Preparation method and application of a Mo-doped Cu2S / Ni3S2 / NF composite material with a heterostructure

Abstract

The application discloses a preparation method and application of a Mo-doped Cu2S / Ni3S2 / NF composite material with a heterostructure, and comprises the following steps: pretreatment of NF, hydrothermal preparation of a Mo-doped Ni3S2 / NF precursor, electrodeposition preparation of a Mo-doped CuNi3S2 / NF precursor, and in-situ conversion preparation of a Mo-doped Cu2S / Ni3S2 / NF. The Mo-doped Cu2S / Ni3S2 / NF prepared by the application adjusts the electronic structure by preparing a bimetallic compound to construct a heterostructure; the Mo doping further strengthens the interface bonding, brings faster charge transfer and smaller interface resistance, and further improves the SOR and HER electrocatalytic activity. The application solves the problems of poor HER performance of a copper-based electrocatalyst, easy sulfur poisoning and passivation of a past SOR and HER dual-function electrocatalyst, and provides a more attractive, fast-response, cost-effective, eco-friendly and easy-to-operate road for the recovery of sulfur-containing wastewater.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalysis, and particularly relates to a preparation method and application of a Mo-doped Cu2S / Ni3S2 / NF composite material with a heterostructure. BACKGROUND

[0002] Hydrogen energy, as the most ideal clean energy, has the advantages of high heat value, no pollution, and renewability, and is the most promising alternative energy to fossil fuels. Electrochemical water splitting for hydrogen production, as the dominant technology for hydrogen production, has the advantages of environmental protection and sustainability. However, the anode oxygen evolution reaction (OER) is complex and slow, resulting in high overall water splitting driving voltage and low hydrogen production efficiency. Therefore, it is an urgent need to seek a thermodynamically favorable anode reaction to replace OER to improve the efficiency of hydrogen production. Extraction of H2 from industrial waste is considered to have double advantages, which not only realizes purification and recycling of chemical hazardous waste, but also produces valuable energy raw materials. Specifically, S 2- As a raw material to realize electrocatalytic SOR, it has the following advantages: (1) low oxidation potential and fast kinetics; (2) replacing OER coupled with HER to realize efficient hydrogen production; (3) effectively purifying sulfur-containing wastewater to realize recycling of sulfur resources. Therefore, SOR coupled with HER will become an attractive method for efficient hydrogen production and simultaneous recovery of sulfur-containing wastewater.

[0003] As the core of the SOR and HER coupling system, the design and preparation of electrocatalysts are particularly important. In recent years, copper-based materials have become a hot material for SOR due to their wide range of redox properties and high electrical conductivity. According to the hard-soft acid-base (HSAB) theory, the lattice Cu(I) in the Cu2S electrode is a soft Lewis acid site. In the electrolyte, it is more advantageous to combine with HS - of soft base than other hard acid or edge acid sites. This provides an opportunity for copper catalysts to enhance the adsorption of sulfide ions, further promoting the kinetics of SOR.

[0004] Based on this, researchers further explored the performance improvement of Cu-based electrocatalysts. For example, Pei et al. reported a foam nickel supported bifunctional Cu2S microflake catalyst for catalyzing SOR assisted electrochemical water splitting. The foam nickel, as a conductive substrate, exposes more active edge sites of the catalyst surface to promote mass transfer and electron transfer. However, its HER performance is not satisfactory, and further improvement is needed to realize the coupling application of bifunctional catalysts (DOI: 10.1039 / d1gc01857d). Zhang et al. reported a snowflake-like Pt-Cu2S / MoS2 heterostructure with different compositions for efficient electrocatalytic hydrogen evolution. The heterostructure strengthens the electron interaction and adjusts the electronic structure to improve the intrinsic catalytic activity. However, this method involves the participation of noble metal Pt, which is not economically beneficial and is not conducive to practical application (DOI: 10.1016 / j.apcatb.2022.121540). Wang et al. prepared nitrogen-doped Cu2S / MoS2 heterojunction nanorod arrays on foam copper. By incorporating heteroatoms, the electronic structure of the active sites was improved, but the electrocatalytic activity in alkaline medium decayed to some extent, which could not maintain long-term stability during the reaction process (DOI: 10.1002 / cctc.201801819). In addition, the SOR process is often subject to electrode surface passivation and electrode sulfur poisoning corrosion, which greatly reduces the activity and stability of the electrocatalyst during the reaction process, limiting the widespread application of this technology. As can be seen, the existing SOR and HER bifunctional catalyst design and synthesis have the following problems:

