in fig. 19, the results show that the electrochemical activity specific surface area of the Cu/CNT @ BC composite electrode is the largest, and the electrochemical activity specific surface area of the Cu @ carbon cloth electrode is the smallest, which indicates that the BC with the 3D nano-network structure is beneficial to increase the electrochemical activity specific surface area of the catalyst and has higher catalytic efficiency compared with the conventional carbon cloth electrode; meanwhile, the Cu/CNT @ BC composite electrode subjected to in-situ reduction is more compact in composition with a catalyst than a Cu @ carbon cloth electrode substrate material prepared by a coating method, so that the Cu/CNT @ BC composite electrode has longer electrode life.

Example 2

The silver-based electrode for electrochemical catalysis in the embodiment is composed of a CNT @ BC composite membrane loaded nano-copper electrode which is dynamically cultured in situ, the electrode is synthesized by an in situ catalytic reduction method, and the preparation method comprises the following steps:

(1) using acetobacter xylinum as a strain, adding 200mL of mixed solution of a carbon nano tube and a culture medium with the concentration of 0.1M into a horizontal rotary drum reactor, adding two drops of Tween 80 serving as a dispersing agent by using a rubber head dropper, uniformly mixing, and culturing for 24 hours. Continuously adding 200ml of 0.1M CNT and fermentation liquor mixed culture medium into a glass fermentation tank through a peristaltic pump in an aseptic working platform, and carrying out subsequent fermentation for 24 h. And (3) taking out the CNT @ BC composite membrane, placing the CNT @ BC composite membrane in a sodium hydroxide solution, treating the CNT @ BC composite membrane for 2-4h at 80 ℃, taking out the CNT @ BC composite membrane, and rinsing the CNT @ BC composite membrane to be neutral by using deionized water to obtain the CNT @ BC composite membrane.

(3) Weighing 0.1M AgNO₃(AR, national medicine group reagent Co., Ltd., the same below) was dissolved in 50mL of deionized water, sufficiently stirred and mixed well, and then placed in a volume of 1X 2cm²The CNT @ BC composite membrane is vibrated for 24 hours at the temperature of 30 ℃ in a water bath constant temperature oscillator.

(4) 0.5g NaOH and 0.88g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.14g NaBH₄Mixing thoroughly, adding dropwise into AgNO solution by constant flow pump at 70rpm₃In the CNT @ BC composite membrane in the solution, oscillating for 60min in a water bath constant temperature oscillator at 30 ℃, and thenWashing the membrane with deionized water and ethanol, and drying at 60 ℃ for 2h to obtain the Ag/CNT @ BC electrode (the molar concentration ratio of silver ions to a reducing agent is 4:3, the impregnation time is 24h, the reaction time is 60min, the reaction temperature is 30 ℃, and the molar concentration ratio of silver ions to a stabilizing agent is 1: 1).

As shown in fig. 3, which shows the macro-morphology of the dynamically cultured CNT @ BC composite film, it can be observed that both the inner and outer surfaces of the composite film exhibit a very smooth and uniform black color.

As shown in fig. 5, which is a SEM image of a dynamically cultured 0.1M CNT @ BC composite membrane, CNTs are woven into a BC network from the SEM image, each coarse fiber is spirally wound with a plurality of microfibers, and the CNTs are wrapped inside to form a rope-like structure and penetrate through each other to construct a CNT @ BC three-dimensional network structure.

Example 3

The copper-based electrode for electrochemical catalysis in the embodiment is composed of a CNT @ BC composite membrane loaded nano-copper electrode which is subjected to immersion culture, the electrode is synthesized by an in-situ catalytic reduction method, and the preparation method comprises the following steps:

(1) using acetobacter xylinum as a strain, performing static culture for 2-4 days to prepare a bacterial cellulose pure film, taking out the pure film, placing the pure film into a sodium hydroxide solution, treating the pure film at 80 ℃ for 2-4 hours, taking out the pure film, and rinsing the pure film with deionized water to be neutral to obtain the pure BC film.

(2) And (3) dynamically dipping the BC pure film by using a carbon nano tube aqueous solution with the concentration of 0.1M, dynamically oscillating in a constant temperature oscillator at 30 ℃ for 24h, and taking out to obtain the CNT @ BC composite film. The multi-wall carbon nano-tube can be dispersed for 30min by an ultrasonic probe of an ultrasonic cleaner or an ultrasonic crusher in advance, and two drops of surfactant can be dripped into aqueous solution to be used as dispersing agent, such as Tween 20, Tween 80, coated easy dispersing agent DS-195, DS-172, DS-194H, cationic surfactant cetyl dimethyl ammonium bromide (CTAB), anionic surfactant Sodium Dodecyl Benzene Sulfonate (SDBS) and nonionic surfactant polyethylene glycol octyl phenyl ether (Triton X-100).

(3) 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL deionized water, stirring, mixing, and adding into 1 × 2cm²And the CNT @ BC composite membrane is put in a water bath constant temperature oscillatorShaking at 30 deg.C for 48 h.

(4) 0.5g NaOH and 0.44g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.19g NaBH₄The components are fully mixed, and are dripped into a CNT @ BC composite membrane soaked in a copper sulfate solution through a constant flow pump at 70rpm, the mixture is vibrated for 60min in a water bath constant temperature oscillator at 30 ℃, then the membrane is washed by deionized water and ethanol, and the membrane is dried for 2h at 60 ℃ to obtain a Cu/CNT @ BC electrode (the molar concentration ratio of copper ions to a reducing agent is 4:4, the soaking time is 48h, the reaction time is 60min, the reaction temperature is 30 ℃, and the molar concentration ratio of the copper ions to a stabilizing agent is 2: 1).

