A catalytic material for the electrocatalytic reduction of carbon dioxide, its preparation method and application

Abstract

This invention relates to a catalytic material for the electrocatalytic reduction of carbon dioxide, its preparation method, and its application. The catalytic material is an AuZn alloy-modified ZnO nanotube array, wherein the AuZn alloy is uniformly supported on a continuous ZnO nanotube array. The preparation process of the catalytic material includes: preparing ZnO NRAs, preparing Au / ZnO NRAs, and preparing AuZn / ZnO NTAs. The surface of the catalytic material has a compact porous structure, which increases the effective surface area for the catalytic reaction and significantly enhances the catalytic activity. The Faradaic efficiency for CO reaches as high as 65.56%, and the Faradaic efficiency for H2 reaches as high as 25.88%, and the proportion of syngas is controllable. The catalytic material exhibits good stability, the preparation method is simple and effective, the synthesis process is controllable and environmentally friendly, and it has great practical application prospects in the field of CO2 catalytic reduction.

Description

Technical Field

[0001] This invention relates to the field of CO2 catalytic reduction, specifically to a catalytic material for the electrocatalytic reduction of carbon dioxide, its preparation method, and its application. Background Technology

[0002] The CO2 reduction reaction (CO2RR) is an effective way to utilize CO2 resources and convert it into high-value-added chemical products. It is of great significance for reducing greenhouse gas emissions and has attracted significant attention from scientists worldwide. The CO2 reduction reaction takes place at room temperature and atmospheric pressure, and the required electrical energy can be directly obtained from renewable energy sources such as solar, wind, geothermal, and tidal energy. It is a highly efficient energy storage method that converts green energy into chemical energy. During CO2 catalytic reduction, when an aqueous solution is used as the electrolyte, the hydrogen evolution reaction (HER) occurs at the cathode due to water electrolysis. Since HER has a thermodynamic potential comparable to that of the CO2 reduction reaction, CO2RR and HER are in competition at the cathode. By controlling the reactions at the cathode, a mixture of CO and H2 can be selectively generated, i.e., syngas, an important synthetic raw material in the petrochemical industry, which can be used in Fischer-Tropsch synthesis or to produce methanol, etc.

[0003] Traditional methods for producing syngas, including coal gasification and natural gas reforming, require extreme conditions such as high temperature and high pressure, consuming non-renewable energy sources and contradicting the principles of green chemistry. Using CO2 and H2O as raw materials for the catalytic reduction of CO2 in aqueous solution is an ideal method for sustainable syngas production, eliminating the need to suppress the hydrogen evolution reaction and avoiding difficulties in separating liquid products, making it a current research hotspot. However, existing catalytic materials, such as Zn / ZnO nanorod arrays, suffer from low surface pore density, small effective catalytic area, and low conductivity, leading to slow kinetics and unsatisfactory Faraday efficiency. Summary of the Invention

[0004] To address the above problems, this invention provides a catalytic material for the electrocatalytic reduction of carbon dioxide, its preparation method, and its application.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A catalytic material, preferably, is an AuZn alloy-modified ZnO nanotube array, wherein the AuZn alloy is uniformly loaded on a continuous ZnO nanotube array to form an AuZn / ZnO composite nanotube array.

[0007] Preferably, the catalytic material contains Zn 2+The molar ratio range of Au and Zn 2+ Au = 2:1 to 1:1.

[0008] A method for preparing the catalytic material, characterized in that the preparation method includes the following steps:

[0009] S1. ZnO nanorod arrays (ZnO NRAs) were deposited on a substrate using an electrodeposition method.

[0010] S2. The ZnO nanorod array is photodeposited in HAuCl4 aqueous solution, and Au is obtained by photoreduction loading. After washing with deionized water and drying, Au / ZnO nanorod array (Au / ZnO NRAs) is obtained.

[0011] S3. Electroreducing the Au / ZnO nanorod array in a CO2-saturated solution, removing the reduced electrode sheet, washing it with deionized water and drying it to obtain the AuZn / ZnO nanotube array (AuZn / ZnO NTAs), which is the catalytic material.

[0012] Preferably, in step S1, the electrodeposition temperature is 80–100°C, the time is 40–60 min, and the constant current value is set to -2 mA.

[0013] More preferably, in step S1, the electrodeposition temperature is 90°C and the time is 50 min.

[0014] Preferably, the substrate is FTO conductive glass.

