Preparation method and application of sulfur-doped dual-regulated V2C-supported platinum electrocatalyst for alkaline hydrogen evolution reaction

Abstract

This invention discloses a method for preparing a sulfur-doped, dual-regulated V2C-supported platinum electrocatalyst for alkaline hydrogen evolution reaction and its application. The method includes the following steps: Step (1) Etching a V2AlC precursor at low temperature using a LiF-HCl mixed solution, followed by hydrothermal treatment to obtain layered V2C nanosheets; Step (2) Mixing V2C with sublimed sulfur and calcining under a protected atmosphere to prepare a V5S8-V2C heterostructure material; Step (3) Dispersing V5S8-V2C in an ethylene glycol-water mixed solvent, adding a chloroplatinic acid solution, and reducing by reflux in an oil bath to obtain a Pt@V5S8-V2C catalyst. This invention achieves dual regulation of the interlayer structure and platinum dispersion of the V2C support through sulfur doping, solving the problems of slow kinetics, easy aggregation of platinum nanoparticles, and unstable V2C substrate structure in traditional MXene-supported platinum catalysts during alkaline hydrogen evolution reaction.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic water splitting for hydrogen production technology, and relates to a method for preparing an alkaline hydrogen evolution (HER) electrocatalytic material. Specifically, it relates to a method for preparing a sulfur-doped, dual-regulated V2C MXene-supported platinum alkaline HER electrocatalytic material and its application in an alkaline HER and anion exchange membrane water electrolyzer. Background Technology

[0002] Hydrogen (H2), as a clean energy source with high energy density and zero carbon emissions, is considered an important direction for replacing traditional fossil fuels. Electrocatalytic water splitting for hydrogen production is one of the key technologies for achieving sustainable hydrogen production. Among numerous electrocatalysts for the hydrogen evolution reaction (HER), platinum (Pt)-based materials have become the performance benchmark due to their near-optimal hydrogen adsorption free energy. However, the scarcity and high cost of Pt limit its large-scale application. Especially in alkaline media, the Volmer step (H2O + e-) on the Pt surface... - →H +OH - The slow kinetics result in its basic HER activity being 2 to 3 orders of magnitude lower than that under acidic conditions.

[0003] Two-dimensional MXene materials are ideal Pt supports, with V2C MXene exhibiting advantages such as abundant resources, high conductivity, and low ion transport barriers, surpassing commonly used Ti3C2. However, the synthesis of traditional V2C typically requires etching with highly toxic hydrofluoric acid, posing safety and environmental risks. Furthermore, the V2C layers are prone to stacking, and the interaction between Pt and the support is weak, leading to Pt nanoparticle agglomeration, low atom utilization, and poor stability. Sulfur doping has been shown to increase the V2C interlayer spacing and enhance Pt anchoring ability, but how to simultaneously control the substrate structure and Pt nanoparticle size, and utilize the interfacial hydrogen spillover effect to improve basic HER performance, remains a subject of unsystematic research. Summary of the Invention

[0004] To address the problems of low platinum utilization, unstable V2C substrate structure, and underutilization of hydrogen spillover effect in existing Pt-based catalysts for alkaline hydrogen evolution reaction (HER), this invention provides a method for preparing a sulfur-doped, dual-regulated V2C-supported platinum electrocatalytic material for HER and its application. This invention employs a sulfur-doped, dual-regulated strategy to prepare Pt@V5S8-V2C electrocatalytic material. Through sulfur doping, the following effects are simultaneously achieved: regulating the V2C layered structure, increasing interlayer spacing, specific surface area, and stability; regulating Pt nucleation and growth, achieving high Pt dispersion and controllable particle size; and in-situ formation of Pt-SV bridging bonds, accelerating interfacial charge transfer and driving hydrogen spillover to synergistically enhance water dissociation and H2 desorption.

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

[0006] A method for preparing a sulfur-doped, dual-regulated V2C-supported platinum electrocatalytic material for alkaline hydrogen evolution reaction, comprising the following steps:

[0007] Step (1) Synthesis of V2C nanosheets: 1~3 g of LiF was mixed with 30~50 mL of 6 M HCl. After stirring in an ice bath, 1~3 g of V2AlC powder was slowly added and stirring continued. Then, the mixture was transferred to a hydrothermal reactor for hydrothermal reaction. The product was centrifuged and washed until pH>6, and then vacuum dried to obtain layered V2C nanosheets. The hydrothermal reaction temperature was 80~100℃ and the time was 48~96 h. The vacuum drying temperature was 60~80℃ and the time was 10~15 h.

