A titanium electrode material with high catalytic activity, a preparation method and application thereof

Abstract

The application provides a high-catalytic-activity titanium electrode material and a preparation method and application thereof, and belongs to the field of electrochemical materials. The method comprises the following steps: pretreating a titanium base to form a microscopically rough surface; depositing a Ni-Co-Mo transition metal alloy layer; phosphorizing treatment in a phosphorus source-containing atmosphere to convert into a crystalline phosphide heterojunction structure containing a Ni5P4 phase, a NiCoP phase and a Mo component; then, surface sulfur treatment in a sulfur-containing atmosphere to form an outer amorphous sulfur-containing layer and a sulfur gradient distribution from the surface to the inside; and finally, tempering and stabilizing treatment at a temperature lower than the sulfur treatment temperature. The application realizes the synergistic improvement of the catalytic activity and structural stability of the titanium electrode material by constructing an inner high-activity crystalline heterojunction, an outer defect-rich amorphous sulfur-containing layer and a sulfur element gradient distribution, and supplementing with low-temperature tempering and stabilizing treatment.

Description

Technical Field

[0001] This application relates to the field of electrochemical materials technology, and in particular to a highly catalytically active titanium electrode material, its preparation method, and its application. Background Technology

[0002] Electrolysis of water is a clean and sustainable method for hydrogen production, and electrode materials are a key factor determining the efficiency and cost of hydrogen production. Titanium-based electrodes are widely used as matrix materials for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in water electrolysis due to their good conductivity, excellent corrosion resistance, and relatively low cost. To enhance the catalytic activity of titanium electrodes, noble metals (such as Pt and IrO2) or transition metal-based compounds (such as phosphides, sulfides, and selenides) are typically loaded onto their surface to reduce overpotential and increase current density. However, an ideal titanium electrode not only needs high intrinsic catalytic activity but also needs to maintain structural integrity and performance stability during long-term electrolysis.

[0003] Existing titanium electrode materials still suffer from significant drawbacks: single-component catalytic coatings have limited active sites and are prone to surface passivation or active phase dissolution under high current densities, leading to rapid catalytic efficiency degradation; while multilayer coatings or heterostructures can enhance activity, differences in thermal expansion coefficients and lattice matching between layers can easily generate internal stress, resulting in coating peeling and cracking during long-term operation or start-stop cycles. Furthermore, many highly active amorphous or nanostructures undergo structural reconstruction or phase transitions in the electrolysis environment, further exacerbating deactivation. Therefore, how to simultaneously improve the electrocatalytic activity and long-term stability of titanium electrode materials has become a pressing technical challenge in the field of water electrolysis for hydrogen production. Summary of the Invention

[0004] This application provides a highly catalytically active titanium electrode material, its preparation method, and its application, in order to solve the following technical problem: how to simultaneously improve the electrocatalytic activity and long-term stability of titanium electrode materials.

[0005] In a first aspect, embodiments of this application provide a method for preparing a highly catalytically active titanium electrode material, the method comprising the following steps: S1. The titanium substrate is pretreated to form a micro-rough surface on the surface of the titanium substrate, thereby obtaining a pretreated substrate; S2. A Ni-Co-Mo transition metal alloy layer is deposited on the surface of the pretreated substrate to obtain the first intermediate. S3. The first intermediate is placed in an atmosphere containing a phosphorus source for phosphating treatment, so that the transition metal alloy layer is transformed into a crystalline phosphide heterostructure containing Ni5P4 phase, NiCoP phase and Mo component, to obtain the second intermediate. S4. The second intermediate is placed in a sulfur-containing atmosphere for surface sulfur treatment to form an amorphous sulfur-containing layer on the outer surface of the electrode, and the sulfur element is distributed in a gradient from the surface to the inside in the thickness direction of the electrode coating to obtain the third intermediate. S5. The third intermediate is subjected to tempering stabilization treatment in an inert atmosphere to obtain the titanium electrode material. The surface sulfur treatment temperature is 300–350°C, and the treatment time is 30–60 min. The temperature of the tempering stabilization treatment is lower than the temperature of the surface sulfur treatment.

[0006] Optionally, the pretreatment includes sequential alkaline degreasing, mixed acid roughening, and oxalic acid etching. The oxalic acid etching process includes the following parameters: the mass concentration of the oxalic acid solution is 8-12 wt%, the temperature is 60-80℃, and the time is 20-40 min.

[0007] Optionally, in the Ni-Co-Mo transition metal alloy layer, the atomic ratio of Ni, Co, and Mo is (5-7):(1-3):(1-3).

[0008] Optionally, the Ni-Co-Mo transition metal alloy layer is deposited using magnetron sputtering. The magnetron sputtering deposition method includes the following parameters: background vacuum ≤ 5 × 10⁻⁶ -4 The working pressure is 0.5–1.0 Pa, the total sputtering power is 150–400 W, the deposition temperature is 150–200 °C, and the deposition thickness is 500–1000 nm.

[0009] Optionally, the phosphorus source is NaH2PO2·H2O; The phosphating treatment includes the following parameters: heating rate of 3-8℃ / min, temperature of 300-400℃, and holding time of 2-4h.

[0010] Optionally, the sulfur-containing atmosphere is a sulfur vapor atmosphere generated by heating sulfur powder, and the carrier gas is an inert gas.

[0011] Optionally, the tempering stabilization treatment is performed at a temperature of 280–310°C for 30–60 minutes.

[0012] Secondly, embodiments of this application provide a highly catalytically active titanium electrode material prepared by the method described in any one of the first aspects, the titanium electrode material comprising: Titanium matrix; A composite catalytic coating is disposed on the surface of the titanium substrate; The composite catalytic coating comprises an inner layer region and an outer layer region sequentially from the surface of the titanium substrate outwards; The inner layer region includes Ni5P4 phase, NiCoP phase, and a crystalline phosphide heterostructure containing Mo. The outer layer region includes an amorphous sulfur-containing layer, and the sulfur element is distributed in a gradient from the surface to the interior along the thickness direction of the composite catalytic coating.

[0013] Optionally, in the composite catalytic coating, the sulfur content in the outer layer is 5-15 at, and the sulfur content in the inner layer is less than 2 at.