[0005] (1) Due to the relatively weak hydrogen adsorption ability of copper-based catalysts, the reaction energy barrier limits the HER activity, making it difficult to achieve bifunctional effect, and the electrocatalytic activity decays to some extent during long-term operation;

[0006] (2) The traditional hydrothermal preparation method of copper-based catalysts has the disadvantages of difficult control of grain size, influence of local supersaturation on crystallinity, and difficulty in controlling reaction conditions, which restricts the exposure of active sites and is not conducive to mass transfer and electron transfer;

[0007] (3) The surface of the electrocatalyst is passivated and corroded by sulfur poisoning, and the S8 product covers the active sites, which significantly reduces the activity and stability of the electrocatalyst during the reaction process, limiting the widespread application of this technology. SUMMARY

[0008] The purpose of this section is to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0009] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0010] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art, and provide a preparation method of a Mo-doped Cu2S / Ni3S2 / NF composite material with a heterostructure.

[0011] To solve the above technical problems, the present application provides the following technical scheme: a preparation method of a Mo-doped Cu2S / Ni3S2 / NF composite material with a heterostructure, comprising,

[0012] C2H5NS and Na2MoO4·2H2O are uniformly dispersed in deionized water, and the obtained reaction solution and the foam nickel NF with the surface oxide layer removed are transferred together into a high-pressure reaction kettle, and Mo-Ni3S2 / NF precursor is obtained through hydrothermal reaction;

[0013] A standard three-electrode system is used, the Mo-Ni3S2 / NF precursor is used as the working electrode in the deposition solution, platinum wire is used as the counter electrode, and Ag / AgCl is used as the reference electrode, Cu is deposited on the surface of the Mo-Ni3S2, and the composite electrode obtained after deposition is washed and dried to obtain Mo-CuNi3S2 / NF;

[0014] Na2S·9H2O is uniformly dispersed in deionized water to obtain a sodium sulfide solution;

[0015] The sodium sulfide solution and the Mo-CuNi3S2 / NF are transferred together into a high-pressure reaction kettle, and Mo-Cu2S / Ni3S2 / NF composite material is obtained through hydrothermal reaction.

[0016] As a preferred scheme of the preparation method of the present application, wherein: the foam nickel NF with the surface oxide layer removed, the preparation method thereof comprises,

[0017] The foam nickel NF is cut to a size of 1.5*1.0*0.1 cm, ultrasonic is applied in 2-5M dilute hydrochloric acid for 20-40 min, then it is washed with deionized water and anhydrous ethanol for 2-4 times, and dried in a 40-70℃ oven for 2h-4h for standby use.

[0018] As a preferred scheme of the preparation method of the present application, wherein: the preparation method of the Mo-Ni3S2 / NF precursor comprises,

[0019] C2H5NS and Na2MoO4·2H2O with a molar ratio of 3:1-5:1 are added into 15-20mL deionized water, and ultrasonic is applied for 10-20min;

[0020] The uniformly dispersed reaction liquid and the pretreated NF are placed in a 100mL stainless steel reaction kettle, and hydrothermal reaction is carried out at 180-220 DEG C for 18-22h, and then the reaction is naturally cooled to room temperature;

[0021] The catalyst sample is taken out, washed with deionized water and anhydrous ethanol for 2-3 times, and dried at 40-70 DEG C.

[0022] As a preferred scheme of the preparation method, the Mo-Ni3S2 / NF precursor is used as the working electrode in the deposition solution, and the deposition solution is a mixed solution of copper chloride and dilute nitric acid.

[0023] As a preferred scheme of the preparation method, the molar ratio of copper chloride and dilute nitric acid in the mixed solution is 1:1-1:3.

