Metal monatomic doped copper-based catalyst as well as preparation method and application thereof
By incorporating single atoms of palladium, iron, nickel, or ruthenium into copper-based catalysts, dendritic or pinecone-like catalysts are prepared, solving the problems of low selectivity and efficiency of copper-based catalysts in electrocatalytic nitrite reduction, and achieving highly selective ammonia synthesis and suppression of hydrogen evolution side reactions.
Patent Information
- Application Number
- CN202410962104.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-18
- Publication Date
- 2026-01-20
AI Technical Summary
Existing copper-based catalysts suffer from competitive hydrogen evolution reactions and low selectivity and efficiency in ammonia production during electrocatalytic nitrite reduction.
A copper-based catalyst doped with metal single atoms is used. By incorporating palladium, iron, nickel or ruthenium single atoms into the copper-based catalyst, the hydrogen generated from water electrolysis is used to reduce nitrite in water to prepare dendritic or pinecone-shaped catalysts for electrocatalytic reduction of nitrite to synthesize ammonia.
Highly selective ammonia synthesis was achieved over a wide potential range with a Faraday efficiency of nearly 100%, effectively suppressing the competitive hydrogen evolution side reaction.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of electrocatalysis, in particular to a metal monatomic doped copper-based catalyst and a preparation method and use thereof. BACKGROUND
[0002] Nitrite is an important intermediate in global nitrogen cycle, and is also one of the most dangerous and harmful pollutants, widely existing in water bodies and soils. Nitrite can irreversibly oxidize hemoglobin in blood to methemoglobin, thereby inhibiting the transport of oxygen in blood and causing anoxic poisoning. Therefore, it is of great significance to environmental protection and human health to convert nitrite into harmless or even valuable chemicals. Ammonia is the most basic chemical raw material, energy storage medium and carbon-free energy carrier. At present, ammonia is mainly produced by Haber-Bosch method, which requires harsh operating conditions, such as high temperature (350-550℃) and high pressure (150-300 atm). The process consumes 1-2% of the world's energy supply and emits a large amount of carbon dioxide, which aggravates the global greenhouse effect. Therefore, it is urgent to solve the above environmental and energy problems in the pursuit of life and health and the development of low-carbon economy today. Under normal temperature and pressure conditions, using renewable energy power to catalyze the reduction of nitrite to synthesize ammonia can not only effectively alleviate the environmental pollution problem caused by nitrite in wastewater, but also replace the energy-intensive Haber-Bosch process to synthesize ammonia with high added value. Copper is widely used in the field of electrocatalytic reduction of nitrite due to its unique properties and low price. However, copper-based catalysts have problems such as competitive hydrogen evolution reaction, low selectivity and efficiency of ammonia production in the field of electrocatalytic reduction of nitrite.
[0003] In order to solve the above problems, the present application is proposed. SUMMARY
[0004] The present application discloses a metal monatomic doped copper-based catalyst for the electroreduction of nitrite to synthesize ammonia. The metal monatomic doped copper-based catalyst uses water as a hydrogen source and reduces nitrite in the water medium by using hydrogen generated by electrolysis of water, which can not only remove harmful substances such as nitrite in water, but also produce valuable chemicals such as ammonia. The catalyst has great development prospects in the field of electroreduction of nitrite to synthesize ammonia.
[0005] The present application provides a metal monatomic doped copper-based catalyst, wherein the metal monatomic atom is selected from the group consisting of palladium monatomic atom, iron monatomic atom, nickel monatomic atom or ruthenium monatomic atom.
[0006] The metal monatomic doping amount is 0.5-1.0%, based on the total mass of the catalyst.
[0007] when the metal monatomic atom is palladium monatomic atom, the catalyst morphology is dendritic, and the size is 3-5 μm;
[0008] when the metal monatomic atom is iron monatomic atom, the catalyst morphology is pinecone-like, and the size is 3-5 μm;
[0009] when the metal monatomic atom is nickel monatomic atom, the catalyst morphology is pinecone-like, and the size is 2-4 μm;
[0010] when the metal monatomic atom is ruthenium monatomic atom, the catalyst morphology is pinecone-like, and the size is 2-4 μm.