As shown in fig. 14, the reduced catalyst particles were smaller and more uniform after addition of ascorbic acid.

Example 4

The copper-based electrode for electrochemical catalysis in the embodiment is composed of a porous CNT @ BC composite membrane loaded nano-copper electrode, the electrode is synthesized by an aqueous solution chemical reduction method, and the preparation method comprises the following steps:

(2) And (3) shearing the prepared BC pure film by using scissors, putting the BC pure film into a high-speed homogenizer to obtain BC homogenate, adding the same amount of CNT powder, uniformly mixing, and performing suction filtration to form the film.

(3) 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL deionized water, stirring, mixing, and adding into 1 × 2cm²The CNT @ BC composite membrane is vibrated for 48 hours at the temperature of 30 ℃ in a water bath constant temperature oscillator.

(4) 0.5g NaOH and 1.76g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.13g KBH₄(97 wt%, national drug group reagents Co., Ltd., the same below) were mixed thoroughly, and the mixture was added dropwise to a CNT @ BC composite membrane immersed in a copper sulfate solution by a constant flow pump at 70rpm, and oscillated in a water bath constant temperature oscillator at 30 ℃ for 30min, and then deionized water and deionized water were addedWashing the membrane with ethanol, and drying at 60 ℃ for 2h to obtain the Cu/CNT @ BC electrode (4:2-48h-30min-30 ℃). (the molar concentration ratio of the copper ions to the reducing agent is 4: 2; the immersion time is 48 h; the reaction time is 30 min; the reaction temperature is 30 ℃, and the molar concentration ratio of the copper ions to the stabilizing agent is 1: 2).

Shown in FIG. 16 as Cu/CNT/@ BC_KBH4The it and Faraday efficiency of the electrode are combined and plotted for a long time, and Cu/CNT @ BC is shown_KBH4The tendency of the current density course of the electrode to decrease first and then increase as the electrolysis time increases, and FE of the electrode at the beginning of the electrolysis_COAnd FE_C2H4Are all small and have FE's with increasing electrolysis time_COAnd FE_C2H4Gradually increase of CO thereof₂The electrochemical reduction performance also gradually increases.

Example 5

The copper-based electrode for electrochemical catalysis in the embodiment is composed of a nano copper electrode loaded with a PPy @ BC composite film obtained by an in-situ polymerization method, the electrode is synthesized by an in-situ catalytic reduction method, and the preparation method comprises the following steps:

(2) Cutting the purified BC membrane into 1 × 2cm²The membrane was placed on a water-absorbent filter paper, a small amount of free water was removed from the BC membrane, and the BC membrane was put into a 150ml notched bottle containing 0.1M pyrrole monomer (chemical purity, national drug group chemical reagents Co., Ltd., the same below) and reacted for 2 hours under magnetic stirring, so that the BC membrane sufficiently adsorbed the pyrrole monomer. Subsequently 15ml FeCl containing 0.1M concentration were added dropwise₃(CP, not less than 97.0%, national drug group chemical reagent Co., Ltd., the same below) solution, reacting for 2h under ice water bath condition, polymerizing pyrrole on the surface of BC membrane, and uniformly coating on BC fiber. And (3) cleaning the membrane by using 75% (v/v) ethanol and distilled water to obtain the PPy @ BC composite membrane.

(3) 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL deionized water, stirring, mixing, and adding into 1 × 2cm²The PPy @ BC composite membrane is combinedOscillating for 24h in a water bath constant temperature oscillator at 30 ℃.

(4) 0.5g NaOH and 1.76g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.20g KBH₄The materials are fully mixed, the mixture is dripped into a PPy @ BC composite membrane soaked in a copper sulfate solution through a constant flow pump at 70rpm, the mixture is vibrated for 60min in a water bath constant temperature oscillator at 30 ℃, then the membrane is washed by deionized water and ethanol, and the membrane is dried for 2h at 60 ℃ to obtain a Cu/PPy @ BC electrode (the molar concentration ratio of copper ions to a reducing agent is 4:3, the soaking time is 24h, the reaction time is 60min, the reaction temperature is 30 ℃, and the molar concentration ratio of silver ions to a stabilizing agent is 1: 2).

Fig. 7 shows a microscopic SEM image of the PPy @ BC composite membrane obtained by in-situ polymerization, which shows that after adding PPy, the three-dimensional network structure of BC is better preserved, and the diameter of the fiber of PPy @ BC composite membrane is increased.

Example 6

The silver-based electrode for electrochemical catalysis in the embodiment is composed of a nano copper electrode loaded on a PANI @ BC composite membrane obtained by an in-situ polymerization method, the electrode is synthesized by an in-situ catalytic reduction method, and the preparation method comprises the following steps:

(2) Cutting the purified BC membrane into 1 × 2cm²Placing on a water absorption filter paper, removing a small amount of free water of a BC membrane, putting the BC membrane into a 150ml cut bottle containing aniline monomer (AR ≥ 99.5%, national drug group chemical reagent, Inc., the same below) with the concentration of 0.1M, and reacting for 2h under the action of magnetic stirring to enable the BC membrane to fully adsorb the aniline monomer. Subsequently 15ml FeCl containing 0.1M concentration were added dropwise₃And (3) reacting the solution for 2 hours under the ice-water bath condition to ensure that the aniline is polymerized on the surface of the BC membrane and uniformly coated on the BC fiber. And (3) cleaning the membrane by using 75% (v/v) ethanol and distilled water to obtain the PANI @ BC composite membrane.

