CN115821318A - Copper-based catalyst, copper-based catalytic electrode, preparation method of copper-based catalytic electrode and electrochemical electrolysis device - Google Patents
Copper-based catalyst, copper-based catalytic electrode, preparation method of copper-based catalytic electrode and electrochemical electrolysis device Download PDFInfo
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Abstract
The invention belongs to the technical field of electrochemical catalysis, and particularly relates to a copper-based catalyst, a copper-based catalytic electrode, a preparation method of the copper-based catalytic electrode and an electrochemical electrolysis device. The invention forms a new copper-based catalyst in a CO-rich environment, which contains a regulator metal element with larger atomic radius than copper besides copper, atoms of the regulator metal element are connected with copper crystal lattices in an atomic-level homogeneous blending mode through metal bonds, and most of the regulator metal element is distributed at the crystal boundary of the surface of the copper crystal lattices to form a copper-based catalyst component with rich defects, so that strong CO bonds and high surface CO coverage rate are realized on the surface of copper, thereby stabilizing OCCO dimer and promoting subsequent CO-OCCOH coupling to form C 3 The product effect improves the selectivity of single multi-carbon products in the electrochemical reduction reaction of carbon dioxide/carbon monoxide, and improves the reaction rate, the energy conversion efficiency and the reactant conversion rate.
Description
Technical Field
The invention belongs to the technical field of electrochemical catalysis, and particularly relates to a copper-based catalyst, a copper-based catalytic electrode, a preparation method of the copper-based catalytic electrode and an electrochemical electrolysis device.
Background
Carbon dioxide/carbon monoxide electrochemical reduction reaction (CO) 2 RR/CORR) is one of effective ways for alleviating greenhouse effect, promoting carbon circulation, reducing carbon net emission and finally achieving 'carbon neutralization'. Meanwhile, carbon dioxide/carbon monoxide is converted into high value-added raw materials (such as ethanol, n-propanol and the like), so that intermittent energy can be efficiently stored, and the energy utilization efficiency is increased.
Wherein, the copper-based catalyst is a catalyst commonly used in the electrochemical reduction reaction of carbon dioxide/carbon monoxide, the electrochemical reduction reaction of carbon dioxide/carbon monoxide reaches low activation energy and low overpotential by adjusting the components, the surface structure and the oxidation valence state of the copper-based catalyst, the Faraday Efficiency (FE) is continuously improved, and C is produced by the current carbon dioxide reduction 1 And C 2 Faradaic efficiencies of products such as carbon monoxide and formate have reached over 90%. But for higher value-added multi-carbon products (C) 3 E.g., n-propanol, etc.), product selectivity, and catalytic activity and durability of the copper-based catalyst during the reaction still need to be further improved.
For example, n-propanol as C 3 Multi-carbon products, a promising chemical, are widely used, such as raw materials and solvents in pharmaceuticals, plastics industries, and fuels. Today, n-propanol is usually produced by a catalytic hydrogenation step of propionaldehyde followed by a thermal carbonylation reaction of ethylene and carbon monoxide (— CO). It can be directly generated by electrochemical CO reduction reaction (CORR) under renewable power, which is a promising approach to achieve closed carbon cycle. However, the synthesis of n-propanol using current copper-based catalysts still has limited Faradic Efficiency (FEs)<40%) and low activity, which severely hampers its industrial application. The root cause is: c 2 Surface of intermediate insufficient CO coverage, and C 2 The C1-C2 coupling between the intermediate and the surface adsorbed CO is weak and noneThe process selectively branches CORR from ethanol to n-propanol.
Disclosure of Invention
The invention aims to provide a copper-based catalyst and a preparation method thereof, which can improve the selectivity of a single product in the electrochemical reduction reaction of carbon dioxide/carbon monoxide and reduce the separation cost of the product.
The invention also aims to provide a copper-based catalytic electrode and a preparation method thereof, and by using the copper-based catalyst, the electrochemical characteristics of the catalytic electrode are improved, the overpotential of the carbon dioxide/carbon monoxide electrochemical reduction reaction is reduced, and the reaction rate, the energy conversion efficiency and the reactant conversion rate are improved.
The invention also aims to provide an electrochemical electrolysis device, which reduces the voltage of a full battery for the carbon dioxide/carbon monoxide electrochemical reduction reaction and improves the reaction rate, the energy conversion efficiency and the stability.
The preparation method of the copper-based catalyst provided by the invention comprises the following specific steps:
(1) Preparing a first solution in which a metal salt precursor is dissolved, the metal salt precursor containing at least one modifier metal element, and the modifier metal element including at least one transition metal element or main group metal element having a larger atomic radius than copper;
(2) Adding a nanoscale powder containing copper oxide into the first solution, further adding a first binder, and stirring to produce a uniformly dispersed mixed slurry;
(3) Spraying or dripping the mixture slurry on a conductive substrate placed on a hot table and evaporating the solvent;
(4) Placing the conductive base material in a corresponding electrolyte, applying a reduction potential to the conductive base material to perform electrochemical reduction reaction under the environment of continuously introducing carbon monoxide, covering the reduced copper on the conductive base material to form a copper electrode, dissolving out atoms of the regulator metal element, depositing the atoms on the copper electrode in situ, and further combining the atoms on the copper lattice of the copper electrode to form a regulator metal element doped copper-based catalyst, wherein the distribution of the atoms of the regulator metal element at the grain boundary of the copper lattice is richer than that at other positions of the copper lattice in the copper-based catalyst;
the metal element of the regulator is selected from at least one of Pb, sb, sn, in, au, bi, cd and Hg;
the atomic molar ratio of the copper element in the copper-based catalyst to the metal element of the regulator is 1: Y, wherein Y is 0.005-0.1;
continuously introducing carbon monoxide, wherein the flow rate of the carbon monoxide is not lower than 20 ml/min;
the first adhesive is at least one selected from a group consisting of a Nafion solution, a polyvinylidene fluoride monomer solution, and a polytetrafluoroethylene monomer solution.
Alternatively, the step of preparing the first solution in which the metal salt precursor is dissolved includes:
(1) Mixing water in a polar organic solvent to produce an organic-water mixed solvent;
(2) Dissolving the metal salt precursor in the organic-aqueous mixed solvent to produce the first solution.
Optionally, the nanoscale powder containing copper oxide is nanoscale copper oxide powder or nanoscale copper oxide-carbon support composite material powder, and the preparation step of the nanoscale copper oxide-carbon support composite material powder comprises the following steps:
(1) Dissolving a copper salt precursor in water to produce a copper salt solution;
(2) Mixing an alkali solution in a copper salt solution and stirring to generate a second solution;
(3) Adding a carbon carrier into the second solution, and continuously stirring to generate a uniform mixed solution;
(4) Transferring the uniform mixed solution into a hydrothermal reaction kettle for hydrothermal reaction to obtain a suspension containing the copper oxide-carbon carrier composite material;
(5) Centrifuging the suspension obtained in the hydrothermal reaction kettle to obtain a powder sample;
(6) And washing, drying and grinding the powder sample to obtain the copper oxide-carbon carrier composite nano-grade powder.
Optionally, the carbon support is selected from at least one of nano carbon powder, carbon nano tube, graphene, reduced graphene oxide, conductive carbon black super P, conductive carbon black XC-72, conductive carbon black acetylene black and conductive carbon black BP 2000.
Optionally, in the copper oxide-carbon carrier composite nano-scale powder, the molar ratio of the copper element to the carbon element is 1: X, where X is 0.2 to 1.2.