[0014] Thirdly, embodiments of this application provide an application of the highly catalytically active titanium electrode material described in the second aspect in water electrolysis for hydrogen production.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application discloses a method for preparing a highly catalytically active titanium electrode material. By constructing an inner layer of highly active crystalline heterostructure, an outer layer of defect-rich amorphous sulfur-containing layer, and a sulfur element gradient distribution, and supplementing it with low-temperature tempering stabilization treatment, the catalytic activity and structural stability of the titanium electrode material are synergistically improved.

[0016] In terms of electrocatalytic activity, the Ni-Co-Mo transition metal alloy layer deposited in step S2, after phosphating in step S3, forms a crystalline phosphide heterostructure containing Ni5P4 phase, NiCoP phase, and Mo-containing components. The multiphase heterostructure generates a large number of lattice mismatch and coordination unsaturated sites at the nanoscale, providing a high density of catalytic active centers. Step S4 involves surface sulfur treatment at 300–350 °C, generating an amorphous sulfur-containing layer in the outer region of the electrode. This amorphous layer contains abundant unsaturated sulfur atoms and defect sites, further increasing the number and types of surface active sites, thereby significantly reducing the overpotential of the hydrogen / oxygen evolution reaction in water electrolysis and improving catalytic efficiency.

[0017] In terms of long-term stability, the micro-rough surface formed by the S1 pretreatment enhances the mechanical interlock between the titanium substrate and the subsequent coating, improving the bonding strength. In the S4 step, sulfur exhibits a gradient distribution from the surface to the interior along the coating thickness direction, avoiding abrupt changes in sulfur concentration at the interface and effectively alleviating lattice stress and internal stress concentration caused by sulfur diffusion. The tempering stabilization treatment temperature in the S5 step is set below the surface sulfur treatment temperature. This process eliminates the residual internal stress accumulated from the previous multi-step treatments. At the same time, due to the lower temperature, it significantly inhibits the continued diffusion of sulfur into the deeper layers, thereby stabilizing and maintaining the formed sulfur gradient distribution and the heterogeneous interface structure of the crystalline phosphide. Finally, the inner crystalline phosphide itself has high thermochemical stability, while the outer amorphous sulfur-containing layer matches well with the inner layer through gradient transition, avoiding delamination and peeling. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic flowchart illustrating a method for preparing a highly catalytically active titanium electrode material provided in this application embodiment; Figure 2 This is a schematic diagram of the structure of the titanium electrode material provided in the embodiments of this application; Figure 3 This is a schematic diagram of the titanium electrode material provided in Embodiment 1 of this application; Figure 4 This is a surface SEM image of the titanium electrode material provided in Embodiment 1 of this application; Figure 5 XRD patterns of titanium electrode materials provided in Examples 1, 1, 2 and 6 of this application; Figure 6 The embodiments 1-3 of this application provide a constant 10 mA / cm 2 Potential change curves after 1000 hours of continuous operation at current density. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Figure 1 This is a schematic flowchart illustrating a method for preparing a highly catalytically active titanium electrode material, as provided in an embodiment of this application.

[0023] like Figure 1 As shown in the embodiments of this application, a method for preparing a highly catalytically active titanium electrode material is provided, the method comprising the following steps: S1. The titanium substrate is pretreated to form a micro-rough surface on the surface of the titanium substrate, thus obtaining a pretreated substrate; S2. Deposit a Ni-Co-Mo transition metal alloy layer on the surface of the pretreated substrate to obtain the first intermediate; S3. The first intermediate is placed in an atmosphere containing a phosphorus source for phosphating treatment, so that the transition metal alloy layer is transformed into a crystalline phosphide heterostructure containing Ni5P4 phase, NiCoP phase and Mo component, to obtain the second intermediate. S4. The second intermediate is placed in a sulfur-containing atmosphere for surface sulfur treatment to form an amorphous sulfur-containing layer on the outer surface of the electrode, and the sulfur element is distributed in a gradient from the surface to the inside in the thickness direction of the electrode coating to obtain the third intermediate. S5. The third intermediate is tempered and stabilized in an inert atmosphere to obtain titanium electrode material. The surface sulfur treatment temperature is 300–350℃, and the treatment time is 30–60 min. The temperature for tempering and stabilization is lower than the temperature for surface sulfur treatment.

[0024] It should be noted that step S1 pretreatment of the titanium substrate forms a micro-rough structure on its surface. Its main function is to increase the specific surface area of ​​the electrode, enhance the mechanical locking and bonding force between the subsequent deposited layer and the substrate, and provide more nucleation sites for the loading of active components.

[0025] Step S2 deposits a Ni-Co-Mo transition metal alloy layer on the pretreated substrate surface. This alloy layer is not only the basic source of electrocatalytic activity, but also preliminarily optimizes the electronic structure and catalytic properties through the synergistic effect of Ni, Co and Mo, providing a uniform and compositionally controllable precursor for subsequent phosphating treatment.

[0026] Step S3 employs a phosphorus-containing atmosphere for phosphating, transforming the transition metal alloy layer into a crystalline phosphide heterostructure containing Ni5P4 phase, NiCoP phase, and Mo component. The multiphase heterostructure formed during this process generates abundant lattice distortion and interface defects, significantly enhancing the catalytic activity of the electrode for electrochemical reactions such as hydrogen evolution and oxygen evolution. Simultaneously, the introduction of the Mo component further modulates the electronic state density of the phosphide.

[0027] Step S4 involves surface sulfur treatment at 300–350℃ for 30–60 min, generating an amorphous sulfur-containing layer in the outer region of the electrode, with a sulfur concentration gradient distribution from the surface inwards along the coating thickness direction. The amorphous sulfur-containing layer provides numerous unsaturated coordination sites and surface defects, which are beneficial for reactant adsorption and intermediate transformation; while the sulfur gradient distribution avoids drastic interfacial abrupt changes, mitigating lattice mismatch and stress concentration caused by inward diffusion of sulfur atoms, and simultaneously imparting a unique electronic modification effect to the electrode surface.

[0028] Step S5 involves tempering and stabilizing the material in an inert atmosphere at a temperature lower than that of the surface sulfur treatment. This process aims to eliminate internal stresses generated during the preceding multi-step treatments, stabilize the formed crystalline phosphide heterostructure and amorphous sulfur-containing layer structure, and prevent excessive diffusion or unnecessary phase transformation of sulfur at high temperatures. This, in turn, enhances the overall structural stability and catalytic durability of the titanium electrode material under long-term electrochemical operating conditions.