(3) Weighing 0.1M AgNO₃Dissolving in 50mL deionized water, fillingStirring, mixing, and placing into a container of 1 × 2cm²The PANI @ BC composite membrane is oscillated for 12 hours in a water bath constant temperature oscillator at the temperature of 30 ℃.

(4) 0.5g NaOH and 1.76g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.14g NaBH₄Mixing thoroughly, adding dropwise into AgNO solution by constant flow pump at 70rpm₃In the PANI @ BC composite membrane in the aqueous solution, oscillating for 60min in a water bath constant temperature oscillator at 30 ℃, washing the membrane with deionized water and ethanol, and drying for 2h at 60 ℃ to obtain the Ag/PANI @ BC electrode (the molar concentration ratio of silver ions to a reducing agent is 4:3, the impregnation time is 12h, the reaction time is 60min, the reaction temperature is 30 ℃, and the molar concentration ratio of the silver ions to a stabilizing agent is 1: 2).

Example 7

The copper-based electrode for electrochemical catalysis in the embodiment is composed of a CNT @ BC composite film loaded nano-copper electrode obtained by an impregnation method, the electrode is synthesized by an in-situ catalytic reduction method, and the preparation method comprises the following steps:

(2) The BC film obtained was cut into 1X 2cm²Prefreezing with liquid nitrogen, and freeze drying at 40 deg.C for 48 hr. And after the freeze drying is finished, soaking the carbon nano tube into 50mL of aqueous solution containing 0.1M of carbon nano tube, dynamically oscillating the carbon nano tube in a constant temperature oscillator at 30 ℃ for 24 hours, and taking the carbon nano tube out to obtain the CNT @ BC composite membrane.

(4) 0.5g NaOH and 0.88g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.14g NaBH₄Fully mixing, dripping into a CNT @ BC composite membrane immersed in a copper sulfate solution through a constant flow pump at 70rpm, and carrying out water bath at 30 DEG COscillating for 60min in a constant temperature oscillator, washing the membrane with deionized water and ethanol, and drying for 2h at 60 ℃ to obtain the Cu/CNT @ BC electrode (the molar concentration ratio of copper ions to a reducing agent is 4:3, the immersion time is 48h, the reaction time is 60min, the reaction temperature is 30 ℃, and the molar concentration ratio of copper ions to a stabilizing agent is 1: 1).

Example 8

The copper-based electrode for electrochemical catalysis in the embodiment is composed of a PPy @ BC composite membrane loaded nano-copper electrode which is dynamically cultured in situ, the electrode is synthesized by an in situ catalytic reduction method, and the preparation method comprises the following steps:

(1) acetobacter xylinum is taken as a strain, and a 400mL culture medium is added into a horizontal rotary drum reactor in a sterile workbench for culture for 2-3 days. And taking out the pure BC membrane, placing the pure BC membrane in a sodium hydroxide solution, treating the pure BC membrane for 2-4h at 80 ℃, taking out the pure BC membrane, and rinsing the pure BC membrane to be neutral by using deionized water to obtain the pure BC membrane.

(2) Cutting the BC pure membrane cultured dynamically into 1 × 2cm²Placing on a water absorption filter paper, removing a small amount of free water of the BC membrane, putting the BC membrane into a 150ml cut bottle containing pyrrole monomer with the concentration of 0.1M, and reacting for 2h under the action of magnetic stirring to ensure that the BC membrane fully adsorbs the pyrrole monomer. Subsequently 15ml FeCl containing 0.1M concentration were added dropwise₃And (3) reacting the solution for 2 hours under the ice-water bath condition to ensure that the pyrrole is polymerized on the surface of the BC membrane and uniformly coated on the BC fiber. And (3) cleaning the membrane by using 75% (v/v) ethanol and distilled water to obtain the dynamically cultured PPy @ BC composite membrane.

(3) 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL deionized water, stirring, mixing, and adding into 1 × 2cm²The PPy @ BC composite membrane is oscillated for 48 hours in a water bath constant temperature oscillator at the temperature of 30 ℃.

(4) 0.5g NaOH and 1.76g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.14g NaBH₄Fully mixing, dropwise adding the mixture into a PPy @ BC composite membrane soaked in a copper sulfate solution through a constant flow pump at 70rpm, oscillating the mixture in a water bath constant temperature oscillator at 30 ℃ for 30min, washing the membrane with deionized water and ethanol, and drying the membrane at 60 ℃ for 2h to obtain a Cu/PPy @ BC electrode (molar concentration ratio of copper ions to a reducing agent)Examples are 4: 3; the dipping time is 48 h; the reaction time is 30 min; the reaction temperature is 30 ℃; the molar concentration ratio of the copper ions to the stabilizer is 1: 2. ).

Example 9

The copper-based electrode for electrochemical catalysis in the embodiment is composed of a nano copper electrode loaded on a PANI @ BC composite membrane through dynamic in-situ culture, the electrode is synthesized through an in-situ catalytic reduction method, and the preparation method comprises the following steps:

(2) Cutting the BC pure membrane cultured dynamically into 1 × 2cm²Placing on a water absorption filter paper, removing a small amount of free water of the BC membrane, putting the BC membrane into a 150ml aniline monomer cut bottle with the concentration of 0.1M, and reacting for 2h under the action of magnetic stirring to ensure that the BC membrane fully adsorbs the aniline monomer. Subsequently 15ml FeCl containing 0.1M concentration were added dropwise₃And (3) reacting the solution for 2 hours under the ice-water bath condition to ensure that the aniline is polymerized on the surface of the BC membrane and uniformly coated on the BC fiber. And (3) cleaning the membrane by using 75% (v/v) ethanol and distilled water to obtain the dynamically cultured PANI @ BC composite membrane.