[0024] As a preferred scheme of the preparation method, the Cu is deposited on the surface of the Mo-Ni3S2, and the deposition parameters are as follows: working current 0.05-0.15A, working time 400-700s, and cycle 1-2 times.

[0025] As a preferred scheme of the preparation method, the Mo-Cu2S / Ni3S2 / NF composite material is prepared by the following method, which comprises the following steps:

[0026] As a preferred scheme of the preparation method, the Mo-Cu2S / Ni3S2 / NF composite material is prepared by the following method, which comprises the following steps:

[0027] 22.0-25.0mmol of Na2S·9H2O is uniformly dispersed in 20-40mL of deionized water, and the obtained sodium sulfide solution and the Mo-CuNi3S2 / NF are transferred into a stainless steel high-pressure reaction kettle, and hydrothermal reaction is carried out at 80-120 DEG C for 8-12h.

[0028] After the reaction is completed, the reaction is naturally cooled to room temperature, the catalyst sample is taken out, washed with water and anhydrous ethanol for 2-3 times, the residual sodium sulfide on the surface is removed, and the catalyst is dried at 40-70 DEG C overnight.

[0029] Another object of the present application is to overcome the deficiencies in the prior art and provide a preparation method of a Mo-doped Cu2S / Ni3S2 / NF composite material with a heterostructure.

[0030] Another object of the present application is to overcome the deficiencies in the prior art and provide a preparation method of a Mo-doped Cu2S / Ni3S2 / NF composite material with a heterostructure.

[0031] The present application has the following beneficial effects:

[0032] (1) This invention uses a hydrothermal method to introduce Mo, thereby altering the electronic structure and active sites on the surface of metal atoms, wherein S 2- As electron acceptors, Cu and Ni transfer electrons through the interface, promoting electron transfer on the surface of metal atoms, resulting in faster charge transfer and lower interfacial resistance, reducing the energy barrier of intermediate reaction steps, and effectively improving the electrocatalytic activity of SOR and HER.

[0033] (2) This invention utilizes the tunability of electrodeposition to dynamically reconstruct and achieve the coating of Mo-Ni2S3 nanosheets, constructing a nanorod array. This structural change helps increase the specific surface area of ​​the catalyst. A high specific surface area can increase the density of active centers, providing a more convenient diffusion path and improving the electron transfer and ion diffusion rates. Furthermore, this strategy also constructs a heterostructure between Cu2S and Ni3S2, strengthening interfacial electronic interactions and effectively promoting the adsorption of water by the catalyst. This not only improves the formation of H+, but also... ads The Volmer step, and can also improve the SH ads The Heyrovsky step, which transfers the catalyst to H2, further enhances its HER performance.

[0034] (3) Mo-doped Cu2S / Ni3S2 / NF composite materials can replace traditional OERs in novel assisted water splitting systems. By coupling the extraction of valuable sulfur resources with efficient hydrogen production, the electrochemical decomposition of sulfur-containing compounds can be achieved without the need for additional oxidants and complex separation. 2- Wastewater treatment yields economic benefits while simultaneously restoring the environment. In a two-electrode SOR||HER coupling system, 100 mA m -2 At the specified current density, the required applied voltage is 0.693V, far lower than the voltage required for overall water splitting (2.163V), reducing energy consumption by 68.0%. The Faraday efficiency of hydrogen production reaches 98%, and the system produces 75.56mL of H2 within 100min. The hydrogen production is in good agreement with the theoretical calculations, and the hydrogen production rate reaches 0.76mL / min. -1 . Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0036] Figure 1 A schematic diagram of the preparation process of Mo-doped Cu2S / Ni3S2 / NF;

[0037] Figure 2 XRD patterns of Mo-doped Cu2S / Ni3S2 / NF, Mo-doped Ni3S2 / NF and Cu2S / Ni3S2 / NF;

[0038] Figure 3 SEM and TEM images of Mo-doped Cu2S / Ni3S2 / NF;

[0039] Figure 4 Electrochemical performance diagrams of Mo-doped Cu2S / Ni3S2 / NF and example catalysts;

[0040] Figure 5 LSV curve diagrams of SOR||HER and OER||HER coupling systems based on Mo-doped Cu2S / Ni3S2 / NF electrodes;

[0041] Figure 6 Hydrogen production and faradic efficiency diagrams of SOR||HER systems based on Mo-doped Cu2S / Ni3S2 / NF electrodes. DETAILED DESCRIPTION

[0042] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the embodiments of the present application.

