High-activity and high-stability graphene supported hydrogen tungsten bronze electrocatalytic material, and preparation method and application thereof
By using graphene-supported hydrogen tungsten bronze material, the problems of high cost of precious metal electrocatalysts and low catalytic activity of tungsten oxide were solved, realizing efficient and low-cost electrocatalytic water splitting to produce hydrogen, and preparing a highly active and stable electrocatalyst.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHAANXI UNIV OF SCI & TECH
- Filing Date
- 2022-09-27
- Publication Date
- 2026-04-21
AI Technical Summary
Existing electrocatalysts are mainly composed of precious metals, which are expensive. Furthermore, tungsten oxide has low catalytic activity and poor conductivity when used as a non-precious metal catalyst, which limits its application in electrocatalytic water splitting for hydrogen production.
By using graphene-supported hydrogen tungsten bronze material, graphene oxide was prepared by modifying the Hummer's method, and then mixed with ammonium tungstate and annealed in a protective atmosphere to prepare hydrogen tungsten bronze nanoparticles uniformly loaded on graphene. This controlled the hydrogen intercalation reaction and formed a high-performance non-noble metal hydrogen evolution catalyst.
This method achieves highly active and stable electrocatalytic hydrogen evolution, reducing hydrogen production costs. It features high electrocatalytic activity, low overpotential, small Tafel slope, and high electrocatalytic efficiency. Furthermore, the raw materials are inexpensive and readily available, and the preparation method is simple.
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Figure CN115418671B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of functional materials technology, and relates to electrocatalytic materials, specifically to a highly active and stable graphene-supported hydrogen tungsten bronze electrocatalytic material, its preparation method, and its application. Background Technology
[0002] With the increasing severity of global resource shortages and environmental degradation, hydrogen energy has received widespread attention as a clean energy source. Currently, most commercial hydrogen production utilizes steam reforming of natural gas or water gas. This method has low conversion rates and generates carbon dioxide, exacerbating global warming. Therefore, developing inexpensive and efficient hydrogen production methods is of great significance. Electrocatalytic water splitting has very high conversion efficiency and is considered a green route to hydrogen production. However, mainstream electrocatalysts are composed of highly active noble metals, whose high cost limits commercial application. Designing and synthesizing non-noble metal electrocatalysts with hydrogen evolution performance comparable to noble metals is currently a hot research topic.
[0003] Tungsten oxide, as a type of transition metal oxide, is abundant in the Earth's crust, readily available, and environmentally friendly, possessing advantages such as easily tunable structure and high cost-effectiveness. However, experimental and theoretical studies have shown that its use as a hydrogen evolution electrocatalyst suffers from low catalytic activity due to the high binding energy of tungsten for adsorbed hydrogen, and its intrinsic conductivity is poor, thus limiting its application as a catalyst. Theoretically, defects can cause changes in the electronic structure of tungsten oxide, thereby altering the surface hydrogen adsorption energy intensity and thus regulating the electrocatalytic hydrogen production performance. Summary of the Invention
[0004] To address the shortcomings of existing technologies, the present invention aims to provide a highly active and stable graphene-supported hydrogen tungsten bronze electrocatalytic material, its preparation method, and its application. The invention produces a highly active and stable graphene-supported hydrogen tungsten bronze electrocatalytic material with high electrocatalytic hydrogen evolution efficiency. Furthermore, the raw materials are inexpensive and readily available, and the preparation method is simple and low-cost.
[0005] To achieve the above objectives, the present invention employs the following technical solution:
[0006] A method for preparing a highly active and stable graphene-supported hydrogen tungsten bronze electrocatalytic material includes the following steps:
[0007] Step 1: Graphene oxide was prepared using the modified Hummer's method and then freeze-dried to obtain graphene oxide powder.
[0008] Step 2: Disperse the graphene oxide powder prepared in Step 1 in deionized water at a mass concentration of 1-2 mg / ml, and sonicate at room temperature to form a dispersion. According to the mass ratio of graphene oxide powder to ammonium tungstate powder of 1:(0.5-2), inject ammonium tungstate powder into the dispersion at room temperature under magnetic stirring, and mix it evenly by heating in a water bath and continuously stirring with magnetic force. After freeze-drying, a brownish-yellow powder is formed.
[0009] Step 3: Transfer the brownish-yellow powder sample to a tube furnace and anneal it at 400-600℃ for 1-4 hours in a protective gas atmosphere to obtain a catalyst with uniformly supported hydrogen tungsten bronze nanoparticles on graphene oxide.