The present invention also provides a copper-based catalyst obtained by the above production method, which has a copper crystal lattice and atoms of a modifier metal element connected to the copper crystal lattice by a metallic bond, the modifier metal element including at least one transition metal element or main group metal element having an atomic radius larger than that of copper, and the distribution of the atoms of the modifier metal element at the grain boundary of the copper crystal lattice being richer than that at other positions of the copper crystal lattice.
The metal element of the regulator is at least one selected from Pb, sb, sn, in, au, bi, cd and Hg.
The atomic molar ratio of the copper element in the copper-based catalyst to the metal element of the regulator is 1: Y, wherein Y is 0.005-0.1.
Optionally, the copper-based catalyst further comprises a nanoscale carbon carrier, and the molar ratio of the copper element in the copper-based catalyst to the carbon element in the carbon carrier is 1: X, wherein X is 0.2-1.2.
Optionally, the carbon support is selected from at least one of nano carbon powder, carbon nano tube, graphene, reduced graphene oxide, conductive carbon black super P, conductive carbon black XC-72, conductive carbon black acetylene black and conductive carbon black BP 2000.
The copper-based catalyst prepared by the invention has excellent catalytic performance.
The invention also provides a preparation method of the copper-based catalytic electrode, which comprises the following steps:
firstly, the preparation method of the copper-based catalyst is adopted to obtain the copper-based catalyst on a conductive substrate as an electrode substrate;
then, the electrode substrate is subjected toWashing and drying to obtain a copper-based catalytic electrode; the conductive substrate is selected from one of conductive glass, a conductive metal sheet and a stainless steel plate, the thickness of the conductive substrate is 0.5 mm-2.0 mm, and the loading amount of a copper-based catalyst in the copper-based catalytic electrode is 0.2 mg/cm 2 ~5.0 mg/cm 2 。
The invention also provides a copper-based catalytic electrode obtained by the method.
The invention also provides a preparation method of the copper-based catalytic electrode used as the gas diffusion electrode, which comprises the following steps:
firstly, obtaining an electrode substrate containing the copper-based catalyst by adopting the preparation method of the copper-based catalyst;
then, peeling the copper-based catalyst layer in the electrode base from the conductive substrate, and after washing the obtained copper-based catalyst, mixing with water, a second binder and an organic solvent to produce a catalyst slurry;
then, the catalyst paste is sprayed or dropped on the conductive diffusion layer and dried to form a gas diffusion electrode covered with a copper-based catalyst layer.
Wherein the second adhesive is at least one selected from Nafion solution, polyvinylidene fluoride monomer solution, polytetrafluoroethylene monomer solution, polyethylene-tetrafluoroethylene copolymer monomer solution and Dowex ion exchange resin solution, and the organic solvent is at least one selected from ethanol, methanol, N-propanol, isopropanol, glycol, glycerol, acetone and N, N-dimethylformamide.
Wherein the conductive diffusion layer can be selected from hydrophobic carbon paper, a PTFE film of hot-evaporated copper or a PTFE film of ion beam sputtered copper, the thickness of the conductive diffusion layer is 0.1mm to 2.0mm, and the loading amount of a copper-based catalyst in the formed gas diffusion electrode is 1mg/cm 2 ~10mg/cm 2 。
The invention also provides a copper-based catalytic electrode, namely a gas diffusion electrode, obtained by the method.
The present invention also provides an electrochemical electrolysis apparatus using the copper catalyst of the present invention as an electrode catalyst; or the electrochemical electrolysis device is provided with the copper-based catalytic electrode, and also provided with an oxygen generating electrode or a urea oxidizing electrode.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1. the copper-based catalyst and the preparation method thereof provided by the invention form a new copper-based catalyst in a CO (carbon monoxide) -rich environment, and the new copper-based catalyst contains a regulator metal element with the atomic radius larger than that of copper atoms besides the copper element, atoms of the regulator metal element are connected with copper lattices in an atomic-level homogeneous blending mode through metal bonds, most of the regulator metal element is distributed at the grain boundary of the surface of the copper lattices, so that a copper-based catalyst component with rich defects at the grain boundary is formed, strong CO bonds and high surface CO coverage rate are realized on the copper surface, an OCCO dimer is stabilized, and the subsequent CO-OCCOH coupling is promoted to form C 3 The product effect improves the selectivity of single multi-carbon products in the electrochemical reduction reaction of carbon dioxide/carbon monoxide, and improves the reaction rate, the energy conversion efficiency and the reactant conversion rate;
2. the preparation process is simple and convenient, the cost is low, the high-activity and high-stability carbon dioxide/carbon monoxide electrochemical reduction reaction can be realized, and the preparation method has wide application prospect.
Drawings
FIG. 1 is a flow chart of a method for preparing a copper-based catalyst according to an embodiment of the present invention.
Fig. 2 is a Scanning Electron Microscope (SEM) photograph of copper oxide-carbon support composite nano-scale powder particles used in the method for preparing a copper-based catalyst according to an embodiment of the present invention.
FIG. 3 is a schematic diagram showing atomic scale changes of substances in a method for preparing a copper-based catalyst according to an embodiment of the present invention.
FIG. 4 is a Scanning Electron Microscope (SEM) photograph of copper-based catalyst powder particles obtained in an embodiment of the present invention.
FIG. 5 is a scanning transmission electron microscope high-angle annular dark-field photograph (STEM-HAADF) of the copper-based catalyst powder obtained in the present embodiment, in which a is a STEM-HAADF photograph, and b and c are STEM photographs at different atomic resolution, respectively.
FIG. 6 is an energy spectrum (EDX) distribution diagram with a scale of 100 nm, wherein a is an energy spectrum distribution diagram of the copper-based catalyst as a whole according to an embodiment of the present invention, and b is an energy spectrum distribution diagram of a copper-lead alloy in the copper-based catalyst; c is a graph of the spectral distribution of copper in the copper-based catalyst; d is the spectrum distribution diagram of lead in the copper-based catalyst.
FIG. 7 is an in-situ X-ray absorption spectrum of a copper-based catalyst obtained in accordance with an embodiment of the present invention in an electrochemical reduction reaction of carbon monoxide, wherein a is an X-ray absorption fine structure spectrum (EXAFS) of a Cu K edge; b is Pb L 3 The X-ray absorption of the edges is near-edge spectrum (XANES).
FIG. 8 is the electrochemical performance of the copper-based catalytic electrode obtained in the embodiment 1 of the present invention in the electrochemical reduction reaction of carbon monoxide, wherein a is C at different potentials 2+ Product distribution; b is a graph of faradaic efficiency and bias current density of n-propanol at different potentials; and c is a current curve and the faradaic efficiency of the n-propanol of the stability test in a constant potential mode. The electrolyte was 1M KOH in water and the potential for the constant voltage test was-0.68V (relative to the reversible hydrogen electrode, RHE).
FIG. 9 shows the voltage curve and the Faraday efficiencies of all products obtained by using the copper-based catalytic electrode obtained in the embodiment of the present invention as a cathode and using the copper-based catalytic electrode as a carbon monoxide reduction reaction device of an alkaline system polymer anion exchange membrane and performing a stability test in a constant current mode, wherein the current density is 200 mA/cm 2 。
Fig. 10 is the electrochemical performance of the copper-based catalytic electrode obtained in embodiment 2 of the present invention in the electrochemical reduction reaction of carbon monoxide, wherein a is the product distribution at different potentials, and b is the bias current density of n-propanol at different potentials.
Fig. 11 shows the electrochemical performance of the copper-based catalytic electrode obtained in embodiment 3 of the present invention in the electrochemical reduction reaction of carbon monoxide. Wherein a is the product distribution at different potentials, and b is the bias current density of n-propanol at different potentials.