[0029] In some embodiments, the pretreatment includes a sequential alkaline degreasing treatment, a mixed acid roughening treatment, and an oxalic acid etching treatment; The oxalic acid etching process includes the following parameters: oxalic acid solution concentration of 8–12 wt%, temperature of 60–80 °C, and time of 20–40 min.

[0030] The oxalic acid solution concentration was limited to 8–12 wt%, the temperature to 60–80 °C, and the etching time to 20–40 min. This concentration range provides a moderate and stable etching rate, avoiding insufficient roughening due to too low a concentration or excessive corrosion of the titanium substrate surface due to too high a concentration, resulting in a porous layer. The temperature of 60–80 °C accelerates the reaction between oxalic acid and the titanium surface without causing excessive evaporation of the solution or uneven etching due to excessive temperature. The etching time of 20–40 min ensures the formation of a uniform micro-rough surface. Too short a time will not achieve the ideal anchoring structure, while too long a time may cause excessive expansion of micropits, reducing mechanical strength, thus providing the best bonding interface for subsequent alloy layer deposition.

[0031] In some embodiments, the atomic ratio of Ni, Co, and Mo in the Ni-Co-Mo transition metal alloy layer is (5-7):(1-3):(1-3).

[0032] The atomic ratio of Ni, Co, and Mo in the Ni-Co-Mo transition metal alloy layer is limited to (5–7):(1–3):(1–3). This ratio range aims to balance the synergistic catalytic effects of the three metals: a higher Ni content (5–7 parts) ensures good conductivity and corrosion resistance of the alloy layer, while providing sufficient nickel source for the formation of the highly active Ni5P4 phase after phosphating; an appropriate amount of Co (1–3 parts) can induce the formation of the NiCoP phase, regulate the hydrogen adsorption free energy, and enhance the hydrogen evolution activity; an equal proportion of Mo (1–3 parts) can change the electronic structure of the alloy, reduce the overpotential of hydrogen evolution, and promote the formation of a Mo-containing heterogeneous interface during phosphating; exceeding this range may lead to an excess of one element, resulting in inert phase separation or disrupting the uniformity of the alloy layer.

[0033] In some embodiments, the Ni-Co-Mo transition metal alloy layer is deposited using magnetron sputtering; Magnetron sputtering deposition includes the following parameters: background vacuum ≤ 5 × 10⁻⁶ -4 The working pressure is 0.5–1.0 Pa, the total sputtering power is 150–400 W, the deposition temperature is 150–200 °C, and the deposition thickness is 500–1000 nm.

[0034] A thickness controlled between 500 and 1000 nm ensures sufficient active components to participate in subsequent phosphating and sulfidation reactions while preventing excessively thick films from peeling off due to increased internal stress; the base vacuum degree is ≤5×10⁻⁶. -4 Pa significantly reduces contamination of the alloy film by residual gases (oxygen, water vapor), ensuring film purity. The working pressure of 0.5–1.0 Pa adjusts the mean free path and energy of sputtered particles. If the pressure is too low, the particle bombardment energy will be too high, causing defects in the film. If the pressure is too high, the particle scattering will be severe, reducing the deposition rate and density. The total sputtering power of 150–400 W provides a stable atomic escape rate. If the power is too low, the film will be loose. If the power is too high, the substrate may overheat and the grains may coarsen. The deposition temperature of 150–200 °C promotes the surface diffusion of deposited atoms, enhances the adhesion between the film and the titanium substrate, and avoids premature oxidation of the alloy layer or abnormal grain growth caused by excessive temperature.

[0035] In some embodiments, the phosphorus source is NaH2PO2·H2O; The phosphating treatment includes the following parameters: heating rate of 3-8℃ / min, temperature of 300-400℃, and holding time of 2-4h.

[0036] A heating rate of 3–8 °C / min can control the rate at which hypophosphite decomposes and produces PH3 gas. Too slow a rate reduces production efficiency, while too fast a rate may cause violent gas release and damage the alloy layer structure. The phosphating temperature of 300–400 °C is the critical range for the formation of the Ni5P4 and NiCoP phases. Too low a temperature results in incomplete conversion and poor crystallinity, while too high a temperature may cause the phases to transform into thermodynamically more stable but less catalytically active phosphides (such as Ni3P or Ni...). 12 P5); a holding time of 2 to 4 hours ensures that the alloy layer is completely transformed into a crystalline phosphide heterostructure. If the time is insufficient, unconverted metal or amorphous precursor will remain, while if the time is too long, it may cause grain coarsening, reducing the density and catalytic activity of the heterostructure.

[0037] In some embodiments, the sulfur-containing atmosphere is a sulfur vapor atmosphere generated by heating sulfur powder, and the carrier gas is an inert gas.

[0038] Sulfur vapor is generated by heating sulfur powder instead of directly introducing toxic gases such as H2S, which facilitates safe control of sulfur partial pressure. Inert gas (such as argon or nitrogen) is used as a carrier gas, which protects the system from oxidation on the one hand, and controls the concentration and transport rate of sulfur vapor by adjusting the airflow speed on the other hand, so that sulfur can diffuse smoothly to the outer surface of the electrode and form a gradient distribution from the surface to the inside, avoiding local over-sulfidation or uneven sulfur deposition.

[0039] In some embodiments, the tempering stabilization treatment temperature is 280–310°C, and the holding time is 30–60 min.

[0040] Limiting the tempering range to 280–310°C effectively eliminates residual internal stress generated in the preceding multi-step treatment (especially magnetron sputtering and phosphating processes), while preventing crystallization of the amorphous sulfur-containing layer on the outer surface of the electrode or excessive inward diffusion of sulfur, which would disrupt the gradient distribution. Setting the temperature below the surface sulfur treatment temperature ensures that the tempering process will not trigger new phase transitions or redistribution of sulfur. Holding the temperature for 30–60 minutes is sufficient to achieve uniform stress release and structural stabilization. Too short a time will result in insufficient stabilization, while too long a time will increase energy consumption and may cause local ordering of the amorphous layer, thereby comprehensively improving the catalytic durability and long-term working stability of the titanium electrode material.