[0011] The second aspect of the present application provides a metal monatomic atom doped copper-based catalyst, and a preparation method thereof, which comprises the following steps:
[0012] 1) mixing H2SO4 and CuSO4 solution to obtain a mixed solution A; mixing H2SO4 and a metal salt solution to obtain a mixed solution B; the metal in the metal salt solution is selected from palladium, iron, nickel or ruthenium;
[0013] 2) mixing the mixed solution A and the mixed solution B in a certain proportion to obtain a mixed solution C;
[0014] 3) using a graphite electrode as a counter electrode, an Ag / AgCl electrode as a reference electrode, a hydrophilic carbon paper as a working electrode, and the mixed solution C as an electrolyte, a metal monatomic atom doped copper-based catalyst is obtained on the hydrophilic carbon paper by constant potential deposition.
[0015] In step 1), the concentration of the H2SO4 solution is 0.1 M, the concentration of the CuSO4 solution is 0.1 M, and the concentration of the metal salt solution is 0.1 M;
[0016] The H2SO4 solution and the CuSO4 solution are mixed in a volume ratio of 1:20;
[0017] The H2SO4 solution and the metal salt solution are mixed in a volume ratio of 1:20.
[0018] Preferably, in step 2), the mixed solution A: mixed solution B is in a volume ratio of 1:(0.5%-1.0%).
[0019] Preferably, in step 3), when the metal salt solution is a palladium salt solution, the constant potential deposition condition is -1.0 V;
[0020] when the metal salt solution is an iron salt solution, the constant potential deposition condition is -1.3 V;
[0021] when the metal salt solution is a nickel salt solution, the constant potential deposition condition is -1.0 V;
[0022] When the metal salt solution is a ruthenium salt solution, the potentiostatic deposition condition is -1.5 V.
[0023] The third aspect of the present application provides the use of the metal monatomic doped copper-based catalyst of the first aspect as a hydrogen source for the electrocatalytic reduction of nitrite to synthesize ammonia.
[0024] Preferably, in the electrolytic cell, the cathode electrolytic cell electrolyte is a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 is 0.1-1.0 M, and the concentration of KNO2 is 0.02-0.1 M.
[0025] The anode electrolytic cell electrolyte is a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 is 0.1-1.0 M, and the concentration of KNO2 is 0.02-0.1 M.
[0026] The cathode and the anode electrolytic cell are connected by a proton exchange membrane.
[0027] Preferably, the electrocatalytic method is as follows: using an H-type electrolytic cell, carrying out electrocatalytic reaction in the cathode electrolytic cell, the electrolysis substrate is potassium nitrite, carrying out electrochemical experiment, electrocatalytic nitrite to generate ammonia, the reference electrode in the electrolysis is an Ag / AgCl electrode, the counter electrode is a graphite electrode, and the metal monatomic doped copper-based catalyst deposited on the carbon paper by potentiostatic deposition in the first aspect is the working electrode.
[0028] The above technical solutions can be freely combined without contradiction.
[0029] Compared with the prior art, the present application has the following beneficial effects:
[0030] The present application has the following beneficial effects:
[0031] 1. The present application provides a new metal monatomic doped copper-based catalyst, which can use renewable electricity to catalyze the reduction of harmful substance nitrite into chemical ammonia with economic value-added, can solve the environmental and energy problems caused by nitrite pollution and Haber-Bosch method for producing ammonia, and realize waste-to-resource.
