A method for preparing and applying a metal-modified tungsten carbide electrocatalyst
By preparing metal-modified tungsten carbide electrocatalysts and utilizing polymer coordination confinement and metal cluster modification, the problems of high cost and insufficient activity of oxygen evolution catalysts in water electrolysis have been solved, achieving a highly efficient oxygen evolution reaction in water electrolysis, which has the potential for industrial application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2023-06-12
- Publication Date
- 2026-06-30
AI Technical Summary
Existing oxygen evolution catalysts for water electrolysis are expensive and lack sufficient activity, which limits energy conversion efficiency. There is a need to develop low-cost alternative catalysts with high catalytic activity.
By preparing metal-modified tungsten carbide electrocatalysts, the electronic structure of WCx can be regulated and its catalytic activity improved by utilizing polymer coordination confinement and a two-dimensional sheet-like porous carbon framework, combined with metal cluster modification.
The prepared catalyst exhibits superior activity compared to commercial IrO2, is low in cost, easy to prepare in large quantities, and has promising prospects for industrial application, thereby improving the efficiency of the oxygen evolution reaction in water electrolysis.
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Figure CN116623226B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrocatalysts, and more particularly to a method for preparing and applying a metal-modified tungsten carbide electrocatalyst. Background Technology
[0002] With the rapid growth of the national economy, my country's energy demand has increased dramatically. Overexploitation and use of fossil fuels such as coal, oil, and natural gas have led to increasingly strained energy supply and security. Wind and solar energy, as green and renewable energy sources, occupy an indispensable position in the future energy architecture. However, a significant drawback of wind and solar energy is the uncertainty of their daily, seasonal, and regional supply. To eliminate this uncertainty, they need to be connected to energy storage systems. Among these, water electrolyzers play a crucial role in the development of sustainable energy systems. A water electrolyzer is an electrochemical energy conversion device that produces hydrogen and oxygen from intermittent energy sources. Simultaneously, hydrogen energy can be converted back into electrical energy through fuel cells, making it an ideal energy carrier. Therefore, hydrogen production is of great significance for promoting the development of a clean and low-carbon economy. Water electrolysis has advantages such as simple process, convenient operation, no greenhouse gas emissions during production, and high product purity. However, its efficiency and durability still need improvement to meet the requirements of practical applications. The oxygen evolution reaction occurring on the anode side has a high overpotential, limiting the energy conversion efficiency. Developing highly active oxygen evolution catalysts has become a key research focus.
[0003] Currently, iridium oxide (IrO2) is the commonly used commercial catalyst for oxygen evolution in water electrolysis. However, due to its high price and limited resources as a typical secondary metal, Ir is not conducive to practical production and application. Reducing the amount of precious metals used or using transition metal catalysts to replace precious metal catalysts to reduce production costs has become a research focus. Tungsten (W) metal has good thermal / chemical stability and low cost, and is widely used in the field of electrocatalysis. Notably, tungsten carbide (WCx) has a d-band center similar to that of precious metals and is stable under acid and alkaline conditions, making it a good alternative to precious metal catalysts. Previously, tungsten carbide materials showed good catalytic activity in hydrogen evolution in water electrolysis, but research on its application in the anodic oxygen evolution reaction was very limited, and the activity was not high.
[0004] Therefore, those skilled in the art are dedicated to developing a method for preparing and applying a metal-modified tungsten carbide electrocatalyst. Summary of the Invention
[0005] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to develop a low-cost, high-catalytic-activity oxygen evolution catalyst for water electrolysis.
[0006] To achieve the above objectives, the present invention provides a method for preparing a metal-modified tungsten carbide electrocatalyst, the method comprising the following steps:
[0007] Step 1: Dissolve the polymer precursor in a water / ethanol mixture, adjust the pH with HCl, then add ammonia and tungstate solution dropwise, and stir for a period of time to obtain a tungsten-complex solution.
[0008] Step 2: Add acetone solution dropwise to the tungsten-complex solution, let stand for a period of time, filter, wash, dry, and pyrolyze under argon protection to obtain a porous carbon-supported tungsten carbide electrocatalyst.
[0009] Step 3: Disperse the porous carbon-supported tungsten carbide electrocatalyst and the metal salt precursor in an aqueous solution, add KOH to adjust the pH, and then add hydrazine hydrate for reduction to obtain the metal-modified tungsten carbide electrocatalyst.
[0010] Further, the polymer described in step 1 is 6-hydroxydopamine hydrochloride.
[0011] Furthermore, the pH is adjusted to less than 2 as described in step 1.
[0012] Furthermore, the stirring time described in step 1 is 2 hours.
