Method for ultrafast preparation of porous Cu / Zn heterojunction electrocatalytic material and application thereof

Abstract

The application relates to a method for rapidly preparing a porous Cu / Zn heterojunction electrocatalytic material and application. The method utilizes a dynamic hydrogen bubble template method to prepare the heterojunction electrocatalytic material, and the preparation is carried out under the condition of a higher cathode deposition current. The specific steps are as follows: firstly, copper sulfate, zinc sulfate and ammonium sulfate are dissolved in deionized water according to a certain ratio to serve as an electrodeposition solution. The electrodeposition is carried out at room temperature, the deposition condition is controlled by using a direct current power supply, a hydrophilic carbon paper is used as a substrate electrode, and the porous Cu / Zn heterojunction material is deposited for 30 seconds under the condition of a deposition current of-1.0 A. The preparation scheme can realize in-situ rapid preparation of the porous material, the loading is uniform and stable, the operation process of a relatively cumbersome hard template method is avoided, and the electrocatalytic carbon dioxide reduction preparation carbon monoxide performance is very high.

Description

Technical Field

[0001] This invention relates to a porous Cu / Zn heterojunction electrocatalytic material, its preparation method, and its application, particularly to a porous Cu / Zn heterojunction electrocatalytic material, its preparation method, and its application in the field of electrocatalytic carbon dioxide reduction. Background Technology

[0002] The concentration of carbon dioxide (CO2) in the atmosphere is increasing year by year, making it urgent to seek technologies such as CO2 capture, storage, and conversion to control and reduce atmospheric CO2 levels. To address these issues, many researchers have made significant efforts to mitigate the impact of large-scale CO2 emissions and have developed a range of processing technologies to achieve efficient carbon capture, utilization, and storage. Among these technologies, converting CO2 into renewable energy-driven value-added fuels and chemicals is an effective way to achieve a sustainable carbon cycle and improve the utilization rate of renewable energy.

[0003] Electrocatalytic carbon dioxide reduction (eCO2RR) is a promising pathway for converting CO2 into chemicals and fuels, especially using intermittent renewable electrical energy resources. Research on the reduction of CO2 to carbon monoxide (CO) has become a hot topic due to its relatively high selectivity, considerable current density, and ease of separation from liquid electrolytes. Although various catalysts have been reported to effectively reduce CO2 to high-value-added chemicals, their catalytic activity, selectivity, and stability are still insufficient to meet industrial demands. Therefore, there is still much room for improvement in eCO2RR CO production through the design of novel catalytic systems. However, much work remains to be done to further enhance the performance of carbon dioxide conversion in this process.

[0004] Three-dimensional hierarchical pores and open branched micro / nanostructures possess a large surface area to volume ratio, providing easier solution transport and faster electron transfer capabilities. However, porous metal structures are mechanically fragile, leading to rapid decomposition and microstructure reconstruction during the eCO2RR process. To address the issue of structural stability, an effective strategy is to construct intermetallic compounds. In the eCO2RR process, regulating the stability of the active metal's electronic valence state is an effective strategy to prevent metal catalyst aggregation and maintain high activity. Recent studies have shown that constructing bimetallic catalysts exhibits very high catalytic activity and stability. Furthermore, intermetallic compounds prepared by in-situ electrodeposition possess good conductivity, enabling relatively rapid electron transfer during catalysis. Summary of the Invention

[0005] The purpose of this invention is to provide a rapid, efficient, and simple method for synthesizing three-dimensional porous Cu / Zn heterojunction catalysts. The preparation method involves directly fixing the material onto carbon paper, which is simple and easy to implement. Compared to traditional powder materials, it avoids the use of electrodes in the fabrication process, reduces costs, and contributes to improved performance. The objective of this invention is to provide a rapid, efficient, and simple method for preparing Cu / Zn heterojunction catalysts.

[0006] Another objective of this invention is to provide a Cu / Zn heterojunction catalyst product and its application.

