Preparation method and application of copper borate electrocatalyst

Abstract

The invention relates to the technical field of electrocatalysts, and particularly to a preparation method and application of a copper borate electrocatalyst. The method comprises the following steps: dissolving a sodium tetraborate solution in water to form a single uniform solution to obtain a solution A; weighing a copper salt and dissolving it in deionized water to form a single uniform solution to obtain a solution B; slowly dropping the solution B into the solution A to form a blue solution C; heating and keeping the solution C warm, cooling the solution after the reaction is completed to obtain a reactant, washing and drying the reactant to obtain a copper borate electrocatalyst; and using the copper borate electrocatalyst to reduce CO2 of different concentrations. The method adopts different copper sources to react with sodium tetraborate, controls the synthesis temperature and time of the reaction to obtain the copper borate, and promotes the adsorption of reaction intermediates by regulating the transfer of electrons, thereby improving the ability of the electrocatalytic reduction of CO2 of different concentrations.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysts, and in particular to a preparation method and application of a copper borate electrocatalyst. Background Art

[0002] Electrocatalytic CO2 reduction utilizes renewable energy to drive a catalytic process. It features mild reaction conditions, a controllable catalytic process, and the products can be used as fuels and chemical raw materials, with the potential for large-scale practical application. However, given the expensive gas processes used to produce pure CO2, direct conversion of low-concentration CO2 is an important approach.

[0003] Among many electrocatalysts, copper-based catalysts have been widely studied in the electrocatalytic reduction of CO2 as an electrocatalyst that can obtain C2 products.

[0004] However, the practical application of traditional copper-based catalysts in the field of electrocatalytic CO2 reduction is limited by their low current density, low product selectivity and low activity. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method and application of a copper borate electrocatalyst, which solves the problem that traditional copper-based catalysts have low current density, low product selectivity and low activity in application, which limits the practical application of copper-based catalysts in the field of electrocatalytic CO2 reduction.

[0006] To achieve the above object, the present invention provides a copper borate nanosheet structure catalyst, wherein the length of the nanosheet is 100 to 300 nm and the width is 40 to 50 nm.

[0007] The present invention also provides a preparation method and application of a copper borate electrocatalyst, comprising the following steps:

[0008] Solution A was prepared by dissolving sodium tetraborate solution in water to form a single homogeneous solution;

[0009] Solution B was prepared by weighing copper salt and dissolving it in deionized water to form a single homogeneous solution;

[0010] Slowly add the solution B dropwise to the solution A to form a blue solution C;

[0011] The solution C is heated and kept warm, and after the reaction is completed, it is cooled to obtain a reactant, and the reactant is washed and dried to obtain a copper borate electrocatalyst;

[0012] The copper borate electrocatalyst was used to reduce CO2 at different concentrations.

[0013] Wherein, in “dissolving the sodium tetraborate solution in water to form a single uniform solution to prepare solution A”, the method further comprises:

[0014] The sodium tetraborate solution has a concentration of 1 to 10 g / L.

[0015] Wherein, in “weighing a copper salt and dissolving it in deionized water to form a single uniform solution to prepare solution B”, the method further comprises:

[0016] The copper salt is one of CuSO4, CuCl2, Cu(NO3)2, and Cu(CH3COO)2, wherein the concentration of the copper salt is 10 to 500 g / L.

[0017] Wherein, in “slowly adding the solution B dropwise to the solution A to form a blue solution C”, the method further comprises:

[0018] The dropping speed is controlled at 1-3 mL / min, the heating temperature is controlled at 25-200 DEG C, and the reaction time is controlled at 1-10 hours.

[0019] Wherein, in “reducing CO2 of different concentrations using the copper borate electrocatalyst”, the method further comprises:

[0020] Dispersing the copper borate electrocatalyst in an aqueous solution containing isopropyl alcohol, adding a perfluorosulfonic acid resin solution, and uniformly mixing by ultrasonication to prepare a liquid A;

[0021] Applying the liquid A on hydrophobic carbon paper and vacuum drying;

[0022] The vacuum-dried carbon paper was used as the working electrode with a loading of 0.5-1.5 mg / cm 2 , using a flow-type reaction cell for electrocatalytic CO2 reduction.

[0023] Among them, the vacuum-dried carbon paper was used as the working electrode, with a loading of 0.5 to 1.5 mg / cm 2 , wherein the method further comprises:

[0024] The dilution gas is one of N2 and Ar.

[0025] Among them, the vacuum-dried carbon paper was used as the working electrode, with a loading of 0.5 to 1.5 mg / cm 2 , wherein the method further comprises:

[0026] The dilution concentration of N2 and Ar with CO2 as diluent gases is 5% to 100% CO2.

[0027] The copper borate electrocatalyst prepared by the present invention is used to reduce CO2 with different concentrations.