[0008] Step (2) Synthesis of V5S8-V2C heterostructure: Take 0.15~0.2 g of V2C and add it to a mixture containing 1~2 mL of NMP and 3~4 mL of CS2. Add sublimed sulfur and stir until the solvent evaporates. Calcine under a protective atmosphere: keep warm at 150~160℃ for 10~15 h and at 400~500℃ for 1~3 h to obtain V5S8-V2C, wherein the mass ratio of sulfur powder to V2C is 1:2.

[0009] Step (3) Synthesis of Pt@V5S8-V2C: 100 mg of V5S8-V2C was dispersed in 100 ml of ethylene glycol-water mixed solvent, and 10 ml of chloroplatinic acid solution with a concentration of 1~4 mM was added. The mixture was refluxed in an oil bath at 120~140℃ for 1~3 h, cooled and filtered, washed with deionized water, rapidly frozen in liquid nitrogen, and freeze-dried to obtain Pt@V5S8-V2C electrocatalytic material.

[0010] Application of a sulfur-doped dual-regulated V2C support platinum electrocatalytic material prepared by the above method in alkaline water electrolysis and hydrogen evolution reaction.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] 1. This invention achieves dual regulation of the interlayer structure and platinum dispersion of the V2C support through sulfur doping, solving the problems of slow kinetics, easy aggregation of platinum nanoparticles and unstable V2C substrate structure of traditional MXene-supported platinum catalysts in alkaline hydrogen evolution reaction.

[0013] 2. This invention achieves both structural control of the V2C substrate and size control of Pt nanoparticles through sulfur doping, forming Pt-SV interfacial bridges, optimizing interfacial charge transfer, promoting interfacial charge transfer and hydrogen overflow effect, significantly improving the activity and stability of alkaline hydrogen evolution reaction, and is suitable for industrial alkaline water electrolysis hydrogen production scenarios. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the microstructure of the electrocatalytic materials V2C, V3S4-V2C, V5S8-V2C and VS2-V2C used in alkaline HER according to the present invention.

[0015] Figure 2 This is a schematic diagram of the microstructure and Pt particle size distribution of the electrocatalytic materials 0.5Pt@V5S8-V2C, 1.0Pt@V5S8-V2C, 1.5Pt@V5S8-V2C, and 2.0Pt@V5S8-V2C used in alkaline HER according to the present invention.

[0016] Figure 3 This is a schematic diagram showing the specific surface area and pore size distribution of the electrocatalytic materials 0.5Pt@V5S8-V2C, 1.0Pt@V5S8-V2C, 1.5Pt@V5S8-V2C, and 2.0Pt@V5S8-V2C used in alkaline HER according to the present invention.

[0017] Figure 4 This is a schematic diagram of the X-ray diffraction spectra of the electrocatalytic materials 0.5Pt@V5S8-V2C, 1.0Pt@V5S8-V2C, 1.5Pt@V5S8-V2C, and 2.0Pt@V5S8-V2C used in alkaline HER according to the present invention.

[0018] Figure 5 This is a schematic diagram of the linear sweep voltammetry curves and Tafel slopes of the electrocatalytic materials V3S4-V2C, V5S8-V2C, and VS2-V2C used in alkaline HER according to the present invention.

[0019] Figure 6 Linear sweep voltammetric curves and Tafel slope diagrams of the electrocatalytic materials 0.5Pt@V5S8-V2C, 1.0Pt@V5S8-V2C, 1.5Pt@V5S8-V2C, and 2.0Pt@V5S8-V2C used in alkaline HER according to the present invention.

