Transition metal sulfide@wood charcoal self-supporting electrode material and preparation and use thereof

Abstract

This invention discloses a transition metal sulfide@wood charcoal self-supporting electrode material, its preparation, and its application. The invention involves carbonizing delignified wood in an inert gas atmosphere to obtain three-dimensional porous conductive wood charcoal; dispersing a nickel and iron source in a solvent to obtain a mixed solution A; subjecting the wood charcoal to a hydrothermal reaction in mixed solution A to obtain wood charcoal loaded with metal double hydroxides; dispersing a molybdenum and sulfur source in a solvent to obtain a mixed solution B; and subjecting the wood charcoal loaded with metal double hydroxides to a hydrothermal reaction in mixed solution B to obtain a wood charcoal electrode loaded with molybdenum sulfide and nickel-iron sulfide nanosheets, which is the transition metal sulfide@wood charcoal self-supporting electrode material. This invention utilizes a simple two-step hydrothermal method to synthesize the transition metal sulfide@wood charcoal self-supporting electrode material, constructing a heterostructure of molybdenum sulfide and nickel-iron sulfide nanosheets, thereby improving electrocatalytic activity and stability.

Description

Technical Field

[0001] This invention relates to the field of electrolytic plastic hydrolysis products technology, specifically to transition metal sulfide@wood charcoal self-supporting electrode materials and their preparation and application. Background Technology

[0002] Plastics, as a vital commercial and industrial material, have become indispensable in modern society. Global annual plastic production exceeds 460 million tons, with cumulative production reaching a staggering 10 billion tons. Among various types, polyethylene terephthalate (PET) has wide applications in packaging, containers, films, textiles, and medical devices. However, its slow rate of natural degradation leads to severe environmental pollution, urgently requiring effective strategies for the degradation and recycling of plastic waste.

[0003] Currently, while traditional fossil fuels meet the needs of daily life, the environmental pollution and resource depletion they cause are equally significant. Therefore, the development of clean energy should be prioritized. Hydrogen, as a clean energy source, has water as its only reduction product, making it the ideal clean energy source. Water electrolysis technology can decompose water and produce hydrogen using green energy, offering advantages such as environmental friendliness and high efficiency, and holds promise for reshaping the energy structure in the future.

[0004] Hydrogen production technology through water electrolysis involves two reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. However, the traditional anodic oxidation reaction in water electrolysis consumes a large amount of energy to produce oxygen and increases the difficulty of collecting the hydrogen produced at the cathode. PET can be hydrolyzed in an alkaline environment to produce ethylene glycol (EG) and terephthalic acid (TPA). Therefore, replacing the oxygen evolution reaction with the ethylene glycol oxidation reaction (EGOR) will further improve anode utilization efficiency, reduce gas collection difficulty, and yield the chemical product potassium diformate.

[0005] Currently, nickel foam, as an excellent conductive material and a three-dimensional porous structure, has become a widely used substrate for in-situ catalyst growth. However, due to its high price, poor acid resistance, and complex preparation process, it cannot be used on a large scale in industry (Banhart J. Manufacture, characterisation and application of cellular metals and metal foams[J]. Progress in materials science, 2001, 46(6): 559-632.).

[0006] Lignocarbon, as a self-supporting material, has attracted widespread attention due to its low cost, high specific surface area, lightweight, high mechanical properties, and corrosion resistance. Its low tortuosity and ordered conductive pathway structure enables rapid ion diffusion and charge conduction. Lignocarbon possesses great potential in the field of green energy due to its sustainability and unique structural advantages, but targeted optimization is needed to overcome its performance shortcomings. Summary of the Invention

[0007] The purpose of this invention is to provide a transition metal sulfide@wood charcoal self-supporting electrode material, its preparation and application. The in-situ grown molybdenum sulfide and nickel iron sulfide nanosheet electrode material on wood charcoal by a simple and efficient method exhibits excellent electrocatalytic activity and stability in the electrolytic reaction of plastic hydrolysates under alkaline conditions, thereby solving the above-mentioned problems.

[0008] The technical solution adopted in this invention is as follows:

[0009] This invention provides a transition metal sulfide@wood charcoal self-supporting electrode material, which is synthesized by a simple two-step hydrothermal method. Its composition includes wood charcoal and molybdenum sulfide and nickel iron sulfide nanosheets grown in situ on the surface of the wood charcoal matrix. The molybdenum sulfide and nickel iron sulfide nanosheets have heterogeneous structures and electron transfer between them.

