Silver core catalyst regulated and controlled by amorphous oxide shell layer, preparation method and application of silver core catalyst

Abstract

The invention discloses an amorphous oxide shell regulation and control silver core catalyst as well as a preparation method and application thereof, and belongs to the technical field of electrochemical catalysis and energy storage. The catalyst is prepared by taking silver nanoparticles or silver alloy nanoparticles as a core and amorphous transition metal oxide as a shell layer through a chemical reduction-in-situ coating two-step method, the loading capacity of the amorphous metal oxide shell layer is 1.0-10wt%, and the amorphous metal oxide shell layer is selected from at least one of MnOx, CrOx, ScOx, YOx, LaOx and CeOx. The silver core is silver nanoparticles or silver alloy nanoparticles, and the particle size is 20-50 nm; the shell thickness is 0.5-2 nm, and no obvious crystal phase diffraction peak is represented by XRD (X-Ray Diffraction); and the shell layer and the silver core are tightly coated. When the catalyst is used as a cathode catalyst in a Zn-CO2 battery, CO2 reduction reaction can be efficiently catalyzed, and side reaction can be inhibited. The catalyst is simple in preparation process and controllable in cost, and a corresponding Zn-CO2 battery can stably charge and discharge under the current density of 2 mA / cm < 2 > for cyclic gt; therefore, a feasible scheme is provided for CO2 resource utilization and industrial application of a novel energy storage battery.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysis and energy storage technology, specifically relating to an amorphous oxide shell-controlled silver core catalyst, its preparation method, and its application in Zn-CO2 batteries. Background Technology

[0002] With the advancement of the global goal of "carbon neutrality," the integration of CO2 resource utilization and novel energy storage technologies has become a research hotspot. Zn-CO2 batteries, as a novel device that combines energy storage and CO2 conversion, have advantages such as high energy density, environmental friendliness, and abundant raw material reserves. However, their development is limited by the performance bottleneck of the cathode catalyst.

[0003] Silver-based catalysts have become an important choice for cathode catalysts in Zn-CO2 batteries due to their high selectivity for CO2 reduction to CO and excellent conductivity. However, traditional silver-based catalysts suffer from three major problems: first, they are prone to particle agglomeration during catalysis, leading to the loss of active sites; second, their surface electronic structure is simple, limiting their adsorption and activation capacity for CO2; and third, they lack compatibility with electrolytes, easily undergoing structural degradation during long-term cycling, which restricts the long-term stable operation of the battery. To address these issues, researchers have attempted to optimize the performance of silver-based catalysts through composite modification strategies. Combining metal oxides with silver-based materials allows for the regulation of the electronic state of silver through electronic interactions, thereby improving catalytic selectivity. In existing technologies, silver-metal oxide composite materials are mostly crystalline oxide dispersion systems. Core-shell amorphous metal oxide-coated silver-based catalysts still have shortcomings in terms of loading control, compatibility of multi-metal oxide composites, and electrolyte compatibility. Furthermore, their preparation processes are complex and costly, making them difficult to meet the needs of industrial applications. Therefore, developing a silver core catalyst with stable structure, excellent performance, simple preparation, and adaptability to multi-electrolyte systems that is regulated by an amorphous oxide shell is of great significance for promoting the practical application of Zn-CO2 batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a silver core catalyst with an amorphous oxide shell. Amorphous metal oxides, due to their irregular crystal structure, possess characteristics such as large specific surface area, abundant active sites, and strong structural tunability, providing more sites for CO2 adsorption and activation. The core-shell structure design combines the high conductivity of silver with the catalytic activity of metal oxides, while simultaneously inhibiting silver particle aggregation and enhancing structural stability. This addresses the problems of insufficient active sites, poor stability, and poor electrolyte compatibility of traditional silver-based catalysts in Zn-CO2 batteries. Furthermore, it provides a simple and controllable preparation method and application, achieving high performance and long-cycle stability in Zn-CO2 batteries.

[0005] A silver core catalyst regulated by an amorphous oxide shell, characterized in that it comprises: (1) Silver core, wherein the silver core is silver nanoparticles or silver alloy nanoparticles with a particle size of 20~50 nm; (2) Shell, wherein the shell is an amorphous oxide coating the surface of the silver core, and the amorphous oxide is selected from MnO. x CrO x ScO x 、YO x LaO x CeO x At least one of the following; the loading of the amorphous oxide is 1.0~15wt%, and no obvious crystalline phase diffraction peaks are observed by XRD characterization.