[0032] 2. In the present application, it is found for the first time that the metal monatomic doped in Cu can provide hydrogen for the reduction reaction of nitrite at a higher overpotential, so as to realize high-selectivity synthesis of ammonia in a wide potential range, and the selectivity is nearly 100%. Figure 1 The free energy of H adsorption on monatomic sites in different metal monatomic doped copper-based catalysts is compared in the following figure, Figure 1It can be seen that: in the Cu-based catalyst, the adsorption free energy of Zn monatomic site to H is-0.13 eV, the adsorption free energy of Pd monatomic site to H is-0.15 eV, the adsorption free energy of Fe monatomic site to H is-0.48 eV, the adsorption free energy of Ni monatomic site to H is-0.51 eV, and the adsorption free energy of Ru monatomic site to H is-0.74 eV, and the ability to adsorb H from large to small is arranged as: Ru>Ni>Fe>Pd>Zn. Therefore, the Ru, Ni, Fe and Pd monatomic atoms incorporated in the Cu in the application can improve the product faradic efficiency obtained by electrocatalytic reduction of nitrite. BRIEF DESCRIPTION OF DRAWINGS
[0033] Figure 1 It is a comparison chart of the adsorption free energy of monatomic sites in different metal monatomic doped copper-based catalysts to H.
[0034] Figure 2 It is a scanning electron microscope image of the electro-deposited pure copper catalyst.
[0035] Figure 3 It is a scanning electron microscope image of the electro-deposited palladium monatomic doped copper-based catalyst.
[0036] Figure 4 It is a scanning electron microscope image of the electro-deposited iron monatomic doped copper-based catalyst.
[0037] Figure 5 It is a scanning electron microscope image of the electro-deposited nickel monatomic doped copper-based catalyst.
[0038] Figure 6 It is a scanning electron microscope image of the electro-deposited ruthenium monatomic doped copper-based catalyst.
[0039] Figure 7 It is a scanning electron microscope image of the electro-deposited zinc monatomic doped copper-based catalyst.
[0040] Figure 8 It is a product faradic efficiency chart obtained by electrocatalytic reduction of nitrite on the pure copper catalyst.
[0041] Figure 9 It is a product faradic efficiency chart obtained by electrocatalytic reduction of nitrite on the palladium monatomic doped copper-based catalyst.
[0042] Figure 10 It is a product faradic efficiency chart obtained by electrocatalytic reduction of nitrite on the iron monatomic doped copper-based catalyst.
[0043] Figure 11 It is a product faradic efficiency chart obtained by electrocatalytic reduction of nitrite on the nickel monatomic doped copper-based catalyst.
[0044] Figure 12Product Faradaic efficiency plot for the electrocatalytic reduction of nitrite by a ruthenium monatomic-doped copper-based catalyst.
[0045] Figure 13 Product Faradaic efficiency plot for the electrocatalytic reduction of nitrite by a zinc monatomic-doped copper-based catalyst. DETAILED DESCRIPTION
[0046] The present application is further described in the following examples without limitation. The experimental methods in the examples, unless otherwise specified, were generally performed according to conventional conditions and as described in the manuals, or using general equipment, materials, reagents, etc. recommended by the manufacturers, and were commercially available, unless otherwise specified. The raw materials required in the following examples and comparative examples were commercially available.
[0047] Comparative Example 1
[0048] The preparation method of the pure copper catalyst comprises the following steps:
[0049] 1) The hydrophilic carbon paper was washed and dried for standby use;
[0050] 2) 0.1M H2SO4 and 0.1M CuSO4 solution were mixed in a volume ratio of 1:20 to obtain a mixed solution A;
[0051] 3) A graphite electrode was used as a counter electrode, an Ag / AgCl electrode was used as a reference electrode, the hydrophilic carbon paper was used as a working electrode, and the mixed solution C was used as an electrolyte. The pure copper catalyst was obtained on the carbon paper by constant potential deposition at a potential of -1.0V, terminated based on the electric quantity of -8C.
[0052] The material characterization and performance test were as follows:
[0053] Figure 2 The scanning electron microscope image of the electrodeposited pure copper-based catalyst is shown, Figure 2 It can be seen that the morphology of the electrodeposited pure copper-based catalyst is dendritic.