[0010] Furthermore, the transition metal sulfide@wood charcoal self-supporting electrode material has good conductivity and specific surface area, and its three-dimensional porous structure and low curvature microchannels can quickly disperse gas and wet liquid.

[0011] This invention also provides a method for preparing the above-mentioned transition metal sulfide@wood charcoal self-supporting electrode material, comprising the following steps: S1. The wood is subjected to delignification treatment and freeze-dried to obtain delignified wood. S2. The delignified wood obtained in step S1 is placed in a protective atmosphere for carbonization to obtain three-dimensional porous conductive wood carbon, which is the wood carbon matrix. S3. Disperse the nickel source and iron source in a solvent and stir until they are fully dissolved to obtain mixed solution A; S4. Three-dimensional porous conductive wood carbon is placed in mixed solution A for hydrothermal reaction. After cooling, it is washed and dried to obtain wood carbon loaded with metal double hydroxides. S5. Disperse the molybdenum source and sulfur source in a solvent and stir until they are fully dissolved to obtain mixed solution B; S6. Place the wood-based carbon loaded with metal double hydroxides in mixed solution B for hydrothermal reaction. After cooling, wash and dry to obtain wood-based carbon loaded with molybdenum sulfide and nickel iron sulfide heterostructure, which is the transition metal sulfide@wood-based carbon self-supporting electrode material.

[0012] Furthermore, the wood chips are washed and subjected to a lignin removal process.

[0013] Further, in step S1, the treatment solution for the delignification treatment contains water: sodium chlorite: glacial acetic acid = 300 mL: 3~6 g: 1 mL.

[0014] Further, in step S1, the lignin removal treatment is carried out at a temperature of 90~120℃ and a stirring speed of 5~20r / min for 2~4h.

[0015] Furthermore, in step S1, the freeze-drying temperature is -50 ~ -40℃, and the time is 6 ~ 24h.

[0016] Further, in step S2, the protective atmosphere is N2, the gas flow rate is 20~120mL / min, the carbonization temperature is 300℃~1000℃, the heating rate is 1~20℃ / min, and the carbonization time is 1~15h.

[0017] Further, in step S3, the nickel source is one of nickel sulfate, oxalate, nitrate, halide, or acetate; the iron source is one of iron sulfate, oxalate, nitrate, halide, or acetate; the solvent is deionized water; and urea and ammonium fluoride are also added to the mixed solution; the concentration of urea is 0.1~1 mol / L, and the concentration of ammonium fluoride is 0.1~1 mol / L. Furthermore, in step S3, the molar ratio of nickel to iron in the mixed solution A is 3:1, and the total concentration of nickel and iron in the mixed solution A is 0.01~0.1 mol / L.

[0018] Furthermore, in step S4, the hydrothermal reaction temperature is 100~120℃ and the time is 8~12h; the drying temperature is 60℃ and the time is 12~24h.

[0019] Further, in step S5, the molybdenum source is sodium molybdate, the sulfur source is one of sulfur powder, thiourea, urea, sodium sulfide, sodium thiocyanate, ethylenediamine, or thioacetamide, and the solvent is deionized water; in the mixed solution B, the molar ratio of molybdenum to sulfur is 5:1, and the total concentration of molybdenum and sulfur in the mixed solution is 0.1~0.3 mol / L.

[0020] Furthermore, in step S6, the hydrothermal reaction temperature is 120~200℃ and the time is 8~12h; the drying temperature is 60℃ and the time is 12~24h.

[0021] This invention also provides the application of the aforementioned transition metal sulfide@wood charcoal self-supporting electrode material in electrolytic plastic hydrolysates.

[0022] The beneficial effects of the technical solution are: 1. The transition metal sulfide@wood charcoal self-supporting electrode material synthesized by a simple two-step hydrothermal method provided by this invention uses waste wood as raw material, which is easy to obtain and has low cost.

[0023] 2. The transition metal sulfide@wood charcoal self-supporting electrode material synthesized by the present invention through a simple two-step hydrothermal method has a simple preparation process, is suitable for large-scale manufacturing, and exhibits good industrialization capabilities.

[0024] 3. The transition metal sulfide@wood charcoal self-supporting electrode material synthesized by a simple two-step hydrothermal method provided by this invention has a three-dimensional porous structure, low curvature microchannels and good mechanical properties, which provides an efficient solid-liquid-gas three-phase reaction interface for electrolytic plastic hydrolysates.

