Wood-based charcoal derived free-standing integrated electrode materials, methods of making and applications thereof

Abstract

The application discloses a wood charcoal derived self-supporting integrated electrode material and a preparation method and application thereof. The preparation method comprises the following steps: S1, poplar slices are carbonized in a protective atmosphere after removing lignin to obtain a wood charcoal derived three-dimensional porous carbonized wood; S2, a mixed solution containing a nickel source and a molybdenum source is prepared; S3, a molybdenum-nickel oxide electrode material precursor grown on the wood charcoal is prepared by using the three-dimensional porous wood charcoal and the mixed solution; S4, the precursor is reduced by high-temperature ammonia gas to obtain the wood charcoal derived self-supporting integrated electrode material; and application of the electrode material in hydrogen production by water electrolysis. The electrode material is synthesized by using a hydrothermal synthesis method and a high-temperature ammonia gas mixed gas reduction method, nickel nanoparticles are in-situ grown on the wood charcoal in a heterostructure embedded in molybdenum nitride nanosheets, the fast material transmission of the porous wood charcoal structure is combined, the electronic structure is adjusted, the water dissociation energy barrier is reduced, and the electrode material has excellent electrocatalytic activity and stability for the water electrolysis reaction under an alkaline condition.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, specifically to a lignocarbon-derived self-supporting integrated electrode material, its preparation method, and its application. Background Technology

[0002] The extensive burning of fossil fuels such as coal, oil, and natural gas has led to severe environmental pollution, and these resources are finite and difficult to renew. Therefore, researching clean, renewable new energy sources and energy storage devices has become an urgent priority; among these, hydrogen, due to its light weight, high calorific value, pollution-free combustion, and sustainable utilization, is considered one of the most promising energy carriers. However, hydrogen energy is not an energy resource abundant in nature and needs to be produced. Among the many methods for producing hydrogen, water electrolysis is a simple, clean, and mature technology, and is currently one of the well-known and accepted methods for hydrogen production.

[0003] Water electrolysis for hydrogen production (OWS) is a complex process involving gas-liquid-solid three-phase interfacial reactions. To maximize the utilization of active materials, accelerate gas-liquid transport, and enhance electrocatalytic activity and stability, the design and selection of electrode structure and surface properties are crucial. Currently, nickel foam and copper foam are widely used as three-dimensional porous supports for in-situ growth of electrode materials; however, they are costly and susceptible to corrosion in the complex electrolysis environment.

[0004] OWS involves two half-reactions: the cathode hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). However, the hydrogen and oxygen evolution reaction rates are relatively slow, which limits the catalytic efficiency. Currently, the power consumption for hydrogen production by water electrolysis is 4.5–5.5 kWh / Nm³. 3 The main reason for the high energy consumption of the anodic oxygen production reaction is the use of H2. Research has shown that using highly efficient catalytic electrode materials to lower the reaction activation energy can effectively reduce energy consumption. Therefore, in water electrolysis for hydrogen production, improving the activity of the electrode catalytic material, reducing the overpotential of the hydrogen evolution reaction, and enhancing the stability of the electrode material are crucial.

[0005] Existing Pt / C electrode materials exhibit excellent hydrogen evolution catalytic performance, while noble metal-based RuO2 and IrO2 electrode materials show good performance in oxygen evolution catalysis. However, these noble metal-based electrode materials face challenges such as high cost, limited reserves, and poor long-term stability, restricting their large-scale application. In contrast, transition metal alloys and their oxides are attractive as potential alternatives due to their low cost and abundant reserves. However, the catalytic activity of transition metals and their oxides still lags behind that of noble metals. Therefore, how to achieve controllable design in transition metal alloys and their oxides to improve catalytic activity is a pressing problem to be solved in this field. Summary of the Invention

[0006] This invention aims to provide a lignocarbon-derived self-supporting integrated electrode material, its preparation method, and its application. The lignocarbon-derived self-supporting integrated electrode material is synthesized by hydrothermal synthesis and high-temperature ammonia mixed gas reduction method. The resulting heterostructure of nickel nanoparticles embedded with molybdenum nitride is grown in situ on lignocarbon, exhibiting excellent electrocatalytic activity and stability in the water electrolysis reaction under alkaline conditions, thereby solving the aforementioned problems.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing a self-supporting integrated electrode material derived from charcoal includes the following steps:

[0009] S1. First, poplar wood is sliced ​​along its vertical growth direction, then it is treated with lignin removal, and then carbonized in a protective atmosphere to obtain three-dimensional porous charcoal derived from charcoal.