[0054] Performance test:
[0055] The obtained pure copper-based catalyst was tested for performance. The electrochemical experiment used a Koster three-electrode system, the reference electrode was an Ag / AgCl electrode, the counter electrode was a graphite electrode, and the pure copper-based catalyst obtained on the carbon paper was the working electrode. In the H-type electrolytic cell, the cathode electrolyte and the anode electrolyte were both mixed solutions containing KHCO3 and KNO2, wherein the concentration of KHCO3 was 0.1 M and the concentration of KNO2 was 0.02 M. The cathode electrolytic cell and the anode electrolytic cell were connected by a proton exchange membrane, and constant potential tests were carried out at a potential range of -0.3 V to -0.9 V, the test time was 1 h, and the gas phase products during the test were quantitatively tested by gas chromatography. The concentration of ammonia in the solution after 1 h of constant potential test was tested by color development, and then the Faraday efficiency (FE) was calculated.
[0056] Figure 8 The Faraday efficiency diagram of the product obtained by electrocatalytic reduction of nitrite on the pure copper catalyst. Figure 8 It is found that the FE of ammonia produced by electrocatalytic reduction of nitrite on the pure copper catalyst in the electrolyte of KHCO3 and KNO2 is 84.14% at -0.3 V, 81.22% at -0.5 V, 63.99% at -0.7 V, and 48.98% at -0.9 V. It can be seen that within the potential range of -0.3 V to -0.9 V, the FE of ammonia production gradually decreases with the increase of overpotential.
[0057] Example 1
[0058] The preparation method of the palladium single atom doped copper-based catalyst includes the following steps:
[0059] 1) The hydrophilic carbon paper was washed and dried for standby use;
[0060] 2) 0.1 M H2SO4 and 0.1 M CuSO4 solution were mixed according to a volume ratio of 1:20 to obtain a mixed solution A; 0.1 M H2SO4 and 0.1 M PdCl2 solution were mixed according to a volume ratio of 1:20 to obtain a mixed solution B;
[0061] 3) The mixed solution A and the mixed solution B were mixed according to a ratio of 1:0.5% to obtain a mixed solution C,
[0062] 4) The graphite electrode was used as the counter electrode, the Ag / AgCl electrode was used as the reference electrode, the hydrophilic carbon paper was used as the working electrode, the mixed solution C was used as the electrolyte, and the palladium single atom doped copper-based catalyst was obtained on the carbon paper by constant potential deposition at a potential of -1.0 V, based on an electric quantity of -8 C.
[0063] The material characterization and performance test are as follows:
[0064] Figure 3 The scanning electron microscope image of the electrodeposited palladium single atom doped copper-based catalyst is shown.Figure 3 It can be seen that the morphology of the palladium single-atom doped copper-based catalyst is dendritic, and the size is 3-5 μm.
[0065] Performance test:
[0066] The palladium single-atom doped copper-based catalyst obtained above was subjected to performance test. The electrochemical experiment used a Koster three-electrode system, the reference electrode was an Ag / AgCl electrode, the counter electrode was a graphite electrode, and the palladium single-atom doped copper-based catalyst obtained on the carbon paper was the working electrode. In an H-type electrolytic cell, the cathode electrolyte and the anode electrolyte were both mixed solutions containing KHCO3 and KNO2, wherein the concentration of KHCO3 was 0.1 M, and the concentration of KNO2 was 0.02 M. The cathode electrolyte and the anode electrolyte were connected by a proton exchange membrane, and constant potential test was carried out at a potential range of -0.3 V to -0.9 V, the test time was 1 h, the gaseous products in the test process were quantitatively tested by gas chromatography, the concentration of ammonia in the solution after 1 h of constant potential test was tested by color development, and then the Faraday efficiency was calculated.
[0067] Figure 9 Faraday efficiency diagram of the product obtained by electrocatalytic reduction of nitrite on the palladium single-atom doped copper-based catalyst. Figure 9 It can be seen that in the electrolyte of KHCO3 and KNO2, the palladium doped copper-based catalyst electrocatalytically reduces nitrite, the FE of ammonia production at -0.3 V is 99.69%, the FE of ammonia production at -0.5 V is 92.97%, the FE of ammonia production at -0.7 V is 91.33%, and the FE of ammonia production at -0.9 V is 91.53%. It can be seen that in the potential range of -0.3 V to -0.9 V, the Faraday efficiency of ammonia synthesis is higher than 90%, and the hydrogen evolution side reaction is effectively inhibited.