[0041] Figure 2 This is a schematic diagram of the structure of the titanium electrode material provided in the embodiments of this application.

[0042] Based on a general inventive concept, such as Figure 2 As shown, this application provides a highly catalytically active titanium electrode material prepared by any one of the methods described above. The titanium electrode material includes: Titanium matrix; A composite catalytic coating is applied to the surface of a titanium substrate. The composite catalytic coating consists of an inner layer region and an outer layer region from the surface of the titanium substrate outwards. The inner layer region contains Ni5P4 phase, NiCoP phase, and crystalline phosphide heterostructure with Mo component; The outer layer contains an amorphous sulfur-containing layer, and the sulfur element is distributed in a gradient from the surface to the interior along the thickness direction of the composite catalytic coating.

[0043] In some embodiments, the sulfur content in the outer layer of the composite catalytic coating is 5 to 15 at, and the sulfur content in the inner layer is less than 2 at.

[0044] The formation process of the highly catalytically active titanium electrode material in this application involves constructing a composite catalytic coating consisting of a crystalline phosphide heterointerface inner layer region and an amorphous sulfur-containing gradient outer layer region, extending from the titanium matrix outwards.

[0045] The formation of the specific crystalline phosphide heterostructure in the inner layer region originates from the selective phase transformation of the Ni-Co-Mo transition metal alloy layer pre-deposited in step S2 during subsequent phosphating treatment (300–400℃, holding for 2–4 h). Within this temperature range, the PH3 released from the decomposition of sodium hypophosphite reacts with the alloy layer: Ni tends to form the thermodynamically metastable but highly catalytically active Ni5P4 phase, rather than the more common Ni2P or Ni3P. Ni5P4 possesses a unique [P]... 4- The ionic and electron-deficient structure significantly optimizes the hydrogen adsorption free energy. The introduction of Co, together with Ni and P, forms a ternary NiCoP phase, which combines the conductivity of Ni-based phosphides with the hydroxyl adsorption capacity of Co-based phosphides, reducing the overpotential of the hydrogen / oxygen evolution reaction through bimetallic synergy. During phosphating, the Mo component exists either as the MoP phase or as Mo atoms doped into the Ni5P4 or NiCoP lattice, thereby regulating the overall electron density and enhancing corrosion resistance. Due to the differences in phosphating rates and product crystal forms among Ni, Co, and Mo, under the kinetic conditions of holding at 300–400℃ for 2–4 h, these three phosphides do not exist as independent homogeneous layers, but rather interpenetrate, coherently, or semi-coherently at the nanoscale, forming a large number of crystalline phosphide heterojunctions. These interfaces contain lattice mismatch and disordered atomic arrangement, resulting in abundant dangling bonds and coordination unsaturated sites, which become highly active regions for catalytic reactions. At the same time, the coexistence of multiple phases also inhibits the structural degradation of a single phase during long-term electrolysis, thereby endowing the inner layer with high intrinsic activity and structural stability.

[0046] The gradient distribution of sulfur in the coating thickness direction, from the surface inwards, is shaped by the specific conditions of the surface sulfur treatment in step S4 (300–350℃, 30–60 min) and the temperature difference design of the subsequent tempering treatment in step S5. During the surface sulfur treatment stage, sulfur powder is heated in an inert carrier gas to generate sulfur vapor, which then contacts the electrode surface at 300–350℃. Although this temperature is higher than the subsequent tempering temperature, it is still within the medium temperature range, and sulfur atoms mainly penetrate into the formed crystalline phosphide coating through thermal diffusion. Due to the limited treatment time of only 30–60 min, sulfur atoms cannot diffuse uniformly to the entire coating depth within a finite time; instead, they gradually penetrate from the outer surface inwards, forming a gradient distribution where the concentration decreases with increasing depth. Simultaneously, at this temperature, sulfur reacts moderately with the coating surface to generate an amorphous sulfur-containing layer. The amorphous structure itself has numerous unsaturated coordination sites and an open framework, which can further expose active sites. Furthermore, the smooth gradient transition between the amorphous layer and the underlying crystalline inner layer avoids stress concentration and peeling risks caused by sharp interfaces. The subsequent S5 step tempering and stabilization treatment (280–310℃, 30–60 min) was intentionally set below the surface sulfur treatment temperature. This served two purposes: firstly, it eliminated the internal stress introduced by the preceding multi-step treatment, allowing the amorphous sulfur-containing layer and gradient distribution to be stably maintained; secondly, because the tempering temperature was lower than the sulfur treatment temperature, it prevented sulfur from continuing to diffuse deeper. The resulting sulfur gradient distribution from the surface inwards prevented excessive diffusion from increasing the sulfur content in the inner layer and damaging the heterogeneous interface structure of the crystalline phosphide. Ultimately, this gradient composite coating, with an outer high-sulfur amorphous layer and an inner low-sulfur crystalline heterogeneous interface, combined abundant active sites on the surface with a stable, highly catalytically active phosphide framework inside, achieving a synergistic improvement in catalytic performance and durability.

[0047] Based on a general inventive concept, embodiments of this application provide an application of the highly catalytically active titanium electrode material described above in water electrolysis for hydrogen production.

[0048] The high catalytic activity titanium electrode material of this application is suitable for hydrogen production by water electrolysis mainly due to its unique gradient composite coating structure. This titanium electrode material can simultaneously achieve high catalytic activity and long-term operational stability, meeting the stringent requirements for electrode performance in hydrogen production by water electrolysis.

[0049] The inner layer contains Ni5P4 phase, NiCoP phase, and a crystalline phosphide heterostructure containing Mo. Ni5P4 has an optimized hydrogen adsorption free energy, NiCoP bimetallic synergy reduces the hydrogen evolution overpotential, and the Mo-containing component further modulates the electronic structure. The multiphase heterostructure provides a large number of highly active regions, thereby significantly improving the efficiency of the cathodic hydrogen evolution reaction (HER).

[0050] The amorphous sulfur-containing layer in the outer region and the gradient distribution of sulfur elements from the surface to the inside provide the electrode surface with abundant unsaturated coordination sites, enhancing the adsorption capacity for reaction intermediates. On the other hand, the gradient transition avoids interfacial stress concentration and improves the structural stability of the coating during long-term electrolysis.