[0013] Furthermore, the pyrolysis temperature in step 2 is 1000℃.
[0014] Furthermore, the tungstate in step 1 is sodium tungstate.
[0015] Furthermore, the pyrolysis time in step 2 is 2 hours.
[0016] Furthermore, the metal salt precursor mentioned in step 3 is one of iridium chloride, ruthenium chloride, and platinum chloride.
[0017] Furthermore, the pH in step 3 is 10.
[0018] And the application of a metal-modified tungsten carbide electrocatalyst prepared by the above method in oxygen evolution through water electrolysis.
[0019] The technical effects of this invention are as follows:
[0020] (1) By utilizing the coordination confinement effect of polymer, the size of WCx nanoparticles can be controlled. At the same time, the two-dimensional sheet-like porous carbon skeleton is conducive to exposing more active sites, which has a good promoting effect on improving catalytic activity.
[0021] (2) The electronic structure of WCx is controlled by using metal cluster modification. The synergistic effect of tungsten carbide and metal clusters such as iridium, ruthenium, and platinum can improve the catalytic activity of WCx-based hybrid catalysts in water electrolysis and oxygen evolution, thereby reducing the amount of precious metals used.
[0022] (3) The preparation method is simple and low-cost, and it is easy to achieve large-scale preparation. The prepared catalyst has high catalytic activity and better performance than commercial IrO2 catalysts, and has the prospect of industrial application.
[0023] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description
[0024] Figure 1 This is the XRD pattern of Ir-WCx in Embodiment 1 of the present invention;
[0025] Figure 2 These are SEM images of Ir-WCx in Embodiment 1 of the present invention;
[0026] Figure 3 This is a photograph of the actual weighing of the Ir-WCx catalyst in Example 4 of this invention;
[0027] Figure 4 This is a comparison chart of the electrocatalytic oxygen evolution reaction performance of the preferred embodiment of the present invention, the comparative example WCx, and commercial IrO2. Detailed Implementation
[0028] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.
[0029] Comparative Example 1
[0030] This example describes the preparation of a WCx electrocatalyst, and the process is as follows:
[0031] First, 0.95 g of 6-hydroxydopamine hydrochloride (DA) was dissolved in a water-alcohol mixture, and then 2 mL of 1M HCl was added to adjust the pH of the solution to approximately 2. 1.5 mL of ammonia water was added dropwise, followed by 1.65 g of Na₂WO₄ dissolved in the water-alcohol mixture, which was then slowly added dropwise to the DA solution. The solution gradually turned dark brown, and the mixture was stirred vigorously for 2 hours to obtain a DA-W complex solution. 100 mL of acetone solution was slowly added to the vigorously stirred DA-W complex solution, allowed to stand, filtered, and washed three times with acetone, deionized water, and ethanol solutions, respectively, and then allowed to air dry. The resulting solid powder was placed in a tube furnace and pyrolyzed at 1000 °C for 2 hours under an Ar atmosphere at a heating rate of 2 °C / min to obtain the WCx catalyst (porous carbon-supported tungsten carbide electrocatalyst).
[0032] Example 1
[0033] This example describes the preparation of an iridium-modified tungsten carbide hybrid catalyst (Ir-WCx), and the process is as follows:
[0034] First, 0.95 g of 6-hydroxydopamine hydrochloride (DA) was dissolved in a water-alcohol mixture, and then 2 mL of 1M HCl was added to adjust the pH of the solution to approximately 2 (less than 2). 1.5 mL of ammonia water was added dropwise, followed by 1.65 g of Na₂WO₄ dissolved in the water-alcohol mixture, which was slowly added dropwise to the DA solution. The solution gradually turned dark brown, and the mixture was stirred vigorously for 2 hours to obtain a DA-W complex solution. 100 mL of acetone solution was slowly added to the vigorously stirred DA-W complex solution, allowed to stand, filtered, and washed three times with acetone, deionized water, and ethanol solutions, respectively, and then allowed to dry naturally. The resulting solid powder was placed in a tube furnace and pyrolyzed at 1000 °C for 2 hours under an Ar atmosphere at a heating rate of 2 °C / min to obtain the WCx catalyst.
[0035] 100 mg of WCx and 10 mg of iridium chloride were weighed and added to 100 mL of aqueous solution, and dispersed by ultrasonication. Then, KOH aqueous solution was added to adjust the pH to 10, and the mixture was stirred vigorously. 10 mL of hydrazine hydrate was slowly added dropwise to the above solution. After reacting for 1 hour, the mixture was filtered, washed three times with deionized water and ethanol solution, and dried at 60 °C to obtain Ir-WCx (Ir-modified tungsten carbide hybrid catalyst).
