Vanadium nitride / transition metal single-atom supported electrocatalyst, and preparation method and application thereof
A simple hydrothermal combined with heat treatment method was used to prepare vanadium nitride/transition metal single-atom supported electrocatalysts, which solved the problems of complex preparation and low conductivity, and achieved a significant improvement in high-efficiency electrocatalytic performance and catalytic activity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHAANXI UNIV OF SCI & TECH
- Filing Date
- 2023-06-13
- Publication Date
- 2026-04-28
AI Technical Summary
Existing methods for preparing vanadium nitride are cumbersome, require harsh conditions, have long production cycles, and have poor reproducibility, resulting in poor catalytic activity and low conductivity that affects electron transfer rates.
A simple hydrothermal combined heat treatment method was adopted. By controlling the atomic ratio and distribution of transition metal and vanadium atoms, coordination compounds were synthesized in an alkaline aqueous solution using alkaline substances and surfactants to form a three-dimensional structure of nanotubes grown on nanosheets, which loaded transition metal single atoms and improved the conductivity and catalytic activity of the material.
The preparation cycle is short, the raw materials are simple and feasible, the material morphology is uniform, and it exposes abundant catalytic sites, which improves catalytic activity and stability. A current density of 10 mA/cm2 can be achieved with an overpotential of only 166 mV.
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Figure CN116536704B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrocatalyst materials technology, specifically relating to a vanadium nitride / transition metal single-atom supported electrocatalyst, its preparation method, and its application. Background Technology
[0002] Hydrogen is a potential green energy carrier that can reduce dependence on fossil fuels (such as oil, coal, and natural gas) and mitigate the environmental problems caused by their overuse. Currently, there are three main routes for industrial hydrogen production: methane steam reforming, coal gasification, and water electrolysis. The first two methods still consume fossil fuels and emit the greenhouse gas carbon dioxide, which is clearly undesirable. Water electrolysis is widely considered a very promising green hydrogen production route. Its feedstock is abundant and renewable water, making sustainable hydrogen production possible, and its products are hydrogen and oxygen, without causing secondary pollution. Therefore, water electrolysis, as an environmentally friendly hydrogen production route, is increasingly favored and is one of the most cutting-edge and active research topics in hydrogen production technology.
[0003] In recent years, transition metal nitrides (TMNs) have attracted increasing attention from researchers due to their Pt-like electronic behavior and unique physicochemical properties. Among them, vanadium nitride (VN), with its platinum-like electronic structure and high conductivity, good electrochemical performance, and corrosion resistance, has shown promising applications in oxygen reduction, capacitors, and battery materials. Furthermore, as a representative interstitial compound, VN's unique electronic structure also makes it an ideal HER electrocatalyst. However, current methods for preparing VN suffer from cumbersome processes, demanding conditions, long production cycles, and poor reproducibility. Therefore, exploring efficient, inexpensive, and simple processes to prepare VN-based composite materials and utilizing their synergistic effects and unique microstructure to improve electrochemical catalytic performance is essential. Moreover, VN's inherently low conductivity severely affects the electron transfer rate at its individual catalytic sites during electrocatalysis, resulting in poor catalytic activity.
[0004] To address the above issues, employing appropriate synthesis and structure regulation strategies to develop inexpensive and efficient VN-based electrocatalytic materials for hydrogen production is of great theoretical significance. Summary of the Invention
[0005] The purpose of this invention is to provide a vanadium nitride / transition metal single-atom supported electrocatalyst, its preparation method, and its application, which solves the problems of complex preparation and difficult process in the prior art.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst includes the following steps:
[0008] Step 1: Weigh water-soluble transition metal salts, vanadium sources, alkaline substances, and surfactants in a molar ratio of 0.002-0.010:0.001-0.020:0.01-0.06:0.001-0.005.
[0009] Step 2: Dissolve the water-soluble transition metal salt, vanadium source, and alkaline substance in deionized water, and mix and stir to form an alkaline aqueous solution;
[0010] Add a surfactant to an alkaline aqueous solution, stir until homogeneous, and prepare a mixed solution;
[0011] Step 3: The mixed solution is subjected to a hydrothermal reaction at 100-200℃ for 8-24 hours. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain vanadium / metal hydroxide powder.