[0020] Figure 7 This is a schematic diagram of the anion exchange membrane water electrolysis device for alkaline HER according to the present invention;

[0021] Figure 8 This is a schematic diagram of the chronopotential of the electrocatalytic material 1.5Pt@V5S8-V2C used in alkaline HER according to the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0023] This invention provides a method for preparing a sulfur-doped, dual-regulated V2C-supported platinum electrocatalyst for alkaline hydrogen evolution reaction (HER). The method proposes a sulfur-doped, dual-regulated strategy, synthesizing V2C under mild conditions, further doping with sulfur to form a V5S8-V2C heterostructure, and then controllably anchoring Pt nanoparticles to construct Pt-SV interfacial bridges, thereby significantly improving the activity and stability of alkaline HER. The specific steps include:

[0024] Step (1) Synthesis of V2C nanosheets: The V2AlC precursor was etched at low temperature using a LiF-HCl mixed solution, and layered V2C MXene nanosheets were obtained by hydrothermal treatment. The specific steps are as follows:

[0025] Mix 1-3 g of LiF with 30-50 mL of 6 M HCl, stir in an ice bath for 30-60 min, then slowly add 1-3 g of V2AlC powder, continue stirring for 1-3 h, then transfer to a hydrothermal reactor and react at 80-100℃ for 48-96 h. The product is centrifuged and washed until pH > 6, then vacuum dried at 60-80℃ for 10-15 h to obtain layered V2C nanosheets.

[0026] Step (2) Synthesis of V5S8-V2C heterostructure: V2C was mixed with sublimed sulfur and calcined under a protective atmosphere with programmed temperature increase to prepare V5S8-V2C heterostructure material. The specific steps are as follows: 0.15~0.2 g of V2C was added to a mixture containing 1~2 mL of NMP and 3~4 mL of CS2, and sublimed sulfur was added. The mixture was stirred until the solvent evaporated. Calcination was carried out under a protective atmosphere: 150~160℃ for 10~15 h, and 400~500℃ for 1~3 h. h, V5S8-V2C was obtained, wherein: when the mass ratio of sulfur powder to V2C is 1:4, a V3S4-V2C heterostructure is obtained; when the mass ratio of sulfur powder to V2C is 1:2, a V5S8-V2C heterostructure is obtained; and when the mass ratio of sulfur powder to V2C is 1:1, a VS2-V2C heterostructure is obtained. The protective atmosphere is high-purity nitrogen, and the heating rate is 5~10℃ / min.

[0027] Step (3) Synthesis of Pt@V5S8-V2C: V5S8-V2C was dispersed in an ethylene glycol-water mixed solvent, and chloroplatinic acid solutions of different concentrations were added. The mixture was then reduced by reflux in an oil bath to obtain Pt@V5S8-V2C catalysts with different Pt loadings. The specific steps are as follows: 100 mg of V5S8-V2C was dispersed in 100 ml of an ethylene glycol-water mixed solvent and sonicated for 10-30 min; 10 ml of chloroplatinic acid solution with a concentration of 1-4 mM was added and stirred at room temperature for 10-15 h; the mixture was then refluxed in an oil bath at 120-140℃ for 1-3 h, cooled and filtered, washed with deionized water, rapidly frozen in liquid nitrogen, and freeze-dried to obtain Pt@V5S8-V2C. In the ethylene glycol-water mixed solvent, the volume ratio of ethylene glycol to water was 67:33; the concentrations of chloroplatinic acid were 1 mM, 2 mM, 3 mM, and 4 mM, respectively. The concentrations of chloroplatinic acid (CPA) are 0.5M, 1.0M, 1.5M, and 2.0M, respectively, with the optimal concentration being 3 mM. Pt in the catalyst is uniformly dispersed in nanoparticle form with a particle size of 0.9–4.5 nm, and the optimal particle size is 3.3 ± 0.2 nm. The material maintains a layered porous structure with a large specific surface area and abundant active sites. Stable Pt-SV bonds exist at the interface, resulting in strong electronic interactions.

[0028] This invention also provides the application of the above-mentioned sulfur-doped dual-regulated V2C support-supported platinum electrocatalyst in the alkaline water electrolysis hydrogen evolution reaction. In a 1.0 M KOH electrolyte, this material exhibits [results] at 10 mA cm⁻¹. -2 The overpotential was 28.8 mV, and the Tafel slope was 23.3 mV dec. -1 Furthermore, it serves as the cathode of an anion exchange membrane water electrolyzer at 500 mA cm⁻¹ -2 It can run stably for more than 50 hours.