[0010] S2. First, disperse the nickel source and molybdenum source separately in a solvent and stir until they are fully dissolved; then mix them to obtain a mixed solution.

[0011] S3. The three-dimensional porous wood charcoal obtained in step S1 and the mixed solution obtained in step S2 are transferred together to a high-pressure reactor for reaction. After the reaction is completed, the mixture is cooled to room temperature, washed with deionized water, and dried by blowing air to obtain the electrode material precursor of molybdenum nickel oxide grown on wood charcoal.

[0012] S4. Place the electrode material precursor obtained in step S3 into a tube furnace and reduce it at high temperature in a mixed atmosphere containing ammonia to obtain the desired charcoal-derived self-supporting integrated electrode material.

[0013] Furthermore, in S1, the length*width*height of the poplar wood slices is 2-6cm×1-3cm×0.1-0.3cm, preferably 4cm×2cm×0.1cm; the lignin removal solution is a high-temperature sodium hypochlorite aqueous solution at a temperature of 80-120℃, and the sodium hypochlorite concentration is 0.1-0.5mol / L; the protective atmosphere is either Ar2 or N2, the flow rate of the protective atmosphere is 30-120mL / min, the carbonization temperature is 300-1000℃, the heating rate is 1-20℃ / min, and the carbonization time is 1-15h.

[0014] Further, in S2, the nickel source is one of sulfate, oxalate, nitrate, halide, acetate, or acetylacetone-soluble salt; the molybdenum source is molybdate; and the solvent is one of analytical grade ethanol, ethanolamine, diethanolamine, triethanolamine, N,N-dimethylformamide, ethylenediamine, or an aqueous solution diluted with deionized water. The concentration of the nickel source in the solvent is 0.01 mol / L to 0.05 mol / L; the concentration of the molybdenum source in the solvent is 0.01 mol / L to 0.15 mol / L.

[0015] Furthermore, in S2, the molar ratio of the added nickel source to the molar source is 1:0.1 to 3.

[0016] Furthermore, in S3, the reaction temperature in the high-pressure reactor is 120–200°C, and the reaction time is 1–36 h.

[0017] Furthermore, in S4, the reaction temperature in the tubular furnace is 200–700°C, the reaction time is 0.5–5 h, and the gas contains a mixture of ammonia and nitrogen or a mixture of ammonia and argon, with a flow rate of 30–120 mL / min.

[0018] The self-supporting integrated electrode material derived from charcoal, prepared by the above-mentioned method, has a heterogeneous structure with nanoparticles embedded in nanosheets. It has a three-dimensional hierarchical porous structure, low curvature microchannels, tunable hydrophilicity / hydrophobicity, good mechanical properties, good electrical conductivity, and high specific surface area.

[0019] The application of the self-supporting integrated electrode material derived from charcoal prepared by the above-mentioned method in water electrolysis for hydrogen production.

[0020] The beneficial effects of the technical solution are:

[0021] 1. This invention synthesizes a lignocarbon-derived self-supporting integrated electrode material using a hydrothermal synthesis method and a high-temperature ammonia mixed gas reduction method. The lignocarbon-derived three-dimensional porous lignocarbon has good conductivity and high specific surface area, providing more reactive sites and electron transport channels. Molybdenum-nickel oxide is grown on the lignocarbon electrode material precursor, which can increase the energy storage capacity and electrochemical activity of the electrode material. The electrode material has good structural stability and mechanical strength, and can effectively resist volume expansion and structural damage. Moreover, the preparation method is simple, easy to implement, and low in cost, making it suitable for large-scale production.

[0022] 2. The self-supporting integrated electrode material derived from charcoal prepared in this invention can synthesize a heterogeneous electrocatalyst with a special embedding mode by changing the ratio of transition metal nickel / molybdenum raw materials and the reduction temperature of the mixed gas. Combined with the rapid mass transport of the porous charcoal structure, the resulting catalyst has a high specific surface area and high intrinsic electrochemical activity, which is conducive to the contact between the catalyst and water molecules in the electrolyte and promotes the water molecule electrolysis reaction.