[0006] Furthermore, the silver alloy nanoparticles are Ag-Cu alloys or Ag-Zn alloys, wherein the molar percentage of Cu or Zn elements is 1~10%.

[0007] Furthermore, the shell layer has a thickness of 0.5~2 nm, and transmission electron microscopy shows that it has no obvious interface gaps with the silver core, forming a tightly bonded core-shell structure.

[0008] The method for preparing the amorphous oxide shell-controlled silver core catalyst is characterized by comprising the following steps: (1) Preparation of silver nucleus precursor solution: Dissolve silver salt, or silver salt and alloy metal salt, in deionized water, add stabilizer, stir evenly to obtain silver nucleus precursor solution with a concentration of 0.1~2 mmol / L; the stabilizer is a steric hindrance stabilizer or an electrostatic stabilizer; (2) Preparation of silver core: Add a chemical reducing agent to the precursor solution of step (1) and react at room temperature to obtain well dispersed silver or silver alloy nanoparticles; (3) Formation of amorphous oxide shell: Add the shell metal salt precursor to the silver core nanoparticle dispersion obtained in step (2), stir evenly, then add sodium borohydride aqueous solution to promote the formation of amorphous oxide coating and initiate gelation, and then place the solution in a water bath at 50~70 ℃ for constant temperature reaction for 2~3 hours. (4) Post-processing: The product of step (3) is washed with deionized water, then subjected to solvent exchange and freeze-drying to obtain the target catalyst.

[0009] In the above scheme, the silver salt in step (1) is one of silver nitrate and silver acetate, and the alloy metal salt is at least one of copper or zinc nitrate or acetate; the stabilizer is selected from one of polyvinylpyrrolidone K30 (PVP), hexadecyltrimethylammonium bromide (CTAB) or sodium citrate (NaCA), and its addition amount is 5 to 10 times the amount of silver nucleus precursor.

[0010] In the above scheme, in step (2), the chemical reducing agent is selected from one of sodium borohydride, ascorbic acid, hydrazine hydrate, and sodium hypophosphite. The molar ratio of the reducing agent to the silver nucleus precursor is 0.25:1 to 4:1, and the reaction time is 5 to 20 minutes.

[0011] In the above scheme, in step (3), the metal salt precursor is any one or more of metal nitrate, acetate, and chloride, and the molar ratio of the metal element in the shell metal salt precursor to the silver or silver alloy in the silver core is 1:99~1:9.

[0012] In the above scheme, the freeze-drying temperature in step (4) is -60 ℃, the pressure is 1~10 Pa, and the time is 36~48 h.

[0013] The application of the amorphous oxide shell-regulated silver core catalyst in Zn-CO2 batteries is characterized in that the catalyst is mixed with solvent and polytetrafluoroethylene in a certain proportion and then ultrasonically prepared into catalyst ink. The solvent is either ethanol or isopropanol; The concentration of polytetrafluoroethylene is 1 wt%, and its volume ratio with the solvent is 5~20%; The catalyst ink is coated onto a conductive substrate to form a cathode, which is then assembled with a zinc foil anode and an electrolyte to form a Zn-CO2 battery.

[0014] Furthermore, the anode electrolyte has a concentration of 1~6 mol / L. A mixed aqueous solution of KOH and 0.02 mol / L Zn(OAc)2 or ZnSO4, the cathode electrolyte is KHCO3 with a concentration of 0.5~1 mol / L, and the conductive substrate is carbon paper with a microporous gas diffusion layer.

[0015] In the amorphous oxide shell-controlled silver core catalyst of this invention, the silver core is silver nanoparticles or low-alloyed silver alloy nanoparticles, ensuring the catalyst's high conductivity. The particle size is controlled at 20-50 nm, balancing specific surface area and electron transport efficiency; the molar proportion of alloying elements is 1-10%, and the electronic structure is further optimized through appropriate alloying; the amorphous oxide shell is selected from MnO. x CrO x ScO x 、YO x LaO x CeO xThe catalyst comprises one or more composite metal oxides. This amorphous structure provides abundant active sites and oxygen vacancies, with a loading of 1.0-15 wt%, ensuring a balance between catalytic activity, structural stability, and electrolyte compatibility. Furthermore, the shell of the silver-core catalyst is tightly coated with the silver core, and transmission electron microscopy shows no obvious gaps. The electronic state of the silver core is modulated through electronic interactions, simultaneously improving the interfacial compatibility between the catalyst and the electrolyte, thus synergistically enhancing catalytic performance and cycle stability.