[0068] Example 2
[0069] The preparation method of the iron single-atom doped copper-based catalyst comprises the following steps:
[0070] 1) The hydrophilic carbon paper was washed and dried for standby use;
[0071] 2) 0.1 M H2SO4 and 0.1 M CuSO4 solution were mixed in a volume ratio of 1:20 to obtain mixed solution A; 0.1 M H2SO4 and 0.1 M FeSO4 solution were mixed in a volume ratio of 1:20 to obtain mixed solution B;
[0072] 3) mixed solution A and mixed solution B were mixed in a ratio of 1:1.0% to obtain mixed solution C,
[0073] 4) with graphite electrode as counter electrode, Ag / AgCl electrode as reference electrode, hydrophilic carbon paper as working electrode, mixed solution C as electrolyte, constant potential deposition at-1.3V, terminated based on electric quantity-8C, iron monatomic doped copper-based catalyst was obtained on carbon paper.
[0074] Material characterization and performance test as follows:
[0075] Figure 4 Scanning electron microscope image of the electrodeposited iron monatomic doped copper-based catalyst, Figure 4 It can be seen that the morphology of the iron monatomic doped copper-based catalyst is pinecone-shaped, with a size of 3-5μm.
[0076] Performance test:
[0077] The performance of the above obtained iron monatomic doped copper-based catalyst was tested. The electrochemical experiment used a three-electrode system of Koster, the reference electrode was Ag / AgCl electrode, the counter electrode was graphite electrode, and the iron monatomic doped copper-based catalyst obtained on carbon paper was working electrode. In the H-type electrolytic cell, the cathode electrolyte and the anode electrolyte were both mixed solutions containing KHCO3 and KNO2, and the concentration of KHCO3 was 0.1M and the concentration of KNO2 was 0.1M. The cathode and anode electrolytic cells were connected by proton exchange membrane, and constant potential test was carried out at-0.3V to-0.9V, the test time was 1h, the gaseous product in the test process was quantitatively tested by gas chromatography, the concentration of ammonia in the solution after 1h constant potential test was tested by color development, and then the Faraday efficiency was calculated.
[0078] Figure 10 Faraday efficiency diagram of the product obtained by electrocatalytic reduction of nitrite on the iron monatomic doped copper-based catalyst. Figure 10 It can be seen that in the electrolyte of KHCO3 and KNO2, the iron doped copper-based catalyst electrocatalytically reduces nitrite, the FE of ammonia production at-0.3V is 99.66%, the FE of ammonia production at-0.5V is 94.59%, the FE of ammonia production at-0.7V is 96.59%, and the FE of ammonia production at-0.9V is 93.09%. It can be seen that in the potential range of-0.3V to-0.9V, the Faraday efficiency of ammonia synthesis is higher than 90%, and the hydrogen evolution side reaction is effectively inhibited.
[0079] Example 3
[0080] The preparation method of nickel monatomic doped copper-based catalyst includes the following steps:
[0081] 1) The hydrophilic carbon paper was cleaned and dried for standby use;
[0082] 2) 0.1M H2SO4 and 0.1M CuSO4 solution were mixed in a volume ratio of 1:20 to obtain mixed solution A; 0.1M H2SO4 and 0.1M NiSO4 solution were mixed in a volume ratio of 1:20 to obtain mixed solution B;
[0083] 3) mixed solution A and mixed solution B were mixed in a ratio of 1:0.50% to obtain mixed solution C,
[0084] 4) using a graphite electrode as a counter electrode, an Ag / AgCl electrode as a reference electrode, a hydrophilic carbon paper as a working electrode, and mixed solution C as an electrolyte, iron monatomic doped copper-based catalyst was obtained on the carbon paper by constant potential deposition at a potential of -1.0V, and terminated based on an electric quantity of -8C.