[0043] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the concept of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0044] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an independent or alternative embodiment that excludes other embodiments.

[0045] Two-electrode SOR||HER coupling system performance test in the embodiments of the present application: using CHI 660E electrochemical workstation, taking the prepared electrocatalyst as two working electrodes in an H-type electrolytic cell, cathode electrolyte 1M NaOH, and anode electrolyte 1.0M NaOH+1.0M Na2S;

[0046] In the electrolytic cell with a scan rate of 5mV·s -1 The voltammetric linear curve (LSV) of the two-electrode SOR||HER coupling system was obtained with 90% resistance compensation.

[0047] The comparative material prepared in the embodiment is characterized and analyzed using an X-ray diffractometer, a scanning electron microscope and a transmission electron microscope.

[0048] Example 1

[0049] The embodiment provides a preparation method of Mo-doped Cu2S / Ni3S2 / NF, and main steps are as follows:

[0050] (1) Pretreatment of the foam nickel: first, the foam nickel is cut into a size of 1.5*1.0*0.1 cm, then the cut foam nickel is ultrasonically treated in 3M dilute hydrochloric acid for 30 min to remove the surface oxide layer, and finally the foam nickel is repeatedly washed with deionized water and anhydrous ethanol to remove the dilute hydrochloric acid on the surface, and is dried at 60 DEG C after washing to be ready for use.

[0051] (2) Preparation of Mo-Ni3S2 / NF: 0.90 mmol C2H5NS and 0.20 Na2MoO4*2H2O are uniformly dispersed in 16 mL deionized water, the obtained reaction solution and the pretreated NF are placed in a 100 mL stainless steel reactor, and hydrothermal reaction is carried out at 200 DEG C for 21 h, the catalyst sample is taken out after the reaction is completed, and is washed with deionized water and anhydrous ethanol for 2-3 times, and is dried at 60 DEG C to obtain Mo-Ni3S2 / NF.

[0052] (3) Preparation of Mo-CuNi3S2 / NF:

[0053] First, a mixed solution of CuCl2 (0.5M) and HNO3 (1M) is prepared, and is magnetically stirred for 10 min;

[0054] In a standard three-electrode system, the mixed solution of copper chloride and dilute nitric acid is used as a deposition solution, Mo-Ni3S2 / NF is used as a working electrode, a platinum wire is used as a counter electrode, and Ag / AgCl is used as a reference electrode, and Cu is deposited on the surface of Mo-Ni3S2 by using a multi-step current method (ISTEP);

[0055] In the method, the working current is 0.1 A, the working time is 600 s, and the cycle is 1 time; and the composite electrode obtained after the deposition is repeatedly washed with deionized water and anhydrous ethanol for 2-3 times, and is dried at 60 DEG C to obtain Mo-CuNi3S2 / NF.

[0056] (4) Preparation of Mo-Cu2S / Ni3S2 / NF: Na2S·9H2O (5.6 g, 23.0 mmol) was uniformly dispersed in 30 mL of deionized water, and the sodium sulfide solution was transferred into a 100 mL stainless steel autoclave together with the Mo-CuNi3S2 / NF. The hydrothermal reaction was carried out at 100 °C for 10 h. After the reaction, the catalyst sample was taken out, washed with water and anhydrous ethanol for 2-3 times to remove the residual sodium sulfide on the surface, and dried at 60 °C to obtain the Mo-Cu2S / Ni3S2 / NF catalyst sample.