[0028] Specifically: copper borate electrocatalyst Cu(BO2)2 is drop-coated on hydrophobic carbon paper as the working electrode, solid Ag / AgCl (3M) electrode is used as the reference electrode, Pt sheet is used as the counter electrode, 1M KOH is used as the electrolyte, and the cathode and anode are separated by an ion exchange membrane. The three-electrode system is passed through the flow-cell, and the flow rates of N2 and CO2 are controlled by flow meters respectively to achieve the effect of diluting CO2, thereby electrocatalyzing the reduction of CO2 of different concentrations to multi-carbon products.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present invention utilizes a simple oil bath method to heat the reaction solution and, by controlling the reaction temperature, produces Cu(BO2)2 nanosheets with good crystallinity. The reaction conditions are mild, the raw materials are readily available and low-cost, and the preparation process is simple and environmentally friendly.

[0031] 2. In the material of the present invention, inorganic non-metallic ions (BO 2- ) modification of copper ions is beneficial to changing the valence band state density of the metal, so that copper ions have a stronger adsorption ability for *CO intermediates in the CO2 reduction process, exposing more effective active sites, which is beneficial to the occurrence of CC coupling reaction, thereby enhancing the selectivity for C2 products.

[0032] 3. The material of the present invention exhibits good C2 selectivity in the electrocatalytic low-concentration CO2 reduction process, providing an effective solution to the economic and environmental problems brought about by further realizing industrial electrocatalytic CO2 reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art.

[0034] Figure 1 The XRD spectra of Cu(BO2)2 materials prepared at different reaction temperatures in Example 1 are shown.

[0035] Figure 2 This is a TEM image of the material prepared in Example 1 at a reaction temperature of 65°C.

[0036] Figure 3 This is a graph showing the electrocatalytic reduction performance of Cu(BO2)2 prepared in Example 1 at a reaction temperature of 65°C under pure CO2 conditions.

[0037] Figure 4 This is a performance comparison chart of Cu(BO2)2 prepared in Example 1 at a reaction temperature of 65°C and CO2 reduction to produce C2 products under different CO2 concentration conditions.

[0038] Figure 5 This is a comparison chart of the current density of Cu(BO2)2 prepared in Example 1 at a reaction temperature of 65°C under different CO2 concentration conditions.

[0039] Figure 6 The present invention is a flow chart of the preparation method of the copper borate electrocatalyst.

[0040] Figure 7 The present invention is a flow chart of the method for reducing CO2 of different concentrations using copper borate electrocatalyst. DETAILED DESCRIPTION

[0041] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0042] A method for preparing a copper borate electrocatalyst comprises the following steps:

[0043] S101: dissolving a sodium tetraborate solution in water to form a single homogeneous solution to prepare a solution A;

[0044] S102: Weigh copper salt and dissolve it in deionized water to form a single uniform solution to prepare solution B;

[0045] S103: slowly adding the solution B dropwise to the solution A to form a blue solution C;

[0046] S104: heating the solution C and keeping it warm, cooling it after the reaction is completed to obtain a reactant, washing and drying the reactant to obtain a copper borate electrocatalyst;

[0047] S105: using the copper borate electrocatalyst to reduce CO2 of different concentrations.

[0048] First embodiment:

[0049] Weigh 2.0 g of sodium tetraborate decahydrate and dissolve it in 250 mL of deionized water to form Solution A, stirring to dissolve. At room temperature (25°C), dissolve 5.0 g of copper sulfate pentahydrate in 10 mL of deionized water and sonicate to form Solution B. Slowly add the copper sulfate solution B dropwise to the sodium tetraborate solution A with stirring to form Solution C. Solution C turns blue and solid precipitates. Heat Solution C to 65°C and maintain for 7 hours. Wash and dry to obtain a blue-green solid powder (Cu(BO2)2).

[0050] Second embodiment:

[0051] Weigh 2.0 g of sodium tetraborate decahydrate and dissolve it in 250 mL of deionized water to form Solution A, stirring to dissolve. At room temperature, dissolve 3.2 g of copper nitrate trihydrate in 10 mL of deionized water and sonicate to form Solution B. Slowly add copper nitrate solution B dropwise to sodium borate solution A with stirring to form Solution C. Solution C will turn blue and solid will precipitate. Heat to 100°C and maintain for 5 hours. Wash and dry to obtain a blue-green solid powder.

[0052] Third embodiment:

[0053] Weigh 1.5 g of sodium tetraborate decahydrate and dissolve it in 200 mL of deionized water to form solution A. Dissolve 2.5 g of cupric chloride dihydrate in 10 mL of deionized water at room temperature to form solution B. Slowly add cupric chloride solution B dropwise to sodium tetraborate solution A with stirring to form solution C. Solution C turns blue and solid precipitates. Maintain the mixture at room temperature (25°C) for 7 h, then wash and dry to obtain a blue-green solid powder.