[0016] The preparation method of the amorphous oxide shell-regulated silver core catalyst adopts a two-step "chemical reduction-in-situ coating" method, which is simple, mild, and controllable. When the silver core catalyst is used in a Zn-CO2 battery, the assembled Zn-CO2 battery, under room temperature and a 1 atm CO2 atmosphere, exhibits a performance of 2 mA / cm². 2 Stable charge-discharge cycle life >150 hours at current density. Attached Figure Description

[0017] Figure 1 The Ag@CrO prepared in Example 1 x XRD plot of -y (y=3, 5 or 7).

[0018] Figure 2 The Ag@CrO prepared in Example 1 x -5 high-resolution TEM image.

[0019] Figure 3 The Ag@MnO prepared in Example 2 x HAADF-STEM images and elemental EDX spectra.

[0020] Figure 4 The Ag@MnO prepared in Example 2 x Figure showing the charge-discharge cycle stability test results in Zn-CO2 batteries.

[0021] Figure 5 The Ag@Mn prepared in Example 3 0.5 Y 0.5 O x TEM image.

[0022] Figure 6 The AgCu@CeO prepared in Example 4 x TEM image.

[0023] Figure 7 The AgZn@La prepared in Example 5 0.2 Ce 0.8 O x TEM image. Detailed implementation method:

[0024] Example 1: Amorphous CrO x Shell-controlled silver core catalyst (Ag@CrO) x Preparation and application of ) Dilute 9 mL of 0.1 mol / L silver nitrate solution to 410 mL, add 1.64 g of CTAB as a stabilizer, and stir at room temperature for 10 min to obtain a silver nucleus precursor solution. Dissolve 39.5 mg of sodium hypophosphite in 10 mL of deionized water, then add it to the above silver nucleus precursor solution, and continue stirring for 10 min to obtain CTAB-stabilized silver nanoparticles.

[0025] 4.5 mL of 0.01 mol / L chromium nitrate precursor was added to a CTAB-stabilized silver nanoparticle solution, and the mixture was stirred at room temperature for 5 min to ensure homogeneity. 0.34 g of sodium borohydride was dissolved in 30 mL of deionized water and added to the mixture to promote the formation of the amorphous oxide coating and initiate gelation. The mixture was then reacted in a 60 °C water bath for 2–3 h. The product was collected, washed with deionized water, and solvent-displaced with tert-butanol. Finally, the product was freeze-dried at −60 °C for 24 h to obtain the target catalyst, denoted as Ag@CrO. x -5. Characterized, as Figure 1 As shown, Ag@CrO x The XRD pattern at -5°C only shows the face-centered cubic phase diffraction peaks of Ag, with no Cr-related diffraction peaks observed. x The shell exhibits an amorphous phase. From Figure 2 CrO can be clearly observed in the high-resolution TEM image shown. x It is also wrapped in an amorphous form on the surface of the Ag nucleus.

[0026] The amorphous CrO prepared in this embodiment x The shell-controlled silver core catalyst was ultrasonically dispersed in a mixed solvent containing 800 μL of isopropanol and 200 μL of 1% PTFE, and then sprayed onto carbon paper with a microporous gas diffusion layer to form a cathode with a loading of 1 mg / cm². 2 A Zn-CO2 battery was assembled using polished zinc foil as the anode, KHCO3 as the cathode electrolyte, and a mixed solution of 6 mol / L KOH and 0.02 mol / L Zn(OAc)2 as the anode electrolyte for charge-discharge testing.

[0027] A catalyst is coated on carbon paper with a microporous gas diffusion layer to serve as the cathode, Zn foil as the anode, and a mixed solution of KOH and Zn(OAc)2 or ZnSO4 as the anode electrolyte. The two chambers are separated by a bipolar membrane to form a Zn-CO2 battery.