[0023] 3. The lignocarbon-derived self-supporting integrated electrode material prepared in this invention can be used as an electrode material for electrolytic hydrogen production. Due to the heterogeneous structure of nanoparticles embedded in nanosheets, this electrode material can improve the activity of active sites and expose more active sites, thereby improving electrocatalytic activity. At the same time, its morphology can be optimized by controlling the reactant concentration, the temperature of the high-temperature reduction reaction of the mixed gas, and the reaction time. It has good repeatability, and the obtained catalyst has a high specific surface area and high intrinsic electrochemical activity, which is conducive to the contact between the catalyst and water molecules in the electrolyte and promotes the electrolysis reaction of water molecules.

[0024] 4. The self-supporting integrated electrode material derived from charcoal prepared by this invention has a three-dimensional hierarchical porous structure, low curvature microchannels, tunable hydrophilicity / hydrophobicity and good mechanical properties, which can build an efficient gas-liquid-solid three-phase reaction interface for water electrolysis. Moreover, using charcoal as a substrate is beneficial to further reduce the cost of large-scale production. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the preparation of a lignocarbon-derived self-supporting integrated electrode material according to the present invention.

[0026] Figure 2 The images show the XRD patterns of DWC in Example 1 and Ni / MoN@DWC in Example 2 of this invention.

[0027] Figure 3 This is a SEM image of DWC in Embodiment 1 of the present invention.

[0028] Figure 4 The images show the SEM / TEM image and selected electron diffraction pattern of the electrode material prepared in Example 2 of this invention.

[0029] Figure 5 This is the EDS diagram of Ni / MoN@DWC in Embodiment 2 of the present invention.

[0030] Figure 6 The images show the HER performance and HER overpotential of the electrode materials obtained in Examples 1, 2, 1, and 2 of this invention and the commercial Pt / C catalyst.

[0031] Figure 7The OER performance diagram and OER overpotential diagram of Ni / MoN@DWC and commercial RuO2 catalyst in Example 2 of this invention are shown.

[0032] Figure 8 The figures show the hydrogen production from Ni / MoN@DWC / / Ni / MoN@DWC electrolysis and the electrolysis performance of commercial Pt / C / / RuO2, as well as the stability of Ni / MoN@DWC / / Ni / MoN@DWC electrolysis.

[0033] Figure 9 This is the actual assembly of the Ni / MoN@DWC / / Ni / MoN@DWC water electrolysis device in Embodiment 2 of the present invention.

[0034] Figure 10 The figures show the results of long-term hydrogen evolution stability tests and actual schematic diagrams of the Ni / MoN@DWC assembled water electrolysis hydrogen production device in Embodiment 2 of the present invention under different current densities. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0036] Example 1

[0037] The steps for preparing three-dimensional porous charcoal are as follows:

[0038] Pretreatment of natural wood: First, slice natural poplar wood perpendicular to its growth direction, with the slices measuring 4cm × 2cm × 0.1cm (length × width × height). Then, clean the slices and soak them in a 0.2mol / L sodium hypochlorite solution for 2 hours, followed by drying in an 80℃ forced-air drying oven overnight. Preparation of three-dimensional porous conductive wood charcoal: Place the dried slices in a quartz tube furnace, purge with nitrogen, and heat to 500℃ for 1.5h at a rate of 5℃ / min. Then, heat to 900℃ and carbonize for another 1h to obtain three-dimensional porous conductive wood charcoal derived from wood charcoal, denoted as DWC.

[0039] Example 2

[0040] The steps for preparing three-dimensional porous charcoal are as follows:

[0041] Pretreatment of natural wood: First, slice natural poplar wood perpendicular to its growth direction, with the slices measuring 4cm x 2cm x 0.1cm (length x width x height). Then, clean the slices and soak them in a 0.2mol / L sodium hypochlorite solution at 110℃ for 1 hour, followed by drying in a forced-air drying oven at 80℃ overnight. Preparation of three-dimensional porous conductive wood charcoal: Place the dried slices in a quartz tube furnace, purge with nitrogen, and heat to 500℃ at a rate of 5℃ / min for carbonization for 1.5h. Then, heat to 900℃ and carbonize for another 1h to obtain three-dimensional porous conductive wood charcoal derived from wood charcoal.

[0042] Preparation of a mixed solution containing nickel and molybdenum sources: 1 mmol NiCl2·6H2O and 2 mmol Na2MoO4·2H2O were added to 15 mL of deionized water, stirred and dissolved, and then mixed to form a homogeneous mixed solution.