[0025] 4. The transition metal sulfide@wood-based self-supporting electrode material provided by this invention, synthesized via a simple two-step hydrothermal method, features molybdenum sulfide and nickel-iron sulfide, both of which have nanosheet structures with larger specific surface area and more active sites. The molybdenum sulfide nanosheets, embedded within the nickel-iron sulfide nanosheets, form a heterostructure that promotes electron transfer and exhibits high catalytic activity. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the two-step hydrothermal construction of a transition metal sulfide@wood charcoal self-supporting electrode material according to the present invention.

[0027] Figure 2 This is the X-ray diffraction (XRD) pattern of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 of this invention.

[0028] Figure 3 This is a scanning electron microscope (SEM) image of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 of this invention.

[0029] Figure 4 This is a high-resolution transmission electron microscope (HRTEM) image of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 of this invention.

[0030] Figure 5 The image shows the energy dispersive X-ray spectrum (EDS) of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 of this invention.

[0031] Figure 6 This is a comparison chart of the linear sweep voltammetry (LSV) performance of the electrode materials obtained in Example 1 and Comparative Examples 1 and 2 of this invention for the cathodic hydrogen evolution reaction (HER).

[0032] Figure 7 This is a comparison chart of the linear sweep voltammetry (LSV) performance of the electrode materials obtained in Example 1 and Comparative Examples 1 and 2 of this invention.

[0033] Figure 8 The image shows the linear sweep voltammetry (LSV) curves of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 of this invention for the anodic oxygen evolution reaction (OER) and ethylene glycol oxidation reaction (EGOR).

[0034] Figure 9 The stability curve of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 of this invention under constant current density when used in the hydrogen evolution reaction (HER) at the cathode.

[0035] Figure 10 The stability curve of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 of this invention under constant current density when used in ethylene glycol oxidation reaction (EGOR).

[0036] Figure 11 The MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 of this invention is used to assemble an electrolytic plastic hydrolysate device.

[0037] Figure 12 The linear sweep voltammetry (LSV) curve of the device for electrolyzing plastic hydrolysate assembled with MoS2-(Ni,Fe)S2@WC electrode material in Example 1 is shown.

[0038] Figure 13 This is a comparison chart of the linear sweep voltammetry (LSV) performance of the electrode materials obtained in Examples 1, 2 and 3 of the present invention for the cathodic hydrogen evolution reaction (HER) (where MoS2-(Ni,Fe)S2@WC-0.6 refers to MoS2-(Ni,Fe)S2@WC).

[0039] Figure 14 This is a comparison chart of the linear sweep voltammetry (LSV) performance of the electrode materials obtained in Examples 1, 2 and 3 of this invention for the oxygen evolution reaction (OER). Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the implementation and protection of the present invention are not limited thereto.

[0041] Figure 1 The present invention illustrates the process of constructing a transition metal sulfide@wood charcoal self-supporting electrode material via a two-step hydrothermal process.

[0042] Example 1 Preparation methods of transition metal sulfide@wood-based self-supported electrode materials, such as... Figure 1 As shown, it includes the following steps: 1) Preparation of delignin-treated carbonized wood: First, natural poplar wood was sliced ​​perpendicular to its growth direction, with dimensions of 4cm × 2cm × 0.1cm (length × width × height). Eight wood slices were cleaned and immersed in a mixed solution containing 3.0g sodium chlorite, 1.0mL glacial acetic acid, and 300mL deionized water. The solution was heated in an oil bath at 110℃ and stirred at 5r / min for 2h to perform delignin treatment. Finally, the treated wood was freeze-dried at -47℃ for 24h to obtain delignin-treated wood. 2) Preparation of wood charcoal: Place the delignified wood in a quartz tube furnace, pass N2 (gas flow rate of 80 mL / min), heat to 500℃ for 1.5 h at a rate of 5℃ / min, and then heat to 900℃ for another 1 h to obtain three-dimensional porous conductive wood charcoal. 3) Preparation of precursors: Add 0.72g of urea and 0.22g of ammonium fluoride to 30 mL of homogeneous aqueous solution (1.8 mmol nickel nitrate + 0.6 mmol ferric nitrate), stir until homogeneous and clear, to obtain mixed solution A; 4) Loading metal double hydroxides on wood charcoal: Mixed solution A and three-dimensional porous conductive wood charcoal were transferred to a stainless steel autoclave with a 50 mL polytetrafluoroethylene liner for hydrothermal reaction. The autoclave was sealed and heated at 120 °C for 12 h. After cooling to room temperature, the sample was removed, washed with deionized water, and then dried at 60 °C for 12 h to obtain wood charcoal loaded with metal double hydroxides. 5) Preparation of sulfidation: Add 0.3024 g of sodium molybdate dihydrate (molecular weight 241.95, molar amount here is approximately 0.00125 mol) and 0.4696 g of thioacetamide (molecular weight 75.133, molar amount here is approximately 0.00625 mol) to 30 mL of deionized water, stir until homogeneous and clear, to obtain mixed solution B; 6) Loading molybdenum sulfide and nickel iron sulfide onto lignocarbon: Mixed solution B and a piece of lignocarbon loaded with metal double hydroxides were transferred to a stainless steel autoclave lined with 50 mL of polytetrafluoroethylene for hydrothermal reaction. The autoclave was sealed and heated at 200 °C for 8 h. After cooling to room temperature, the sample was removed, washed with deionized water, and then dried at 60 °C for 12 h to obtain lignocarbon with a heterostructure of molybdenum sulfide and nickel iron sulfide (denoted as MoS2-(Ni,Fe)S2@WC), which is the transition metal sulfide@lignocarbon self-supporting electrode material.