[0010] The present invention also has the following technical features:
[0011] Preferably, the freeze-drying described in steps one and two involves freezing for 2-4 hours followed by vacuum drying for 24 hours.
[0012] Preferably, the ultrasound time in step two is 10 to 30 minutes.
[0013] Preferably, the magnetic stirring time in step two is 0.5 to 1 hour.
[0014] Preferably, the water bath heating temperature in step two is 70–90°C.
[0015] Preferably, the protective gas in step three is nitrogen, argon, or an argon-hydrogen mixture.
[0016] This invention also protects a highly active and stable graphene-supported hydrogen tungsten bronze electrocatalytic material prepared by the method described above, wherein hydrogen tungsten bronze nanoparticles are uniformly loaded on a sheet-like graphene oxide support, and the particle size of the hydrogen tungsten bronze nanoparticles is <200 nm.
[0017] This invention also protects the application of a highly active and stable graphene-supported hydrogen tungsten bronze electrocatalytic material as described above in water electrolysis for hydrogen production.
[0018] Preferably, the material is suitable for hydrogen production by acidic water electrolysis.
[0019] Compared with the prior art, the present invention has the following technical effects:
[0020] The preparation method of this invention uses inexpensive and readily available ammonium tungstate as the raw material for the hydrogen evolution catalyst of water splitting. Based on the study of the influence of internal defects of tungsten oxide on its electrocatalytic hydrogen evolution performance, the presence of hydrogen in the precursor is controlled. A well-dispersed single-crystal hydrogen tungsten bronze is successfully grown on a sheet-like graphene oxide support using a simple solid-state sintering method. H2 is then produced without altering the tungsten trioxide lattice framework. +The intercalation reaction is used to prepare a high-performance non-precious metal hydrogen evolution catalyst, thereby reducing the cost of hydrogen production by electrocatalytic water splitting. The overall preparation process is simple and the reaction conditions are not harsh.
[0021] The graphene-supported hydrogen tungsten bronze electrocatalytic material prepared according to the method of the present invention has low overpotential, small Tafel slope, high electrocatalytic activity, high electrocatalytic hydrogen evolution efficiency, excellent stability, and low preparation cost. Attached Figure Description
[0022] Figure 1 The XRD spectra of the electrocatalytic materials prepared in Example 1 and Comparative Example 1 of this invention;
[0023] Figure 2 SEM images of the electrocatalytic material prepared in Example 1 of this invention;
[0024] Figure 3 Here is a SEM image of the electrocatalytic material prepared in Comparative Example 1 of this invention;
[0025] Figure 4 This is a TEM image of the electrocatalytic material prepared in Example 1 of the present invention;
[0026] Figure 5 The LSV diagram is shown for the catalyst prepared in Comparative Example 1 of this invention.
[0027] Figure 6 The cyclic voltammetry curves of the electrocatalytic material prepared in Example 1 of this invention are shown below.
[0028] Figure 7 This is a constant voltage test diagram of the electrocatalytic material prepared in Example 1 of the present invention. Detailed Implementation
[0029] The specific content of the present invention will be further explained in detail below with reference to the embodiments.
[0030] Example 1
[0031] Step 1: Graphene oxide was prepared using the modified Hummer's method and then vacuum dried for 24 hours after being frozen for 2 hours.
[0032] Step 2: Disperse 150 mg of graphene oxide powder obtained in Step 1 at a mass concentration of 1.5 mg / ml in deionized water and sonicate at room temperature for 20 min to form a uniform dispersion. Inject 150 mg of ammonium tungstate powder into the dispersion at room temperature under magnetic stirring. Mix the powder evenly by heating in a 70°C water bath and continuously stirring magnetically for 30 min. After freezing for 2 h, vacuum dry for 24 h to form a brownish-yellow powder.
[0033] Step 3: Transfer the brownish-yellow powder sample to a tube furnace and anneal it at 600°C for 2 hours under a protective nitrogen atmosphere to obtain black powder H. 0.23 WO3 / rGO is a catalyst in which highly active and stable hydrogen tungsten bronze nanoparticles are uniformly supported on graphene.
[0034] Example 2
[0035] Step 1: Graphene oxide was prepared using the modified Hummer's method and then vacuum dried for 24 hours after being frozen for 3 hours.