(3) 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL deionized water, stirring, mixing, and adding into 1 × 2cm²The PANI @ BC composite membrane is oscillated for 48 hours in a water bath constant temperature oscillator at the temperature of 30 ℃.

(4) 0.5g NaOH and 1.76g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.14g NaBH₄The mixed solution is fully mixed, the mixed solution is dripped into a PANI @ BC composite membrane soaked in a copper sulfate solution through a constant flow pump at 70rpm, the mixed solution is vibrated for 90min in a water bath constant temperature oscillator at 30 ℃, then the membrane is washed by deionized water and ethanol, and the washed membrane is dried for 2h at 60 ℃ to obtain a Cu/PANI @ BC electrode (the molar concentration ratio of copper ions to a reducing agent is 4:3, the soaking time is 48h, the reaction time is 90min, the reaction temperature is 30 ℃, and the molar concentration ratio of the copper ions to a stabilizing agent is 1: 2).

Example 10

The copper-based electrode for electrochemical catalysis consists of a CNT @ BC composite membrane loaded nano-copper electrode which is statically cultured in situ, the electrode is synthesized by an in situ catalytic reduction method, and the preparation method comprises the following steps:

(1) the method comprises the steps of taking acetobacter xylinum as a strain, adding a carbon nano tube with the concentration of 0.1M, standing in situ for constant temperature culture for 2-3 days, taking out the CNT @ BC composite membrane, placing the CNT @ BC composite membrane in a sodium hydroxide solution, treating at 80 ℃ for 2-4 hours, taking out, rinsing with deionized water to be neutral, and obtaining the CNT @ BC composite membrane.

(2) 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL of 70% ethanol solution (15mL of deionized water +35mL of ethanol), stirring, mixing, and adding into 1 × 2cm²The CNT @ BC composite membrane is vibrated for 48 hours at the temperature of 30 ℃ in a water bath constant temperature oscillator.

(3) Dissolving 0.5g NaOH in 12.5mL deionized water, ice-cooling, stirring thoroughly, adding 0.14g NaBH₄The components are fully mixed, and are dripped into a CNT @ BC composite membrane soaked in a copper sulfate solution through a constant flow pump at 70rpm, the mixture is vibrated for 90min in a water bath constant temperature oscillator at 30 ℃, then the membrane is washed by deionized water and ethanol, and the membrane is dried for 2h at 60 ℃ to obtain a Cu/CNT @ BC electrode (the molar concentration ratio of copper ions to a reducing agent is 4:3, the soaking time is 48h, the reaction time is 90min, the reaction temperature is 30 ℃ and ethanol).

(4) CO is carried out on the prepared Cu/CNT @ BC electrode at different potentials₂Electrochemical testing, collecting CO therefrom₂The product was electrochemically reduced, the product was measured, and the faradaic efficiency was calculated to obtain fig. 17.

Shown in FIG. 15 is Cu/CNT/@ BC_NaBH4It plot of electrodes at different voltages, showing Cu/CNT @ BC as the potential increases_NaBH4The current density of the electrode also gradually increases, and the two show positive correlation.

Shown in FIG. 17 as Cu/CNT/@ BC_NaBH4The Faraday efficiency diagram of the electrode under different voltages can be obtained from the diagram, the hydrogen evolution reaction is continuously reduced along with the increase of the potential, the higher overpotential in the reaction process is also continuously reduced, and the reaction products CO and C₂H₄Is continuously increased in the conversion rate of CO₂The utilization rate and the conversion rate of (a) are gradually increased. This indicates that the reaction is carried out with NaBH₄The electrode prepared for the reducing agent has the advantages of increased contact specific surface area of carbon dioxide and catalyst, increased catalytic active sites and CO₂The utilization rate and the conversion rate are higher. Cu/CNT/@ BC_NaBH4Electrode pair H at different voltages₂、CO、C₂H₄The two products have different selectivities, the hydrogen evolution reaction is reduced along with the increase of the voltage, and the product H₂The content of (A) is reduced; as the voltage increases, product C₂H₄The content of (A) is obviously increased; the CO content of the product is 1.5-1.91V_RHEGradually increased under voltage at 1.5V_RHEThe maximum value is reached.

Shown in FIG. 18 is Cu/CNT @ BC_KBH4And Cu/CNT @ BC_NaBH4Shows the influence of the reducing agent species on the electrochemically active specific surface area as NaBH₄The specific surface area of the electrode prepared by the reducing agent is larger than KBH₄An electrode prepared for a reducing agent.

Shown in FIG. 23 is Cu/CNT @ BC_KBH4And Cu/CNT @ BC_NaBH4From the SEM micrographs, it can be seen that copper-based electrocatalysts prepared with different reducing agents have different micro-morphologies, Cu/CNT @ BC_NaBH4The copper catalyst in the electrode has two morphologies, with the plate-like dendritic catalyst having a higher surface area, i.e., having more CO₂Catalytic reduction of active sites, and Cu/CNT @ BC_KBH4The electrode does not exhibit such morphology.