[0028] Precise control of CrO by adjusting the amount of chromium nitrate precursor added x The loading amount. 2.7 mL and 6.3 mL of chromium nitrate precursor were taken respectively, and the target catalysts prepared according to the above preparation process were denoted as Ag@CrO. x -3、Ag@CrO x -7, its XRD diffraction pattern is as follows Figure 1 As shown, only the face-centered cubic phase diffraction peaks of Ag can be observed in the XRD pattern, and there are no Cr-related diffraction peaks. x The shell also exhibits an amorphous phase.

[0029] Example 2: Amorphous MnO x Shell-controlled silver core catalyst (Ag@MnO) x Preparation and application of ) 4.5 mL of 0.1 mol / L silver nitrate solution was diluted to 410 mL, and 0.25 g of PVP was added as a stabilizer. The mixture was stirred at room temperature for 10 min to obtain a silver core precursor solution. 17 mg of sodium borohydride was dissolved in 10 mL of deionized water and added to the above solution. The mixture was stirred for another 5 min to obtain PVP-stabilized silver nanoparticles. 3.15 mL of 0.01 mol / L manganese acetate precursor was added to the PVP-stabilized silver nanoparticle solution, and the mixture was stirred at room temperature for 5 min to ensure homogeneity. 0.34 g of sodium borohydride was dissolved in 30 mL of deionized water and added to the mixed solution to promote the formation of the amorphous oxide coating layer and initiate gelation. The mixture was then placed in a 60 ℃ water bath and reacted for 2–3 h. The product was collected, washed with deionized water, and solvent-displaced with tert-butanol. After freeze-drying at −60 ℃ for 24 h, the target catalyst was obtained.

[0030] like Figure 3 and Figure 4 As shown, Mn and O elements are clearly distributed on the outer surface of Ag, forming a distinct MnO layer. x Shell.

[0031] The catalyst was ultrasonically dispersed in a mixed solvent containing 800 μL of ethanol and 200 μL of 1% PTFE, and then sprayed onto carbon paper with a microporous gas diffusion layer to form a cathode. A Zn-CO2 battery was assembled with a zinc foil anode and a mixed solution of 3 mol / L KOH and 0.02 mol / L ZnSO4 as the electrolyte. The cathode was tested at room temperature and under a 1 atm CO2 atmosphere at 2 mA·cm⁻¹. −2 It exhibits excellent stability for 165 h at a given current density.

[0032] Example 3: Amorphous Mn 0.5 Y 0.5 O xShell-controlled silver core catalyst (Ag@Mn) 0.5 Y 0.5 O x Preparation and application of ) Dilute 9 mL of 0.1 mol / L silver acetate solution to 410 mL, add 0.5 g of PVP as a stabilizer, and stir at room temperature for 10 min to obtain a silver core precursor solution. Add 0.25 mmol of hydrazine hydrate to the above solution and continue stirring for 10 min to obtain PVP-stabilized silver nanoparticles. Add 2.25 mL of 0.01 mol / L manganese acetate and yttrium nitrate precursor to the PVP-stabilized silver nanoparticle solution and stir at room temperature for 5 min to mix thoroughly. Dissolve 0.34 g of sodium borohydride in 30 mL of deionized water and add it to the mixed solution to promote the formation of the amorphous oxide coating layer and initiate gelation. Place the solution in a 50 ℃ water bath for 2-3 h. Collect the product and wash it with deionized water. Replace the product with tert-butanol and freeze-dry it at −60 ℃ for 36 h to obtain Ag@Mn. 0.5 Y 0.5 O x Catalyst. (See attached image) Figure 5 As shown, the Ag core is covered by a distinct amorphous oxide shell.

[0033] By adjusting the amount of manganese acetate and yttrium nitrate precursors added, the elemental ratio of Mn and Y in the amorphous oxide shell can be precisely controlled.

[0034] The catalyst was ultrasonically dispersed in a mixed solvent containing 900 μL of ethanol and 100 μL of 1% PTFE, and then sprayed onto carbon paper with a microporous gas diffusion layer to form a cathode. This cathode was then reacted with a zinc foil anode, 6 mol / L KOH, and 0.02 mol / L... Zn(OAc)2 mixed solution was used as an electrolyte to assemble Zn-CO2 batteries.