[0036] Step 2: Disperse 150 mg of graphene oxide powder obtained in Step 1 at a mass concentration of 2 mg / ml in deionized water and sonicate at room temperature for 30 min to form a uniform dispersion. Inject 75 mg of ammonium tungstate powder into the dispersion at room temperature under magnetic stirring. Mix the powder evenly by heating in a 70°C water bath and continuously stirring with magnetic stirring for 30 min. After freezing for 3 h, vacuum dry for 24 h to form a brownish-yellow powder.
[0037] Step 3: Transfer the brownish-yellow powder sample to a tube furnace and anneal it at 400°C for 1 hour under a protective nitrogen atmosphere to obtain black powder H. 0.23 WO3 / rGO is a catalyst in which highly active and stable hydrogen tungsten bronze nanoparticles are uniformly supported on graphene.
[0038] Example 3
[0039] Step 1: Graphene oxide was prepared using the modified Hummer's method and then vacuum dried for 24 hours after being frozen for 4 hours.
[0040] Step 2: Disperse 150 mg of graphene oxide powder obtained in Step 1 at a mass concentration of 1 mg / ml in deionized water and sonicate at room temperature for 10 min to form a uniform dispersion. Inject 225 mg of ammonium tungstate powder into the dispersion at room temperature under magnetic stirring. Mix the powder evenly by heating in an 80°C water bath and continuously stirring magnetically for 50 min. After freezing for 4 h, vacuum dry for 24 h to form a brownish-yellow powder.
[0041] Step 3: Transfer the brownish-yellow powder sample to a tube furnace and anneal it at 500°C for 4 hours under a protective argon atmosphere to obtain black powder H. 0.23 WO3 / rGO is a catalyst in which highly active and stable hydrogen tungsten bronze nanoparticles are uniformly supported on graphene.
[0042] Example 4
[0043] Step 1: Graphene oxide was prepared using the modified Hummer's method and then vacuum dried for 24 hours after being frozen for 4 hours.
[0044] Step 2: Disperse 150 mg of graphene oxide powder obtained in Step 1 at a mass concentration of 1 mg / ml in deionized water and sonicate at room temperature for 10 min to form a uniform dispersion. Inject 300 mg of ammonium tungstate powder into the dispersion at room temperature under magnetic stirring. Add 3 mol / L hydrochloric acid solution dropwise under magnetic stirring to adjust the pH to 2. Mix the powder evenly by heating in a 90℃ water bath and continuously stirring magnetically for 60 min. After freezing for 4 h, vacuum dry for 24 h to form a brownish-yellow powder.
[0045] Step 3: Transfer the brownish-yellow powder sample to a tube furnace and anneal it at 600°C for 3 hours in an argon-hydrogen mixed atmosphere with a hydrogen volume content of 10% to obtain black powder H. 0.23 WO3 / rGO is a catalyst in which highly active and stable hydrogen tungsten bronze nanoparticles are uniformly supported on graphene.
[0046] Comparative Example 1
[0047] Step 1: Graphene oxide was prepared using the modified Hummer's method and then vacuum dried for 24 hours after being frozen for 2 hours.
[0048] Step 2: Disperse 150 mg of graphene oxide powder obtained in Step 1 at a mass concentration of 1.5 mg / ml in deionized water and sonicate at room temperature for 20 min to form a uniform dispersion. At room temperature, inject 150 mg of ammonium tungstate powder into the dispersion under magnetic stirring. Add 3 mol / L hydrochloric acid solution dropwise under magnetic stirring to adjust the pH to 2, forming dispersion B.
[0049] Step 3: Transfer the dispersion B obtained in Step 2 to a hydrothermal reactor lined with polytetrafluoroethylene and react it hydrothermally at 150°C for 6 hours. After cooling to room temperature with the furnace, aerogel C is obtained. After freeze-drying, it is ground to obtain a black powder. The black powder is placed in a tube furnace and annealed at 600°C for 2 hours under the protective gas nitrogen to obtain black powder WO3 / rGO, which is a catalyst of tungsten oxide supported on graphene.
[0050] The H prepared in Example 1 0.23 The catalytic performance of WO3 / rGO and WO3 / rGO prepared in Comparative Example 1 for hydrogen desorption by water electrolysis was tested.
[0051] The specific method for testing electrochemical performance is as follows: Mix 5 mg of catalyst powder with 1.95 ml of ethanol and 50 μL of 5% Nafion solution, and sonicate for 30 mins to disperse it evenly to obtain a uniform dispersion. Take 50 μL of the dispersion and drop it onto the surface of a glassy carbon electrode. Let it stand and dry at room temperature. Place the coated electrode in a three-electrode system to test its electrochemical performance.