FIG. 12 shows the electrochemical performance of the copper-based catalytic electrode obtained in the embodiment 4 of the present invention in the electrochemical reduction reaction of carbon monoxide. Wherein a is the product distribution at different potentials, and b is the bias current density of n-propanol at different potentials.
Detailed Description
At present, the carbon dioxide/carbon monoxide electrochemical reduction reaction (CO) which has been successfully developed 2 RR/CORR) is adopted, due to the randomness of the adsorption of reaction intermediates on the surface and the phase separation phenomenon in the reaction process, the selectivity of single multi-carbon products such as n-propanol and the like, the activity and the long-term stability of the catalyst still face challenges, and the industrial development is limited.
The core of the technical scheme of the invention is to provide a copper-based catalyst, an electrode, a preparation method thereof and an electrochemical electrolysis device, wherein the novel copper-based catalyst is formed in a CO (carbon monoxide) rich environment, the novel copper-based catalyst contains a regulator metal element with larger atomic radius than copper besides copper, atoms of the regulator metal element are connected with a copper lattice in an atomic-level homogeneous blending mode through metal bonds, most of the atoms of the regulator metal element are distributed at a crystal boundary on the surface of the copper lattice, a copper-based catalyst component with rich defects at the crystal boundary is formed, strong CO bonds and high surface CO coverage rate are realized on the surface of copper, OCCO dimer is stabilized, and subsequent CO-OCCOH coupling is promoted to form C 3 The product effect improves the selectivity of single multi-carbon products in the electrochemical reduction reaction of carbon dioxide/carbon monoxide, and improves the reaction rate, the energy conversion efficiency and the reactant conversion rate. The copper-based catalyst is detected by experimental detection technologies such as XRD, TEM, XAFS and the like, and interaction exists among copper atoms, between the copper atoms and atoms of metal elements of a regulator and between a copper alloy and a carbon carrier, so that the adsorption energy of the intermediate of the electrochemical reduction reaction of carbon dioxide/carbon monoxide can be favorably regulated, and the activity of the catalyst in the electrochemical reduction reaction of carbon dioxide/carbon monoxide is improved. And the interaction between the copper alloy and the carbon carrier overcomes the catalytic reaction processThe phase separation problem of the metal solid solution in the catalyst can promote the atoms of the metal elements of the regulator to stably exist in the copper-based catalyst in an atomic-level homogeneous blending mode, thereby effectively improving the stability of the copper-based catalyst. The copper-based catalyst has excellent carbon dioxide/carbon monoxide electrochemical reduction reaction performance and excellent stability.
The present invention can be realized in various forms and should not be limited to the embodiments described below, however, the present invention is not limited to the embodiments. Unless otherwise noted, all applied voltages in this work refer to Reversible Hydrogen Electrodes (RHE) without iR compensation.
Referring to fig. 1, an embodiment of the present invention provides a method for preparing a copper-based catalyst, which includes the following steps:
s1, preparing a first solution dissolved with a metal salt precursor, wherein the metal salt precursor contains at least one regulator metal element J, and the regulator metal element J comprises at least one transition metal element or main group metal element with the atomic radius larger than that of copper;
s2, adding the nano-scale powder containing the copper oxide into the first solution, further adding a first binder D, and stirring to generate uniformly dispersed mixed slurry;
s3, spraying or dripping the mixture slurry on a conductive substrate E placed on a hot table and evaporating the solvent to dryness;
s4, placing the conductive base material E in a corresponding electrolyte F, applying a reduction potential to the conductive base material to perform an electrochemical reduction reaction under the environment of continuously introducing carbon monoxide, covering the reduced copper on the conductive base material to form a copper electrode, dissolving out atoms of the regulator metal element, depositing the atoms on the copper electrode in situ, and further combining the atoms on the copper lattice of the copper electrode to form a regulator metal element-doped copper-based catalyst, wherein the atoms of the regulator metal element are distributed at the grain boundary of the copper lattice more enriched relative to other positions of the copper lattice in the copper-based catalyst.
In step S1, the step of preparing a first solution in which a metal salt precursor is dissolved includes:
s1.1, mixing a certain amount of water in a polar organic solvent A to generate an organic-water mixed solvent B, wherein the polar organic solvent A comprises at least one of methanol, ethanol, n-propanol, isopropanol, ethylene glycol, glycerol and acetone. When a certain amount of water is mixed in the polar organic solvent A to produce the organic-water mixed solvent B, the required amount of water is determined by the solubility of the metal precursor salt of the metal element as the regulator in the mixed solvent;
s1.2, fully dissolving a metal salt precursor containing at least one regulator metal element in an organic-water mixed solvent B by an ultrasonic technology to generate a first solution. The regulator metal element J comprises at least one transition metal element or main group metal element with the atomic radius larger than that of copper Cu, and is selected from at least one of Pb, sb, sn, in, au, bi, cd and Hg. The metal salt precursor C comprises one or at least two of metal halide, metal nitrate, metal sulfate, metal phosphate, metal alkoxide and metal ester.
In step S2, the nanosized powder with copper oxide used is a nanosized powder of copper oxide or a nanosized powder of a copper oxide-carbon support composite material. Wherein the preparation steps of the copper oxide-carbon carrier composite nano-powder comprise:
s2.1, dissolving a copper salt precursor G in water to generate a copper salt solution, wherein the copper salt precursor is selected from at least one of copper halide, copper nitrate, copper sulfate, copper phosphate and copper perchlorate;
s2.2, mixing an alkali liquor H in the copper salt solution and carrying out ultrasonic stirring to generate a second solution, wherein the alkali liquor H is a potassium hydroxide solution or a sodium hydroxide solution or a mixed solution of the two solutions;
s2.3, adding a carbon carrier C into the second solution, and continuously performing ultrasonic stirring to generate a uniform mixed solution, wherein the carbon carrier is selected from at least one of nano carbon powder, carbon nano tubes, graphene, reduced graphene oxide, conductive carbon black super P, conductive carbon black XC-72, conductive carbon black acetylene black and conductive carbon black BP 2000;
s2.4, transferring the uniform mixed solution into a hydrothermal reaction kettle for hydrothermal reaction to obtain a suspension containing the copper oxide-carbon carrier composite material;
s2.5, centrifuging the suspension obtained in the hydrothermal reaction kettle to obtain a powder sample;
s2.6, soaking the powder sample in water for washing to remove an unreacted copper salt precursor G from the powder sample, and then drying and grinding the powder sample under the condition of no annealing to obtain the copper oxide-carbon carrier composite nano-grade powder, wherein the molar ratio of copper elements to carbon elements in the copper oxide-carbon carrier composite nano-grade powder is 1: X, and X is 0.2-1.2. The particles of the prepared copper oxide-carbon carrier composite nano-grade powder are in a sheet structure, and the particle size is about 300 nm, as shown in figure 2.
Wherein, the carbon carrier can provide the voltage of the finally prepared copper-based catalyst in the actual reduction reaction of carbon monoxide/carbon dioxide, thereby improving the output efficiency of the multi-carbon product.
In step S2, after preparing the required copper oxide-carbon carrier composite nano-scale powder, adding the powder into the first solution prepared in step S1, and further adding a first binder D for ultrasonic stirring to generate uniformly dispersed mixed slurry. The first adhesive D is selected from one of Nafion solution, polyvinylidene fluoride monomer solution and polytetrafluoroethylene monomer solution.
In step S3, the mixture slurry obtained in step S2 is sprayed or dropped-coated on the conductive substrate E placed on the hot stage and the organic solvent in the mixture slurry is sufficiently evaporated to dryness. Wherein the conductive substrate E is selected from conductive glass, conductive metal sheet or stainless steel plate. The thickness of the conductive base material is 0.5mm to 2.0 mm.