[0035] Example 4: Amorphous CeO x Shell-controlled silver-copper core catalyst (AgCu@CeO) x Preparation and application of ) 8.55 mL of 0.1 mol / L silver nitrate solution and 0.45 mL of 0.1 mol / L copper nitrate solution were mixed and diluted to 410 mL. 1.16 g of NaCA was added as a stabilizer, and the mixture was stirred at room temperature for 10 min to obtain a silver-copper core precursor solution. 34 mg of sodium borohydride was dissolved in 10 mL of deionized water and added to the above solution. Stirring was continued for 10 min to obtain NaCA-stabilized silver-copper alloy nanoparticles. 6.3 mL of 0.01 mol / L cerium nitrate precursor was added to the NaCA-stabilized silver-copper alloy nanoparticle solution, and the mixture was stirred at room temperature for 5 min to ensure homogeneity. 0.34 g of sodium borohydride was dissolved in 30 mL of deionized water and added to the mixed solution to promote the formation of the amorphous metal oxide coating and initiate gelation. The solution was reacted in a 70 ℃ water bath for 2–3 h. The product was collected, washed with deionized water, solvent-displaced with tert-butanol, and then freeze-dried at −60 ℃ for 24 h to obtain AgCu@CeO. x Catalyst. (See attached image) Figure 6 As shown, an amorphous oxide shell also exists outside the AgCu alloy. The elemental ratio of Ag and Cu in the silver core can be precisely controlled by adjusting the amount of silver nitrate and copper nitrate precursors added.

[0036] The catalyst was ultrasonically dispersed in a mixed solvent containing 900 μL of isopropanol and 100 μL of 1% PTFE, and then sprayed onto carbon paper with a microporous gas diffusion layer to form a cathode. A Zn-CO2 battery was assembled with a zinc foil anode, a mixed solution of 6 mol / L KOH and 0.02 mol / L Zn(OAc)2 as the electrolyte.

[0037] Example 5: Amorphous La 0.2 Ce 0.8 O x Shell-controlled silver-zinc nuclear catalyst (AgZn@La) 0.2 Ce 0.8 O x Preparation and application of ) 8.1 mL of 0.1 mol / L silver acetate solution and 0.9 mL of 0.1 mol / L zinc acetate solution were mixed and diluted to 410 mL. 1 g of PVP was added as a stabilizer, and the mixture was stirred at room temperature for 20 min to obtain a silver-zinc core precursor solution. 34 mg of sodium borohydride was dissolved in 10 mL of deionized water and added to the above solution. The mixture was stirred for another 10 min to obtain PVP-stabilized silver-zinc alloy nanoparticles. 0.9 mL of 0.01 mol / L lanthanum nitrate and 3.6 mL of 0.01 mol / L cerium nitrate precursor were added to the PVP-stabilized silver-zinc alloy nanoparticle solution and stirred at room temperature for 5 min to mix thoroughly. 0.34 g of sodium borohydride was dissolved in 30 mL of deionized water and added to the mixed solution to promote the formation of the amorphous metal oxide coating layer and initiate gelation. The solution was placed in a 70 ℃ water bath for 2–3 h to react. The product was collected, washed with deionized water, solvent-displaced with tert-butanol, and then freeze-dried at −60 °C for 36 h to obtain AgZn@La. 0.2 Ce 0.8 O x Catalyst. (See attached image) Figure 7 As shown, AgZn@La 0.2 Ce 0.8 O x It also exhibits a core-shell structure characterized by an amorphous shell. By adjusting the amount of lanthanum nitrate and cerium nitrate added beforehand, the elemental ratio of La and Ce in the amorphous oxide shell can be precisely controlled.

[0038] The catalyst was ultrasonically dispersed in a mixed solvent containing 800 μL of ethanol and 200 μL of 1% PTFE, and then sprayed onto carbon paper with a microporous gas diffusion layer to form a cathode. This cathode was then reacted with a zinc foil anode, 6 mol / L KOH, and 0.02 mol / L... Zn(OAc)2 mixed solution was used as an electrolyte to assemble Zn-CO2 batteries.