Table 1 shows that the voltage is 1.5V_RHECu/CNT @ BC at voltage_KBH4And Cu/CNT @ BC_NaBH4The faraday efficiencies and catalytic products of (a) can be seen in fig. 23 and table 1, and more CO can be obtained by effectively regulating and controlling the electrode preparation conditions₂A catalytic reduction active site. Thereby improving the catalytic activity of the catalyst and the selectivity of catalytic products and improving the Faraday efficiency of the products.

TABLE 1 Cu/CNT @ BC_KBH4And Cu/CNT @ BC_NaBH4And its Faraday efficiency

Example 11

The copper-based electrode for electrochemical catalysis consists of a porous CNT @ BC composite membrane loaded nano copper electrode, is synthesized by an aqueous solution chemical reduction method, and is prepared by the following steps:

(2) And (3) dynamically dipping the BC pure film by using a carbon nano tube solution with the concentration of 0.1M, dynamically oscillating in a constant temperature oscillator at 30 ℃ for 24 hours, and taking out to obtain the CNT @ BC composite film.

(3) 0.1M CuCl was weighed₂(99%, national pharmaceutical group chemical reagent Co., Ltd., the same below) was dissolved in 50mL of 70% ethanol solution (15mL of deionized water +35mL of ethanol), stirred well, mixed well, and placed in a 1X 2cm cell²The CNT @ BC composite membrane is vibrated for 24 hours at the temperature of 30 ℃ in a water bath constant temperature oscillator.

(4) Dissolving 0.5g NaOH in 12.5mL deionized water, ice-cooling, stirring thoroughly, adding 0.14g NaBH₄Fully mixing, dropwise adding the mixture into a CNT @ BC composite membrane soaked in a copper chloride solution through a constant flow pump at 70rpm, oscillating the mixture in a water bath constant temperature oscillator at 30 ℃ for 60min, washing the membrane with deionized water and ethanol, and drying the membrane at 60 ℃ for 2h to obtain a Cu/CNT @ BC electrode (4:3-24h-60min-30 ℃ -ethanol). (the molar concentration ratio of the copper ions to the reducing agent is 4: 3; the immersion time is 24 h; the reaction time is 60 min; the reaction temperature is 30 ℃; ethanol).

Example 12

The copper-based electrode for electrochemical catalysis consists of a porous PPy/CNT @ BC composite membrane loaded nano-copper electrode, the electrode is synthesized by an aqueous solution chemical reduction method, and the preparation method comprises the following steps:

(2) Using acetobacter xylinum as a strain, performing static culture for 2-4 days to prepare a bacterial cellulose pure film, taking out the pure film, placing the pure film into a sodium hydroxide solution, treating the pure film at 80 ℃ for 2-4 hours, taking out the pure film, and rinsing the pure film with deionized water to be neutral to obtain the pure BC film.

(3) Cutting the purified BC membrane into 1 × 2cm²The membrane was placed on a water-absorbent filter paper, a small amount of free water was removed from the BC membrane, and the BC membrane was put into a 150ml notched bottle containing 0.1M pyrrole monomer (chemical purity, national drug group chemical reagents Co., Ltd., the same below) and reacted for 2 hours under magnetic stirring, so that the BC membrane sufficiently adsorbed the pyrrole monomer. Subsequently 15ml FeCl containing 0.1M concentration were added dropwise₃(CP, not less than 97.0%, national drug group chemical reagent Co., Ltd., the same below) solution, reacting for 2h under ice water bath condition, polymerizing pyrrole on the surface of BC membrane, and uniformly coating on BC fiber. And (3) cleaning the membrane by using 75% (v/v) ethanol and distilled water to obtain the PPy @ BC composite membrane.

(4) Adopting a carbon nano tube with the concentration of 0.05M, obtaining the CNT @ BC composite film cultured in situ in the rest step (1), and then cutting the CNT @ BC composite film cultured in situ into 1 multiplied by 2cm²Placing the film on absorbent filter paper, removing a small amount of free water of the CNT @ BC composite film, putting the film into a 150ml cut bottle containing pyrrole monomers with the concentration of 0.05M, and reacting for 2 hours under the action of magnetic stirring to ensure that the CNT @ BC composite film fully adsorbs the pyrrole monomers. Subsequently 15ml FeCl containing 0.1M concentration were added dropwise₃And (3) reacting the solution for 2 hours under the ice-water bath condition, so that pyrrole is polymerized on the surface of the BC membrane and uniformly coated on the CNT @ BC composite membrane. And (3) cleaning the membrane by using 75% (v/v) ethanol and distilled water to obtain the dynamically cultured PPy/CNT @ BC composite membrane.

Adopting a carbon nano tube with the concentration of 0.05M and the rest conditions are the same as the step (1) to obtain the CNT @ BC composite film cultured in situ, and then cutting the CNT @ BC composite film cultured in situ into 1 multiplied by 2cm²Placing on water-absorbing filter paper, removing a small amount of free water of CNT @ BC composite membrane, placing the BC membrane into a 150ml aniline monomer incision bottle with 0.05M concentrationAnd reacting for 2 hours under the action of magnetic stirring to ensure that the BC film fully adsorbs aniline monomers. Subsequently 15ml FeCl containing 0.1M concentration were added dropwise₃And (3) reacting the solution for 2 hours under the ice-water bath condition to ensure that the aniline is polymerized on the surface of the BC membrane and uniformly coated on the BC fiber. And (3) cleaning the membrane by using 75% (v/v) ethanol and distilled water to obtain the dynamically cultured PANI/CNT @ BC composite membrane.

