Preparation method and application of transition metal V-VI main group multi-element phosphorus compound

Abstract

The invention discloses a preparation method and application of a transition metal V-VI main group multi-element phosphorus compound, and the method specifically comprises the following steps: S1, a double-cavity graphite boat is adopted as a reaction container, a transition metal precursor and phosphorus source mixture is loaded in a main reaction cavity, and a chalcogenide element precursor is loaded in an auxiliary deposition cavity; s2, instantaneous heating and cooling are achieved through a Joule thermal system, specifically, the temperature of the main reaction cavity is increased to 800-1000 DEG C within 0-10 seconds so that the metal precursor can be decomposed, and the temperature of the auxiliary deposition cavity is kept at 400-600 DEG C so that chalcogenide elements can be controlled to be reduced and gasified; s3, a graphite rotating valve between the main reaction cavity and the auxiliary deposition cavity is periodically opened, and P / Se / Te atomic-scale doping is achieved through the Knudsen diffusion effect; and S4, carrying out gradient cooling at a rate of 50-100 DEG C / s within 30-40 seconds, and inducing lattice stress to form a high-density dislocation defect. According to the invention, accurate control of multi-element doping can be realized, the reaction efficiency is greatly improved, and the product structure is improved.

Description

Technical Field

[0001] The present application relates to the field of new material technology, and in particular to a preparation method and application of a transition metal V-VI main group polynary phosphorus compound. Background Art

[0002] Hydrogen has become an ideal alternative energy source due to its excellent energy density. In order to produce hydrogen through electrochemical water splitting, low-cost and efficient electrocatalysts are essential. In the past few decades, chemists have made great efforts to develop non-precious metal-based catalysts for water splitting. Some studies have shown that the synergistic effect between transition metal phosphides (TMPs) and transition metal chalcogenides (TMCs) can effectively improve the electrocatalytic performance. Multi-metal transition metal phosphide chalcogenides (TMPCs) have been considered as a promising water splitting electrocatalyst.

[0003] As high-performance electrocatalysts and hydrogen storage materials, the synthesis technology of TMPCs has always been a research hotspot in the field of materials. Currently, the main methods for preparing transition metal V-VI main group multi-phosphine compounds are hydrothermal / solvothermal method, chemical vapor deposition (CVD) and Joule heating method. In the existing technology, PNi3S2 synthesized by hydrothermal method has a good alkaline HER performance of 10mAcm -2 The transition point is only 137mV at a current density of 1000V. However, the traditional hydrothermal / solvothermal method has the disadvantages of high temperature and long reaction cycle (>20h), low material purity, and by-products such as PO4 3- It is difficult to completely remove (EDS test shows that the deviation of P / Ni atomic ratio is up to 15%); Se / Te precursors are easy to form precipitation in alkaline hydrothermal system, which makes it difficult to dope chalcogen elements; and the synthesized TMPCs material has poor dispersion and is easy to agglomerate, affecting stability. In the existing technology, there are also methods to synthesize NiP by CVD vapor deposition. 0.62 S 0.38 , the HER performance is 10mA cm -2 The low cross-point is 52mV at a current density of 1000V; CoNiP2S2 quaternary compound was synthesized by solid-phase high-temperature method, and the alkaline OER performance was 20mAcm -2 The low cross-point is 400mV at a current density of 1000 nm. However, the high-temperature solid-phase method consumes a lot of energy during the preparation process, and the crystal phase is uncontrollable. The solid-gas reaction between phosphorus vapor and metal easily leads to multiphase coexistence (such as FeP / FeP2 mixed phase); and it is impossible to meet the preparation of TMCs multi-components, because the chalcogen elements (S / Se / Te) are difficult to be incorporated simultaneously due to the difference in vapor pressure. Therefore, this method cannot achieve multi-component doping. In the existing technology, there is also a method that forms amorphous CoFeNi phosphate by inducing ultrafast Joule heat, which has an alkaline OER performance of 10mAcm -2The transition point is as low as 235mV at a current density of 100 nm, and the single Joule heat output is low (<1g / batch). It is limited by the single cavity volume (diameter ≤ 20mm) and the temperature gradient in the cavity causes local supersaturation of phosphorus vapor, resulting in uneven element distribution. In addition, the chalcogenide elements need to be pre-mixed, and the gas phase transport cannot be independently controlled, which limits the multi-element doping.

[0004] The bottleneck of the preparation of polyvalent phosphorus compounds in the existing technology mainly comes from the contradiction between reaction kinetics and equipment design: ① The traditional liquid phase method is limited by the solubility and reactivity of the element precursors (such as TeO2 is poorly soluble in water and Se powder is easily oxidized); ② The solid phase method relies on high temperature diffusion, but the vapor pressure difference of chalcogen elements (Te:10 -7 Pa@800℃vs.Se:10 2 Pa@800℃) leads to co-doping failure; ③ The single-cavity Joule heating device lacks an independent control mechanism for multi-element gas-phase transport and cannot achieve atomic-level mixing. Summary of the Invention

[0005] In response to the defects in the existing technology, the present invention proposes a preparation method and application of transition metal V-VI main group multi-phosphorus compounds, which can achieve precise and controllable multi-element doping, greatly improve reaction efficiency, and improve product structure.