[0039] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above examples are merely technical solutions of the present invention and not limitations on the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A silver core catalyst regulated by an amorphous oxide shell, characterized in that, include: (1) Silver core, wherein the silver core is silver nanoparticles or silver alloy nanoparticles with a particle size of 20~50 nm; (2) Shell, wherein the shell is an amorphous oxide coating the surface of the silver core, and the amorphous oxide is selected from MnO. x CrO x ScO x 、YO x LaO x CeO x At least one of the following; the loading of the amorphous oxide is 1.0~15wt%, and no obvious crystalline phase diffraction peaks are observed by XRD characterization.

2. The silver core catalyst with amorphous oxide shell controlled according to claim 1, characterized in that, The silver alloy nanoparticles are Ag-Cu alloys or Ag-Zn alloys, wherein the molar percentage of Cu or Zn elements is 1~10%.

3. The silver core catalyst with amorphous oxide shell controlled according to claim 1, characterized in that, The shell layer has a thickness of 0.5~2 nm, and transmission electron microscopy shows that it has no obvious interface gap with the silver core, forming a tightly bonded core-shell structure.

4. A method for preparing a silver core catalyst with amorphous oxide shell controlled as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Preparation of silver nucleus precursor solution: Dissolve silver salt, or silver salt and alloy metal salt, in deionized water, add stabilizer, stir evenly to obtain silver nucleus precursor solution with a concentration of 0.1~2 mmol / L; the stabilizer is a steric hindrance stabilizer or an electrostatic stabilizer; (2) Preparation of silver core: Add a chemical reducing agent to the precursor solution in step (1) and react at room temperature to obtain a well dispersed solution of silver or silver alloy nanoparticles; (3) Formation of amorphous oxide shell: Add the shell metal salt precursor to the silver core nanoparticle dispersion obtained in step (2), stir evenly, then add sodium borohydride aqueous solution to promote the formation of amorphous oxide coating layer and initiate gelation, and then place the solution in a water bath at 50~70 ℃ for constant temperature reaction for 2~3 hours. (4) Post-processing: The product from step (3) is washed with deionized water, solvent replaced, and freeze-dried to obtain the target catalyst.

5. The preparation method according to claim 4, characterized in that, In step (1), the silver salt is one of silver nitrate and silver acetate, and the alloy metal salt is at least one of copper or zinc nitrate or acetate. The stabilizer is selected from one of polyvinylpyrrolidone K30 (PVP), hexadecyltrimethylammonium bromide (CTAB), or sodium citrate (NaCA), and the amount of stabilizer added is 5 to 10 times the amount of the silver nucleus precursor.

6. The preparation method according to claim 4, characterized in that, In step (2), the chemical reducing agent is selected from one of sodium borohydride, ascorbic acid, hydrazine hydrate, and sodium hypophosphite. The molar ratio of the chemical reducing agent to the silver nucleus precursor is 0.25:1 to 4:1, and the reaction time is 5 to 20 minutes.

7. The preparation method according to claim 4, characterized in that, The shell metal salt precursor mentioned in step (3) is any one or more of metal nitrates, acetates, and chlorides, and the molar ratio of the metal element in the shell metal salt precursor to the silver or silver alloy in the silver core is 1:99 to 1:

9.

8. The preparation method according to claim 4, characterized in that, In step (4), the freeze-drying temperature is -60 ℃, the pressure is 1~10 Pa, and the time is 36~48 h.

9. The application of a silver core catalyst with an amorphous oxide shell regulated as described in any one of claims 1 to 3 in a Zn-CO2 battery, characterized in that, The catalyst was mixed with a solvent and polytetrafluoroethylene in a certain proportion and then ultrasonically prepared to form a catalyst ink. The solvent is either ethanol or isopropanol; The concentration of polytetrafluoroethylene is 1 wt%, and its volume ratio with the solvent is 5~20%; The catalyst ink is coated onto a conductive substrate to form a cathode, which is then assembled with a zinc foil anode and an electrolyte to form a Zn-CO2 battery.

10. The application according to claim 9, characterized in that, The anode electrolyte is a mixed aqueous solution of 1-6 mol / L KOH and 0.02 mol / L Zn(OAc)2 or ZnSO4, the cathode electrolyte is 0.5-1 mol / L KHCO3, and the conductive substrate is carbon paper with a microporous gas diffusion layer.

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