[0036] Example 2
[0037] This example illustrates the preparation of a platinum-modified tungsten carbide hybrid catalyst (Pt-WCx), and the process is as follows:
[0038] First, 0.95 g of 6-hydroxydopamine hydrochloride (DA) was dissolved in a water-alcohol mixture, and then 2 mL of 1M HCl was added to adjust the pH of the solution to approximately 2. 1.5 mL of ammonia water was added dropwise, followed by 1.65 g of Na₂WO₄ dissolved in the water-alcohol mixture, which was then slowly added dropwise to the DA solution. The solution gradually turned dark brown, and the mixture was stirred vigorously for 2 hours to obtain a DA-W complex solution. 100 mL of acetone solution was slowly added to the vigorously stirred DA-W complex solution, allowed to stand, filtered, and washed three times with acetone, deionized water, and ethanol solutions, respectively, and then allowed to air dry. The resulting solid powder was placed in a tube furnace and pyrolyzed at 1000 °C for 2 hours under an Ar atmosphere at a heating rate of 2 °C / min to obtain the WCx catalyst.
[0039] Weigh 100 mg of WCx and 10 mg of platinum chloride and add them to 100 mL of aqueous solution, then disperse by ultrasonication. Next, add KOH aqueous solution to adjust the pH to 10, stir vigorously, and slowly add 10 mL of hydrazine hydrate to the solution. Continue the reaction for 1 hour, then filter, wash three times with deionized water and ethanol solution, and dry at 60 °C to obtain Pt-WCx.
[0040] Example 3
[0041] This example demonstrates the preparation of a ruthenium-modified tungsten carbide hybrid catalyst (Ru-WCx), and the process is as follows:
[0042] First, 0.95 g of 6-hydroxydopamine hydrochloride (DA) was dissolved in a water-alcohol mixture, and then 2 mL of 1M HCl was added to adjust the pH of the solution to approximately 2. 1.5 mL of ammonia water was added dropwise, followed by 1.65 g of Na₂WO₄ dissolved in the water-alcohol mixture, which was then slowly added dropwise to the DA solution. The solution gradually turned dark brown, and the mixture was stirred vigorously for 2 hours to obtain a DA-W complex solution. 100 mL of acetone solution was slowly added to the vigorously stirred DA-W complex solution, allowed to stand, filtered, and washed three times with acetone, deionized water, and ethanol solutions, respectively, and then allowed to air dry. The resulting solid powder was placed in a tube furnace and pyrolyzed at 1000 °C for 2 hours under an Ar atmosphere at a heating rate of 2 °C / min to obtain the WCx catalyst.
[0043] 100 mg of WCx and 10 mg of ruthenium chloride were weighed and added to 100 mL of aqueous solution, and dispersed by ultrasonication. Then, KOH aqueous solution was added to adjust the pH to 10, and the mixture was stirred vigorously. 10 mL of hydrazine hydrate was slowly added dropwise to the solution. After reacting for 1 hour, the mixture was filtered, washed three times with deionized water and ethanol solution, and dried at 60 °C to obtain Ru-WCx.
[0044] Example 4
[0045] This example demonstrates the large-scale preparation of the Ir-WCx catalyst, and the process is as follows:
[0046] First, 1.8 g of 6-hydroxydopamine hydrochloride (DA) was dissolved in a water-alcohol mixture, and then 4 mL of 1M HCl was added to adjust the pH of the solution to approximately 2 (less than 2). 3 mL of ammonia water was added dropwise, followed by 3.3 g of Na₂WO₄ dissolved in the water-alcohol mixture, which was then slowly added dropwise to the DA solution. The solution gradually turned dark brown, and the mixture was stirred vigorously for 2 hours to obtain a DA-W complex solution. 100 mL of acetone solution was slowly added to the vigorously stirred DA-W complex solution, allowed to stand, filtered, and washed three times with acetone, deionized water, and ethanol solutions, respectively, and then allowed to air dry. The resulting solid powder was placed in a tube furnace and pyrolyzed at 1000 °C for 2 hours under an Ar atmosphere at a heating rate of 2 °C / min to obtain the WCx catalyst.
[0047] The prepared WCx and 100 mg of iridium chloride were added to 500 mL of aqueous solution and dispersed by ultrasonication. Then, KOH aqueous solution was added to adjust the pH to 10, and the mixture was stirred vigorously. 50 mL of hydrazine hydrate was slowly added dropwise to the solution. After reacting for 1 hour, the mixture was filtered, washed three times with deionized water and ethanol solution, and dried at 60 °C to obtain Ir-WCx.