[0043] Example 2 Preparation methods of transition metal sulfide@wood-based self-supported electrode materials, such as... Figure 1 As shown, it includes the following steps: 1) Preparation of delignin-treated carbonized wood: First, natural poplar wood was sliced ​​perpendicular to its growth direction, with dimensions of 4cm × 2cm × 0.1cm (length × width × height). Eight wood slices were cleaned and immersed in a mixed solution containing 3.0g sodium chlorite, 1.0mL glacial acetic acid, and 300mL deionized water. The solution was heated in an oil bath at 110℃ and stirred at 5r / min for 2h to perform delignin treatment. Finally, the treated wood was freeze-dried at -47℃ for 24h to obtain delignin-treated wood. 2) Preparation of wood charcoal: Place the delignified wood in a quartz tube furnace, pass N2 (gas flow rate of 80 mL / min), heat to 500℃ for 1.5 h at a rate of 5℃ / min, and then heat to 900℃ for another 1 h to obtain three-dimensional porous conductive wood charcoal. 3) Preparation of precursors: Add 0.48g of urea and 0.1482g of ammonium fluoride to 30 mL of homogeneous aqueous solution (1.2 mmol nickel nitrate + 0.4 mmol ferric nitrate), stir until homogeneous and clear, to obtain mixed solution A; 4) Loading metal double hydroxides on wood charcoal: Mixed solution A and three-dimensional porous conductive wood charcoal were transferred to a stainless steel autoclave with a 50 mL polytetrafluoroethylene liner for hydrothermal reaction. The autoclave was sealed and heated at 120 °C for 12 h. After cooling to room temperature, the sample was removed, washed with deionized water, and then dried at 60 °C for 12 h to obtain wood charcoal loaded with metal double hydroxides. 5) Preparation of sulfidation: Add 0.3024 g of sodium molybdate dihydrate (molecular weight 241.95, molar amount here is approximately 0.00125 mol) and 0.4696 g of thioacetamide (molecular weight 75.133, molar amount here is approximately 0.00625 mol) to 30 mL of deionized water, stir until homogeneous and clear, to obtain mixed solution B; 6) Loading molybdenum sulfide and nickel iron sulfide onto lignocarbon: Mixed solution B and a piece of lignocarbon loaded with metal double hydroxides were transferred to a stainless steel autoclave lined with 50 mL of polytetrafluoroethylene for hydrothermal reaction. The autoclave was sealed and heated at 200 °C for 8 h. After cooling to room temperature, the sample was removed, washed with deionized water, and then dried at 60 °C for 12 h to obtain lignocarbon with a heterostructure of molybdenum sulfide and nickel iron sulfide (denoted as MoS2-(Ni,Fe)S2@WC-0.4), which is the transition metal sulfide@lignocarbon self-supporting electrode material.