In step S4, the acidity and basicity of the selected electrolyte F are determined by the solubility of the metal ions of the metal element as the regulator. The electrolyte F comprises at least one of potassium hydroxide solution, sodium hydroxide solution, cesium hydroxide solution, sulfuric acid, perchloric acid, hydrochloric acid, potassium bicarbonate solution and potassium carbonate solution. The flow rate of the carbon monoxide is continuously introduced to be not lower than 20 ml/min. Applying a required reduction potential (relative to the potential of the reversible hydrogen electrode RHE) to the conductive substrate E, controlling the reaction time, and performing an electrochemical reduction reaction, referring to fig. 3, forming a copper electrode on the conductive substrate E by copper Cu reduced by copper oxide CuO, and dissolving out atoms of the modifier metal element J and depositing the atoms on the copper electrode in situ and further combining the atoms on the copper lattice of the copper electrode, thereby forming the copper-based catalyst doped with the modifier metal element J. The formed copper-based catalyst powder is in a nano-granular shape, the size is about 200 nm, the regulator metal element J atom doping causes slight lattice expansion of a Cu lattice, the Cu lattice after the regulator metal element J atom doping is slightly larger than the standard lattice constant in a pure Cu catalyst, and the distribution of the regulator metal element J atoms at the crystal boundary of the copper lattice of the copper-based catalyst is more enriched relative to other positions of the copper lattice.
The invention also provides a copper-based catalyst which can be prepared by adopting the preparation method of the copper-based catalyst. The copper-based catalyst has a copper lattice and atoms of a modifier metal element J connected to the copper lattice by a metallic bond, the modifier metal element J comprising at least one transition metal element or main group metal element having an atomic radius larger than that of copper, and the distribution of the atoms of the modifier metal element J at the grain boundary of the copper lattice is richer than at other positions of the copper lattice.
Optionally, the modifier metal element J is selected from at least one of Pb, sb, sn, in, au, bi, cd, and Hg.
Optionally, the atomic molar ratio of the copper element to the modifier metal element in the copper-based catalyst is 1: Y, wherein Y is 0.005 to 0.1.
Optionally, the copper-based catalyst also comprises a nanoscale carbon carrier, and the molar ratio of the copper element in the copper-based catalyst to the carbon element in the carbon carrier is 1: X, wherein X is 0.2-1.2. Wherein the carbon carrier is at least one selected from nano carbon powder, carbon nano tubes, graphene, reduced graphene oxide, conductive carbon black super P, conductive carbon black XC-72, conductive carbon black acetylene black and conductive carbon black BP 2000.
The invention also provides a preparation method of the copper-based catalytic electrode, which comprises the following steps:
firstly, obtaining an electrode substrate containing the copper-based catalyst by adopting the preparation method of the copper-based catalyst;
then, washing and drying the electrode substrate to obtain a copper-based catalytic electrode; the conductive substrate E is selected from one of conductive glass, a conductive metal sheet and a stainless steel plate, the thickness of the conductive substrate E is 0.5 mm-2.0 mm, and the loading amount of a copper-based catalyst in the copper-based catalytic electrode is 0.2 mg/cm 2 ~5.0 mg/cm 2 。
The invention also provides a copper-based catalytic electrode which can be prepared by adopting the preparation method of the copper-based catalytic electrode. The copper-based catalytic electrode comprises a conductive substrate E and the copper-based catalyst covered on the conductive substrate E.
The invention also provides a preparation method of the copper-based catalytic electrode used as the gas diffusion electrode, which comprises the following steps:
firstly, obtaining an electrode substrate containing the copper-based catalyst by adopting the preparation method of the copper-based catalyst;
then, peeling the copper-based catalyst layer in the electrode base from the conductive substrate E, and after peeling the obtained copper-based catalyst and washing, mixing with water, a second binder and an organic solvent to produce a catalyst slurry, wherein the second binder is at least one selected from the group consisting of Nafion solution, polyvinylidene fluoride monomer solution, polytetrafluoroethylene monomer solution, polyethylene-tetrafluoroethylene copolymer monomer solution, and Dowex ion exchange resin solution, and the organic solvent is at least one selected from the group consisting of ethanol, methanol, N-propanol, isopropanol, ethylene glycol, glycerol, acetone, and N, N-dimethylformamide;
then, the catalyst paste is sprayed or dropped on the conductive diffusion layer and dried to form a gas diffusion electrode covered with a copper-based catalyst layer. Wherein the conductive diffusion layer can be selected from hydrophobic carbon paper, a PTFE film of hot-evaporation copper plating or a PTFE film of ion beam sputtering copper, the thickness of the conductive diffusion layer is 0.1mm to 2.0mm, and the formed gasThe loading of the copper-based catalyst in the bulk diffusion electrode was 1mg/cm 2 ~10mg/cm 2 。
The invention also provides a copper-based catalytic electrode which is a gas diffusion electrode and can be prepared by adopting the preparation method of the copper-based catalytic electrode used as the gas diffusion electrode.
Example 1, a copper-based catalyst and a copper-based catalytic electrode were formed using Pb as a regulator metal element, and technical effects thereof.
1. Preparation of Pb-doped copper-based catalyst (i.e., cu-Pb catalyst) and copper-based catalytic electrode (i.e., cu-Pb catalytic electrode)
(1) Preparing copper oxide-carbon carrier composite nano powder: weighing 2.40 g of sodium hydroxide, 1.02 g of copper salt and 50 mg of nano carbon powder, dissolving in 30 ml of deionized water, fully stirring, and transferring the mixed solvent to a hydrothermal reaction kettle; placing the reaction kettle in a high-temperature oven, and keeping the temperature at 130 ℃ for 12 hours; respectively centrifuging, washing, drying and grinding the obtained sample, wherein the particles of the prepared copper oxide-carbon carrier composite material nano powder are in a sheet structure with the particle size of about 300 nm as shown in figure 2;
(2) Preparation of Pb (NO) 3 ) 2 Methanol solution of (2): weighing 3 mg of Pb (NO) 3 ) 2 Dissolving in 1ml of methanol, and performing ultrasonic treatment for 0.5 h to fully dissolve;
(3) Preparing copper oxide suspension: 15 mg of the above copper oxide-carbon carrier composite nanopowder was weighed and added to 1ml of the prepared Pb (NO) 3 ) 2 Adding 50 mu l of perfluorosulfonic acid resin monomer solution (5 wt%) into the methanol solution, and carrying out ultrasonic treatment on the mixed liquid for 60 min until the mixed liquid is uniformly dispersed;
(4) Preparation of Pb-doped copper-based catalysts (i.e., cu-Pb catalysts) and electrodes (i.e., cu-Pb catalytic electrodes): dropping 1ml of the suspension on a 4 cm hot plate 2 Controlling the temperature of a hot plate to be 50 ℃ on a gas diffusion layer (Freudenberg H23C 9) to fully evaporate the methanol, and diffusing the dripped gasThe layers were placed in 1mol L -1 In potassium hydroxide solution for 20 ml min -1 Under the condition of introducing carbon monoxide at a flow rate of 0.28V (relative to a reversible hydrogen electrode, RHE), the reaction time was controlled to 100 s, and Pb was caused to react with the compound 2+ After dissolution, the solution is deposited on the surface of the copper electrode obtained by electroreduction in situ under a reduction potential to obtain the gas diffusion electrode loaded with the Pb-doped copper-based catalyst. As shown in fig. 4 to 5, the Pb-doped copper-based catalyst (i.e., cu — Pb catalyst) is in the form of nano-particles having a size of about 200 nm, and the lattice of the Pb-doped Cu-based catalyst is slightly larger than the standard lattice constant of the Cu catalyst, demonstrating that the Pb-doping causes a slight expansion of the Cu lattice.