[0057] As shown in FIGS. 1a and 1b, Mo-doped Cu2S / Ni3S2 / NF was synthesized on the foam nickel substrate by a three-step method: first, Mo-doped Ni3S2 was grown on the surface of NF by a simple hydrothermal process; then, Mo-Ni3S2 / NF was dynamically restructured at the potential of the electro-reduction in an acidic electrolyte to obtain Mo-CuNi3S2 / NF; finally, Mo-CuNi3S2 / NF was sulfidized with sodium sulfide as the sulfur source to obtain Mo-doped Cu2S / Ni3S2 / NF. Figure 1 As shown in FIGS. 1a and 1b, Mo-doped Cu2S / Ni3S2 / NF was synthesized on the foam nickel substrate by a three-step method: first, Mo-doped Ni3S2 was grown on the surface of NF by a simple hydrothermal process; then, Mo-Ni3S2 / NF was dynamically restructured at the potential of the electro-reduction in an acidic electrolyte to obtain Mo-CuNi3S2 / NF; finally, Mo-CuNi3S2 / NF was sulfidized with sodium sulfide as the sulfur source to obtain Mo-doped Cu2S / Ni3S2 / NF.

[0058] As shown in FIGS. 1a and 1b, Mo-doped Cu2S / Ni3S2 / NF was synthesized on the foam nickel substrate by a three-step method: first, Mo-doped Ni3S2 was grown on the surface of NF by a simple hydrothermal process; then, Mo-Ni3S2 / NF was dynamically restructured at the potential of the electro-reduction in an acidic electrolyte to obtain Mo-CuNi3S2 / NF; finally, Mo-CuNi3S2 / NF was sulfidized with sodium sulfide as the sulfur source to obtain Mo-doped Cu2S / Ni3S2 / NF. Figure 2 As shown in FIGS. 1a and 1b, Mo-doped Cu2S / Ni3S2 / NF was synthesized on the foam nickel substrate by a three-step method: first, Mo-doped Ni3S2 was grown on the surface of NF by a simple hydrothermal process; then, Mo-Ni3S2 / NF was dynamically restructured at the potential of the electro-reduction in an acidic electrolyte to obtain Mo-CuNi3S2 / NF; finally, Mo-CuNi3S2 / NF was sulfidized with sodium sulfide as the sulfur source to obtain Mo-doped Cu2S / Ni3S2 / NF. x As shown in FIGS. 1a and 1b, Mo-doped Cu2S / Ni3S2 / NF was synthesized on the foam nickel substrate by a three-step method: first, Mo-doped Ni3S2 was grown on the surface of NF by a simple hydrothermal process; then, Mo-Ni3S2 / NF was dynamically restructured at the potential of the electro-reduction in an acidic electrolyte to obtain Mo-CuNi3S2 / NF; finally, Mo-CuNi3S2 / NF was sulfidized with sodium sulfide as the sulfur source to obtain Mo-doped Cu2S / Ni3S2 / NF.

[0059] As shown in FIGS. 1a and 1b, Mo-doped Cu2S / Ni3S2 / NF was synthesized on the foam nickel substrate by a three-step method: first, Mo-doped Ni3S2 was grown on the surface of NF by a simple hydrothermal process; then, Mo-Ni3S2 / NF was dynamically restructured at the potential of the electro-reduction in an acidic electrolyte to obtain Mo-CuNi3S2 / NF; finally, Mo-CuNi3S2 / NF was sulfidized with sodium sulfide as the sulfur source to obtain Mo-doped Cu2S / Ni3S2 / NF. Figure 3 As shown in FIGS. 1a and 1b, Mo-doped Cu2S / Ni3S2 / NF was synthesized on the foam nickel substrate by a three-step method: first, Mo-doped Ni3S2 was grown on the surface of NF by a simple hydrothermal process; then, Mo-Ni3S2 / NF was dynamically restructured at the potential of the electro-reduction in an acidic electrolyte to obtain Mo-CuNi3S2 / NF; finally, Mo-CuNi3S2 / NF was sulfidized with sodium sulfide as the sulfur source to obtain Mo-doped Cu2S / Ni3S2 / NF. Figure 3 As shown in FIGS. 1a and 1b, Mo-doped Cu2S / Ni3S2 / NF was synthesized on the foam nickel substrate by a three-step method: first, Mo-doped Ni3S2 was grown on the surface of NF by a simple hydrothermal process; then, Mo-Ni3S2 / NF was dynamically restructured at the potential of the electro-reduction in an acidic electrolyte to obtain Mo-CuNi3S2 / NF; finally, Mo-CuNi3S2 / NF was sulfidized with sodium sulfide as the sulfur source to obtain Mo-doped Cu2S / Ni3S2 / NF. Figure 3 As shown in FIGS. 1a and 1b, Mo-doped Cu2S / Ni3S2 / NF was synthesized on the foam nickel substrate by a three-step method: first, Mo-doped Ni3S2 was grown on the surface of NF by a simple hydrothermal process; then, Mo-Ni3S2 / NF was dynamically restructured at the potential of the electro-reduction in an acidic electrolyte to obtain Mo-CuNi3S2 / NF; finally, Mo-CuNi3S2 / NF was sulfidized with sodium sulfide as the sulfur source to obtain Mo-doped Cu2S / Ni3S2 / NF.