[0085] Material characterization and performance testing are as follows:
[0086] Figure 5 The scanning electron microscope image of the electrodeposited nickel monatomic doped copper-based catalyst is shown, Figure 5 It can be seen that the morphology of the nickel monatomic doped copper-based catalyst is pinecone-shaped, and the size is 2-4μm.
[0087] Performance test:
[0088] The nickel monatomic doped copper-based catalyst obtained above was subjected to performance test. The electrochemical experiment used a Koster three-electrode system, the reference electrode was an Ag / AgCl electrode, the counter electrode was a graphite electrode, and the nickel monatomic doped copper-based catalyst obtained on the carbon paper was a working electrode. In an H-type electrolytic cell, the cathode electrolyte was a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 was 1M, and the concentration of KNO2 was 0.1M. The anode electrolyte was a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 was 1M, and the concentration of KNO2 was 0.1M. The cathode and anode electrolyte were connected by a proton exchange membrane, and constant potential test was carried out at a potential range of -0.3V to -0.9V, the test time was 1h, the gaseous product in the test process was quantitatively tested by gas chromatography, the concentration of ammonia in the solution after 1h of constant potential test was tested by color development, and then the Faraday efficiency was calculated.
[0089] Figure 11 The product Faraday efficiency diagram obtained by electrocatalytic reduction of nitrite on the nickel monatomic doped copper-based catalyst. Figure 11Seen: In the electrolyte of KHCO3 and KNO2, the nickel-doped copper-based catalyst electrocatalyzes the reduction of nitrite, the FE of ammonia production at -0.3V is 90.91%, the FE of ammonia production at -0.5V is 90.61%, the FE of ammonia production at -0.7V is 93.37%, and the FE of ammonia production at -0.9V is 93.67%. It can be seen that in the potential range of -0.3V to -0.9V, the Faraday efficiency of ammonia synthesis is higher than 90%, and the hydrogen evolution side reaction is effectively inhibited.
[0090] Example 4
[0091] The preparation method of the ruthenium single-atom-doped copper-based catalyst comprises the following steps:
[0092] 1) Clean the hydrophilic carbon paper and dry it for standby use;
[0093] 2) Mix 0.1M H2SO4 and 0.1M CuSO4 solution according to the volume ratio of 1:20 to obtain mixed solution A; mix 0.1M H2SO4 and 0.1M RuCl3 solution according to the volume ratio of 1:20 to obtain mixed solution B;
[0094] 3) Mix mixed solution A and mixed solution B according to the ratio of 1:1.00% to obtain mixed solution C,
[0095] 4) Take graphite electrode as the counter electrode, Ag / AgCl electrode as the reference electrode, hydrophilic carbon paper as the working electrode, and mixed solution C as the electrolyte, and then constant potential deposition is carried out at a potential of -0.6V, and the ruthenium single-atom-doped copper-based catalyst is obtained on the carbon paper based on the electric quantity of -8C.
[0096] The material characterization and performance test are as follows:
[0097] Figure 6 The scanning electron microscope image of the electrodeposited ruthenium single-atom-doped copper-based catalyst is shown, Figure 6 It can be seen that the morphology of the ruthenium single-atom-doped copper-based catalyst is pinecone-shaped, and the size is 2-4μm.
[0098] Performance test:
[0099] The obtained ruthenium single-atom doped copper-based catalyst was tested for performance. The electrochemical experiment used a Koster three-electrode system, the reference electrode was an Ag / AgCl electrode, the counter electrode was a graphite electrode, and the ruthenium single-atom doped copper-based catalyst obtained on the carbon paper was the working electrode. In the H-type electrolytic cell, the cathode electrolyte was a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 was 0.1 M, and the concentration of KNO2 was 0.02 M. The anode electrolyte was a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 was 0.1 M, and the concentration of KNO2 was 0.02 M. The cathode and anode electrolyte were connected by a proton exchange membrane, and constant potential testing was carried out at a potential range of -0.3 V to -0.9 V, the testing time was 1 h, and the gas phase products during the testing were quantitatively tested by gas chromatography. The concentration of ammonia in the solution after 1 h of constant potential testing was tested by color development, and then the Faraday efficiency was calculated.