[0048] X-ray diffraction (XRD) was performed on the Ir-WCx in Example 1. The generator voltage was 40 kV, the generator current was 40 mA, and the scan rate was 6°min. -1 .like Figure 1 The XRD pattern shows that the material exhibits distinct diffraction peaks at 2θ = 12.5°, 25.7°, 33.5°, 36.4°, and 40°. Comparison with standard cards and experimental results confirms that its structure is a heterostructure of WC and W₂C. This heterostructure, with its abundant interfaces, contributes to the enhancement of catalytic active sites. Furthermore, no metal peaks attributed to Ir were detected, indicating that Ir exists in the form of nanoclusters.
[0049] Scanning electron microscopy (SEM) was performed on the Ir-WCx sample from Example 1. A small amount of sample 1 was dispersed on conductive tape for SEM testing, and the results are as follows. Figure 2 As shown, Ir-WCx exhibits a flower-like morphology composed of numerous two-dimensional sheets with a diameter of approximately 500 nm. This two-dimensional carbon sheet structure is beneficial for exposing more active sites, thereby improving catalytic activity.
[0050] The product obtained in Example 4 was weighed, and 1.3 g of catalyst could be prepared in a single batch. Figure 3 It is easy to scale up the preparation of catalysts and has practical application prospects.
[0051] The example was tested for oxygen evolution reaction in water electrolysis. The test electrode was prepared as follows: 2 mg of the sample was ultrasonically stirred and dispersed in 200 μL of 0.05 wt% Nafion solution to prepare a catalyst slurry. 8 μL of the slurry was pipetted and uniformly drop-coated onto a glassy carbon electrode, then air-dried to obtain the test electrode. The specific testing method was as follows: a rotating disk electrode system was used, in which the catalyst-loaded disk electrode was the working electrode, the silver / silver chloride electrode was the reference electrode, and the platinum sheet was the counter electrode.
[0052] Test results are as follows Figure 4 As shown, the electrocatalysts modified with metal tungsten carbide exhibit superior performance in the oxygen evolution reaction compared to WCx and commercial IrO2. Specifically, the Ir-WCx in Example 1 demonstrates the lowest overpotential at 10 mA cm⁻¹. -2 At the specified current density, the overpotential was 320 mV (vs. RHE), and it can be seen that Ir-WCx also exhibits a higher current density at the same potential. Therefore, the Ir-WCx in Example 1 has higher catalytic activity compared to the catalysts in other examples. Furthermore, compared to pure WCx, the catalytic performance of Pt and Ru metal-modified WCx is significantly improved, which is due to the synergistic effect of metal clusters such as Ir, Pt, and Ru with WCx nanoparticles.
[0053] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.
Claims
1. A method for preparing a metal-modified tungsten carbide electrocatalyst, characterized in that, The method includes the following steps: Step 1: Dissolve the polymer precursor in a water / ethanol mixture, adjust the pH with HCl, then add ammonia and tungstate solution dropwise, and stir for a period of time to obtain a tungsten-complex solution. Step 2: Add acetone solution dropwise to the tungsten-complex solution, let stand for a period of time, filter, wash, dry, and pyrolyze under argon protection to obtain a porous carbon-supported tungsten carbide electrocatalyst. Step 3: Disperse the porous carbon-supported tungsten carbide electrocatalyst and the metal salt precursor in an aqueous solution, add KOH to adjust the pH, and then add hydrazine hydrate for reduction to obtain the metal-modified tungsten carbide electrocatalyst; The polymer precursor in step 1 is 6-hydroxydopamine hydrochloride; The metal salt precursor mentioned in step 3 is one of iridium chloride, ruthenium chloride, and platinum chloride.
2. The preparation method of the metal-modified tungsten carbide electrocatalyst as described in claim 1, characterized in that, The pH is adjusted to less than 2 as described in step 1.
3. The preparation method of the metal-modified tungsten carbide electrocatalyst as described in claim 1, characterized in that, The stirring time described in step 1 is 2 hours.
4. The preparation method of the metal-modified tungsten carbide electrocatalyst as described in claim 1, characterized in that, The pyrolysis temperature in step 2 is 1000℃.
5. The preparation method of the metal-modified tungsten carbide electrocatalyst as described in claim 1, characterized in that, The tungstate mentioned in step 1 is sodium tungstate.
6. The method for preparing the metal-modified tungsten carbide electrocatalyst as described in claim 1, characterized in that, The pyrolysis time in step 2 is 2 hours.
7. The preparation method of the metal-modified tungsten carbide electrocatalyst as described in claim 1, characterized in that, The pH value in step 3 is 10.
8. The application of a metal-modified tungsten carbide electrocatalyst prepared by the method according to any one of claims 1-7 in oxygen evolution by water electrolysis.