[0051] The micro-roughened surface of the titanium substrate, formed by pretreatment, is firmly bonded to the alloy layer. Combined with appropriate tempering stabilization treatment, this ensures the corrosion resistance and durability of the electrode in strongly alkaline or acidic electrolytes.

[0052] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards / industry standards / the disclosure herein; if there are no corresponding national standards / industry standards / the disclosure herein, they are performed according to generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer.

[0053] Example 1 This embodiment provides a method for preparing a highly catalytically active titanium electrode material, the specific steps of which are as follows: S1. Pretreatment: The titanium substrate was subjected to alkaline degreasing, mixed acid roughening, and oxalic acid etching sequentially. Alkaline degreasing: The substrate was immersed in a 10wt% NaOH solution at 60℃ for 30 min, then rinsed with deionized water. Mixed acid roughening: The substrate was treated in a mixed acid solution with a volume ratio of HF:HNO3:H2O = 1:4:5 at room temperature for 2 min, then rinsed with deionized water. Oxalic acid etching: The titanium substrate was placed in a 10wt% oxalic acid solution and etched at 70℃ for 30 min. After etching, the substrate was ultrasonically cleaned with deionized water for 10 min and dried with nitrogen to obtain a pretreated substrate with a micro-roughened surface structure.

[0054] S2. Deposition of Ni-Co-Mo transition metal alloy layer: A Ni-Co-Mo alloy layer is deposited on the pretreated substrate surface using magnetron sputtering. The sputtering targets are independent Ni, Co, and Mo targets (99.95% purity), and the alloy composition is controlled by adjusting the sputtering power of each target. Sputtering parameters: Base vacuum 5 × 10⁻⁶ -4 The working pressure was 0.8 Pa (argon), the sputtering power of the Ni target was 180 W, the sputtering power of the Co target was 90 W, and the sputtering power of the Mo target was 90 W. The deposition temperature was 180℃, the deposition time was 60 min, and the thickness was controlled to be 800 nm. EDS determination showed that the atomic ratio of Ni, Co, and Mo in the obtained Ni-Co-Mo alloy layer was 6.2:1.9:1.9, thus obtaining the first intermediate.

[0055] S3. Phosphating Treatment: The first intermediate was placed in a tube furnace with NaH2PO2·H2O as the phosphorus source (placed in the upstream temperature zone), and the sample was placed in the downstream temperature zone. Under an argon atmosphere, it was heated to 350℃ at a heating rate of 5℃ / min and held for 3 hours. During this period, NaH2PO2·H2O decomposed to produce PH3, which reacted with the alloy layer. After the reaction, it was naturally cooled to room temperature to obtain the second intermediate. XRD analysis showed that the surface coating of the second intermediate contained Ni5P4 phase, NiCoP phase, and a small amount of MoP phase, forming a crystalline phosphide heterostructure.

[0056] S4. Surface Sulfur Treatment: The second intermediate was placed in a tube furnace, with sulfur powder (99.9% purity) in the upstream temperature zone and the sample in the downstream temperature zone. Argon gas was introduced as the carrier gas (flow rate 100 sccm), and the sulfur powder was heated to 150°C to generate sulfur vapor. Simultaneously, the sample area was heated to 320°C and held at this temperature for 45 minutes. After treatment, the sample was allowed to cool naturally in an argon atmosphere to obtain the third intermediate. XPS depth profiling revealed an amorphous sulfur-containing layer on the outer surface of the electrode. The sulfur content gradually decreased from the surface to the interior along the coating thickness direction, with the outer layer containing approximately 8–10 at% sulfur and the inner layer containing less than 2 at%.

[0057] S5. Tempering and stabilization treatment: The third intermediate is placed in a tube furnace and heated to 290°C at 3°C / min under an argon atmosphere, held for 45 min, and then cooled to room temperature with the furnace to obtain the final titanium electrode material.

[0058] Example 2 This embodiment provides a method for preparing a highly catalytically active titanium electrode material, the specific steps of which are as follows.

[0059] S1. Pretreatment: The titanium substrate was subjected to alkaline degreasing, mixed acid roughening, and oxalic acid etching sequentially. Alkaline degreasing: The substrate was immersed in a 10wt% NaOH solution at 60℃ for 30 min, then rinsed with deionized water. Mixed acid roughening: The substrate was treated in a mixed acid solution with a volume ratio of HF:HNO3:H2O = 1:4:5 at room temperature for 2 min, then rinsed with deionized water. Oxalic acid etching: The titanium substrate was placed in an 8wt% oxalic acid solution and etched at 80℃ for 20 min. After etching, the substrate was ultrasonically cleaned with deionized water for 10 min and dried with nitrogen to obtain a pretreated substrate with a micro-roughened surface structure.

[0060] S2. Deposition of Ni-Co-Mo transition metal alloy layer: A Ni-Co-Mo alloy layer is deposited on the pretreated substrate surface using magnetron sputtering. The sputtering target is an independent Ni, Co, and Mo target (99.95% purity). Sputtering parameters: Base vacuum 4 × 10⁻⁶ -4The working pressure was 0.6 Pa (argon), the sputtering power of the Ni target was 150 W, the sputtering power of the Co target was 70 W, and the sputtering power of the Mo target was 70 W. The deposition temperature was 160℃, the deposition time was 90 min, and the thickness was controlled to be 500 nm. EDS determination showed that the atomic ratio of Ni, Co, and Mo in the obtained Ni-Co-Mo alloy layer was 5.2:2.4:2.4, thus obtaining the first intermediate.

[0061] S3. Phosphating Treatment: The first intermediate was placed in a tube furnace with NaH2PO2·H2O as the phosphorus source (placed in the upstream temperature zone), and the sample was placed in the downstream temperature zone. Under an argon atmosphere, the temperature was increased to 320℃ at a rate of 3℃ / min and held for 4 hours. After the reaction, the mixture was allowed to cool naturally to room temperature to obtain the second intermediate. XRD analysis showed that the surface coating of the second intermediate contained Ni5P4 phase, NiCoP phase, and a small amount of MoP phase, forming a crystalline phosphide heterostructure.