[0100] Figure 12 Faraday efficiency diagram of the product obtained by electrocatalytic reduction of nitrite on the ruthenium single-atom doped copper-based catalyst. Figure 12 It is found that the ruthenium doped copper-based catalyst electrocatalytically reduces nitrite in the electrolyte of KHCO3 and KNO2, the FE of ammonia production at -0.3 V is 96.07%, the FE of ammonia production at -0.5 V is 97.20%, the FE of ammonia production at -0.7 V is 94.14%, and the FE of ammonia production at -0.9 V is 92.61%. It can be seen that in the potential range of -0.3 V to -0.9 V, the Faraday efficiency of ammonia synthesis is higher than 90%, and the hydrogen evolution side reaction is effectively inhibited.
[0101] Comparative Example 2
[0102] The preparation method of the zinc single-atom doped copper-based catalyst includes the following steps:
[0103] 1) The hydrophilic carbon paper was cleaned and dried for standby use;
[0104] 2) 0.1 M H2SO4 and 0.1 M CuSO4 solution were mixed in a volume ratio of 1:20 to obtain a mixed solution A; 0.1 M H2SO4 and 0.1 M ZnSO4 solution were mixed in a volume ratio of 1:20 to obtain a mixed solution B;
[0105] 3) mixed solution A and mixed solution B were mixed in a ratio of 1:0.50% to obtain mixed solution C,
[0106] 4) with graphite electrode as counter electrode, Ag / AgCl electrode as reference electrode, hydrophilic carbon paper as working electrode, and mixed solution C as electrolyte, constant potential deposition was carried out at a potential of -1.5 V, and the zinc single-atom doped copper-based catalyst was obtained on the carbon paper based on the electric quantity of -8 C.
[0107] The material characterization and performance test are as follows:
[0108] Figure 7 The scanning electron microscope image of the zinc monatomic doped copper-based catalyst, Figure 7 It can be seen that the morphology of the zinc monatomic doped copper-based catalyst is dendritic, and the size is 1-3 μm.
[0109] Performance test:
[0110] The zinc monatomic doped copper-based catalyst obtained above was subjected to performance test. The electrochemical experiment used a Koster three-electrode system, the reference electrode was an Ag / AgCl electrode, the counter electrode was a graphite electrode, and the zinc monatomic doped copper-based catalyst obtained on the carbon paper was the working electrode. In an H-type electrolytic cell, the cathode electrolyte was a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 was 0.1 M, and the concentration of KNO2 was 0.02 M. The anode electrolyte was a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 was 0.1 M, and the concentration of KNO2 was 0.02 M. The cathode and anode electrolyte were connected by a proton exchange membrane, and constant potential test was carried out at a potential range of-0.3 V to-0.9 V, the test time was 1 h, the gaseous product in the test process was quantitatively tested by gas chromatography, the solution after 1 h of constant potential test was subjected to color development test for the concentration of ammonia, and then the Faraday efficiency was calculated.
[0111] Figure 13 The product Faraday efficiency diagram obtained by electrocatalytic reduction of nitrite on the zinc monatomic doped copper-based catalyst. Figure 13 It can be seen that in the electrolyte of 0.1 M KHCO3 and 0.02 M KNO2, the zinc doped copper-based catalyst electrocatalytically reduces nitrite, the FE of ammonia production at-0.3 V is 92.90%, the FE of ammonia production at-0.5 V is 86.99%, the FE of ammonia production at-0.7 V is 88.28%, and the FE of ammonia production at-0.9 V is 84.82%. It can be seen that in the potential range of-0.3 V to-0.9 V, as the overpotential increases, the FE of ammonia production decreases.
[0112] As can be seen from the above, compared with the pure copper-based catalyst of Comparative Example 1, the Faraday efficiency of ammonia production of the palladium, iron, nickel, and ruthenium monatomic doped copper-based catalysts of the application can be increased to more than 90%.