[0060] As Figure 4 a and 4b, at 30 mA cm -2 The overpotential of the Mo-doped Cu2S / Ni3S2 / NF catalyst for SOR was 0.268 V, and the overpotential for catalyzing HER was 0.149 V at a current density of 30 mA cm

[0061] Example 2

[0062] The CHI 660E electrochemical workstation was used, and the electrocatalyst prepared in Example 1 was used as the two working electrodes in the H-type electrolytic cell. The cathode electrolyte was 1M NaOH, and the anode electrolyte was 1.0M NaOH + 1.0M Na2S. The electrolytic cell was operated at a scan rate of 5mV·s -1

[0063] The hydrogen produced in the cathode of the two-electrode coupled system electrolytic cell was collected by the drainage method, and the hydrogen production was recorded every 10 minutes. The relationship between hydrogen production and system operation time within 100 minutes of system operation time was obtained.

[0064] The experimental results are shown in Figure 6 It can be seen that the Faraday efficiency of hydrogen is 98%, the system produces 75.56mL H2 within 100 minutes, and the hydrogen production rate is 0.76mL min -1 .

[0065] Comparative Example 1

[0066] This comparative example provides a preparation method of Ni3S2 / NF, and the main steps are as follows:

[0067] (1) Pretreatment of foamed nickel: first, cut the foamed nickel into a size of 1.5×1.0×0.1cm, then ultrasonically treat the cut foamed nickel in 3M dilute hydrochloric acid for 30min to remove the surface oxide layer, and finally rinse the surface with deionized water and anhydrous ethanol to remove the dilute hydrochloric acid. After rinsing, dry at 60℃ for standby use.

[0068] (2) Hydrothermal preparation of Ni3S2 / NF: accurately weigh 0.90mmol C2H5NS and disperse in 16mL deionized water, magnetically stir for 10min, and then place the obtained reaction solution and pretreated NF in a 100mL stainless steel reaction kettle. Hydrothermal reaction at 200℃ for 21h, and then naturally cool to room temperature. Take out the catalyst sample, rinse with deionized water and anhydrous ethanol for 2-3 times, and dry at 60℃ to obtain Ni3S2 / NF.

[0069] As Figure 4 a and 4b, at 30 mA cm -2 ​The overpotential of the SOR catalyzed by the Mo-doped Ni3S2 / NF was 0.454 V at a current density of 30 mA cm-2, and the overpotential of the HER catalyzed by the Mo-doped Ni3S2 / NF was -0.208 V. The electrochemical performance of the Mo-doped Ni3S2 / NF was better than that of the Ni3S2 / NF, because the incorporation of Mo adjusted the surface electronic structure of the metal atoms and optimized the electrochemical surface active sites.

[0070] Comparative Example 2

[0071] The present comparative example provides a preparation method of Mo-doped Ni3S2 / NF, and the main steps are as follows:

[0072] (1) Pretreatment of the foamed nickel: first, the foamed nickel was cut into a size of 1.5 x 1.0 x 0.1 cm, then the cut foamed nickel was ultrasonically treated in 3M dilute hydrochloric acid for 30 min to remove the surface oxide layer, and finally the foamed nickel was repeatedly washed with deionized water and anhydrous ethanol to remove the dilute hydrochloric acid on the surface. After washing, the foamed nickel was dried at 60°C for standby use.