[0029] Example 1:

[0030] This embodiment provides a method for preparing electrocatalyst materials V2C, V3S4-V2C, V5S8-V2C, and VS2-V2C for alkaline HER. The method steps are as follows: 2 g LiF is stirred with 40 mL 6 M HCl in an ice bath for 30 min, and then 2 g V2AlC is slowly added, and stirring is continued for 2 h. The above solution is transferred to a polytetrafluoroethylene reactor and subjected to hydrothermal reaction at 90 °C for 72 h. The obtained product is centrifuged and washed with water until pH > 6, and then vacuum dried at 60 °C for 12 h to obtain V2C MXene nanosheets. Subsequently, 0.18 g V2C is added to a mixture containing 1.5 mL NMP and 3.5 mL CS2, and 0.045 g, 0.09 g, and 0.18 g of sublimed sulfur are added respectively, and the mixture is stirred at room temperature until the solvent evaporates. The obtained solid material was placed in a crucible and calcined in a tube furnace under a nitrogen atmosphere: 155℃ / 12 h, 450℃ / 2 h, to obtain layered V3S4-V2C, V5S8-V2C and VS2-V2C catalytic materials, respectively.

[0031] In this embodiment, scanning electron microscopy was used to characterize and analyze the microstructure of the catalytic material. Figure 1 As can be seen, this type of material has a layered nanosheet structure, and the integrity of the layered structure gradually decreases with the increase of sulfur content, with VS2-V2C having the worst structural integrity.

[0032] Example 2:

[0033] This embodiment provides a method for preparing Pt@V5S8-V2C catalyst materials with different Pt loadings. The method includes the following steps: 100 mg of synthesized V5S8-V2C powder is dispersed in a mixed solvent containing 33 mL of deionized water and 67 mL of ethylene glycol, and magnetically stirred for 20 minutes, followed by ultrasonic stirring for 10 minutes. Then, 10 mL of H2PtCl6 solutions with concentrations of 1 mM, 2 mM, 3 mM, and 4 mM are added to the dispersion to obtain loadings of 0.5 Pt, 1.0 Pt, 1.5 Pt, and 2.0 Pt. The mixture is stirred at room temperature for 12 hours to promote deposition. The resulting suspension is transferred to a constant-temperature oil bath equipped with a condenser and reflux device and stirred at 130°C for 2 hours. After cooling, the solid is separated by filtration and thoroughly washed with deionized water. The collected solids were rapidly frozen with liquid nitrogen and then freeze-dried to obtain 0.5Pt@V5S8-V2C, 1.0Pt@V5S8-V2C, 1.5Pt@V5S8-V2C, and 2.0Pt@V5S8-V2C catalysts, respectively.

[0034] Figure 2Transmission electron microscopy (TEM) images of Pt@V5S8-V2C catalysts with different Pt loadings and schematic diagrams of Pt particle size distributions are shown. The Pt particle size gradually increases with increasing H2PtCl6 solution concentration, demonstrating the uniform dispersion of Pt on the V5S8-V2C heterojunction.

[0035] Figure 3 This is a schematic diagram showing the specific surface area and pore size distribution of the catalyst material of this invention. From Figure 3 As can be seen, 1.5Pt@V5S8-V2C with optimal sulfur doping (0.09 g) and Pt loading (3 mM) has the largest specific surface area and a relatively uniform mesoporous structure.

[0036] Figure 4 This is a schematic diagram of the X-ray diffraction spectrum of the catalyst material of this invention. From... Figure 4 As can be seen, the 1.5Pt@V5S8-V2C catalyst material was successfully prepared according to the above method.

[0037] Figure 5 This is a schematic diagram of the linear sweep voltammetry curves and Tafel slopes for V3S4-V2C, V5S8-V2C, and VS2-V2C. As can be seen from the figure, at 10 mA cm⁻¹... -2 Under the given current density, V5S8-V2C exhibited the best HER activity, and the optimal mass ratio of sulfur powder to V2C was determined to be 1:2.

[0038] Figure 6 This is a schematic diagram of the linear sweep voltammetry curves and Tafel slopes for 0.5Pt@V5S8-V2C, 1.0Pt@V5S8-V2C, 1.5Pt@V5S8-V2C, and 2.0Pt@V5S8-V2C. As can be seen from the figure, at 10 mA cm⁻¹... -2 At the given current density, 1.5Pt@V5S8-V2C exhibited the best HER activity, and the optimal Pt loading was determined to be obtained by adding 3 mM H2PtCl6 solution.