[0007] The specific technical solution to achieve the objective of this invention is: a rapid, efficient, and simple method for preparing a Cu / Zn heterojunction catalyst, using copper sulfate and zinc sulfate as raw materials, directly preparing and attaching the metal material to a carbon paper substrate using an electrodeposition method, and adjusting the catalyst loading by controlling the deposition time, including the following steps:

[0008] Step 1: Pretreatment of the carbon paper substrate:

[0009] 1-1. Cut the carbon paper into 1×1.1cm pieces. 2 A small rectangle;

[0010] 1-2. The hydrophilic carbon paper is ultrasonically cleaned in sequence with acetone, ethanol and deionized water for 15 minutes.

[0011] 1-3. Place the cleaned carbon paper in a drying oven and dry it at 60℃.

[0012] Step 2: Preparation of electrodeposition solution:

[0013] 2-1. Dissolve a certain amount of copper sulfate and zinc sulfate in 50 mL of sulfuric acid solution, stir for 15 min until completely dissolved, then add a certain amount of ammonium sulfate to the above solution and sonicate to dissolve.

[0014] 2-2, Different [Cu] 2+ ] / [Zn 2+ The electrodeposition solution with the specified molar ratio can be prepared using the method described in step 2-1.

[0015] Step 3: Preparation of porous Cu / Zn heterojunction catalytic materials:

[0016] 3-1. Take the prepared electrodeposition solution and place it in a single-chamber electrolytic cell. Use a dual-electrode deposition method, and clamp the carbon paper sheet on the cathode electrode of the galvanometer. Connect the platinum counter electrode to the anode electrode.

[0017] 3-2. Simultaneously immerse the carbon paper sheet and platinum counter electrode into an electrolytic cell containing electrodeposition solution, adjust the constant current electrodeposition program, set the deposition current, and control a certain deposition time to begin deposition;

[0018] 3-3. After deposition, remove the carbon paper sheet loaded with active material, rinse it slowly several times with deionized water, irradiate it under an infrared lamp for a certain period of time, and then dry it. This yields the porous Cu / Zn heterojunction catalytic material.

[0019] This invention presents a rapid, high-loading, and stably attached catalyst preparation technique. Utilizing an in-situ electrodeposition method, the bimetallic heterojunction catalyst is grown in situ on a carbon paper substrate, avoiding the cumbersome steps of traditional drop-coating of powder materials for electrode preparation. Characterization by SEM and TEM revealed that the porous heterojunction catalyst in this invention exhibits uniform and stable loading and excellent morphology. This invention uses only the corresponding metal salt as a raw material, and through rapid electrodeposition, a dynamic hydrogen bubble template method can prepare porous bimetallic heterojunction electrocatalytic materials.

[0020] The method for preparing the porous Cu / Zn heterojunction catalytic material is characterized in that the electrodeposition solution in step 2, [Cu 2+ ] / [Zn 2+ The molar ratio is 1:1, the concentration of H2SO4 is 20mM, and the concentration of (NH4)2SO4 is 1.5M. The specific amount of solution to be prepared is determined based on the amount of sample deposited each time.

[0021] The method for preparing the porous Cu / Zn heterojunction catalytic material is characterized in that the deposition time in the third step is determined according to the amount of active catalyst material required, and is selected as 15-60s.

[0022] A porous Cu / Zn heterojunction catalytic material, characterized in that it is prepared by the method according to any one of claims 1-4.

[0023] Application of the porous Cu / Zn heterojunction catalytic material according to claim 5 in the field of electrocatalytic CO2 reduction.

[0024] The method for ultra-fast preparation of porous Cu / Zn heterojunction electrocatalytic materials described in this invention requires strict control of the consistency of electrodeposition conditions during electrodeposition to ensure the uniformity and repeatability of catalyst loading during electrode preparation.