[0073] (2) Hydrothermal preparation of Mo-doped Ni3S2 / NF: 0.90 mmol of C2H5NS and 0.20 mmol of Na2MoO4·2H2O were uniformly dispersed in 16 mL of deionized water, and the obtained reaction solution and the pretreated foamed nickel were placed in a 100 mL stainless steel reaction kettle. The reaction was carried out at 200°C for 21 h, and then the reaction was naturally cooled to room temperature. The catalyst sample was taken out and washed with deionized water and anhydrous ethanol for 2-3 times, and then dried at 60°C to obtain Mo-Ni3S2 / NF.

[0074] As shown in FIGS. 4a and 4b, the Mo-doped Ni3S2 / NF had a 110 crystal plane of Ni3S. Figure 2

[0075] As shown in FIGS. 4a and 4b, the Mo-doped Ni3S2 / NF had a 110 crystal plane of Ni3S. Figure 4 a and 4b, the Mo-doped Ni3S2 / NF had a 110 crystal plane of Ni3S. -2 The overpotential of the SOR catalyzed by the Mo-doped Ni3S2 / NF was 0.454 V at a current density of 30 mA cm-2, and the overpotential of the HER catalyzed by the Mo-doped Ni3S2 / NF was -0.208 V. The electrochemical performance of the Mo-doped Ni3S2 / NF was better than that of the Ni3S2 / NF, because the incorporation of Mo adjusted the surface electronic structure of the metal atoms and optimized the electrochemical surface active sites.

[0076] Comparative Example 3

[0077] The present comparative example provides a preparation method of Cu2S / Ni3S2 / NF, and the main steps are as follows:

[0078] (1) Pretreatment of the foamed nickel: first, the foamed nickel was cut into a size of 1.5 x 1.0 x 0.1 cm, then the cut foamed nickel was ultrasonically treated in 3M dilute hydrochloric acid for 30 min to remove the surface oxide layer, and finally the foamed nickel was repeatedly washed with deionized water and anhydrous ethanol to remove the dilute hydrochloric acid on the surface. After washing, the foamed nickel was dried at 60°C for standby use.

[0079] ​(2) Preparation of CuNi / NF precursor: A mixed solution of copper chloride (0.5M) and nitric acid (1M) was used as the deposition solution. A standard three-electrode system was employed, with pretreated NF as the working electrode, Pt wire as the counter electrode, and Ag / AgCl as the reference electrode. Cu was deposited onto the NF surface using the ISTEP method. The experimental parameters were as follows: working current 0.1A, working time 600s, and one cycle. After deposition, the resulting composite electrode was repeatedly rinsed 2-3 times with deionized water and anhydrous ethanol, and then dried at 60℃ to obtain the CuNi / NF precursor.

[0080] (3) Preparation of Cu2S / Ni3S2 / NF: 23 mmol of Na2S·9H2O was dispersed in 30 mL of deionized water and magnetically stirred for 30 min. The sodium sulfide solution and the above CuNi / NF precursor were transferred to a 100 mL stainless steel high-pressure reactor and hydrothermally reacted at 100 °C for 10 h. After the reaction was completed, the catalyst sample was naturally cooled to room temperature. The catalyst sample was taken out and washed 2 to 3 times with water and anhydrous ethanol to remove residual sodium sulfide on the surface. The sample was dried at 60 °C to obtain the Cu2S / Ni3S2 / NF catalyst sample.

[0081] like Figure 2 Cu2S / Ni3S2 / NF has the 139 and 341 crystal planes of Cu2S and the weaker 110 crystal plane of Ni3S2.

[0082] like Figure 3 b, Cu2S / Ni3S2 / NF exhibits a nanosheet structure.

[0083] like Figure 4 a and 4b, at 30mA cm -2 At the specified current density, the overpotential for Cu2S / Ni3S2 / NF catalyzing SOR was 0.287V, and the overpotential for HER catalysis was -0.203V. Its performance is significantly better than that of Ni3S2 / NF prepared in Example 1. This is because the heterostructure between Cu2S and Ni3S2 constructed using an electrodeposition combined with a bimetallic strategy enhances interfacial electronic interactions, contributing to the optimization of its electrocatalytic performance.