[0113] Compared with the zinc monatomic doped copper-based catalyst of Comparative Example 2, the Faraday efficiency of ammonia production of the palladium, iron, nickel, and ruthenium monatomic doped copper-based catalysts of the application in the potential range of-0.3 V to-0.9 V can be increased to more than 90%. It can be seen that the selection of the specific doped metal is particularly important.
Claims
1. A metal monatomic-doped copper-based catalyst, characterized in that, The metal monatomic in the catalyst is selected from the group consisting of a palladium monatomic, an iron monatomic, a nickel monatomic or a ruthenium monatomic; The metal monatomic doping amount is 0.5% to 1% based on the total mass of the catalyst; When the metal monatomic is a palladium monatomic, the catalyst morphology is dendritic with a size of 3 to 5 μm; When the metal monatomic is an iron monatomic, the catalyst morphology is pinecone-shaped with a size of 3 to 5 μm; When the metal monatomic is a nickel monatomic, the catalyst morphology is pinecone-shaped with a size of 2 to 4 μm; When the metal monatomic is a ruthenium monatomic, the catalyst morphology is pinecone-shaped with a size of 2 to 4 μm.
2. A metal monatomic-doped copper-based catalyst, characterized in that, The preparation method comprises the following steps: 1) mixing H2SO4 solution and CuSO4 solution to obtain a mixed solution A; mixing H2SO4 solution and a metal salt solution to obtain a mixed solution B; the metal in the metal salt solution is selected from the group consisting of palladium, iron, nickel or ruthenium; 2) mixing the mixed solution A and the mixed solution B in a certain proportion to obtain a mixed solution C; 3) using a graphite electrode as a counter electrode, an Ag / AgCl electrode as a reference electrode, a hydrophilic carbon paper as a working electrode, and the mixed solution C as an electrolyte, a metal monatomic doped copper-based catalyst is obtained on the hydrophilic carbon paper by constant potential deposition.
3. The metal monatomic-doped copper-based catalyst of claim 1, wherein, In step 1), the concentration of the H2SO4 solution is 0.1 M, the concentration of the CuSO4 solution is 0.1 M, and the concentration of the metal salt solution is 0.1 M; The H2SO4 solution and the CuSO4 solution are mixed in a volume ratio of 1:20; The H2SO4 solution and the metal salt solution are mixed in a volume ratio of 1:
20.
4. The metal mono-atom doped copper-based catalyst of claim 1, wherein, In step 2), the mixed solution A and the mixed solution B are mixed in a volume ratio of 1:(0.5% to 1.0%).
5. The metal mono-atom doped copper-based catalyst of claim 1, wherein, In step 3), when the metal salt solution is a palladium salt solution, the constant potential deposition condition is -1.0 V; When the metal salt solution is an iron salt solution, the constant potential deposition condition is -1.3 V; When the metal salt solution is a nickel salt solution, the constant potential deposition condition is -1.0 V; When the metal salt solution is a ruthenium salt solution, the constant potential deposition condition is -1.5 V.
6. The use of the metal monatomic doped copper-based catalyst of claim 1 for electrocatalytic reduction of nitrite to synthesize ammonia with water as a hydrogen source.
7. Use according to claim 6, characterized in that, In the electrolytic cell, the cathode electrolyte is a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 is 0.1 to 1.0 M, and the concentration of KNO2 is 0.02 to 0.1 M; the anode electrolyte is a mixed solution containing KHCO3 and KNO2, the concentration of KHCO3 is 0.1 to 1.0 M, and the concentration of KNO2 is 0.02 to 0.1 M; the cathode and anode electrolytic cells are connected by a proton exchange membrane.
8. Use according to claim 6, characterized in that, The electrocatalytic method is as follows: an H-type electrolytic cell is used, an electrocatalytic reaction is carried out in the cathode electrolytic cell, potassium nitrite is used as an electrolysis substrate, an electrochemical experiment is carried out, ammonia is generated by electrocatalytic reduction of nitrite, the reference electrode in the electrolysis is an Ag / AgCl electrode, the counter electrode is a graphite electrode, and the metal monatomic doped copper-based catalyst on the carbon paper obtained by constant potential deposition in claim 1 is used as the working electrode.