[0012] Step 4: Mix vanadium / metal hydroxide powder with nitrogen-containing carbon source at a mass ratio of (1-6):(2-9), grind thoroughly, and heat to 500℃ under a protective atmosphere for 1-4 hours, then continue heating to 800℃ for 2-6 hours to obtain vanadium nitride / transition metal single-atom supported electrocatalyst.
[0013] Furthermore, the transition metals are iron, cobalt, or nickel.
[0014] Furthermore, the vanadium source is vanadium chloride, ammonium metavanadate, sodium vanadate, or vanadium acetylacetonate.
[0015] Furthermore, the surfactant is hexamethyltetramine.
[0016] Furthermore, the alkaline substance is NaOH, KOH, or NH4Cl.
[0017] Furthermore, in step four, the nitrogen-containing carbon source is one or more of dicyandiamide, melamine, and glucose.
[0018] Furthermore, in step four, the heating rate is 3-10℃ / min.
[0019] The present invention also discloses a vanadium nitride / transition metal single-atom supported electrocatalyst prepared by the above preparation method. The vanadium nitride / transition metal single-atom supported electrocatalyst is an inorganic material, exhibiting a morphological structure of nanotubes grown on nanosheets, and forming a three-dimensional structure that is spatially interwoven.
[0020] Furthermore, the diameter of the nanotubes is 10-50 nm.
[0021] This invention also discloses the application of the vanadium nitride / transition metal single-atom supported electrocatalyst as an electrocatalyst for alkaline hydrogen production from water splitting.
[0022] The present invention has the following beneficial effects:
[0023] This invention discloses a method for preparing vanadium nitride / transition metal single-atom supported electrocatalysts. A simple hydrothermal combined with heat treatment method is employed, in which water-soluble transition metal salts, vanadium sources, and alkaline solutions are mixed. The hydrothermal reaction allows for the control of the atomic ratio and distribution of transition metal and vanadium atoms. With the addition of alkaline substances and hexamethyltetramine, in an alkaline aqueous solution environment, hexamethyltetramine reacts with inorganic salts to synthesize coordination compounds, resulting in the activation of surface functional groups (such as -OH, -OOH). This leads to a more uniform and complete microstructure and structure of the precursor (vanadium / metal hydroxide) (such as nanorods / nanobluster), thereby achieving the goal of controllable synthesis of vanadium nitride / transition metal single-atom supported electrocatalysts. The use of highly active transition metal single atoms improves the overall conductivity of the material and increases catalytic sites, accelerating electron transfer during the reaction process and facilitating the control of catalytic site activity.
[0024] Furthermore, the introduction of alkaline substances and surfactants can make the microstructure and structure of the hydrothermal precursor (vanadium / metal hydroxide) more uniform and complete (e.g., nanorods / nanobluster). The surfactants and inorganic salts form coordination compounds, which help provide a favorable coordination environment during the chemical reaction, acting as a surface activation catalyst and further regulating the morphology and structure of the material. Subsequently, the vanadium / metal hydroxide precursor is placed in a tube furnace (Ar atmosphere) and subjected to heat treatment with a carbon-nitrogen source to generate an inorganic material compound, namely, a vanadium nitride / transition metal single-atom supported electrocatalyst.
[0025] This method boasts a short preparation cycle, readily available and readily available raw materials, and easily controllable processes. It requires no large-scale equipment or stringent reaction conditions. Furthermore, single-atom loading enhances the intrinsic activity of vanadium nitride materials. The morphology of the nanotube structures grown on the prepared single-atom-loaded nanosheets exposes abundant active sites at the edges of the nanosheets and nanotubes, thereby promoting improved electrocatalytic hydrogen production activity at 10 mA / cm². 2 It requires an extremely low overpotential of only 166mV at current densities.