[0062] S4. Surface Sulfur Treatment: The second intermediate was placed in a tube furnace, with sulfur powder (99.9% purity) in the upstream temperature zone and the sample in the downstream temperature zone. Argon gas was introduced as the carrier gas (flow rate 120 sccm), and the sulfur powder was heated to 150°C to generate sulfur vapor. Simultaneously, the sample area was heated to 300°C and held for 60 minutes. After treatment, the sample was allowed to cool naturally in an argon atmosphere to obtain the third intermediate. XPS depth profiling revealed an amorphous sulfur-containing layer on the outer surface of the electrode. The sulfur content gradually decreased from the surface to the interior along the coating thickness direction, with the outer layer containing approximately 5–7 at% sulfur and the inner layer containing less than 2 at%.

[0063] S5. Tempering and stabilization treatment: The third intermediate is placed in a tube furnace and heated to 280°C at 2°C / min under an argon atmosphere, held for 60 min, and then cooled to room temperature with the furnace to obtain the final titanium electrode material.

[0064] Example 3 This embodiment provides a method for preparing a highly catalytically active titanium electrode material, the specific steps of which are as follows.

[0065] S1. Pretreatment: The titanium substrate was subjected to alkaline degreasing, mixed acid roughening, and oxalic acid etching sequentially. Alkaline degreasing: The substrate was immersed in a 10wt% NaOH solution at 60℃ for 30 min, then rinsed with deionized water. Mixed acid roughening: The substrate was treated in a mixed acid solution with a volume ratio of HF:HNO3:H2O = 1:4:5 at room temperature for 2 min, then rinsed with deionized water. Oxalic acid etching: The titanium substrate was placed in a 12wt% oxalic acid solution and etched at 60℃ for 40 min. After etching, the substrate was ultrasonically cleaned with deionized water for 10 min and dried with nitrogen to obtain a pretreated substrate with a micro-roughened surface structure.

[0066] S2. Deposition of Ni-Co-Mo transition metal alloy layer: A Ni-Co-Mo alloy layer is deposited on the pretreated substrate surface using magnetron sputtering. The sputtering target is an independent Ni, Co, and Mo target (99.95% purity). Sputtering parameters: Base vacuum 3×10⁻⁶ -4 The working pressure was 1.0 Pa (argon), the sputtering power of the Ni target was 200 W, the sputtering power of the Co target was 100 W, and the sputtering power of the Mo target was 100 W. The deposition temperature was 200℃, the deposition time was 120 min, and the thickness was controlled to be 1000 nm. EDS determination showed that the atomic ratio of Ni, Co, and Mo in the obtained Ni-Co-Mo alloy layer was 6.8:1.6:1.6, thus obtaining the first intermediate.

[0067] S3. Phosphating Treatment: The first intermediate was placed in a tube furnace with NaH2PO2·H2O as the phosphorus source (placed in the upstream temperature zone), and the sample was placed in the downstream temperature zone. Under an argon atmosphere, the temperature was increased to 400℃ at a rate of 8℃ / min and held for 2 hours. After the reaction, the mixture was allowed to cool naturally to room temperature to obtain the second intermediate. XRD analysis showed that the surface coating of the second intermediate contained Ni5P4 phase, NiCoP phase, and a small amount of MoP phase, forming a crystalline phosphide heterostructure.

[0068] S4. Surface Sulfur Treatment: The second intermediate was placed in a tube furnace, with sulfur powder (99.9% purity) in the upstream temperature zone and the sample in the downstream temperature zone. Argon gas was introduced as the carrier gas (flow rate 80 sccm), and the sulfur powder was heated to 150°C to generate sulfur vapor. Simultaneously, the sample area was heated to 330°C and held for 30 minutes. After treatment, the sample was allowed to cool naturally in an argon atmosphere to obtain the third intermediate. XPS depth profiling revealed an amorphous sulfur-containing layer on the outer surface of the electrode. The sulfur content gradually decreased from the surface to the interior along the coating thickness direction, with the outer layer containing approximately 12–15 at% sulfur and the inner layer containing less than 2 at%.

[0069] S5. Tempering and stabilization treatment: The third intermediate is placed in a tube furnace and heated to 290°C at 4°C / min under an argon atmosphere, held for 30 min, and then cooled to room temperature with the furnace to obtain the final titanium electrode material.

[0070] Comparative Example 1 This comparative example is based on Example 1, with the following modifications: Step S2 is omitted, meaning the Ni-Co-Mo transition metal alloy layer is not deposited.

[0071] Because the surface of the obtained titanium electrode material lacks a Ni-Co-Mo alloy layer, it cannot form active phases such as Ni5P4 and NiCoP after phosphating treatment. The surface coating is mainly composed of titanium phosphides or oxides.

[0072] Comparative Example 2 This comparative example is based on Example 1, with the following modifications: Step S3 is omitted, meaning phosphating is not performed.

[0073] The surface coating of the obtained titanium electrode material is a sulfur-containing layer covered by a Ni-Co-Mo alloy outer layer, but it lacks the heterogeneous interface of crystalline phosphide formed by phosphating, and the inner layer lacks the highly active Ni5P4 and NiCoP phases.

[0074] Comparative Example 3 This comparative example is based on Example 1, with the following modifications: Step S4 is omitted, meaning surface sulfur treatment is not performed.

[0075] The obtained titanium electrode material has no outer amorphous sulfur-containing layer on its surface, nor does it have a sulfur element gradient distribution.

[0076] Comparative Example 4 This comparative example is based on Example 1, with the following modifications: Step S5 is omitted, meaning that tempering stabilization is not performed.

[0077] The resulting titanium electrode material contains residual stress, and the coating is prone to stress release during long-term immersion in electrolyte or electrochemical cycling, leading to microcracks or even peeling.

[0078] Comparative Example 5 This comparative example is based on Example 1, with the following modifications: The surface sulfur treatment temperature for step S4 is 250℃.

[0079] Due to the low temperature, the sulfur atom diffusion rate on the surface of the obtained titanium electrode material is insufficient, the sulfur content in the outer layer is less than 2 at%, making it difficult to form a continuous amorphous sulfur-containing layer. Furthermore, the sulfur element gradient distribution is not obvious, and there are few surface active sites.

[0080] Comparative Example 6 This comparative example is based on Example 1, with the following modifications: The S5 step tempering and stabilization treatment temperature is 350℃ (higher than the surface sulfur treatment temperature of 320℃).