[0015] Preferably, step S1 involves dissolving ammonium acetate, zinc nitrate, and hexamethylenetetramine in water to obtain a ZnO plating solution; then pouring the ZnO plating solution into a clean electrolytic cell, placing a clean FTO conductive glass piece inside, heating, and electroplating a uniform layer of ZnO onto the FTO conductive glass. After electroplating, the glass piece is removed, washed with deionized water, and dried to obtain a ZnO nanorod array.

[0016] Preferably, in step S1, the concentrations of ammonium acetate, zinc nitrate, and hexamethylenetetramine are 0.76 g / L, 5.96 g / L, and 1.4 g / L, respectively.

[0017] Preferably, in step S2, the volume of the HAuCl4 aqueous solution is 5-10 mL, and the concentration is 10-20 mmol / L.

[0018] More preferably, in step S2, the volume of the HAuCl4 aqueous solution is 5 mL.

[0019] Preferably, in step S2, the photodeposition time is 5 minutes.

[0020] Preferably, in step S3, the electrolyte of the CO2 saturated solution is 0.1 mol / L KHCO3.

[0021] Preferably, in step S3, the counter electrode for electroreduction is Pt, the reference electrode is Ag / AgCl, the reduction potential is set to -1.7V, and the reduction time is 10min.

[0022] An application of the catalytic material, characterized in that the catalytic material is used in the catalytic reduction reaction of CO2.

[0023] Preferably, in the application, the reduction voltage (vs. RHE) is adjusted to generate syngas with a controllable ratio of CO and H2.

[0024] Preferably, in the application, the reduction voltage (vs. RHE) ranges from -0.5V to -1.0V.

[0025] The beneficial effects of this invention are as follows: By first constructing a ZnO nanorod array and then doping it with gold atoms to obtain an AuZn / ZnO nanotube array, compared with the traditional Zn / ZnO nanorod array, the AuZn / ZnO nanotube array has a compact porous structure on its surface, increasing the effective area for catalytic reactions, thus exhibiting stronger catalytic ability in the CO2 catalytic reduction reaction (ECR). This invention provides a highly efficient catalytic material for the CO2 catalytic reduction reaction. Furthermore, the catalytic material exhibits good stability, the preparation method is simple and effective, and the synthesis process is controllable and environmentally friendly. This invention also provides more references for catalytic materials for the reduction of CO2 to produce H2 and CO syngas. Attached Figure Description

[0026] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0027] Figure 1 These are scanning electron microscope (SEM) images of the catalytic materials in Examples 1-3 and the comparative examples.

[0028] Figure 2 This is the elemental mapping diagram of the catalytic material obtained in Example 2. Figure 2 a) and transmission electron microscopy images ( Figure 2 b)

[0029] Figure 3 The values ​​represent the Faraday efficiencies of the carbon dioxide reduction products of the catalytic materials in Examples 1-3 and the comparative examples.

[0030] Figure 4The ratio (CO / H2) of the catalytic materials in Examples 1-3 and the comparative examples is the ratio of the carbon dioxide reduction product syngas in the reduction voltage range of -0.5 to -1.0V. Detailed Implementation

[0031] The present invention will be further described in conjunction with the following embodiments.

[0032] Example 1

[0033] 1. Preparation of Au-2Zn / ZnO NTAs as catalysts for CO2 catalytic reduction reaction

[0034] (1) Preparation of ZnO NRAs: 0.19g ammonium acetate, 1.49g zinc nitrate and 0.35g hexamethylenetetramine were dissolved in deionized water and diluted to 250mL in a volumetric flask to obtain ZnO plating solution. Then 20mL of the plating solution was placed in an electrolytic cell and then the electrolytic cell was transferred to an oil bath at 90℃. A conductive glass plate was then placed in the electrolytic cell. The constant current electrodeposition method was used, with the current set to -2.0 mA. Electrodeposition was performed in an oil bath at 90℃ for 50min. After that, the conductive glass plate was removed, rinsed with deionized water and dried to obtain white thin film ZnO NRAs.

[0035] (2) Preparation of Au / ZnO NRAs: Dissolve 0.62g of chloroauric acid in 100mL of deionized water, take 5mL and place it in a quartz tube, put the ZnO NRAs obtained in step (1) into the quartz tube, and use photodeposition to photoreduced for 5min. Then take out the material and rinse and dry it with deionized water to obtain Au-2 / ZnO NRAs.