[0044] Example 3 Preparation methods of transition metal sulfide@wood-based self-supported electrode materials, such as... Figure 1 As shown, it includes the following steps: 1) Preparation of delignin-treated carbonized wood: First, natural poplar wood was sliced ​​perpendicular to its growth direction, with dimensions of 4cm × 2cm × 0.1cm (length × width × height). Eight wood slices were cleaned and immersed in a mixed solution containing 3.0g sodium chlorite, 1.0mL glacial acetic acid, and 300mL deionized water. The solution was heated in an oil bath at 110℃ and stirred at 5r / min for 2h to perform delignin treatment. Finally, the treated wood was freeze-dried at -47℃ for 24h to obtain delignin-treated wood. 2) Preparation of wood charcoal: Place the delignified wood in a quartz tube furnace, pass N2 (gas flow rate of 80 mL / min), heat to 500℃ for 1.5 h at a rate of 5℃ / min, and then heat to 900℃ for another 1 h to obtain three-dimensional porous conductive wood charcoal. 3) Preparation of precursors: Add 0.96 g of urea and 0.296 g of ammonium fluoride to 30 mL of homogeneous aqueous solution (2.4 mmol nickel nitrate + 0.8 mmol ferric nitrate), stir until homogeneous and clear, to obtain mixed solution A; 4) Loading metal double hydroxides on wood charcoal: Mixed solution A and three-dimensional porous conductive wood charcoal were transferred to a stainless steel autoclave with a 50 mL polytetrafluoroethylene liner for hydrothermal reaction. The autoclave was sealed and heated at 120 °C for 12 h. After cooling to room temperature, the sample was removed, washed with deionized water, and then dried at 60 °C for 12 h to obtain wood charcoal loaded with metal double hydroxides. 5) Preparation of sulfidation: Add 0.3024 g of sodium molybdate dihydrate (molecular weight 241.95, molar amount here is approximately 0.00125 mol) and 0.4696 g of thioacetamide (molecular weight 75.133, molar amount here is approximately 0.00625 mol) to 30 mL of deionized water, stir until homogeneous and clear, to obtain mixed solution B; 6) Loading molybdenum sulfide and nickel iron sulfide onto lignocarbon: Mixed solution B and a piece of lignocarbon loaded with metal double hydroxides were transferred to a stainless steel autoclave lined with 50 mL of polytetrafluoroethylene for hydrothermal reaction. The autoclave was sealed and heated at 200 °C for 8 h. After cooling to room temperature, the sample was removed, washed with deionized water, and then dried at 60 °C for 12 h to obtain lignocarbon with a heterostructure of molybdenum sulfide and nickel iron sulfide (denoted as MoS2-(Ni,Fe)S2@WC-0.8), which is the transition metal sulfide@lignocarbon self-supporting electrode material.

[0045] Comparative Example 1 A self-supporting electrode material derived from lignocarbon is prepared as follows: 1) Preparation of de-lignified wood: First, natural poplar wood was sliced ​​perpendicular to its growth direction, with dimensions of 4cm × 2cm × 0.1cm (length × width × height). Eight wood slices were cleaned and immersed in a mixed solution containing 3.0 g sodium chlorite, 1.0 mL glacial acetic acid, and 300 mL deionized water. The solution was heated in an oil bath at 110℃ and stirred at 5 r / min for 2 h. Finally, the treated wood was freeze-dried at -47℃ for 24 h to obtain de-lignified wood. 2) Preparation of wood charcoal: Place the delignified wood in a quartz tube furnace, pass N2 (gas flow rate of 80 mL / min), heat to 500℃ for 1.5h at a rate of 5℃ / min, and then heat to 900℃ for another 1h to obtain three-dimensional porous conductive wood charcoal. 3) Preparation of precursors: Add 0.72 g of urea and 0.22 g of ammonium fluoride to 30 mL of homogeneous aqueous solution (0.06 mol / L nickel nitrate + 0.02 mol / L ferric nitrate), stir until homogeneous and clear, to obtain mixed solution A; 4) Loading metal double hydroxides on wood charcoal: Mixed solution A and three-dimensional porous conductive wood charcoal were transferred to a stainless steel autoclave with a 50 mL polytetrafluoroethylene liner for hydrothermal reaction. The autoclave was sealed and heated at 120 °C for 12 h. After cooling to room temperature, the sample was removed, washed with deionized water, and then dried at 60 °C for 12 h to obtain wood charcoal loaded with metal double hydroxides. 5) Preparation of sulfidation: Add 0.4696 g of thioacetamide to 30 mL of deionized water and stir until homogeneous and clear to obtain mixed solution B; 6) Loading nickel iron sulfide onto lignocarbon: Mixed solution B and a piece of lignocarbon loaded with metal double hydroxide were transferred to a stainless steel autoclave with a 50 mL polytetrafluoroethylene liner for hydrothermal reaction. The autoclave was sealed and heated at 200 °C for 8 h. After cooling to room temperature, the sample was removed, washed with deionized water, and then dried at 60 °C for 12 h to obtain lignocarbon loaded with nickel iron sulfide (denoted as (Ni,Fe)S2@WC).