0.1M CuCl was weighed₂Dissolving in 50mL of 70% ethanol solution (15mL of deionized water +35mL of ethanol), stirring, mixing, and adding into 1 × 2cm²The PPy/CNT @ BC and PANI/CNT @ BC composite membrane is oscillated for 24 hours in a water bath constant temperature oscillator at the temperature of 30 ℃.

Dissolving 0.5g NaOH in 12.5mL deionized water, ice-cooling, stirring thoroughly, adding 0.14g NaBH₄Fully mixing, dropwise adding the mixture into a PPy/CNT @ BC and PANI/CNT @ BC composite membrane soaked in a copper chloride solution through a constant flow pump at 70rpm, oscillating the mixture in a water bath constant temperature oscillator at 30 ℃ for 60min, washing the membrane with deionized water and ethanol, and drying the membrane at 60 ℃ for 2h to obtain a Cu/PPy/CNT @ BC and a Cu/PANI/CNT @ BC electrode (4:3-24h-60 min-30-ethanol). (the molar concentration ratio of the copper ions to the reducing agent is 4: 3; the immersion time is 24 h; the reaction time is 60 min; the reaction temperature is 30 ℃ and ethanol).

Weighing 0.1M AgNO₃Dissolving in 50mL of 70% ethanol solution (15mL of deionized water +35mL of ethanol), stirring, mixing, and adding into 1 × 2cm²The PPy/CNT @ BC and PANI/CNT @ BC composite membrane is oscillated for 24 hours in a water bath constant temperature oscillator at the temperature of 30 ℃.

Dissolving 0.5g NaOH in 12.5mL deionized water, ice-cooling, stirring thoroughly, adding 0.14g NaBH₄Fully mixing, dropwise adding the mixture into a PPy/CNT @ BC and PANI/CNT @ BC composite membrane soaked in a silver nitrate solution through a constant flow pump at 70rpm, oscillating the mixture in a water bath constant temperature oscillator at 30 ℃ for 60min, washing the membrane with deionized water and ethanol, and drying the membrane at 60 ℃ for 2h to obtain an Ag/PPy/CNT @ BC and an Ag/PANI/CNT @ BC electrode (4:3-24h-60min-30 ℃ -ethanol). (the molar concentration ratio of the copper ions to the reducing agent is 4: 3; the immersion time is 24 h; the reaction time is 60 min; the reaction temperature is 30 ℃ and ethanol).

FIG. 6 shows that A is the flexibility of the PPy/CNT @ BC composite film and B is the flexibility of the PPy @ BC composite film, which indicates that the flexibility of the PPy @ BC composite film is increased by the CNT.

As shown in Table 2, the conductivities of the composite membranes BC, CNT @ BC (step 1), PPy @ BC (step 3) and PPy/CNT @ BC (step 4) are higher than those of the composite membranes PPy/CNT @ BC and PPy @ BC.

TABLE 2 conductivity of BC, CNT @ BC, PPy/CNT @ BC composite films

Example 13

The silver-based electrode for electrochemical catalysis in the embodiment is composed of a carbon powder @ BC composite membrane loaded nano-copper electrode for dynamic in-situ culture, the electrode is synthesized by an in-situ catalytic reduction method, and the preparation method comprises the following steps:

(1) acetobacter xylinum is taken as a strain, 200mL of a mixed solution of carbon powder (20-50 microns, 10g, Shanghai Yihui potential) with the concentration of 0.1M and a culture medium is added into a horizontal rotary drum reactor, two drops of Tween 80 are added into a rubber head dropper to serve as a dispersing agent, and the mixture is uniformly mixed and cultured for 24 hours. Continuously adding 200ml of 0.1M carbon powder and fermentation liquor mixed culture medium into a glass fermentation tank through a peristaltic pump in an aseptic working platform, and carrying out subsequent fermentation for 24 h. And (3) taking out the carbon powder @ BC composite membrane, placing the carbon powder @ BC composite membrane in a sodium hydroxide solution, treating the carbon powder @ BC composite membrane for 2-4h at 80 ℃, taking out the composite membrane, and rinsing the composite membrane to be neutral by using deionized water to obtain the carbon powder @ BC composite membrane.

(3) 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL deionized water, stirring, mixing, and adding into 1 × 2cm²The carbon powder @ BC composite membrane is oscillated for 24 hours in a water bath constant temperature oscillator at the temperature of 30 ℃.

(4) 0.5g NaOH and 0.88g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.14g NaBH₄Mixing thoroughly, adding dropwise into CuSO under constant flow pump at 70rpm₄·5H₂Carbon powder in O solution @ BC composite membrane and water at 30 DEG COscillating for 60min in a bath constant temperature oscillator, washing the membrane with deionized water and ethanol, and drying for 2h at 60 ℃ to obtain the Cu/carbon powder @ BC electrode (the molar concentration ratio of copper ions to a reducing agent is 4:3, the immersion time is 24h, the reaction time is 60min, the reaction temperature is 30 ℃, and the molar concentration ratio of copper ions to a stabilizing agent is 1: 1).

Comparative example 1

(1) Acetobacter xylinum is taken as a strain, 200mL of mixed solution of carbon powder and culture medium with the concentration of 0.1M is added into a horizontal rotary drum reactor, and the culture is carried out for 24 h. Continuously adding 200ml of 0.1M carbon powder and fermentation liquor mixed culture medium into a glass fermentation tank through a peristaltic pump in an aseptic working platform, and carrying out subsequent fermentation for 24 h. And (3) taking out the carbon powder @ BC composite membrane, placing the carbon powder @ BC composite membrane in a sodium hydroxide solution, treating the carbon powder @ BC composite membrane for 2-4h at 80 ℃, taking out the composite membrane, and rinsing the composite membrane to be neutral by using deionized water to obtain the carbon powder @ BC composite membrane.