[0052] Figure 1The XRD patterns of the electrocatalysts prepared in Example 1 and Comparative Example 1 are shown in the figures. It can be seen from the figures that Comparative Example 1 shows the corresponding WO3 / rGO diffraction peaks, while Example 1 shows the peaks at H... + After its introduction, its XRD pattern changed significantly, showing an H corresponding to the P4 / nmm space group. 0.23 Typical characteristics of WO3 / rGO.
[0053] Figure 2 The image shows the SEM pattern of the electrocatalyst prepared in Comparative Example 1. It can be seen from the image that the catalyst prepared in Comparative Example 1 is a micron-sized structure assembled from WO3 particles that are initially bulk nanostructures. When H... + After its introduction, the distribution of WO3 was significantly improved. Figure 3 The image shows the SEM pattern of the electrocatalyst prepared in Example 1. It can be seen from the image that [the following parameters are present] and [the following parameters are present] make [the following parameters]... Figure 3 H 0.23 The structure of WO3 / rGO exhibits a 250nm wide nanoplate structure similar to that of a single crystal.
[0054] Figure 4 The image shows the TEM spectrum of the electrocatalyst prepared in Example 1. As can be seen from the image, the crystal planes corresponding to lattice distances of 0.388 nm and 0.374 nm are H... 0.23 The (001) and (020) crystal planes of the tetragonal phase of WO3.
[0055] Figure 5 The LSV spectra of the electrocatalysts prepared in Example 1 and Comparative Example 1 are shown in the figures. It can be seen from the figures that compared to the WO3 / rGO catalyst, H... 0.23 WO3 / rGO catalysts exhibit superior catalytic activity.
[0056] Figure 6 The figure shows the cyclic voltammetry curves of the highly active and stable graphene-supported hydrogen tungsten bronze hydrogen evolution catalyst prepared in Example 1. As can be seen from the figure, after 5000 cycles from -0.1 to +0.1 V (vs RHE), the overlap rate of the polarization curves is still very high, indicating that the catalyst has good stability.
[0057] Figure 7 This is a constant voltage test graph of the highly active and stable graphene-supported hydrogen evolution catalyst (HEC) prepared in Example 1. Analysis of the data in the graph shows that, under an overvoltage of 100 mV (vs RHE), the prepared catalyst can achieve high current density (70–80 mA cm⁻¹). -2 The catalyst underwent catalytic hydrogen production for up to 20,000 seconds, demonstrating its excellent catalytic activity and stability.
Claims
1. A method for preparing a high-activity and high-stability graphene-supported hydrogen tungsten bronze electrocatalytic material, characterized in that, Includes the following steps: Step 1: Graphene oxide was prepared using the modified Hummer's method and then freeze-dried to obtain graphene oxide powder. Step 2: Disperse the graphene oxide powder prepared in Step 1 in deionized water at a mass concentration of 1-2 mg / ml, and sonicate at room temperature to form a dispersion. According to the mass ratio of graphene oxide powder to ammonium tungstate powder of 1:(0.5-2), inject ammonium tungstate powder into the dispersion at room temperature under magnetic stirring, and mix it evenly by heating in a water bath and continuously stirring with magnetic force. After freeze-drying, a brownish-yellow powder is formed. Step 3: Transfer the brownish-yellow powder sample to a tube furnace and anneal it at 400-600℃ for 1-4 hours in a protective gas atmosphere to obtain a catalyst with uniformly supported hydrogen tungsten bronze nanoparticles on graphene oxide.
2. The method for preparing high-activity and high-stability graphene supported hydrogen tungsten bronze electro-catalytic material according to claim 1, characterized in that, In steps one and two, the freeze-drying process involves freezing for 2-4 hours followed by vacuum drying for 24 hours.
3. The method for preparing high-activity and high-stability graphene supported hydrogen tungsten bronze electro-catalytic material according to claim 1, characterized in that, The ultrasound time mentioned in step two is 10 to 30 minutes.
4. The preparation method of the highly active and stable graphene-supported hydrogen tungsten bronze electrocatalytic material as described in claim 1, characterized in that, The magnetic stirring time mentioned in step two is 0.5 to 1 hour.
5. The method for preparing high-activity and high-stability graphene supported hydrogen tungsten bronze electro-catalytic material according to claim 1, characterized in that, The water bath heating temperature mentioned in step two is 70-90℃.
6. The method for preparing high-activity and high-stability graphene supported hydrogen tungsten bronze electro-catalytic material according to claim 1, characterized in that, The protective gas mentioned in step three is nitrogen, argon, or a mixture of argon and hydrogen.