2. Analyzing the performance of the prepared Pb-doped copper-based catalyst (namely Cu-Pb catalyst) and the copper-based catalytic electrode (namely Cu-Pb catalytic electrode);
the prepared Pb-doped copper-based catalyst (namely Cu-Pb catalyst) and the prepared copper-based catalytic electrode (namely Cu-Pb catalytic electrode) are analyzed by related technical means, and the method comprises the following steps:
referring to fig. 6 and 7, the X-ray diffraction (XRD) patterns of the Pb-doped copper-based catalyst (i.e., cu-Pb catalyst) and the copper-based catalytic electrode (i.e., cu-Pb catalytic electrode) show that the Cu lattice has no crystalline Pb characteristics therein, similar to a pure copper lattice. While the characteristic peaks of XRD corresponding to the (111) plane are slightly shifted toward the low-angle region, showing a slight lattice expansion of the Pb-doped copper-based catalyst sample because the Pb doping causes a slight lattice expansion of Cu, so that the lattice of the Pb-doped Cu-based catalyst is slightly larger than the standard lattice constant of the pure Cu catalyst. From the analysis of fig. 7a and 7b, it can be seen that Pb is doped in the Cu lattice at atomic level, and both Cu and Pb exist in the metal valence state during CORR.
It is known from High Resolution TEM (HRTEM) image (not shown) and corresponding SAED pattern (not shown) analysis that the Pb-doped copper-based catalyst Cu — Pb surface exhibits a denser band-like structure and Grain Boundaries (GBs), which indicate that the Pb-doped copper-based catalyst has defect-rich characteristics.
Referring to fig. 5, it can be seen from the high angle annular dark field scanning transmission electron microscope (HAADF-STEM) image analysis that the Pb-doped copper-based catalyst has an average particle size of about 20 nm and abundant GBs, in which Pb atoms are distributed in the Cu lattice at an atomic level.
Referring to fig. 6, it can be seen from the high resolution EDX elemental mapping analysis that the Pb atom density in the vicinity of GBs of the Pb-doped copper-based catalyst (i.e., cu — Pb catalyst) is high, indicating that the Pb doping can promote the formation of GBs. And as can be seen from the analysis of fig. 6, cu and Pb elements are distributed in the lattice of the copper-based catalyst at an atomic level, and the atomic ratio of Pb is about 1%.
The presence of Cu and Pb in the Pb-doped copper-based catalyst sample was further confirmed by analysis by inductively coupled plasma emission spectroscopy (ICP-OES) that the average Pb atomic ratio in the Pb-doped copper-based catalyst (i.e., cu-Pb catalyst) was about 2.9%. Furthermore, as shown in fig. 3, the content of Pb atoms near the surface of the Cu lattice is about 8%, which is significantly greater than the content of Pb atoms at other positions of the Cu lattice, as shown by high resolution X-ray photoelectron spectroscopy (XPS), which indicates that Pb doping mainly occurs near the surface of the Cu lattice (or at the surface of the copper electrode) to a depth of about 30 nm.
In addition, in order to understand the adsorption characteristics of the surface of the defect-rich Pb-doped copper-based catalyst, an operational electrochemical attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) analysis was also performed under CORR conditions. The results showed 2027 to 2080 cm -1 Adsorption bonds in the range are due to CO bound at the top of the Cu lattice (COtop, referred to as CO top). COtop on the surface of Cu-Pb is divided into two wave bands, which we will be 2027 to 2067 cm -1 The band of wavelengths is called Low Frequency Band (LFB), and 2075 to 2080 cm -1 The lower band is called the High Frequency Band (HFB). LFB and HFB are due to COtop of the terrace and defect sites, respectively. It was also observed that there was bridge-bound CO (called CO bridge) on the Cu — Pb surface. Clearly, more defects on the Pb-doped copper-based catalyst samples enabled a variety of CO adsorption configurations.
3. CO based on Pb-doped copper-based catalytic electrode agents (i.e., cu-Pb catalytic electrodes) 2 Assembly and property of RR/CORR three-phase flow system deviceThe test can be carried out;
specifically, a gas diffusion electrode loaded with a Pb-doped copper-based catalyst (namely, a nano material of a Cu-Pb catalyst) is used as a cathode, foamed nickel for electrodepositing Fe is used as an anode, a mercury/mercury oxide electrode is used as a reference electrode, an anion exchange membrane of FAB-PK-130 is used as a diaphragm, 1mol/L potassium hydroxide is introduced into two sides of the diaphragm and respectively used as an anode electrolyte and a cathode electrolyte, the cathode electrolyte is arranged on the catalyst layer of the gas diffusion electrode, carbon monoxide is introduced into the back side of the diaphragm, the CORR three-phase flow system device is obtained by assembling, and an electrochemical test is carried out.
As shown in FIG. 8a, C is measured over a wide potential window of-0.38 to-0.98V (RHE relative to the reversible hydrogen electrode) 2+ The selectivity of all the components is over 90 percent; as shown in FIG. 8b, the Faraday efficiency of n-propanol reached 46.6% and the highest bias current density of n-propanol reached 43.9 mA cm at-0.68V (vs. RHE) potential -2 . As shown in figure 8c, the activity of the Pb-doped copper-based catalyst at a constant potential of-0.68V (vs. RHE) is not obviously reduced within 10 h, and the selectivity of the n-propanol is kept above 40%. This has far exceeded the performance of existing n-propanol selective catalysts.
4. Polymer anion exchange membrane CO based on Pb-doped copper-based catalytic electrode agents (i.e., cu-Pb catalytic electrodes) 2 Assembling an RR/CORR device and testing the performance of the RR/CORR device;
specifically, a copper-based catalytic electrode loaded with a Pb-doped copper-based catalyst (namely, a nano material of a Cu-Pb catalyst) is used as a cathode, foamed nickel for electrodepositing Fe is used as an anode, a Sustainion X37-FA anion exchange membrane is used as a diaphragm, a titanium plate or a graphite plate engraved with a flow field is used as a cathode and an anode end plate, 1mol/L potassium hydroxide is introduced into the anode to be used as electrolyte, CO is introduced into the cathode end plate to be used as reaction gas, and the polymer anion exchange membrane water electrolysis device is assembled and subjected to electrochemical test.
As shown in FIG. 9, at 200 mA/cm 2 Under constant current, the device can stably work for more than 100 h and keep nearly 95 percent of C 2+ Selectivity, and n-propanol selectivity is higher than 30%. This has far exceeded the performance of existing n-propanol selective catalysts。
Moreover, the corresponding operational Raman spectrum, infrared absorption spectrum and density functional theory calculation analysis show that Pb atom doping forms a large number of defect sites in the copper-based catalyst, the defect-rich Pb is doped with the grain boundary and the defects on the Cu lattice surface, strong CO bonds and high surface CO coverage rate are realized, the adsorption and combination of CO of various configurations are allowed, and the CO is stabilized 2 Dimers of OCCO (i.e., intermediates) in RR and CORR and facilitate subsequent CO-OCCOH coupling (i.e., C1-C2 coupling) from C2 to C 3 Product formation and stable CO over 30% for more than 100 hours on n-propanol FE in a Membrane Electrode Assembly (MEA) with total current of 1A, which greatly improves the rational catalyst design for CO-n-propanol electrosynthesis and CO 2 Industrial use of RR and CORR.