[0025] One of the objectives of this invention is to provide a porous Cu / Zn bimetallic heterojunction catalyst prepared according to the method provided by this invention. A method for preparing porous materials is proposed, using copper sulfate and zinc sulfate as raw materials, employing a dynamic hydrogen bubble template method to obtain electrocatalytic materials with high activity, high specific surface area, and high stability. The process is easy to control and the method is simple to operate.

[0026] One of the objectives of this invention is to provide the application of porous Cu / Zn bimetallic heterojunction catalysts prepared according to the method provided by this invention in the field of electrocatalytic CO2 reduction, especially in the application of electrocatalytic CO2 reduction to CO.

[0027] The advantages of the method for preparing porous Cu / Zn bimetallic heterojunction catalysts provided by this invention are as follows:

[0028] (1) The present invention prepares porous Cu / Zn bimetallic heterojunction materials using copper sulfate and zinc sulfate as raw materials. The process is convenient, environmentally friendly and clean, with a wide range of raw materials and good prices, making it easy to realize industrial production.

[0029] (2) The hydrogen bubble template method was used to obtain a catalyst material with abundant pores and a large specific surface area.

[0030] (3) It has the characteristics of high catalytic activity and strong structural stability, and still has a good catalytic effect under long-term electrolysis conditions. Attached Figure Description

[0031] Figure 1 Here is a SEM image of the heterojunction material prepared in Example 1;

[0032] Figure 2 This is a magnified SEM image of the heterojunction material prepared in Example 1;

[0033] Figure 3 The image shows the XRD pattern of the heterojunction material prepared in Example 1.

[0034] Figure 4 Electrocatalytic performance results of the catalyst prepared for the example in CO2-saturated 0.5M [Bmim]PF6 / MeCN solution;

[0035] Figure 5 The figure shows the long-term stability test results of the catalyst prepared for the example in a CO2-saturated 0.5M [Bmim]PF6 / MeCN solution. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0037] Example 1

[0038] The electrodeposition solution consisted of 50 mL of sulfuric acid (20 mM), copper sulfate (50 mM), zinc sulfate (50 mM), and ammonium sulfate (1.5 M). Electrodeposition was performed at room temperature. [Cu 2+ ] / [Zn 2+ The molar ratio is 1:1. Constant current control is applied via a DC power supply, and the device is equipped with a boost converter providing up to 5A of current. The porous Cu / Zn layer is applied at -1.0A cm⁻¹. -2 The electrodeposition current density was obtained after 30 s deposition. The catalyst was labeled Cu / Zn-CP-1-30, Cu / Zn-CP-xy (x: electrodeposition current density (A cm⁻¹)). -2 ), y: electrodeposition time (s). All data such as current density per unit area and material loading are based on the geometric surface area of ​​carbon paper. After rinsing with moderately deionized water to remove loose deposits around the carbon paper boundaries, vacuum drying is performed, and the loading is measured using a precision balance. Before use, the carbon paper is dried in a vacuum oven at room temperature and stored.

[0039] The structure and morphology of the prepared porous material were observed using a HITACHI S-4800 scanning electron microscope.

[0040] Figure 1 and Figure 2 The image shows the SEM image of the porous heterojunction catalyst obtained in Example 1. The porous Cu / Zn metal layer with an average thickness of 20 μm is grown in situ on a carbon paper fiber support substrate. The Cu / Zn heterojunction structure is obtained by growing Cu nanodendrites and Zn nanosheets as each other.

[0041] Figure 3 The image shows the XRD pattern of the porous heterojunction catalyst obtained in Example 1. As can be seen from the image, the diffraction peaks at 2θ = 36.3°, 38.9°, 43.2°, 54.4°, and 70.1° correspond to the Zn phase (PDF#04-0831), and the diffraction peaks at 2θ = 43.3°, 50.4°, 74.1°, and 89.9° correspond to the Cu phase (PDF#04-0836), thus proving the formation of the bimetallic heterojunction catalyst.