[0043] Bimetallic oxides grown on three-dimensional porous charcoal: A homogeneous mixed solution and conductive charcoal were transferred to a stainless steel autoclave with a 50 mL polytetrafluoroethylene liner, then sealed and heated at 150 °C for 12 h; after cooling to room temperature, the sample was removed, washed several times with deionized water, and then dried at 60 °C for 12 h to obtain an electrode material precursor of molybdenum nickel oxide grown on charcoal.

[0044] Preparation of charcoal-derived self-supporting integrated electrode material: Molybdenum-nickel oxide grown on charcoal electrode material precursor is placed in a tube furnace, and ammonia / argon gas mixture is introduced. The temperature is raised to 500℃ at a rate of 3℃ / min and held for 2 hours. After cooling to room temperature, the desired charcoal-derived self-supporting integrated electrode material is obtained, denoted as Ni / MoN@DWC.

[0045] Comparative Example 1

[0046] A method for preparing a lignocarbon-derived self-supporting integrated electrode material includes the following steps:

[0047] Preparation of three-dimensional porous charcoal: First, natural poplar wood was sliced ​​along its growth direction, with the slices measuring 4cm × 2cm × 0.1cm (length × width × height). The slices were then soaked in a 0.2mol / L sodium hypochlorite solution at 110℃ for 1 hour. Next, the slices were cleaned and dried overnight in a forced-air drying oven at 80℃. Finally, the dried slices were placed in a quartz tube furnace, and nitrogen gas was introduced. The temperature was increased to 500℃ at a rate of 5℃ / min for carbonization for 1.5 hours. Then, the temperature was increased to 900℃ for another 1 hour to obtain three-dimensional porous conductive charcoal derived from charcoal.

[0048] Preparation of a mixed solution containing nickel and molybdenum sources: 1 mmol NiCl2·6H2O and 2 mmol Na2MoO4·2H2O were added to 15 mL of deionized water, stirred and dissolved, and then mixed to form a homogeneous mixed solution.

[0049] Bimetallic oxides grown on three-dimensional porous charcoal: A homogeneous mixed solution and conductive charcoal were transferred to a stainless steel autoclave with a 50 mL polytetrafluoroethylene liner, then sealed and heated at 150 °C for 12 h; after cooling to room temperature, the sample was removed, washed several times with deionized water, and then dried at 60 °C for 12 h to obtain an electrode material precursor of molybdenum nickel oxide grown on charcoal.

[0050] Preparation of charcoal-derived self-supporting integrated electrode material: The electrode material precursor with molybdenum-nickel oxide grown on charcoal was placed in a tube furnace, and an ammonia / argon mixture was introduced. The temperature was raised to 500℃ at a rate of 3℃ / min and held for 2 hours. After cooling to room temperature, the desired charcoal-derived self-supporting integrated electrode material was obtained. The material was then immersed in 0.5M sulfuric acid for 1 hour, washed with pure water until neutral, and dried to obtain the sample, denoted as MoN@DWC.

[0051] Comparative Example 2

[0052] A method for preparing a lignocarbon-derived self-supporting integrated electrode material includes the following steps:

[0053] Preparation of three-dimensional porous charcoal: First, natural poplar wood was sliced ​​along its growth direction, with the slices measuring 4cm × 2cm × 0.1cm (length × width × height). The slices were then soaked in a 0.2mol / L sodium hypochlorite solution at 110℃ for 1 hour. Next, the slices were cleaned and dried overnight in a forced-air drying oven at 80℃. Finally, the dried slices were placed in a quartz tube furnace, and nitrogen gas was introduced. The temperature was increased to 500℃ at a rate of 5℃ / min for carbonization for 1.5 hours. Then, the temperature was increased to 900℃ for another 1 hour to obtain three-dimensional porous conductive charcoal derived from charcoal.

[0054] Preparation of a mixed solution containing nickel and molybdenum sources: Add 3 mmol NiCl2·6H2O to 30 mL of deionized water and stir until homogeneous.

[0055] Bimetallic oxides grown on three-dimensional porous charcoal: A homogeneous mixed solution and conductive charcoal were transferred to a stainless steel autoclave with a 50 mL polytetrafluoroethylene liner, then sealed and heated at 150 °C for 12 h; after cooling to room temperature, the sample was removed, washed several times with deionized water, and then dried at 60 °C for 12 h to obtain an electrode material precursor of molybdenum nickel oxide grown on charcoal.

[0056] Preparation of charcoal-derived self-supporting integrated electrode material: Molybdenum nickel oxide grown on charcoal electrode material precursor is placed in a tube furnace, and ammonia / argon gas mixture is introduced. The temperature is raised to 500℃ at a heating rate of 3℃ / min and held for 2 hours. After cooling to room temperature, the desired charcoal-derived self-supporting integrated electrode material is obtained, denoted as Ni@DWC.