(2) 0.1M of CuSO was weighed₄·5H₂Dissolving O in 50mL deionized water, stirring, mixing, and adding into 1 × 2cm²The carbon powder @ BC composite membrane is oscillated for 24 hours in a water bath constant temperature oscillator at the temperature of 30 ℃.

(3) 0.5g NaOH and 1.76g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.14g NaBH₄Mixing thoroughly, adding dropwise into CuSO under constant flow pump at 70rpm₄·5H₂And (2) oscillating the carbon powder @ BC composite membrane in the O solution for 60min in a water bath constant-temperature oscillator at 30 ℃, washing the membrane by using deionized water and ethanol, and drying for 2h at 60 ℃ to obtain the Cu/carbon powder @ BC electrode (the molar concentration ratio of copper ions to a reducing agent is 4:3, the impregnation time is 24h, the reaction time is 60min, the reaction temperature is 30 ℃, and the molar concentration ratio of the copper ions to a stabilizing agent is 1: 2).

(4) According to a carbon dioxide electrochemical reduction catalyst in Chinese patent CN108654623A, a preparation method thereof and a gas diffusion electrode loaded with the catalyst, 2mmol of copper chloride dihydrate and 8mmol of nickel chloride hexahydrate are dissolved in 40mL of deionized water in a beaker, 5mL of concentrated ammonia water is dissolved in 45mL of deionized water, the solution is dropwise added into the beaker until the pH value is 9, the solution is stirred for 4 hours, the solution is centrifugally separated, washed to be neutral by deionized water and absolute ethyl alcohol, and the solution is dried in a drying oven at 60 ℃ to obtain solid powder. And grinding the powder, and then putting the powder into a tubular furnace to heat in the air at 350 ℃ for 3h to obtain the nickel-copper sheet layer double metal oxide (the molar ratio of NiO to CuO is 8:2) serving as the carbon dioxide electrochemical reduction catalyst. Dispersing 5mg of the obtained catalyst into 950 mu L of absolute ethyl alcohol, adding 50 mu L of 5 wt% Nafion solution, performing ultrasonic dispersion for 5 hours to obtain a mixed solution, coating 10 mu L of the mixed solution on carbon cloth with the diameter of 4mm, and drying to obtain the gas diffusion electrode loaded with the carbon dioxide electrochemical reduction catalyst.

FIG. 21 is a LSV diagram of the electrodes of Ni-Cu @ carbon cloth (8:2) and Cu/carbon powder @ BC in comparative example 1, from which the current density of the Cu/carbon powder @ BC electrode is higher than that of the Ni-Cu @ carbon cloth (8:2) electrode; the peak potential of the Cu/carbon powder @ BC electrode is greater than that of a nickel-copper @ carbon cloth (8:2) electrode, which shows that the Cu/carbon powder @ BC electrode prepared by the method has higher electrochemical performance.

Comparative example 2

(2) Weighing 0.1M AgNO₃Dissolving in 50mL deionized water, stirring, mixing, and adding into 1 × 2cm²The carbon powder @ BC composite membrane is oscillated for 24 hours in a water bath constant temperature oscillator at the temperature of 30 ℃.

(3) 0.5g NaOH and 1.76g L-ascorbic acid were dissolved in 12.5mL deionized water, ice-bathed, stirred well and added with 0.14g NaBH₄Mixing thoroughly, adding dropwise into AgNO solution by constant flow pump at 70rpm₃Oscillating the carbon powder @ BC composite membrane in the solution for 60min in a water bath constant temperature oscillator at 30 ℃, washing the membrane by deionized water and ethanol, and drying for 2h at 60 ℃ to obtain the Ag/carbon powder @ BC electrode (the molar concentration ratio of silver ions to a reducing agent is 4:3, and the impregnation time is 2: 2)4h, 60min of reaction time, 30 ℃ of reaction temperature and 1:2 of molar concentration ratio of silver ions to the stabilizer).

(4) According to the carbon dioxide electrochemical reduction catalyst in the Chinese patent CN108654623A, the preparation method thereof and the gas diffusion electrode loaded with the catalyst, 9mmol of copper chloride dihydrate and 1mmol of nickel chloride hexahydrate are dissolved in 40mL of deionized water in a beaker, 5mL of concentrated ammonia water is dissolved in 45mL of deionized water, the mixture is dropwise added into the beaker until the pH value is 14, the mixture is stirred for 4 hours, the centrifugal separation is carried out, the mixture is washed to be neutral by the deionized water and absolute ethyl alcohol, and the mixture is dried in a drying box at 60 ℃ to obtain solid powder. And grinding the powder, and then putting the powder into a tube furnace to heat in the air at 750 ℃ for 3h to obtain the nickel-copper sheet layer double metal oxide (the molar ratio of NiO to CuO is 1:9) serving as the carbon dioxide electrochemical reduction catalyst. Dispersing 5mg of the obtained catalyst into 950 mu L of absolute ethyl alcohol, adding 50 mu L of 5 wt% Nafion solution, performing ultrasonic dispersion for 5 hours to obtain a mixed solution, coating 10 mu L of the mixed solution on carbon paper with the diameter of 4mm, and drying to obtain the gas diffusion electrode loaded with the carbon dioxide electrochemical reduction catalyst.