[0026] The vanadium nitride / transition metal single-atom supported electrocatalyst prepared in this invention exhibits a morphological structure of nanotubes grown on nanosheets, exposing a large number of sites on the surface, which is beneficial to the exposure of catalytic active sites. Moreover, the morphology and the supported single atoms can fully exert a synergistic effect, which is beneficial to improving the overall conductivity, catalytic activity and stability of the material.
[0027] The product prepared by this invention has uniform morphology and high purity, and exhibits excellent performance as an electrocatalytic alkaline hydrogen evolution catalyst, with a performance of 10 mA / cm². 2 At current densities, only a low overpotential of 166mV is required. Attached Figure Description
[0028] Figure 1 SEM image of the hydrothermal precursor (vanadium / metal hydroxide) prepared in Example 1 of this invention;
[0029] Figure 2 The XRD pattern of the vanadium nitride / transition metal single-atom supported electrocatalyst prepared in Example 2 of this invention;
[0030] Figure 3 The image shows the SEM image of the vanadium nitride / transition metal single-atom supported electrocatalyst prepared in Example 2 of this invention.
[0031] Figure 4 The TEM image of the vanadium nitride / transition metal single-atom supported electrocatalyst prepared in Example 2 of this invention;
[0032] Figure 5 Aberration-corrected electron microscopy image of the vanadium nitride / transition metal single-atom supported electrocatalyst prepared in Example 2 of this invention;
[0033] Figure 6 The basic LSV hydrogen production performance curve of the vanadium nitride / transition metal single-atom supported electrocatalyst prepared in Example 2 of this invention. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.
[0035] The detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment. All other embodiments obtained by those skilled in the art based on the drawings and embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0036] This invention discloses a method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst, comprising the following steps:
[0037] Step 1: Weigh water-soluble transition metal salts, vanadium sources, alkaline substances, and surfactants in a molar ratio of 0.002-0.010:0.001-0.020:0.01-0.06:0.001-0.005.
[0038] Step 2: Dissolve the water-soluble transition metal salt, vanadium source, and alkaline substance in deionized water, and mix and stir to form an alkaline aqueous solution;
[0039] Add a surfactant to an alkaline aqueous solution, stir until homogeneous, and prepare a mixed solution;
[0040] Step 3: The mixed solution is subjected to a hydrothermal reaction at 100-200℃ for 8-24 hours. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain vanadium / metal hydroxide powder.
[0041] Step 4: Mix vanadium / metal hydroxide powder with nitrogen-containing carbon source at a mass ratio of (1-6):(2-9), grind thoroughly, and heat to 500℃ under a protective atmosphere for 1-4 hours, then continue heating to 800℃ for 2-6 hours to obtain vanadium nitride / transition metal single-atom supported electrocatalyst.
[0042] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0043] Example 1
[0044] This invention discloses a method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst, comprising the following steps:
[0045] Step 1: Mix 0.002 mol of water-soluble ferric nitrate with 0.001 mol of NH4VO3, then weigh 0.01 mol of NaOH, mix them together, and fully dissolve them in 30 mL of deionized water to form an alkaline aqueous solution. Stir for 10 minutes, then add 1 mmol of hexamethyltetramine, stir well, and prepare a mixed solution.
[0046] Step 2: Transfer the mixed solution into a 50mL hydrothermal reactor and carry out a hydrothermal reaction at 100℃ for 10 hours. After the reaction is completed, centrifuge, wash and dry to obtain vanadium / metal hydroxide powder.
[0047] Step 3: Mix the above vanadium / metal hydroxide powder with dicyandiamide at a mass ratio of 1:3, grind thoroughly, and place in a tube furnace. The heating rate is 5℃ / min. Under Ar atmosphere, first heat to 500℃ and hold for 2 hours, then continue to heat to 800℃ and hold for 3 hours to obtain vanadium nitride / transition metal single-atom supported electrocatalyst.