[0084] Example 1 showed significantly better HER and SOR performance than Comparative Examples 1, 2, and 3, demonstrating that the synergistic effect of the Mo doping strategy and the electrodeposition preparation of bimetallic heterostructures further enhances the performance of the electrocatalyst.

[0085] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced, without departing from the spirit and scope of the present application, which should be covered in the scope of the present application.

Claims

1. A method for preparing a Mo-doped Cu₂S / Ni₃S₂ / NF composite material with a heterostructure, characterized in that: comprising, C2H5NS and Na2MoO4·2H2O are uniformly dispersed in deionized water, and the obtained reaction solution and the foam nickel NF with the surface oxide layer removed are transferred into a high-pressure reaction kettle together, and Mo-Ni3S2 / NF precursor is obtained through hydrothermal reaction; A standard three-electrode system is adopted, the Mo-Ni3S2 / NF precursor is used as a working electrode, a platinum wire is used as a counter electrode, Ag / AgCl is used as a reference electrode, a deposition solution is a mixed solution of copper chloride and dilute nitric acid, the molar ratio of copper chloride to dilute nitric acid in the mixed solution is 1:1-1:3, and the deposition parameters are as follows: a working current is 0.05-0.15 A, a working time is 400-700 s, and the cycle is 1-2 times, Cu is deposited on the surface of Mo-Ni3S2, and the composite electrode obtained after the deposition is finished is washed and dried to obtain Mo-CuNi3S2 / NF. Na2S·9H2O is uniformly dispersed in deionized water to obtain a sodium sulfide solution; The sodium sulfide solution and the Mo-CuNi3S2 / NF are transferred into a high-pressure reaction kettle together, and Mo-Cu2S / Ni3S2 / NF composite material is obtained through hydrothermal reaction.

2. The production method according to claim 1, characterized by: The preparation method of the foam nickel NF with the surface oxide layer removed comprises the following steps: The foam nickel NF is cut to a size of 1.5*1.0*0.1 cm, is ultrasonically treated in 2-5 M dilute hydrochloric acid for 20-40 min, is washed with deionized water and anhydrous ethanol for 2-4 times, is dried in an oven at 40-70 DEG C for 2-4 h, and is prepared.

3. The production method according to claim 1 or 2, characterized by: The preparation method of the Mo-Ni3S2 / NF precursor comprises the following steps: C2H5NS and Na2MoO4·2H2O with a molar ratio of 3:1-5:1 are added into 15-20 mL deionized water, and are ultrasonically treated for 10-20 min; The uniformly dispersed reaction solution and the pretreated NF are placed in a 100 mL stainless steel reaction kettle, and hydrothermal reaction is carried out at 180-220 DEG C for 18-22 h, and the catalyst sample is taken out after the reaction is completed, is washed with deionized water and anhydrous ethanol for 2-3 times, and is dried at 40-70 DEG C.

4. The production method according to claim 1, wherein: The preparation method of the Mo-Cu2S / Ni3S2 / NF composite material comprises the following steps: 22.0-25.0 mmol Na2S·9H2O is uniformly dispersed in 20-40 mL deionized water, the obtained sodium sulfide solution and the Mo-CuNi3S2 / NF are transferred into a stainless steel high-pressure reaction kettle, and hydrothermal reaction is carried out at 80-120 DEG C for 8-12 h; The catalyst sample is taken out after the reaction is completed, is washed with water and anhydrous ethanol for 2-3 times, the residual sodium sulfide on the surface is removed, and the sample is dried at 40-70 DEG C overnight.

5. The Mo-doped Cu2S / Ni3S2 / NF composite material with a heterostructure prepared by the preparation method in any one of claims 1-4.

6. Application of the Mo-doped Cu2S / Ni3S2 / NF composite material with a heterostructure in claim 5 in a synchronous hydrogen evolution and sulfur-containing wastewater purification coupling system as a dual-functional electrocatalyst.

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