[0046] Comparative Example 2 A self-supporting electrode material derived from lignocarbon is prepared as follows: 1) Preparation of de-lignified wood: First, natural poplar wood was sliced ​​perpendicular to its growth direction, with dimensions of 4cm × 2cm × 0.1cm (length × width × height). Eight wood slices were cleaned and immersed in a mixed solution containing 3.0 g sodium chlorite, 1.0 mL glacial acetic acid, and 300 mL deionized water. The solution was heated in an oil bath at 110℃ and stirred at 5 r / min for 2 h. Finally, the treated wood was freeze-dried at -47℃ for 24 h to obtain de-lignified wood. 2) Preparation of wood charcoal: Place the delignified wood in a quartz tube furnace, pass N2 (gas flow rate of 80 mL / min), heat to 500℃ for 1.5 h at a rate of 5℃ / min, and then heat to 900℃ for another 1 h to obtain three-dimensional porous conductive wood charcoal. 3) Prepare the metal source: Add 0.3024 g of sodium molybdate and 0.4696 g of thioacetamide to 30 mL of deionized water and stir until homogeneous and clear to obtain mixed solution A; 4) Loading molybdenum sulfide onto wood charcoal: Mixed solution A and a piece of three-dimensional porous conductive wood charcoal were transferred to a stainless steel autoclave with a 50 mL polytetrafluoroethylene liner for hydrothermal reaction. The autoclave was sealed and heated at 200 °C for 8 h. After cooling to room temperature, the sample was removed, washed with deionized water, and then dried at 60 °C for 12 h to obtain wood charcoal loaded with molybdenum sulfide (denoted as MoS2@WC).

[0047] The X-ray diffraction (XRD) pattern of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 is shown below. Figure 2 As shown, by Figure 2 It can be seen that the obtained molybdenum sulfide has three characteristic diffraction peaks at 16°, and nickel iron sulfide has three characteristic diffraction peaks at 32° and 54°, which can be attributed to the (002) crystal plane of molybdenum sulfide, the (200) crystal plane of nickel iron sulfide, and the (311) crystal plane of nickel iron sulfide, respectively.

[0048] Scanning electron microscope (SEM) images of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 are shown below. Figure 3 As shown, by Figure 3 It can be seen that nickel iron sulfide and molybdenum sulfide exhibit a uniform and dense nanosheet structure, with nickel iron sulfide being approximately 150 nm thick and molybdenum sulfide approximately 5 nm thick. Nickel iron sulfide and molybdenum sulfide grow uniformly on the surface of the vertical channels of wood charcoal.

[0049] The high-resolution transmission electron microscope (HRTEM) images of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 are as follows: Figure 4 As shown, by Figure 4 It can be seen that the obtained molybdenum sulfide and nickel iron sulfide wood carbon electrode has two lattice spacings of 0.62 nm and 0.278 nm, which are respectively assigned to the molybdenum sulfide (002) crystal plane and the nickel iron sulfide (200) crystal plane.

[0050] The energy dispersive X-ray spectrum (EDS) of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 is as follows: Figure 5 As shown, by Figure 5 It can be seen that Fe, Ni, Mo, and S are uniformly distributed in the obtained molybdenum sulfide nickel iron sulfide wood carbon electrode.

[0051] The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1, the (Ni,Fe)S2@WC electrode material obtained in Comparative Example 1, and the MoS2@WC electrode material obtained in Comparative Example 2 were tested. Test conditions for HER and OER: A standard three-electrode system was used as the test system. The obtained MoS2-(Ni,Fe)S2@WC electrode material, (Ni,Fe)S2@WC electrode material, and MoS2@WC electrode material were used as working electrodes, respectively. Hg / HgO was used as the reference electrode, a graphite rod as the counter electrode, and 1 mol / L KOH solution (pH≈13.8, solvent: pure water) was used as the electrolyte. The testing instrument was a Shanghai Chenhua CHI... 660E electrochemical workstation. Its linear sweep voltammetry curve was tested at room temperature (25°C).

[0052] Figure 6 The diagram shows a comparison of the linear sweep voltammetry (LSV) performance of the electrode materials obtained in Example 1 and Comparative Examples 1 and 2 of this invention for the cathodic hydrogen evolution reaction (HER). Figure 7 Linear sweep voltammetry (LSV) curves of the anodic oxygen evolution reaction (OER) of the electrode materials obtained in Example 1 and Comparative Examples 1 and 2 of this invention are shown.