[0048] like Figure 1As shown in the figure, the SEM image of the intermediate product (precursor) vanadium / metal hydroxide powder prepared in this embodiment shows that its morphology is: nanorods with a length of about 1 μm, on which a few nanoparticles are attached. The structure and morphology tend to be uniform, which is conducive to exposing a large number of sites on the surface.
[0049] Example 2
[0050] This invention discloses a method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst, comprising the following steps:
[0051] Step 1: Mix 0.004 mol of water-soluble cobalt chloride with 0.009 mol of NH4VO3, then weigh 0.05 mol of NaOH, mix them together, and fully dissolve them in 30 mL of deionized water to form an alkaline aqueous solution. Stir for 20 minutes, then add 2 mmol of hexamethyltetramine, stir well, and prepare a mixed solution.
[0052] Step 2: Transfer the mixed solution into a 50mL hydrothermal reactor and carry out a hydrothermal reaction at 120℃ for 12 hours. After the reaction is completed, centrifuge, wash and dry to obtain vanadium / metal hydroxide powder.
[0053] Step 3: Mix the above powder A with dicyandiamide at a mass ratio of 1:4, grind thoroughly, and place in a tube furnace. The heating rate is 10℃ / min. Under Ar atmosphere, first heat to 500℃ and hold for 1 hour, then continue to heat to 800℃ and hold for 2 hours to obtain vanadium nitride / transition metal single-atom supported electrocatalyst.
[0054] from Figure 2 It can be seen that in addition to the characteristic peaks of VN at 37.6°, 43.7°, 63.5°, and 76.2°, the characteristic peaks of Co at 44.2°, 51.5°, and 75.9° are also observed, which proves the successful preparation of the VN / Co composite phase.
[0055] from Figure 3 As can be seen from the SEM image, the inorganic material exhibits a morphological structure of nanotubes grown on nanosheets, exposing a large number of sites on the surface and forming a three-dimensional structure that is spatially intertwined.
[0056] from Figure 4 The TEM images show that the diameter of the nanotube structure is about 10-50 nm, and the three-dimensional hierarchical structure interwoven with the nanosheets is rich in interfaces and exposes abundant edge active sites, which is beneficial to improving the catalytic activity and stability of the material.
[0057] from Figure 5 Aberration-corrected electron microscopy reveals that the carbon-based substrate is loaded with a large number of cobalt single atoms.
[0058] from Figure 6 As can be seen from the LSV plot, this catalyst exhibits excellent electrocatalytic activity under alkaline conditions, requiring only an overpotential of 166 mV to reach 10 mA / cm². 2 The current density.
[0059] Example 3
[0060] This invention discloses a method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst, comprising the following steps:
[0061] Step 1: Mix 0.006 mol of water-soluble ferric chloride with 0.012 mol of vanadium chloride, then weigh 0.04 mol of NaOH, mix them together, and fully dissolve them in 30 mL of deionized water to form an alkaline aqueous solution. Stir for 6 minutes, then add 3 mmol of hexamethyltetramine, stir evenly, and prepare a mixed solution.
[0062] Step 2: Transfer the mixed solution into a 50mL hydrothermal reactor and carry out a hydrothermal reaction at 140℃ for 18 hours. After the reaction is completed, centrifuge, wash and dry to obtain vanadium / metal hydroxide powder.
[0063] Step 3: Mix the above vanadium / metal hydroxide powder with melamine at a mass ratio of 2:3, grind thoroughly, and place in a tube furnace. The heating rate is 10℃ / min. Under Ar atmosphere, first heat to 500℃ and hold for 4 hours, then continue to heat to 800℃ and hold for 4 hours to obtain vanadium nitride / transition metal single-atom supported electrocatalyst.
[0064] Example 4
[0065] This invention discloses a method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst, comprising the following steps:
[0066] Step 1: Mix 0.008 mol of water-soluble cobalt nitrate with 0.010 mol of sodium vanadate, then weigh 0.03 mol of NH4Cl, mix them together, and fully dissolve them in 30 mL of deionized water to form an alkaline aqueous solution. Stir for 15 minutes, then add 4 mmol of hexamethyltetramine, stir well, and prepare a mixed solution.