[0081] During the tempering process, the outer amorphous sulfur-containing layer of the obtained titanium electrode material crystallized due to the high temperature, and the sulfur element further diffused inward, disrupting the original sulfur gradient distribution and increasing the sulfur content in the inner layer (exceeding 2 at%).

[0082] The physicochemical properties of the titanium electrode materials obtained in Examples 1-3 and Comparative Examples 1-6 were measured, and the results are shown in Table 1.

[0083] The methods for determining physicochemical properties are as follows: Adhesion test: The scratch method is used, and a diamond scratch needle is used to apply a progressive load of 0 to 100 N on the coating surface. The critical load value (unit: N) when the coating first peels off or penetrates is recorded.

[0084] Outer / inner layer sulfur content: determined by X-ray photoelectron spectroscopy (XPS) combined with Ar + Ion sputtering depth profiling was performed, and high-resolution S 2p spectra were collected at depths of 0–50 nm (outer layer region) and approximately 500 nm (inner layer region) in the middle of the coating. Semi-quantitative analysis was conducted using the relative sensitivity factor method to obtain the sulfur atom percentage (unit: at%).

[0085] Electrochemical active area (ECSA): Cyclic voltammetry (CV) was used to measure the double-layer capacitance (Cdl) at different scan rates within the non-Radida potential range. The relationship between current density (j) and scan rate (v) was recorded. The slope of the linear fit is the double-layer capacitance (Cdl, unit: mF / cm). 2 ).

[0086] Table 1. Physicochemical properties of titanium electrode materials in Examples 1-3 and Comparative Examples 1-6 As shown in Table 1, the titanium electrode materials prepared in Examples 1-3 have an adhesion strength of 55-72 N, an outer layer sulfur content of 6.0-13.5 at%, an inner layer sulfur content controlled at 1.1-1.5 at%, and a double-layer capacitance of 35-48 mF / cm. 2 This indicates that the method of this application can obtain a composite catalytic coating with strong bonding, controllable sulfur gradient distribution, and abundant electrochemical active sites.

[0087] Comparative Example 1, due to the omission of alloy layer deposition, could not form a phosphide active phase, resulting in a binding force of only 42 N and a double-layer capacitance reduced to 8 mF / cm. 2 Comparative Example 2, due to the omission of phosphating, retains a low-activity alloy in the inner layer, resulting in a double-layer capacitance of only 18 mF / cm. 2 Comparative Example 3, due to the omission of sulfur treatment, lacked an amorphous sulfur-containing layer on the surface, resulting in insufficient exposure of active sites; Comparative Example 4, due to the omission of tempering, resulted in residual stress causing the bonding strength to drop to 38 N; Comparative Example 5, due to the excessively low sulfur treatment temperature, resulted in insufficient sulfur diffusion, leading to an outer layer sulfur content of only 1.8 at%, and a discontinuous amorphous layer; Comparative Example 6, due to the excessively high tempering temperature, caused sulfur to diffuse inward, increasing the inner layer sulfur content to 3.2 at%, disrupting the gradient distribution and poisoning the inner layer active sites.

[0088] The titanium electrode materials obtained in Examples 1-3 and Comparative Examples 1-6 were tested for their performance in hydrogen production via water electrolysis. The results are shown in Table 2.

[0089] The application performance testing methods are as follows: Hydrogen evolution reaction (HER) overpotential: Linear sweep voltammetry (LSV) was used in a three-electrode system at a scan rate of 5 mV / s. The electrolyte was 1 M KOH solution, the reference electrode was a Hg / HgO electrode, and the counter electrode was a platinum sheet. A reading of 10 mA / cm² was obtained. 2 The absolute value of the difference between the potential at the current density (vs. RHE) and the theoretical hydrogen evolution potential (0 V vs. RHE) is the overpotential (η). 10 (Unit: mV)

[0090] Tafel slope: By performing linear fitting on the data in the low overpotential region of the LSV curve, the relationship between log|j| (logarithm of current density) and η is plotted, and the slope obtained by fitting is the Tafel slope (unit: mV / dec).

[0091] Long-term stability: Using the chronopotential method, under a constant current density (e.g., 10 mA / cm²), 2 The system was continuously operated for 1000 hours, and the change in operating potential over time was recorded. The increase in overpotential after stabilization was used to assess long-term stability.

[0092] Table 2 Application performance of titanium electrode materials in Examples 1-3 and Comparative Examples 1-6 As shown in Table 2, the hydrogen evolution overpotential η in Examples 1-3 is... 10 The overpotential was 41–52 mV, the Tafel slope was 39–49 mV / dec, and the overpotential increase over 1000 h was 4.8–6.1 mV, demonstrating excellent catalytic activity and long-term stability.

[0093] Comparative Example 1, lacking an alloy layer, only produces phosphides / oxides of low-activity titanium after phosphating, η 10 Up to 285 mV; Comparative Example 2, due to the lack of phosphating, has an inner layer of Ni-Co-Mo alloy rather than highly reactive phosphides, η 10 The value was 168 mV; in Comparative Example 3, due to the lack of sulfur layer protection, the crystalline phosphide easily dissolved P in the alkaline solution, leading to η 10 The value increased to 78 mV and increased by 54.8 mV over 1000 h; Comparative Example 4, although initially similar to the example, developed microcracks and spalling during operation due to the lack of stress relief from tempering, with an increase of 27.4 mV over 1000 h; Comparative Example 5, due to the discontinuous sulfur layer and insufficient optimization of surface hydrogen adsorption free energy, η... 10 The value was 108 mV; in Comparative Example 6, the sulfur gradient was disrupted, the inner layer was poisoned by sulfur, and the outer layer crystallized due to excessively high tempering temperature. 10 The voltage was 78 mV and the stability decreased to 22.3 mV.

[0094] Figure 3This is a schematic diagram of the titanium electrode material provided in Embodiment 1 of this application; Figure 4 This is a surface SEM image of the titanium electrode material provided in Embodiment 1 of this application.

[0095] Depend on Figure 3 As can be seen, the physical image shows the overall macroscopic morphology of the electrode, with a uniform and complete black coating on the surface; from Figure 4 As can be seen, the SEM image shows the microstructure of the coating, indicating that the surface layer is dense and uniform with no obvious defects.