[0057] Performance testing:

[0058] The electrode materials prepared in Examples 1, 2, 1, and 2 of this invention were characterized as follows: X-ray diffraction (XRD) was used to analyze the crystal structure and possible phase composition of the synthesized catalyst samples; field emission scanning electron microscopy (SEM) was used to observe the microstructure and morphology of the electrode materials; high-resolution transmission electron microscopy (TEM) was used to characterize the internal structure of the electrode materials; and energy-dispersive X-ray spectroscopy (EDS) was used to study the elemental composition of the electrode materials.

[0059] Depend on Figure 2 It can be seen that the relatively broad XRD diffraction peaks at 22° and 44° belong to the low curvature porous wood charcoal (DWC) framework; the XRD diffraction peaks at 32.4°, 36.6°, 49.6° and 41.7°, 45.0° belong to the (002), (200), and (202) crystal planes of MoN and the (002) and (101) crystal planes of Ni, respectively.

[0060] Figure 3 In the image, a, b, and c are SEM images along the pore growth direction; d, e, and f are SEM images perpendicular to the pore growth direction; from Figure 3 As shown in a, b, c, d, e, and f, the porous and low-curvature radial channel microstructure of the DWC framework generated by the high-temperature carbonization process after lignin removal of wood is preserved.

[0061] Figure 4 In the diagram, a, b, c, d, e, and f are SEM images of Ni / MoN@DWC in Example 2; h and i are TEM images of Ni / MoN@DWC in Example 2; and j is a selected electron diffraction pattern of Ni / MoN@DWC in Example 2.

[0062] Depend on Figure 4 As shown in a, b, and c, Ni / MoN@DWC grows uniformly on the vertical pipe surface of DWC.

[0063] Depend on Figure 4 As can be seen from d, e, and f, the Ni nanoparticles are embedded on the MoN sheets and are uniformly and densely distributed inside the DWC channel.

[0064] Depend on Figure 4As can be seen from h and i, Ni nanoparticles are embedded in the sheet-like MoN and are uniformly and densely distributed on the DWC porous framework.

[0065] Depend on Figure 4 As can be seen from the middle, Ni nanoparticles are encapsulated by highly defective MoN to form a Ni-embedded MoN heterostructure;

[0066] Depend on Figure 4 As can be seen from i, the lattice spacings of 0.271, 0.239 and 0.199 nm in Ni / MoN@DWC belong to the (002) and (121) crystal planes of MoN and the (101) crystal plane of Ni, respectively;

[0067] Depend on Figure 5 The uniform distribution of C, N, Ni, and Mo in Ni / MoN@DWC demonstrates the successful introduction and uniform distribution of Ni / MoN.

[0068] Figure 6 In the diagram, a represents the HER performance graph, and b represents the HER overpotential graph.

[0069] Depend on Figure 6 As can be seen from a, Ni / MoN@DWC exhibits the best HER activity.

[0070] Depend on Figure 6 As shown in b, Ni / MoN@DWC only requires ultra-low overpotentials of 36mV and 149mV to achieve 10mA·cm⁻¹, respectively. -2 and 100mA·cm -2 The current density is significantly higher than that of Ni@DWC(η). 10 =154mV, η 100 =404mV), MoN@DWC(η 10 =221mV, η 100 =395mV), Commercial Pt / C (η) 10 =56mV, η 100 =253mV).

[0071] Depend on Figure 7 As shown in Figure a (OER performance diagram), Ni / MoN@DWC exhibits the best OER activity.

[0072] Depend on Figure 7 As shown in the overpotential diagram (b), Ni / MoN@DWC only requires low overpotentials of 304mV and 385mV to achieve 10mA·cm⁻¹, respectively. -2 and 100mA·cm -2 The current density is higher than that of commercial RuO2 (η). 10 =318mV, η 100 =32mV).