Fig. 22 shows CV graphs of the nickel copper @ carbon paper (1:9) and the Ag/carbon powder @ BC electrode in comparative example 2, and the result also shows that the Ag/carbon powder @ BC electrode prepared by the invention has higher current density.

FIG. 20 shows the LSV plots of the composite films of Cu/CNT @ BC (example 1), Cu/PPy @ BC (example 5), Cu/PANI @ BC (example 9), Cu/PANI/CNT @ BC (example 12), Ag/CNT @ BC (example 2), Ag/PPy @ BC (comparative example 2), Ag/PANI @ BC (example 6), and Ag/PANI/CNT @ BC (example 12), indicating that the current density of the composite films is maximized, and the more conductive material combined with BC the composite electrode the greater the current density, the better the electrochemical performance of the metallic silver catalyst over the metallic copper catalyst.

The conductivity of the composite films, Cu/CNT @ BC (example 1), Cu/PPy @ BC (example 5), Cu/PANI @ BC (example 9), Cu/PANI/CNT @ BC (example 12), Ag/CNT @ BC (example 2), Ag/PPy @ BC (comparative example 2), Ag/PANI @ BC (example 6), and Ag/PANI/CNT @ BC (example 12), is also shown in Table 3, where the conductivity of the composite films is better for metallic silver than for metallic copper, and BC is compounded with a conductive material, in the following order: Cu/CNT @ BC < Ag/PPy @ BC < Cu/PPy @ BC < Cu/PANI @ BC < Ag/CNT @ BC < Cu/PANI/CNT @ BC < Ag/PANI @ BC < Ag/PANI/CNT @ BC.

TABLE 3 conductivity of Cu/CNT @ BC, Cu/PPy @ BC, Cu/PANI/CNT @ BC, Ag/PPy @ BC, Ag/PANI/CNT @ BC composite films

Table 4 shows the product selectivity (ethylene) of the composite films of comparative example 1 and comparative example 2, i.e., copper ion versus C, nickel copper @ carbon cloth (comparative example 1; 8:2), Cu/PPy @ BC (comparative example 1), nickel copper @ carbon paper (comparative example 2; 1:9), Ag/PPy @ BC (comparative example 2) at a reaction potential of 1.5V₂H₄The product of (1) has a selectivity in which Cu/PPy @ BC (comparative example 1) is coupled to C₂H₄The selectivity is optimal.

TABLE 4 reaction potential 1.5V, electrolyte 0.5M K₂HCO₃The selectivity of the composite membrane products (ethylene) of nickel copper @ carbon cloth (comparative example 1; 8:2), Cu/PPy @ BC (comparative example 1), nickel copper @ carbon cloth (comparative example 2; 1:9) and Ag/PPy @ BC (comparative example 2) under the conditions of (1).

Claims

1. The composite electrode material is characterized in that the electrode material is a bacterial cellulose/conductive material composite film with silver or copper nanoparticles loaded on the surface.

2. The electrode material as claimed in claim 1, wherein the electrode material has a porous structure; the conductive material is one or more of a low-dimensional carbon material LDC, polypyrrole PPy and polyaniline PANI; the bacterial cellulose is one or more of bacterial nano cellulose membrane, bacterial nano cellulose homogenate, bacterial nano cellulose flocculent fiber and sponge bacterial nano cellulose after freeze drying.

3. The electrode material of claim 2, wherein the low-dimensional carbon material LDC is one or more of Carbon Nanotube (CNT), graphene and carbon nanopowder.

4. A method of preparing a composite electrode material, comprising:

(1) immersing the bacterial cellulose/conductive material composite membrane into a copper-containing or silver ion aqueous solution, and carrying out oscillation immersion at the temperature of 30-90 ℃;

(2) and (2) under the ice-water bath condition, uniformly mixing sodium hydroxide, a stabilizer and a reducing agent to obtain a mixed solution, then adding the mixed solution into the copper or silver ion aqueous solution containing the composite membrane in the step (1), oscillating at the temperature of 30-90 ℃, and drying to obtain the electrochemical catalytic electrode.

5. The preparation method according to claim 4, wherein the bacterial cellulose/conductive material composite membrane in the step (1) is a 3D nano network structure; the copper ion-containing aqueous solution is a copper sulfate aqueous solution, a copper chloride aqueous solution or a copper nitrate solution; the silver ion-containing aqueous solution is silver nitrate aqueous solution; the concentration of the copper or silver ion-containing aqueous solution is 0.1-0.4M.

6. The method according to claim 4, wherein the shaking and dipping time in the step (1) is 12 to 48 hours.

7. The preparation method according to claim 4, wherein the stabilizer in the step (2) is one or more of L-ascorbic acid, ethanol and citric acid; the reducing agent is one or two of sodium borohydride and potassium borohydride; the concentration of the reducing agent in the mixed solution is 0.2-0.4M, the concentration of the sodium hydroxide is 1M, and the concentration of the stabilizing agent is 0.2-0.8M.

8. The method according to claim 4, wherein the shaking time in the step (2) is 30 to 90 min; the drying is carried out at 50-90 deg.C for 30-90 min.

9. The preparation method according to claim 4, wherein the molar concentration ratio of the copper or silver ions to the reducing agent is 4: 2-4: 4; the molar concentration ratio of the copper/silver ions to the stabilizer is 2: 1-2: 4.

10. Use of the composite electrode material of claim 1 in carbon dioxide electrocatalysis, fuel cells, photocatalysis or biocatalysis.