[0096] Figure 5 The images show the XRD patterns of the titanium electrode materials provided in Examples 1, 1, 2 and 6 of this application.

[0097] Depend on Figure 5 It can be seen that the XRD pattern of Example 1 shows multiple sets of sharp diffraction peaks at 2θ≈32.1°, 40.6°, 41.2°, 42.5°, 44.3°, 44.8°, 47.1°, 50.3°, and 57.1°, which belong to the Ni5P4 phase, NiCoP phase, and MoP phase, respectively. The coexistence of the three phases and the absence of other crystalline impurity peaks indicate that the phosphating treatment is complete and the heterostructure of the crystalline phosphide is well formed. Comparative Example 1 only detected diffraction peaks at 25.3°, 35.2°, 38.6°, 42.0°, and 48.0°, corresponding to the TiP phase and TiO2 (anatase) phase. No Ni, Co, or Mo-related phosphide diffraction peaks were observed, confirming that without a pre-deposited alloy layer, highly active phosphides cannot be formed. The trace oxide layer on the titanium substrate surface was not completely reduced during the phosphating process, hence the detection of trace TiO2. Comparative Example 2 shows only three diffraction peaks at 43.5°, 50.6°, and 74.3°, characteristic of Ni-Co-Mo alloy solid solutions, with no phosphide phase formation. Comparative Example 6 retains the main diffraction peaks of Ni5P4, NiCoP, and MoP, and additional weak diffraction peaks at 30.2° and 53.5°, belonging to the NiS impurity phase. Furthermore, the full width at half maximum (FWHM) of the main peak in the 40–45° range is slightly increased, indicating that the excessively high tempering temperature drives sulfur to diffuse inward and react with nickel to form crystalline sulfides. This also causes lattice distortion, disrupting the stable gradient interface between the amorphous sulfur-containing layer and the crystalline phosphides.

[0098] Figure 6 The constant 10 mA / cm provided in Examples 1-3 of this application 2 Potential change curves after 1000 hours of continuous operation at current density.

[0099] Depend on Figure 6It can be seen that during the 1000-hour long-term hydrogen evolution test, none of the three curves showed drastic fluctuations or sudden increases, and the overpotential only increased slightly and slowly. Among them, Example 3 had the smallest increase in overpotential and the best long-term stability, which is attributed to its optimal sulfur-doped gradient interface structure; Example 1 was second best; Example 2 had relatively weaker interface stability due to its lower surface sulfur content, and the overpotential increase was slightly larger.

[0100] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a high catalytic activity titanium electrode material, characterized in that, The method includes the following steps: S1. The titanium substrate is pretreated to form a micro-rough surface on the surface of the titanium substrate, thereby obtaining a pretreated substrate; S2. A Ni-Co-Mo transition metal alloy layer is deposited on the surface of the pretreated substrate to obtain the first intermediate. S3. The first intermediate is placed in an atmosphere containing a phosphorus source for phosphating treatment, so that the transition metal alloy layer is transformed into a crystalline phosphide heterostructure containing Ni5P4 phase, NiCoP phase and Mo component, to obtain the second intermediate. S4. The second intermediate is placed in a sulfur-containing atmosphere for surface sulfur treatment to form an amorphous sulfur-containing layer on the outer surface of the electrode, and the sulfur element is distributed in a gradient from the surface to the inside in the thickness direction of the electrode coating to obtain the third intermediate. S5. The third intermediate is subjected to tempering stabilization treatment in an inert atmosphere to obtain the titanium electrode material. The surface sulfur treatment temperature is 300–350°C, and the treatment time is 30–60 min. The temperature of the tempering stabilization treatment is lower than the temperature of the surface sulfur treatment.

2. The method for preparing the highly catalytically active titanium electrode material according to claim 1, characterized in that, The pretreatment includes, in sequence, alkaline degreasing, mixed acid roughening, and oxalic acid etching. The oxalic acid etching process includes the following parameters: the mass concentration of the oxalic acid solution is 8-12 wt%, the temperature is 60-80℃, and the time is 20-40 min.

3. The method for preparing the highly catalytically active titanium electrode material according to claim 1, characterized in that, In the Ni-Co-Mo transition metal alloy layer, the atomic ratio of Ni, Co, and Mo is (5-7):(1-3):(1-3).

4. The method for preparing the highly catalytically active titanium electrode material according to claim 1, characterized in that, The Ni-Co-Mo transition metal alloy layer was deposited using magnetron sputtering. The magnetron sputtering method deposition includes the following parameters: base vacuum degree ≤5×10 -4 Pa, working pressure is 0.5-1.0 Pa, total sputtering power is 150-400 W, deposition temperature is 150-200℃, deposition thickness is 500-1000 nm.

5. The method for preparing the highly catalytically active titanium electrode material according to claim 1, characterized in that, The phosphorus source is NaH2PO2·H2O; The phosphating treatment includes the following parameters: heating rate of 3-8℃ / min, temperature of 300-400℃, and holding time of 2-4h.

6. The method for preparing the highly catalytically active titanium electrode material according to claim 1, characterized in that, The sulfur-containing atmosphere is a sulfur vapor atmosphere generated by heating sulfur powder, and the carrier gas is an inert gas.

7. The method for preparing the highly catalytically active titanium electrode material according to claim 1, characterized in that, The tempering stabilization treatment is performed at a temperature of 280–310°C for 30–60 minutes.

8. A highly catalytically active titanium electrode material prepared by the method according to any one of claims 1 to 7, characterized in that, The titanium electrode material includes: Titanium matrix; A composite catalytic coating is disposed on the surface of the titanium substrate; The composite catalytic coating comprises an inner layer region and an outer layer region sequentially from the surface of the titanium substrate outwards; The inner layer region includes Ni5P4 phase, NiCoP phase, and a crystalline phosphide heterostructure containing Mo. The outer layer region includes an amorphous sulfur-containing layer, and the sulfur element is distributed in a gradient from the surface to the interior along the thickness direction of the composite catalytic coating.

9. The highly catalytically active titanium electrode material according to claim 8, characterized in that, In the composite catalytic coating, the sulfur content in the outer layer is 5-15 at, and the sulfur content in the inner layer is less than 2 at.

10. The application of a highly catalytically active titanium electrode material as described in claim 8 or 9 in hydrogen production by water electrolysis.

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