[0073] like Figure 8 and Figure 9 ( Figure 9 As shown in (a) (anode) and (b) (cathode), the Ni / MoN@DWC two-electrode system, using two identical Ni / MoN@DW electrodes as the anode and cathode respectively, is assembled into a Ni / MoN@DWC / / Ni / MoN@DWC water electrolysis hydrogen production device. Hydrogen is produced at the cathode, and oxygen at the anode. In comparison, a Pt / C / / RuO2 water electrolysis hydrogen production device is constructed using commercial Pt / C and commercial RuO2. The Ni / MoN@DWC / / Ni / MoN@DWC water electrolysis hydrogen production device requires only 1.56 and 1.70 V to obtain 10 and 50 mA·cm⁻¹, respectively. -2 The electrolysis current density of the Ni / MoN@DWC / / RuO2 water electrolysis hydrogen production device is 1.59V and 1.79V respectively, while the Pt / C / / RuO2 water electrolysis hydrogen production device requires 1.59V and 1.79V to obtain the same current density; b is a comparison of the stability of water electrolysis, with the Ni / MoN@DWC water electrolysis hydrogen production device at 10mA·cm -2 After operating stably for 35 hours at a current density of [value missing], it can still maintain 94% of the current density.

[0074] Depend on Figure 10 It can be seen that at 10mA·cm -2 Continuous operation for 100 hours or 100 mA·cm at current density -2 After continuous operation at a current density of 1000 rpm for 40 hours, the Ni / MoN@DWC electrolysis of water for hydrogen production showed no significant decrease in current density, demonstrating excellent stability.

[0075] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a self-supporting integrated electrode material derived from lignocarbon, characterized in that, Includes the following steps: S1. Poplar wood is sliced ​​along its perpendicular growth direction and then subjected to a delignification treatment. The delignification treatment involves placing the poplar wood slices at a temperature of 80-120℃ and a concentration of 0.1-0.5%. The process involves treating the material in a sodium hypochlorite aqueous solution at a concentration of mol / L; then carbonizing it under a protective atmosphere to obtain three-dimensional porous wood charcoal derived from wood charcoal; S2, dispersing the nickel and molybdenum sources separately in a solvent and stirring until fully dissolved; then mixing the two to obtain a mixed solution; S3, transferring the three-dimensional porous wood charcoal obtained in step S1 and the mixed solution obtained in step S2 together to a high-pressure reactor for reaction, cooling to room temperature after the reaction is complete, washing with deionized water, and drying with forced air to obtain an electrode material precursor of molybdenum-nickel oxide grown on wood charcoal; S4, placing the electrode material precursor obtained in step S3 in a tube furnace and reducing it at high temperature in a mixed atmosphere containing ammonia to obtain a self-supporting integrated electrode material Ni / MoN@DWC derived from wood charcoal. The electrode material has a heterostructure in which nickel nanoparticles are embedded in molybdenum nitride nanosheets, and this heterostructure is grown in situ on the three-dimensional porous wood charcoal; the mixed atmosphere containing ammonia is a mixture of ammonia and nitrogen or a mixture of ammonia and argon.

2. The method for preparing the lignocarbon-derived self-supporting integrated electrode material according to claim 1, characterized in that, In S1, the length of the poplar slice Width The height is 2~6 cm × 1~3 cm × 0.1~0.3 cm.

3. The method for preparing the lignocarbon-derived self-supporting integrated electrode material according to claim 1, characterized in that, In S1, the protective atmosphere is either Ar2 or N2; the flow rate of the protective atmosphere is 30–120 mL / min.

4. The method for preparing the lignocarbon-derived self-supporting integrated electrode material according to claim 1, characterized in that, In S1, the carbonization temperature is 300–1000°C, the heating rate is 1–20°C / min, and the carbonization time is 1–15 h.

5. The method for preparing the lignocarbon-derived self-supporting integrated electrode material according to claim 1, characterized in that, In S2, the nickel source is one of sulfate, oxalate, nitrate, halide, acetate, or acetylacetone salt; the molybdenum source is molybdate; and the concentration of the nickel source in the solvent is: 0.01 mol / L ~ 0.05 mol / L; the concentration of the molybdenum source in the solvent is: 0.01mol / L ~0.15mol / L.

6. The method for preparing the lignocarbon-derived self-supporting integrated electrode material according to claim 1, characterized in that, In S2, the molar ratio of the added nickel source to the molar source is 1:0.1 to 3.

7. The method for preparing the lignocarbon-derived self-supporting integrated electrode material according to claim 1, characterized in that, In S3, the reaction temperature in the high-pressure reactor is 120–200°C, and the reaction time is 1–36 h.

8. The method for preparing the lignocarbon-derived self-supporting integrated electrode material according to claim 1, characterized in that, In S4, the reaction temperature in the tubular furnace is 200~700℃, the reaction time is 0.5~5h, and the flow rate is 30~120 mL / min.

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