Example 2, a copper-based catalyst and a copper-based catalytic electrode were formed using Sn as a modifier metal element, and technical effects thereof.
1. Preparing a Sn-doped copper-based catalyst (namely, a Cu-Pb catalyst) and a copper-based catalytic electrode (namely, a Cu-Pb catalytic electrode);
(1) Preparing copper oxide-carbon carrier composite nano powder: weighing 2.40 g of sodium hydroxide, 1.02 g of copper salt and 50 mg of nano carbon powder, dissolving in 30 ml of deionized water, fully stirring, and transferring the mixed solvent to a hydrothermal reaction kettle; placing the reaction kettle in a high-temperature oven, and preserving heat for 3 hours at a constant temperature of 200 ℃; respectively centrifuging, washing, drying and grinding the obtained sample, wherein the particles of the prepared copper oxide-carbon carrier composite material nano powder are in a sheet structure with the particle size of about 300 nm as shown in figure 2;
(2) Preparation of SnCl 2 Water-methanol mixed solution of (1): weighing 5 mg SnCl 2 Dissolving in 0.8ml of methanol and 0.2 ml of water, and performing ultrasonic treatment for 0.5 h to fully dissolve;
(3) Preparing copper oxide suspension: weighing 15 mg of the copper oxide-carbon carrier composite nano powder, and adding 1ml of prepared SnCl 2 And 80. Mu.l of a perfluorosulfonic acid resin monomer solution (5 wt%) was added to the mixed solutionUltrasonic treatment for 60 min to disperse uniformly;
(4) Preparation of Sn-doped copper-based catalysts (i.e., cu-Sn catalysts) and electrodes (i.e., cu-Sn catalytic electrodes): dropping 1ml of the suspension on a 4 cm hot plate 2 On a gas diffusion layer (Freudenberg H23C 9), the temperature of a hot plate is controlled to be 50 ℃, water and methanol are fully evaporated to dryness, and the obtained gas diffusion layer after dripping is placed on 1mol L -1 In potassium hydroxide solution for 20 ml min -1 Under the condition of introducing carbon monoxide at a flow rate of-0.35V (relative to a reversible hydrogen electrode, RHE), the reaction time is controlled to be 100 s, and Sn is caused to react 2+ After dissolution, the solution is deposited on the surface of the copper electrode obtained by electroreduction in situ under a reduction potential to obtain the gas diffusion electrode loaded with the Sn-doped copper-based catalyst.
2. CO based on Sn doped copper based catalytic electrode agents (i.e. Cu-Sn catalytic electrodes) 2 Assembling and testing the RR/CORR three-phase flow system device;
specifically, a gas diffusion electrode loaded with an Sn-doped copper-based catalyst (namely a nano material of a Cu-Sn catalyst) is used as a cathode, foamed nickel for electrodepositing Fe is used as an anode, a mercury/mercury oxide electrode is used as a reference electrode, an anion exchange membrane of FAB-PK-130 is used as a diaphragm, 1mol/L potassium hydroxide is introduced into two sides of the diaphragm and respectively used as an anode electrolyte and a cathode electrolyte, the cathode electrolyte is arranged on the catalyst layer of the gas diffusion electrode, carbon monoxide is introduced into the back side of the diaphragm, the CORR three-phase flow system device is obtained by assembling, and an electrochemical test is carried out.
As shown in FIG. 10a, C is measured over a wide potential window of-0.58 to-0.98V (relative to the reversible hydrogen electrode, RHE) 2+ The selectivity of the n-propanol is above 60%, the Faraday efficiency of the n-propanol reaches 35.5% under the potential of-0.68V (vs. RHE), as shown in figure 10b, the highest bias current density of the n-propanol reaches 25.5 mA cm -2 。
Example 3, formation of a copper-based catalyst and a copper-based catalytic electrode with Bi as a regulator metal element, and technical effects thereof.
1. Preparing a Bi-doped copper-based catalyst (namely, a Cu-Bi catalyst) and a copper-based catalytic electrode (namely, a Cu-Bi catalytic electrode);
(1) Preparing copper oxide-carbon carrier composite nano powder: weighing 2.40 g of sodium hydroxide, 1.02 g of copper salt and 50 mg of nano carbon powder, dissolving in 30 ml of deionized water, fully stirring, and transferring the mixed solvent to a hydrothermal reaction kettle; placing the reaction kettle in a high-temperature oven, and preserving heat for 3 hours at a constant temperature of 200 ℃; respectively centrifuging, washing, drying and grinding the obtained sample, wherein the particles of the prepared copper oxide-carbon carrier composite material nano powder are in a sheet structure with the particle size of about 300 nm as shown in figure 2;
(2) Preparation of Bi (NO) 3 ) 2 Water-methanol mixed solution of (1): weighing 5 mg Bi (NO) 3 ) 2 Dissolving in 0.7ml of methanol and 0.3 ml of water, and performing ultrasonic treatment for 0.5 h to fully dissolve;
(3) Preparing copper oxide suspension: 15 mg of the above copper oxide-carbon support composite nanopowder was weighed and added to 1ml of the prepared Bi (NO) 3 ) 2 Adding 80 mu l of perfluorosulfonic acid resin monomer solution (5 wt%), and carrying out ultrasonic treatment on the mixed solution for 60 min until the mixed solution is uniformly dispersed;
(4) Preparation of Bi-doped copper-based catalysts (i.e., cu-Bi catalysts) and electrodes (i.e., cu-Bi catalytic electrodes): dropping 1ml of the suspension on a 4 cm hot plate 2 Controlling the temperature of a hot plate to be 50 ℃ on a gas diffusion layer (Freudenberg H23C 9) to fully evaporate water and methanol, and placing the dripped gas diffusion layer on 1mol L -1 In potassium hydroxide solution for 20 ml min -1 Under the environment of introducing carbon monoxide at the flow rate of (2), applying a potential of-0.48V (relative to a reversible hydrogen electrode, RHE) to the carbon monoxide, and controlling the reaction time to be 100 s to obtain the gas diffusion electrode loaded with the Bi-doped copper-based catalyst.
2. CO based on Bi-doped copper-based catalytic electrode agents (i.e., cu-Bi catalytic electrodes) 2 Assembling and testing the RR/CORR three-phase flow system device;
specifically, a gas diffusion electrode loaded with a Bi-doped copper-based catalyst (namely, a nano material of a Cu-Bi catalyst) is used as a cathode, foamed nickel for electrodepositing Fe is used as an anode, a mercury/mercury oxide electrode is used as a reference electrode, an anion exchange membrane of FAB-PK-130 is used as a diaphragm, 1mol/L potassium hydroxide is introduced into two sides of the diaphragm and respectively used as an anode electrolyte and a cathode electrolyte, the cathode electrolyte is arranged on the surface of the gas diffusion electrode catalyst, carbon monoxide is introduced into the back side of the diaphragm, the CORR three-phase flow system device is obtained by assembling, and an electrochemical test is carried out.
As shown in FIG. 11a, C is measured over a wide potential window of-0.58 to-0.98V (relative to the reversible hydrogen electrode, RHE) 2+ The selectivity of the n-propanol is over 65 percent, the Faraday efficiency of the n-propanol reaches 28.5 percent under the potential of-0.68V (vs. RHE), as shown in figure 11b, the highest bias current density of the n-propanol reaches 24.9 mA cm -2 。
Example 4, a copper-based catalyst and a copper-based catalytic electrode were formed with In as a regulator metal element, and technical effects thereof.