[0042] Example 2

[0043] The electrodeposition solution consisted of 50 mL of sulfuric acid (20 mM), copper sulfate (50 mM), zinc sulfate (50 mM), and ammonium sulfate (1.5 M). Electrodeposition was performed at room temperature. [Cu 2+ ] / [Zn 2+The total concentration of metal ions at a molar ratio of 1:1 and 100 mM was determined. Constant current control was applied via a DC power supply, and the device was equipped with a boost converter providing up to 5 A of current. (The last part, "with -0.1 A cm," appears to be an unrelated fragment and is omitted from the translation.) -2 -0.5A cm -2 and -2A cm -2 Cu / Zn-CP-0.1-30, Cu / Zn-CP-0.5-30, and Cu / Zn-CP-2-30 were obtained by deposition at different current densities for 30 s. All data, such as current density per unit area and material loading, are based on the geometric surface area of ​​the carbon paper. After rinsing with moderately deionized water to remove loose deposits around the carbon paper boundaries, the loading was measured using a precision balance after vacuum drying. The carbon paper was then dried in a vacuum oven at room temperature before use.

[0044] Example 3

[0045] The electrodeposition solution consisted of 50 mL of sulfuric acid (20 mM), copper sulfate (50 mM), zinc sulfate (50 mM), and ammonium sulfate (1.5 M). Electrodeposition was performed at room temperature. [Cu 2+ ] / [Zn 2+ The total concentration of metal ions was 100 mM with a molar ratio of 1:1. Constant current control was applied via a DC power supply, and the device was equipped with a boost converter providing up to 5 A of current. The porous Cu / Zn layer was applied at -1.0 A cm⁻¹. -2 Cu / Zn-CP-1-15 and Cu / Zn-CP-1-60 were obtained by deposition at different current densities for 15 s and 60 s. All data, such as current density per unit area and material loading, are based on the geometric surface area of ​​carbon paper. After removing loose deposits around the carbon paper boundaries with moderately deionized water, the loading was measured using a precision balance after vacuum drying. The carbon paper was then dried in a vacuum oven at room temperature before use.

[0046] Example 4

[0047] All corresponding electrochemical tests were performed on the Shanghai Chenhua Electrochemical Workstation (CHI 660E). Electrolysis tests were conducted in an H-type electrolytic cell using a three-electrode system, including a working electrode (Cu / Zn-CP electrode), a platinum counter electrode, and an Ag / Ag electrode. + Reference electrode. Before each electrolysis, N2 or CO2 is passed into the electrolyte and maintained for 30 minutes to obtain the corresponding saturated electrolyte. The cyclic voltammetry curve of the Cu / Zn-CP-1-30 electrode under N2 or CO2 atmosphere is measured in this saturated solution, with a test potential range of 0V to -2.5V vs. Ag / Ag. + The scan rate is 20 mV·s -1The electrocatalytic reduction of CO2 was performed at a constant potential in a standard H-type electrolytic cell. The experiment was conducted using a three-electrode system, including a working electrode (Cu / Zn-CP-1-30), a platinum counter electrode, and an Ag / AgCl reference electrode. During electrolysis, the cathode and anode chambers were separated by a Nafion-117 proton exchange membrane. 0.5 M [Bmim]PF6 / MeCN solution and 0.5 M H2SO4 solution were used as electrolytes for the cathode and anode chambers, respectively. During the reaction, H... + It can migrate from the anode chamber to the cathode chamber electrolyte through the Nafion-117 proton exchange membrane.