[0067] Step 2: Transfer the mixed solution into a 50mL hydrothermal reactor and carry out a hydrothermal reaction at 160℃ for 16 hours. After the reaction is completed, centrifuge, wash and dry to obtain vanadium / metal hydroxide powder.
[0068] Step 3: Mix the above vanadium / metal hydroxide powder with glucose at a mass ratio of 1:6, grind thoroughly, and place in a tube furnace. Heat at a rate of 8°C / min under an Ar atmosphere, first heat to 500°C and hold for 1 hour, then continue heating to 800°C and hold for 2 hours to obtain the vanadium nitride / transition metal single-atom supported electrocatalyst.
[0069] Example 5
[0070] This invention discloses a method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst, comprising the following steps:
[0071] Step 1: Mix 0.010 mol of water-soluble nickel chloride with 0.020 mol of acetylacetone vanadium oxide, then weigh 0.06 mol of KOH, mix them together, and fully dissolve them in 30 mL of deionized water to form an alkaline aqueous solution. Stir for 20 minutes, then add 5 mmol of hexamethyltetramine and stir evenly to prepare mixed solutions with different molar ratios (transition metal: vanadium).
[0072] Step 2: Transfer the mixture to a 50mL hydrothermal reactor and carry out a hydrothermal reaction at 200℃ for 24 hours. After the reaction is completed, centrifuge, wash, and dry to obtain vanadium / metal hydroxide powder.
[0073] Step 3: Mix the above vanadium / metal hydroxide powder with a variety of carbon and nitrogen sources (a mixture of dicyandiamide, melamine and glucose) at a mass ratio of 1:8, grind thoroughly, and place in a tube furnace. The heating rate is 3℃ / min. Under Ar atmosphere, first heat to 500℃ and hold for 3h, then continue to heat to 800℃ and hold for 3h to obtain vanadium nitride / transition metal single-atom supported electrocatalyst.
[0074] In this invention, by controlling process parameters such as the ratio of transition metal source to vanadium source, the regulation of surfactant, calcination regime and time, the preparation of transition metal single-atom electrocatalysts loaded on vanadium nitride-based materials is realized. The excellent activity of transition metal single atoms is used to improve the overall conductivity of the material and increase the catalytic sites, accelerate electron transfer in the reaction process, and help regulate the activity of catalytic sites.
[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.
Claims
1. A method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst, characterized in that, Includes the following steps: Step 1: Weigh water-soluble transition metal salts, vanadium sources, alkaline substances, and surfactants in a molar ratio of 0.002-0.010:0.001-0.020:0.01-0.06:0.001-0.
005. Step 2: Dissolve the water-soluble transition metal salt, vanadium source, and alkaline substance in deionized water, and mix and stir to form an alkaline aqueous solution; Add hexamethyltetramine to an alkaline aqueous solution, stir well, and prepare a mixed solution; Step 3: The mixed solution is subjected to a hydrothermal reaction at 100-200 ℃ for 8-24 h. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain vanadium / metal hydroxide powder. Step 4: Mix vanadium / metal hydroxide powder with nitrogen-containing carbon source at a mass ratio of (1-6):(2-9), grind thoroughly, and heat to 500 ℃ under a protective atmosphere for 1-4 h, then continue to heat to 800 ℃ for 2-6 h to obtain vanadium nitride / transition metal single-atom supported electrocatalyst. The transition metals are iron, cobalt, or nickel.
2. The method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst according to claim 1, characterized in that, The vanadium source is vanadium chloride, ammonium metavanadate, sodium vanadate, or vanadium acetylacetonate.
3. The method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst according to claim 1, characterized in that, The alkaline substance is NaOH or KOH.
4. The method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst according to claim 1, characterized in that, In step four, the nitrogen-containing carbon source is one or more of dicyandiamide, melamine, and glucose.
5. The method for preparing a vanadium nitride / transition metal single-atom supported electrocatalyst according to claim 1, characterized in that, In step four, the heating rate is 3-10 ℃ / min.