1. Preparing an In-doped copper-based catalyst (i.e., a Cu-In catalyst) and a copper-based catalytic electrode (i.e., a Cu-In catalytic electrode);
(1) Preparing copper oxide-carbon carrier composite nano powder: weighing 2.40 g of sodium hydroxide, 1.02 g of copper salt and 50 mg of nano carbon powder, dissolving in 30 ml of deionized water, fully stirring, and transferring the mixed solvent to a hydrothermal reaction kettle; placing the reaction kettle in a high-temperature oven, and preserving heat for 3 hours at a constant temperature of 200 ℃; respectively centrifuging, washing, drying and grinding the obtained sample, wherein the particles of the prepared copper oxide-carbon carrier composite material nano powder are in a sheet structure with the particle size of about 300 nm as shown in figure 2;
(2) Preparation of In (NO) 3 ) 3 Water-methanol mixed solution of (1): weighing 5 mg In (NO) 3 ) 3 Dissolving in 0.8ml of methanol and 0.2 ml of water, and performing ultrasonic treatment for 0.5 h to fully dissolve;
(3) Preparing copper oxide suspension: 15 mg of the above copper oxide-carbon support composite nanopowder was weighed and added to 1ml of the prepared In (NO) 3 ) 3 Adding 80 mul of perfluorosulfonic acid resin monomer solution (5 wt%) into the water-methanol mixed solution, and carrying out ultrasonic treatment on the mixed solution for 60 min until the mixed solution is uniformly dispersed;
(4) Preparation of In-doped copper-based catalysts (i.e., cu-In catalysts) and electrodes (i.e., cu-In catalytic electrodes): dripping 1ml of the suspension on a 4 cm hot table 2 On a gas diffusion layer (Freudenberg H23C 9), the temperature of a hot plate is controlled to be 50 ℃, water and methanol are fully evaporated to dryness, and the obtained gas diffusion layer after dripping is placed on 1mol L -1 In potassium hydroxide solution for 20 ml min -1 Under the environment of introducing carbon monoxide at the flow rate of (2), a potential of-0.48V (relative to a reversible hydrogen electrode, RHE) is applied to the carbon monoxide, and the reaction time is controlled to be 100 s, so that the gas diffusion electrode loaded with the In-doped copper-based catalyst is obtained.
2. CO based on In-doped copper-based catalytic electrode agents (i.e., cu-In catalytic electrodes) 2 Assembling and testing the RR/CORR three-phase flow system device;
specifically, a gas diffusion electrode loaded with an In-doped copper-based catalyst (namely, a nano material of a Cu-In catalyst) is used as a cathode, foamed nickel for electrodepositing Fe is used as an anode, a mercury/mercury oxide electrode is used as a reference electrode, an anion exchange membrane of FAB-PK-130 is used as a diaphragm, 1mol/L potassium hydroxide is introduced into two sides of the diaphragm and respectively used as an anode electrolyte and a cathode electrolyte, the cathode electrolyte is arranged on the catalyst layer of the gas diffusion electrode, carbon monoxide is introduced into the back side of the diaphragm, the CORR three-phase flow system device is obtained by assembling, and an electrochemical test is carried out.
As shown in FIG. 12a, C is measured over a wide potential window of-0.58 to-0.98V (relative to the reversible hydrogen electrode, RHE) 2+ The selectivity of the n-propanol is over 80 percent, the Faraday efficiency of the n-propanol reaches 34.0 percent under the potential of-0.68V (vs. RHE), as shown in figure 12b, the highest bias current density of the n-propanol reaches 47.2 mA cm -2 。
It is to be understood that the copper-based catalysts of the present invention were mainly formed with several representative regulator metal elements in the above examples, but the technical means of the present invention is not limited thereto, and according to the studies of the present invention, it is possible to obtain copper-based catalysts with improved properties by using an appropriate 4d \5d \6d transition metal element and main group metal element having an atomic radius larger than that of copper as the regulator metal element in place of Pb, and the material modification mechanism and the production method and the like of these copper-based catalysts are similar to those of the above-described copper-based catalysts obtained with Pb or the like as the regulator metal element, and the detailed description thereof is omitted.
In summary, the copper-based catalyst provided in the technical solution of the present invention further includes one or more regulator metal elements in addition to the carbon element, and atoms of the regulator metal elements are distributed in the copper lattice and connected to copper through a metal bond, so as to achieve homogeneous distribution at an atomic level, and the adsorption energy of the intermediate of the carbon dioxide/carbon monoxide electrochemical reduction reaction can be adjusted through interaction between adjacent copper atoms and atoms of the regulator metal elements, thereby improving the activity of the catalyst in the carbon dioxide/carbon monoxide electrochemical reduction reaction. And the copper atoms and the atoms of the metal elements of the regulator respectively interact with the carbon carrier, so that the problem of phase separation of a metal solid solution in the catalytic reaction process is solved, the atoms of the metal elements of the regulator are promoted to stably exist in the catalyst in an atomic-level homogeneous blending mode, and the stability of the catalyst is effectively improved.
In addition, the preparation method of the copper-based catalyst adopts the in-situ electrochemical reduction of copper oxide and the electrochemical deposition method of metal element ions of the regulator, overcomes the problem of uneven element distribution during the preparation of the multi-metal nano material and the preparation of the catalytic electrode, and realizes the atomic-scale homogeneous blending of the multi-metal on the surface of the electrode. And the interaction between the carbon carrier and the metal crystal avoids the atom aggregation in the reaction process and increases the stability of the catalyst. The copper-based catalyst has simple preparation process and low cost, can realize the high-activity and high-stability carbon dioxide/carbon monoxide electrochemical reduction reaction, and has wide application prospect.
In addition, the copper-based catalyst is used as an electrode catalyst layer, so that the electrochemical characteristics of an electrode can be greatly improved, the single product selectivity in the carbon dioxide/carbon monoxide electrochemical reduction reaction is improved, the overpotential of the carbon dioxide/carbon monoxide electrochemical reduction reaction is reduced, and the reaction rate, the energy conversion efficiency and the reactant conversion rate are improved.
Other embodiments of the present invention also provide an electrochemical electrolysis apparatus using the copper-based catalyst of the present invention as an electrode catalyst; alternatively, the electrochemical electrolysis device comprises two electrodes, one electrode being the copper-based catalytic electrode of the present invention as the cathode of the carbon dioxide/carbon monoxide electrochemical reduction device and the other electrode being an oxygen-generating electrode or a urea-oxidizing electrode. The electrochemical electrolysis device is used for the electrochemical reduction reaction of carbon dioxide/carbon monoxide.
Example 5, the electrochemical electrolysis apparatus was a three-phase flow system electrochemical electrolysis apparatus using the copper-based catalyst of the present invention as an electrode catalyst. Or, the three-phase flow system electrochemical electrolyzer comprises three electrodes, wherein one electrode is the gas diffusion electrode (namely the copper-based catalytic electrode of the invention) formed by the conductive gas diffusion layer and the copper-based catalyst covered on the conductive gas diffusion layer together, the gas diffusion electrode is used as the cathode of the carbon dioxide/carbon monoxide electrochemical reduction device, the other electrode is an oxygen generating electrode or a urea oxidation electrode, and the third electrode is a mercury/mercury oxide electrode and is used as a reference electrode. The three-phase flow system electrochemical electrolysis device also adopts an anion exchange membrane with the thickness of 25-250 mu m as a diaphragm, 0.1-1.0 mol/L potassium bicarbonate or 0.1-8.0 mol/L potassium hydroxide is introduced into two sides of the diaphragm to be respectively used as anode electrolyte and cathode electrolyte, a copper-based catalyst of a gas diffusion electrode faces the cathode electrolyte, and carbon dioxide or carbon monoxide is introduced into the back side of the gas diffusion electrode, so that the three-phase flow system electrochemical electrolysis device can be used for the electrochemical reduction reaction of the carbon dioxide/carbon monoxide.