[0048] Using a 0.5M [Bmim]PF6 / MeCN ionic liquid mixed solution as the cathode electrolyte, gas chromatography (Agilent 8890) and nuclear magnetic resonance spectroscopy (NMR) were employed. 1 The composition of gaseous and liquid products was detected and analyzed by ¹H NMR (Bruker Ascend 400-400MHz). The results showed that only CO and H₂ were detected in this system, with a total FE of approximately 100%, and no other reduction products were detected. Figure 4 As shown, the Cu / Zn-CP-1-30 electrode at -2.1V vs. Ag / Ag + The CO bias current density at the electrolysis potential is 91.7 mA cm⁻¹. -2 As the electrolysis potential increases, the Cu / Zn-CP-1-30 electrode shows performance at -2.5V compared to Ag / Ag. + The potential can reach up to 165.5 mA cm. -2 The CO bias current density was measured. The results show that the Cu / Zn-CP-1-30 heterojunction material exhibits good eCO2RR performance. The Cu / Zn-CP-1-30 electrode at -1.9V to -2.5V vs. Ag / Ag... + Over a wide potential range, the electrolytic efficiency (FE) of CO is above 90%. When the electrolysis potential is -2.1V vs. Ag / Ag... + At that time, FE CO The maximum value reached 99.4%. As the electrolysis potential becomes more negative, the competition between hydrogen evolution and CO2 reduction intensifies, leading to increased FE... CO Gradually decrease.

[0049] Besides high selectivity and high current density, high catalyst stability is also crucial for electrocatalytic systems. In this work, we investigated the electrode at -2.1 V vs. Ag / Ag + Stability after continuous electrolysis for 16 hours at a given potential. Figure 5As shown, the FE of CO can still be maintained at over 95% after 16 hours of continuous electrolysis, and the current density does not change much, indicating that the Cu / Zn-CP electrode has good electrocatalytic stability.

[0050] The applicant declares that the specific embodiments of the present invention have been described in detail above, but these are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A method for ultrafast preparation of porous Cu / Zn heterojunction electrocatalytic materials, characterized in that, This catalyst is a Cu / Zn bimetallic heterojunction catalyst grown in situ by electrodeposition on the surface of hydrophilic carbon paper as a substrate. The method includes the following specific steps: Step 1: Pretreatment of the carbon paper substrate: 1-1, cut a piece of carbon paper into a small rectangle of 1 x 1.1 cm 2 ; 1-2. The hydrophilic carbon paper is ultrasonically cleaned for 15 minutes each with a certain amount of anhydrous acetone, anhydrous ethanol and deionized water. 1-3. Place the cleaned carbon paper in a drying oven and dry it at 60℃; Step 2: Preparation of electrodeposition solution: A certain amount of copper sulfate and zinc sulfate were dissolved in 50 mL of sulfuric acid solution, and stirred for 15 min until completely dissolved. Then a certain amount of ammonium sulfate was added to the solution and dissolved by sonication. Step 3: Preparation of porous Cu / Zn heterojunction catalytic materials: 3-1. Take the prepared electrodeposition solution and place it in a single-chamber electrolytic cell. Use a dual-electrode deposition method, and clamp the carbon paper sheet on the cathode electrode of the galvanometer and connect the platinum counter electrode to the anode electrode. 3-2. Simultaneously immerse the carbon paper sheet and platinum counter electrode into an electrolytic cell containing electrodeposition solution, adjust the constant current electrodeposition program, set the deposition current, and control a certain deposition time to begin deposition; 3-3. After deposition, remove the carbon paper pieces loaded with active material, rinse them slowly with deionized water several times, irradiate them under an infrared lamp for 5 minutes, and then dry them; thus, a porous Cu / Zn heterojunction catalytic material is obtained. The electrodeposition solution in step 2, [Cu 2+ ] / [Zn 2+ The molar ratio is 1:1, the concentration of sulfuric acid is 20 mM, and the concentration of ammonium sulfate is 1.5 M. The specific amount of solution to be prepared is determined based on the amount of sample deposited each time.

2. The method of ultrafast preparation of porous Cu / Zn heterojunction electrocatalytic material according to claim 1, characterized in that, The deposition current and deposition time in step 3 are determined based on the amount of active catalyst material required. The deposition current is selected to be -0.1 ~ -2 A and the deposition time is selected to be 15 ~ 60 s.

3. A porous Cu / Zn heterojunction catalytic material, characterized in that... Prepared according to the method described in any one of claims 1-2.

4. The application of the porous Cu / Zn heterojunction catalytic material according to claim 3 in the electrocatalytic reduction of carbon dioxide.

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