[0036] (3) Preparation of AuZn / ZnO NTAs: The Au-2 / ZnO obtained in step (2) was placed in a CO2 saturated solution with 0.1 mol / L KHCO3 electrolyte for electroreduction. The counter electrode was Pt, the reference electrode was Ag / AgCl, the reduction potential was set to -1.7 V, and the reduction time was 10 min. Then, the electrode sheet after reduction was taken out, washed with deionized water, and dried to obtain Au-2Zn / ZnO NTAs. The SEM results are shown in [Figure number missing]. Figure 1 e, f. Zn in the obtained Au-2Zn / ZnO NTAs 2+ The molar ratio of Au is 4:3.

[0037] 2. Electrochemical testing

[0038] The Au-2Zn / ZnO NTAs obtained in the above steps were electrolyzed in a 0.1 mol / L KHCO3 CO2 saturated solution. The counter electrode was Pt, and the reference electrode was Ag / AgCl. The electrolysis potential range was set to -0.5 V to -1.0 V (vs. RHE), and the electrolysis time was 60 min. The electrolysis products were collected, and the Faraday efficiency of the products was calculated. Figure 3 c. Synthesis gas ratio see Figure 4 c.

[0039] Example 2

[0040] 1. Preparation of AuZn-1 / ZnO NTAs as catalysts for CO2 catalytic reduction reaction

[0041] (1) Same as step (1) in Example 1.

[0042] (2) Preparation of Au / ZnO NRAs: Dissolve 0.41g of chloroauric acid in 100mL of deionized water, take 5mL and place it in a quartz tube, put the ZnO NRAs obtained in step (1) into the quartz tube, and use photodeposition to photoreduced for 5min. Then take out the material and rinse and dry it with deionized water to obtain Au-1 / ZnO NRAs.

[0043] (3) Preparation of AuZn / ZnO NTAs: The Au-1 / ZnO obtained in step (2) was placed in a CO2 saturated solution with 0.1 mol / L KHCO3 electrolyte for electroreduction. The counter electrode was Pt, the reference electrode was Ag / AgCl, the reduction potential was set to -1.7 V, and the reduction time was 10 min. Then, the electrode sheet after reduction was taken out, washed with deionized water, and dried to obtain AuZn-1 / ZnO NTAs. The SEM results are shown in [Figure number missing]. Figure 1 c, d. Zn in the obtained AuZn-1 / ZnO NTAs 2+ The molar ratio of Au is 2:1.

[0044] 2. Electrochemical testing

[0045] The AuZn-1 / ZnO NTAs obtained in the above steps were electrolyzed in a 0.1 mol / L KHCO3 CO2 saturated solution. The counter electrode was Pt, and the reference electrode was Ag / AgCl. The electrolysis potential range was set to -0.5 V to -1.0 V (vs. RHE), and the electrolysis time was 60 min. The electrolysis products were collected, and the Faraday efficiency of the products was calculated. Figure 3 b. Syngas ratio see Figure 4 b.

[0046] Example 3

[0047] 1. Preparation of AuZn-3 / ZnO NTAs as catalytic materials for CO2 catalytic reduction reaction

[0048] (1) Same as step (1) in Example 1.

[0049] (2) Preparation of Au / ZnO NRAs: Dissolve 0.82g of chloroauric acid in 100mL of deionized water, take 5mL and place it in a quartz tube, put the ZnO NRAs obtained in step (1) into the quartz tube, and use photodeposition to photoreduced for 5min. Then take out the material and rinse and dry it with deionized water to obtain Au-3 / ZnO NRAs.

[0050] (3) Preparation of AuZn / ZnO NTAs: The Au-3 / ZnO obtained in step (2) was placed in a CO2 saturated solution with 0.1 mol / L KHCO3 electrolyte for electroreduction. The counter electrode was Pt, the reference electrode was Ag / AgCl, the reduction potential was set to -1.7 V, and the reduction time was 10 min. Then, the electrode sheet after reduction was taken out, washed with deionized water, and dried to obtain AuZn-3 / ZnO NTAs. The SEM results are shown in [Figure number missing]. Figure 1 g, h. Zn in the obtained AuZn-3 / ZnO NTAs 2+ The molar ratio of Au is 1:1.

[0051] 2. Electrochemical testing

[0052] The AuZn-3 / ZnO NTAs obtained in the above steps were electrolyzed in a CO2-saturated solution of 0.1 mol / L KHCO3. The counter electrode was Pt, and the reference electrode was Ag / AgCl. The electrolysis potential range was set to -0.5 V to -1.0 V (vs. RHE), and the electrolysis time was 60 min. The electrolysis products were collected, and the Faraday efficiency of the products was calculated. Figure 3 d. See the syngas ratio. Figure 4 d.