Example 6, the electrochemical electrolysis device was a polymer anion exchange membrane based electrochemical electrolysis device using the copper-based catalyst of the present invention as an electrode catalyst. Alternatively, one of the two electrodes of the electrochemical electrolyzer for a polymer anion-exchange membrane is a gas diffusion electrode (i.e., the copper-based catalytic electrode of the present invention) formed by a conductive gas diffusion layer and a copper-based catalyst covering the conductive gas diffusion layer, and serves as a cathode of the electrochemical reduction device for carbon dioxide/carbon monoxide, and the other electrode is an oxygen-generating electrode or a urea-oxidizing electrode. The electrochemical electrolysis device based on the polymer anion exchange membrane also adopts an anion exchange membrane with the thickness of 25-250 mu m as a diaphragm, a titanium plate or a graphite plate with a carved flow field as a cathode and an anode end plate, pure water, 0.1-0.5 mol/L potassium bicarbonate or 0.1-3.0 mol/L potassium hydroxide is introduced into the anode as electrolyte, and carbon dioxide or carbon monoxide is introduced into the cathode end plate as reaction gas, so that the electrochemical electrolysis device can be used for the electrochemical reduction reaction of carbon dioxide/carbon monoxide.
Claims (10)
1. The preparation method of the copper-based catalyst is characterized by comprising the following specific steps:
(1) Preparing a first solution in which a metal salt precursor is dissolved, the metal salt precursor containing at least one modifier metal element, and the modifier metal element including at least one transition metal element or main group metal element having an atomic radius larger than that of copper;
(2) Adding a nanoscale powder containing copper oxide into the first solution, further adding a first binder, and stirring to produce a uniformly dispersed mixed slurry;
(3) Spraying or dripping the mixture slurry on a conductive substrate placed on a hot table and evaporating the solvent;
(4) Placing the conductive base material in corresponding electrolyte, applying a reduction potential to the conductive base material to perform electrochemical reduction reaction under the environment of continuously introducing carbon monoxide, covering the reduced copper on the conductive base material to form a copper electrode, dissolving out atoms of the regulator metal element, depositing the atoms on the copper electrode in situ, and further combining the atoms to a copper crystal lattice of the copper electrode to form a regulator metal element doped copper-based catalyst, wherein the distribution of the atoms of the regulator metal element at the crystal boundary of the copper crystal lattice is richer relative to other positions of the copper crystal lattice in the copper-based catalyst;
the metal element of the regulator is selected from Pb, sb, sn, in, au, bi, cd and Hg;
the atomic molar ratio of the copper element in the copper-based catalyst to the metal element of the regulator is 1: Y, wherein Y is 0.005-0.1;
continuously introducing carbon monoxide, wherein the flow rate of the carbon monoxide is not lower than 20 ml/min;
the first adhesive is at least one selected from a group consisting of a Nafion solution, a polyvinylidene fluoride monomer solution, and a polytetrafluoroethylene monomer solution.
2. The method of claim 1, wherein the step of preparing the first solution in which the metal salt precursor is dissolved comprises:
(1) Mixing water in a polar organic solvent to produce an organic-water mixed solvent;
(2) Dissolving the metal salt precursor in the organic-aqueous mixed solvent to produce the first solution.
3. The method according to claim 1, wherein the copper oxide-containing nanopowder is a copper oxide nanopowder or a copper oxide-carbon support composite nanopowder, and the step of preparing the copper oxide-carbon support composite nanopowder comprises:
(1) Dissolving a copper salt precursor in water to produce a copper salt solution;
(2) Mixing an alkali solution in a copper salt solution and stirring to generate a second solution;
(3) Adding a carbon carrier into the second solution, and continuously stirring to generate a uniform mixed solution;
(4) Transferring the uniform mixed solution into a hydrothermal reaction kettle for hydrothermal reaction to obtain a suspension containing the copper oxide-carbon carrier composite material;
(5) Centrifuging the suspension obtained in the hydrothermal reaction kettle to obtain a powder sample;
(6) And washing, drying and grinding the powder sample to obtain the copper oxide-carbon carrier composite nano-grade powder.
4. The method according to claim 3, wherein the carbon support is at least one selected from the group consisting of carbon nanopowder, carbon nanotubes, graphene, reduced graphene oxide, conductive carbon black super P, conductive carbon black XC-72, conductive carbon black acetylene black, and conductive carbon black BP 2000.
5. The preparation method of claim 4, wherein the molar ratio of copper element to carbon element in the copper oxide-carbon carrier composite nanoscale powder is 1: X, wherein X is 0.2 to 1.2.
6. A copper-based catalyst obtained by the production method according to any one of claims 1 to 5, which has a copper crystal lattice and atoms of a modifier metal element bonded to the copper crystal lattice by a metallic bond, the modifier metal element comprising at least one transition metal element or main group metal element having an atomic radius larger than that of copper atoms, and the distribution of the atoms of the modifier metal element at the grain boundary of the copper crystal lattice is richer than that at other positions of the copper crystal lattice;
the metal element of the regulator is selected from at least one of Pb, sb, sn, in, au, bi, cd and Hg;
the atomic molar ratio of the copper element in the copper-based catalyst to the metal element of the regulator is 1: Y, wherein Y is 0.005-0.1.
7. The preparation method of the copper-based catalytic electrode is characterized by comprising the following specific steps of:
firstly, the method for preparing a copper-based catalyst according to any one of claims 1 to 5 is adopted to obtain a copper-based catalyst on a conductive substrate as an electrode substrate;
then, washing and drying the electrode substrate to obtain a copper-based catalytic electrode;
the conductive substrate is selected from one of conductive glass, a conductive metal sheet and a stainless steel plate, the thickness of the conductive substrate is 0.5 mm-2.0 mm, and the loading amount of a copper-based catalyst in the copper-based catalytic electrode is 0.2 mg/cm 2 ~5.0 mg/cm 2 。
8. The preparation method of the copper-based catalytic electrode is characterized by comprising the following specific steps of:
first, a copper-based catalyst is obtained on a conductive substrate by the method for producing a copper-based catalyst according to any one of claims 1 to 5,
then, peeling the copper-based catalyst layer from the conductive substrate, washing the peeled copper-based catalyst, and mixing with water, a second binder, and an organic solvent to produce a catalyst slurry;
then, spraying or dripping the catalyst slurry on the conductive diffusion layer and drying the slurry to form a gas diffusion electrode covered with a copper-based catalyst layer;
wherein the second adhesive is at least one selected from Nafion solution, polyvinylidene fluoride monomer solution, polytetrafluoroethylene monomer solution, polyethylene-tetrafluoroethylene copolymer monomer solution and Dowex ion exchange resin solution, and the organic solvent is at least one selected from ethanol, methanol, N-propanol, isopropanol, ethylene glycol, glycerol, acetone and N, N-dimethylformamide;
wherein the conductive diffusion layer can be selected from hydrophobic carbon paper, a PTFE film of hot-evaporated copper or a PTFE film of ion beam sputtered copper, the thickness of the conductive diffusion layer is 0.1mm to 2.0mm, and the loading amount of a copper-based catalyst in the formed gas diffusion electrode is 1mg/cm 2 ~10mg/cm 2 。
9. A copper-based catalytic electrode obtained by the production method according to claim 7 or 8.
10. An electrochemical electrolysis device having a copper-based catalytic electrode according to claim 9, and further having an oxygen-producing electrode or a urea-oxidizing electrode.
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