[0053] Depend on Figure 6 , Figure 7 It can be seen that the MoS2-(Ni,Fe)S2@WC electrode material exhibits the best HER and OER activity and a faster response current compared to MoS2@WC and (Ni,Fe)S2@WC. At a current density of 100 mA / cm², [the following is observed]. 2 At that time, the HER and OER overpotentials of the MoS2-(Ni,Fe)S2@WC electrode material were 149 and 241 mV, respectively.

[0054] in Figure 8 The linear sweep voltammetry curves of the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 are shown in 1 mol / L KOH (oxygen evolution reaction group) and 1 mol / L KOH + 0.3 mol / L ethylene glycol EG (ethylene glycol oxidation group). After the addition of EG, the linear sweep voltammetry curves at 100 mA / cm² are shown in the figure. 2 The potential difference of 64 mV indicates that replacing the oxygen evolution reaction with the ethylene glycol oxidation reaction (EGOR) will further improve the anode utilization efficiency.

[0055] The MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 was used to maintain a constant current density (10 mA / cm²) during the hydrogen evolution reaction (HER) at the cathode. 2 The stability curve under ( ) is as follows Figure 9 As shown. The MoS2-(Ni,Fe)S2@WC electrode material at 10 mA / cm 2 It operates stably for 100 hours at current density without significant degradation.

[0056] The MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 was used to maintain a constant current density (100 mA / cm²) during the ethylene glycol oxidation reaction (EGOR). 2 The stability curve under ( ) is as follows Figure 10 As shown. The MoS2-(Ni,Fe)S2@WC electrode material at 100 mA / cm 2 It operates stably for 200 hours at current density without significant attenuation, demonstrating excellent stability.

[0057] Figure 11 The MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1 of this invention is used to assemble an electrolytic plastic hydrolysate device.

[0058] For example Figure 11 Electrochemical performance and stability tests of the electrolyzed plastic hydrolysate were conducted using an electrolytic plastic hydrolysate apparatus. Two identical MoS2-(Ni,Fe)S2@WC electrode materials obtained in Example 1 were used as the cathode and anode, respectively, in the electrolytic cell (e.g., ...). Figure 11 As shown in the figure, hydrogen gas is generated at the cathode, and ethylene glycol is oxidized to formate at the anode, with the following results: Figure 12 As shown.

[0059] Figure 12 The linear sweep voltammetry (LSV) curve of the device for electrolyzing plastic hydrolysates assembled with the MoS2-(Ni,Fe)S2@WC electrode material in Example 1 is shown. The curve is at 100 mA / cm². 2 At that time, the potential for ethylene glycol oxidation was 1.581, which was 63 mV lower than that for the oxygen evolution reaction. This means that at the same voltage, it has a larger current density, indicating that replacing the oxygen evolution reaction with ethylene glycol oxidation (EGOR) will further improve the anode utilization efficiency.

[0060] Figure 12 This invention illustrates that, under the same potential, by using ethylene glycol oxidation to replace the oxygen evolution reaction, a higher current density is obtained, and at the same time, a higher value chemical product (formate) is obtained compared to oxygen.

[0061] Figure 13 The graph shows a comparison of the linear sweep voltammetry (LSV) performance of the electrode materials obtained in Examples 1, 2, and 3 of this invention for the cathodic hydrogen evolution reaction (HER), and at 10 and 100 mA / cm². 2The graphs show a comparison of HER activity at different current densities. The left graph is a comparison of LSV activity, and the right graph is a comparison of HER activity. In the graphs, MoS2-(Ni,Fe)S2@WC-0.6 represents MoS2-(Ni,Fe)S2@WC. As can be seen from the graphs, the MoS2-(Ni,Fe)S2@WC electrode material prepared in Example 1 exhibits high HER activity at current densities of 10 and 100 mA / cm². 2 The HER activity was highest at the current density, with overpotentials of 66 and 149, respectively.

[0062] Figure 14 The graph shows a comparison of the linear sweep voltammetry (LSV) performance of the electrode materials obtained in Examples 1, 2, and 3 of this invention for the oxygen evolution reaction (OER), and at 10 and 100 mA / cm². 2 The graphs show a comparison of OER activity at different current densities, with the left graph showing LSV activity and the right graph showing HER activity. As can be seen from the graphs, the MoS2-(Ni,Fe)S2@WC electrode material prepared in Example 1 exhibits high OER activity at current densities of 10 and 100 mA / cm². 2 The HER activity was highest at the current density, with overpotentials of 176 and 241, respectively.