[0053] Comparative Example

[0054] 1. Preparation of Zn / ZnO NTAs as catalysts for CO2 catalytic reduction reaction

[0055] (1) Same as step (1) in Example 1.

[0056] (2) The ZnO obtained in step (1) was electroreduced in a CO2 saturated solution with 0.1 mol / L KHCO3 electrolyte. The counter electrode was Pt, the reference electrode was Ag / AgCl, the reduction potential was set to -1.7 V, and the reduction time was 10 min. The reduced electrode was then removed, washed with deionized water, and dried to obtain Zn / ZnO NTAs. The SEM results are shown in […]. Figure 1 a, b.

[0057] 2. Electrochemical testing

[0058] The Zn / ZnO NTAs obtained in the above steps were electrolyzed in a 0.1 mol / L KHCO3 CO2 saturated solution. The counter electrode was Pt, and the reference electrode was Ag / AgCl. The electrolysis potential range was set to -0.5 V to -1.0 V (vs. RHE), and the electrolysis time was 60 min. The electrolysis products were collected, and the Faraday efficiency of the products was calculated. Figure 3 a. Syngas ratio is shown in [reference]. Figure 4 a.

[0059] Figure 1 The results show that the catalytic materials obtained in Examples 1-3 have a more compact porous structure on their surface and a larger effective area for catalytic reaction compared to the catalytic materials obtained in the comparative examples. Figure 2 This indicates that the catalyst material obtained in the examples successfully incorporated Au. Figure 3 The results show that, compared with the catalytic material obtained in the comparative example, the catalytic materials obtained in Examples 2 and 3 have significantly increased Faraday efficiency of the carbon dioxide reduction product H2 at potentials of -0.7V and -0.6V, while the Faraday efficiency of CO has not changed significantly; while the catalytic material obtained in Example 1 has significantly increased Faraday efficiency of the carbon dioxide reduction products CO and H2. Figure 4 The results show that, compared with the catalyst obtained in the comparative example, the proportion of syngas from carbon dioxide reduction is more sensitive to changes in reduction voltage in the range of reduction potential from -0.7 to -0.9V for the catalyst obtained in Examples 1 to 3.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A catalytic material for the electrocatalytic reduction of CO2, characterized in that, The catalytic material is an AuZn alloy-modified ZnO nanotube array, wherein the AuZn alloy is uniformly loaded on a continuous ZnO nanotube array. Zn in the catalyst material 2+ The molar ratio range of Au and Zn 2+ Au = 2:1 to 1:1; The preparation method of the catalytic material includes the following steps: S1. A ZnO nanorod array is deposited on an FTO conductive glass substrate by electrodeposition: Ammonium acetate, zinc nitrate and hexamethylenetetramine are dissolved in water to obtain a ZnO plating solution. The ZnO plating solution is then poured into a clean electrolytic cell. A clean FTO conductive glass is placed in the cell, heated, and a uniform layer of ZnO is electroplated on the FTO conductive glass. After electroplating, the glass is removed, washed with deionized water, and dried to obtain a ZnO nanorod array. S2. The ZnO nanorod array is photodeposited in HAuCl4 aqueous solution to obtain Au / ZnO nanorod array; S3. The Au / ZnO nanorod array is electroreduced in a CO2 saturated solution to obtain an AuZn / ZnO nanotube array, which is the catalytic material.

2. The catalytic material according to claim 1, characterized in that, In step S1, the electrodeposition temperature is 80–100°C, the time is 40–60 min, and the constant current value is set to -2 mA.

3. The catalytic material according to claim 1, characterized in that, In the ZnO plating solution, the concentrations of ammonium acetate, zinc nitrate, and hexamethylenetetramine are 0.76 g / L, 5.96 g / L, and 1.4 g / L, respectively.

4. The catalytic material according to claim 1, characterized in that, In step S2, the volume of the HAuCl4 aqueous solution is 5–10 mL, and the concentration is 10–20 mmol / L.

5. The catalytic material according to claim 1, characterized in that, In step S2, the photodeposition time is 5 minutes.

6. The catalytic material according to claim 1, characterized in that, In step S3, the electrolyte of the CO2 saturated solution is 0.1 mol / L KHCO3; the counter electrode for electroreduction is Pt, and the reference electrode is Ag / AgCl; the reduction potential is set to -1.7 V, and the reduction time is 10 min.

7. The application of the catalytic material according to claim 1 in the catalytic reduction of CO2.

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