[0054] Figure 1 This is the X-ray diffraction pattern of the material obtained in Example 1. It can be seen from the figure that when the reaction temperatures are 25, 65 and 100°C, the diffraction peaks of the sample correspond to the characteristic peaks of Cu(BO2)2 (No.01-472), indicating that Cu(BO2)2 material will be generated regardless of the temperature.

[0055] Figure 2 The TEM image in Example 1 shows that, at 65° C., the obtained material has a nanosheet morphology with a diameter of 40 to 50 nm.

[0056] Fourth embodiment:

[0057] Application of copper borate electrocatalyst: 4 mg of Cu(BO2)2 in Example 1 was weighed and dispersed in an aqueous solution containing isopropanol. 10 μL of perfluorosulfonic acid resin solution (Nafion) was added and ultrasonically mixed. 250 μL of liquid (liquid A) was taken and applied to a 1*1 cm 2 The working electrode was prepared by vacuum drying on hydrophobic carbon paper. During the electrocatalytic CO2 reduction reaction, the total reaction gas flow rate was 20 or 30 sccm, and the CO2 / N2 flow rates were controlled to 20:0, 15:5, 10:10, and 5:15, respectively, to define 100% CO2, 75% CO2, 50% CO2, and 25% CO2, but not limited to these ratios. Performance was measured.

[0058] Figures 3 to 5They are respectively the Faraday efficiency diagrams of the electrocatalytic CO2 reduction of Cu(BO2)2 in Example 1 within different CO2 concentration ranges. It can be seen from the diagram that the main C2 products include ethylene and ethanol. When the CO2 concentration is 75%, the highest C2 Faraday efficiency can reach 65.00%.

[0059] The above disclosure is merely one or more preferred embodiments of the present application and is not intended to limit the scope of the present application. A person skilled in the art will understand that all or part of the processes of the above embodiments and equivalent changes made in accordance with the claims of the present application are still within the scope of the present application.

Claims

1. Application of a copper borate electrocatalyst in catalyzing CO2, characterized in that: The catalyst is prepared by the following steps: Solution A was prepared by dissolving sodium tetraborate solution in water to form a single homogeneous solution; Solution B was prepared by weighing copper salt and dissolving it in deionized water to form a single homogeneous solution; Slowly add the solution B dropwise to the solution A to form a blue solution C; The solution C is heated and kept warm, and after the reaction is completed, it is cooled to obtain a reactant, and the reactant is washed and dried to obtain a copper borate electrocatalyst; The copper borate electrocatalyst is used to electrocatalyze the reduction of CO2 with different concentrations in a flow-type reaction cell.

2. The use according to claim 1, characterized in that In "Solution A is prepared by dissolving sodium tetraborate solution in water to form a single homogeneous solution", The concentration of sodium tetraborate in the sodium tetraborate solution is 1-10 g / L.

3. The use according to claim 2, characterized in that In "Weigh copper salt and dissolve it in deionized water to form a single uniform solution to prepare solution B", The copper salt is one of CuSO4, CuCl2, Cu(NO3)2, and Cu(CH3COO)2, wherein the concentration of the copper salt is 10 to 500 g / L.

4. The use according to claim 3, characterized in that In "Slowly adding the solution B dropwise to the solution A to form a blue solution C", The drop rate was controlled at 1-3 mL / min.

5. The use according to claim 4, characterized in that In "heating and keeping the solution C warm, cooling after the reaction is completed to obtain a reactant, washing and drying the reactant to obtain a copper borate electrocatalyst", The heating temperature is controlled at 25-200°C, and the reaction time is 1-10 h.

6. The use according to claim 5, characterized in that In "using the copper borate electrocatalyst to electrocatalyze the reduction of CO2 at different concentrations in a flow-type reaction cell", the method specifically includes: Dispersing the copper borate electrocatalyst in an aqueous solution containing isopropyl alcohol, adding a perfluorosulfonic acid resin solution, and uniformly mixing by ultrasonication to prepare a liquid A; Applying the liquid A on hydrophobic carbon paper and vacuum drying; The vacuum-dried carbon paper was used as the working electrode with a loading of 0.5-1.5 mg / cm 2 , using a flow-type reaction cell for electrocatalytic CO2 reduction.

7. The use according to claim 6, characterized in that The vacuum-dried carbon paper was used as the working electrode, and the loading was 0.5-1.5 mg / cm 2 , using flow cell electrocatalytic CO2 reduction”, The diluting gas is one of N2 and Ar.

8. The use according to claim 7, characterized in that The vacuum-dried carbon paper was used as the working electrode, and the loading was 0.5-1.5 mg / cm 2 , using flow cell electrocatalytic CO2 reduction”, The concentration of CO2 is 5% to 100%.

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