[0063] Mechanical strength tests were conducted on the MoS2-(Ni,Fe)S2@WC electrode material obtained in Example 1. The wood-based carbon electrode, which was synthesized by two hydrothermal processes of molybdenum sulfide and nickel iron sulfide, was placed under a weight 10,000 times its own weight and subjected to pressure for 1 hour. The compressive strength of the MoS2-(Ni,Fe)S2@WC electrode material was as follows: after being subjected to heavy pressure, the material showed no obvious cracks, indicating a certain degree of mechanical strength.

[0064] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A transition metal sulfide@wood charcoal self-supporting electrode material, characterized in that, The product is synthesized via a simple two-step hydrothermal method. Its composition includes a lignocarbon matrix and molybdenum sulfide and nickel-iron sulfide nanosheets grown in situ on the surface of the lignocarbon matrix. The molybdenum sulfide and nickel-iron sulfide nanosheets have heterogeneous structures and electron transfer between them.

2. The method for preparing a transition metal sulfide@wood charcoal self-supporting electrode material according to claim 1, characterized in that, Includes the following steps: S1. The wood is subjected to delignification treatment and freeze-dried to obtain delignified wood. S2. The delignified wood obtained in step S1 is placed in a protective atmosphere for carbonization to obtain three-dimensional porous conductive wood carbon, which is the wood carbon matrix. S3. Disperse the nickel source and iron source in a solvent and stir until they are fully dissolved to obtain mixed solution A; S4. Three-dimensional porous conductive wood carbon is placed in mixed solution A for hydrothermal reaction. After cooling, it is washed and dried to obtain wood carbon loaded with metal double hydroxides. S5. Disperse the molybdenum source and sulfur source in a solvent and stir until they are fully dissolved to obtain mixed solution B; S6. Place the wood-based carbon loaded with metal double hydroxides in mixed solution B for hydrothermal reaction. After cooling, wash and dry to obtain wood-based carbon loaded with molybdenum sulfide and nickel iron sulfide heterostructure, which is the transition metal sulfide@wood-based carbon self-supporting electrode material.

3. The method for preparing a transition metal sulfide@wood charcoal self-supporting electrode material according to claim 2, characterized in that, In S1, the treatment solution for the delignification treatment contains water: sodium chlorite: glacial acetic acid = 300 mL: 3~6 g: 1 mL.

4. The method for preparing a transition metal sulfide@wood charcoal self-supporting electrode material according to claim 2, characterized in that, In S1, the delignification treatment is carried out at a temperature of 90~120℃ and a stirring speed of 1~20r / min for 2~4h; the freeze-drying temperature is -50~-40℃ and the time is 6~24h.

5. The method for preparing a transition metal sulfide@wood charcoal self-supporting electrode material according to claim 2, characterized in that, In S2, the protective atmosphere is N2, the gas flow rate is 20~120 mL / min, the carbonization temperature is 300℃~1000℃, the heating rate is 1~20℃ / min, and the carbonization time is 1~15 h.

6. The method for preparing a transition metal sulfide@wood charcoal self-supporting electrode material according to claim 2, characterized in that, In S3, the nickel source is one of nickel sulfate, oxalate, nitrate, halide, or acetate; the iron source is one of iron sulfate, oxalate, nitrate, halide, or acetate; the solvent is deionized water; urea and ammonium fluoride are also added to the mixed solution; the concentration of urea is 0.1~1 mol / L; the concentration of ammonium fluoride is 0.1~1 mol / L; the molar ratio of nickel to iron in mixed solution A is 3:1; and the total concentration of nickel and iron is 0.01~0.15 mol / L.

7. The method for preparing a transition metal sulfide@wood charcoal self-supporting electrode material according to claim 2, characterized in that, In step S4, the hydrothermal reaction temperature is 100~120℃ and the time is 8~12h.

8. The method for preparing a transition metal sulfide@wood charcoal self-supporting electrode material according to claim 2, characterized in that, In step S5, the molybdenum source is sodium molybdate, the sulfur source is one of sulfur powder, thiourea, urea, sodium sulfide, sodium thiocyanate, ethylenediamine, or thioacetamide, and the solvent is deionized water; the molar ratio of molybdenum to sulfur in mixed solution B is 5:1, and the total concentration of molybdenum and sulfur is 0.1~0.3 mol / L.

9. The method for preparing a transition metal sulfide@wood charcoal self-supporting electrode material according to claim 2, characterized in that, In step S6, the hydrothermal reaction temperature is 120~200℃ and the time is 8~12h.

10. The application of the transition metal sulfide@wood charcoal self-supporting electrode material according to claim 1 in electrolytic plastic hydrolysates.

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