[0039] Figure 7 This is a schematic diagram of an anion exchange membrane water electrolysis device. It features a serpentine flow channel (active area: 1 cm²). 2 The practical application of the 1.5Pt@V5S8-V2C electrocatalyst was evaluated in an anion exchange membrane water electrolyzer. Prior to assembly, a FAB-PK-130 anion exchange membrane (1 cm²) was used. 2 The ions are converted to hydroxide form by soaking in 1 M KOH for 24 hours. The membrane electrode assembly consists of a 1.5Pt@V5S8-V2C cathode, a RuO2 anode, and an activation membrane sandwiched between them.

[0040] Figure 8This is a schematic diagram of the timing potential of a 1.5Pt@V5S8-V2C circuit. From... Figure 8 It can be seen from this that at 500 mA cm -2 At a given current density, the corresponding voltage remained relatively stable over 50 hours, demonstrating that the material possesses a certain degree of catalytic stability.

Claims

1. A preparation method of a sulfur-doped biregulated V2C support loaded platinum electrocatalytic material for alkaline hydrogen evolution reaction, characterized in that The method includes the following steps: Step (1) Synthesis of V2C nanosheets: Mix 1~3 g of LiF with 30~50 mL of 6 M HCl, stir in an ice bath, slowly add 1~3 g of V2AlC powder, continue stirring, and then transfer to a hydrothermal reactor for hydrothermal reaction. The product is centrifuged and washed until pH>6, and then vacuum dried to obtain layered V2C nanosheets. Step (2) Synthesis of V5S8-V2C heterostructure: Take 0.15~0.2 g of V2C and add it to a mixture containing 1~2 mL of NMP and 3~4 mL of CS2. Add sublimed sulfur and stir until the solvent evaporates. Calcine under a protective atmosphere: keep at 150~160℃ for 10~15 h and at 400~500℃ for 1~3 h to obtain V5S8-V2C, wherein the mass ratio of sulfur powder to V2C is 1:2 and the heating rate is 5~10℃ / min. Step (3) Synthesis of Pt@V5S8-V2C: 100 mg of V5S8-V2C was dispersed in 100 ml of ethylene glycol-water mixed solvent, and 10 ml of chloroplatinic acid solution with a concentration of 1~4 mM was added. The mixture was refluxed in an oil bath at 120~140℃ for 1~3 h, cooled and filtered, washed with deionized water, rapidly frozen in liquid nitrogen, and freeze-dried to obtain Pt@V5S8-V2C electrocatalytic material.

2. The method for preparing sulfur-doped bi-regulated V2C support loaded platinum electrocatalytic material for alkaline hydrogen evolution reaction according to claim 1, characterized in that In step (1), the hydrothermal reaction temperature is 80~100℃ and the time is 48~96 h.

3. The method for preparing sulfur-doped bi-regulated V2C support loaded platinum electrocatalytic material for alkaline hydrogen evolution reaction according to claim 1, characterized in that In step (1), the vacuum drying temperature is 60~80℃ and the time is 10~15 h.

4. The method for preparing a sulfur-doped dual-regulated V2C support platinum electrocatalytic material for alkaline hydrogen evolution reaction according to claim 1, characterized in that... In step (2), the protective atmosphere is high-purity nitrogen, and the heating rate is 5~10℃ / min.

5. The method for preparing a sulfur-doped dual-regulated V2C-supported platinum electrocatalytic material for alkaline hydrogen evolution reaction according to claim 1, characterized in that... In step (3), the volume ratio of ethylene glycol to water in the ethylene glycol-water mixed solvent is 67:

33.

6. The method for preparing a sulfur-doped dual-regulated V2C-supported platinum electrocatalytic material for alkaline hydrogen evolution reaction according to claim 1, characterized in that... In step (3), the concentration of chloroplatinic acid is 3 mM.

7. The method for preparing a sulfur-doped dual-regulated V2C support platinum electrocatalytic material for alkaline hydrogen evolution reaction according to claim 1, characterized in that... In step (3), Pt in the Pt@V5S8-V2C electrocatalytic material is uniformly dispersed in the form of nanoparticles with a particle size of 0.9~4.5 nm.

8. The application of a sulfur-doped dual-regulated V2C support platinum electrocatalyst material prepared by the method of any one of claims 1-7 in the alkaline water electrolysis hydrogen evolution reaction.

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