[0006] To achieve the above technical solution, the present invention provides a method for preparing a transition metal V-VI main group polynary phosphorus compound, which specifically comprises the following steps:

[0007] S1. A dual-chamber graphite boat is used as a reaction vessel, wherein the main reaction chamber is loaded with a mixture of a transition metal precursor and a phosphorus source, and the auxiliary deposition chamber is loaded with a chalcogen precursor;

[0008] S2. Instantaneous heating and cooling using a Joule heating system: The main reaction chamber is heated to 800-1000°C within 0-10 seconds to decompose the metal precursor, while the auxiliary deposition chamber is maintained at 400-600°C to control the reduction and vaporization of the chalcogen elements;

[0009] S3. Periodically open the graphite rotary valve between the main reaction chamber and the auxiliary deposition chamber to achieve P / Se / Te atomic-level doping using the Knudsen diffusion effect;

[0010] S4. Gradual cooling at a rate of 50-100°C / s within 30-40s to induce lattice stress and form high-density dislocation defects.

[0011] Preferably, the dual-chamber graphite boat comprises: the main reaction chamber is a boron nitride-coated graphite cylinder with a diameter of 25-35 mm and a length of 40-60 mm; the auxiliary deposition is connected to the main reaction chamber through a porous partition with a porosity of 40-60%; an expandable 4-6 chamber system, and each chamber has an independent temperature control accuracy of ±10°C.

[0012] Preferably, in step S2: the metal precursor is NiCl2, FeCl3 or a combination thereof, and the molar ratio of the metal precursor to red phosphorus is 1:3-5; the chalcogen element precursor is a TeO2 / Se powder mixture, and the molar ratio of Te:Se is 1:0.8-1.2.

[0013] Preferably, in step S3: the valve opening angle is 45-75°, the frequency is 3-7 Hz; the H2 / Ar mixed gas is pulse-injected, with H2 accounting for 10-20%; and the element ratio is adjusted to P:Se:Te=5:2:3 through mass spectrometry feedback.

[0014] Preferably, in step S4: the gradient cooling is divided into two stages: first, the temperature is reduced to 500°C at 40-60°C / s and held for 5-10s, and then quenched at 80-120°C / s; NH3 gas is introduced during the cooling process with a flow rate of 15-25sccm.

[0015] The present invention also provides a transition metal pnictogen compound prepared according to the above preparation method, comprising a multi-component system such as Ni-P-Se-Te or Fe-PS; the nanosheet thickness is less than 5nm, the interlayer spacing is 0.6-0.9nm; the surface dislocation density is greater than 10 12 / cm 2 , BET specific surface area>150m 2 / g.

[0016] The present invention also provides a core-shell structure material, wherein the transition metal pnictide compound prepared according to the above preparation method is used as a carrier of carbon nanotubes, and a FePS3 shell is epitaxially grown on the surface; the shell thickness is 10-30nm, and the interface lattice mismatch is <2%.

[0017] The present invention also provides an application of a transition metal pnictide compound in hydrogen production by electrolysis of water. The above transition metal pnictide compound is applied in hydrogen production by electrolysis of water, and the oxygen evolution overpotential η 10 <230mV, mass activity ≥12A / mg@2V; stability >500h in 1M KOH electrolyte.

[0018] The present invention also provides an application of a transition metal pnictide compound in the preparation of a hydrogen storage material. When the transition metal pnictide compound is applied to the hydrogen storage material, the hydrogen storage capacity is ≥5.2wt%; the hydrogen absorption and desorption cycle life is >500 times, and the capacity retention rate is ≥95%.

[0019] The present invention also provides an application of a transition metal pnictogen compound in an electrochemical oxygen evolution reaction and a hydrogen evolution reaction, wherein the transition metal pnictogen compound is applied in the electrochemical oxygen evolution reaction and the hydrogen evolution reaction.

[0020] Compared with the prior art, the present invention achieves the following technical effects:

[0021] (1) Precise and controllable multi-element doping: Through dual-cavity partitioning design and pulse gas path control, the four-element (P / S / Se / Te) atomic-level uniform doping with phosphorus (P) as the main body is achieved, the element ratio deviation is <5% (EDS verification), the P content is ≥50at%, the Se / Te content is 5-20at%, and the ratio can be adjusted by adjusting the loading amount of the auxiliary deposition chamber; the atomic ratio of transition metals to phosphorus elements is 1:1.5-2.5 (EDS verification), which solves the doping failure problem caused by vapor pressure differences in traditional methods (such as Te doping amount is increased to more than 15at%). Performance improvement: The hydrogen evolution overpotential (η 10 =35mV) is higher than that of single element phosphide (η 10 >120mV) is reduced by 71%, and the mass activity (12A / mg@2V) is twice the US Department of Energy (DOE) 2025 technology goal.

[0022] (2) Revolutionary breakthrough in reaction efficiency: time cost, shortening the synthesis cycle from 20h of the traditional hydrothermal method to 40s (increased by 1800 times), and the single batch production time is less than 5min; single output, the dual-chamber design enables the single output to reach 5g / batch (the traditional single-chamber method is only 1g), and after expansion to a 6-chamber system, the production capacity is increased to 30g / batch, meeting the needs of industrial continuous production; energy consumption optimization, utilizing the instantaneous temperature rise and fall characteristics of Joule heat, energy consumption is reduced to 0.3kWh / g (traditional solid-phase method>5kWh / g), and the overall energy efficiency is increased by 16 times.

[0023] (3) Product structural advantages: Crystal purity, XRD half-peak width reduced from 1.2° to 0.3° by traditional methods, lattice distortion rate <0.5% (HRTEM statistics); surface active sites, lattice defects induced by gradient cooling, dislocation density >10 12 / cm 2 (Verified by geometric phase analysis), the active site exposure rate increased by 8 times; specific surface area, nanosheet thickness <5nm (AFM measurement), interlayer spacing 0.6-0.9nm (XRD corresponding to (002) crystal plane); surface porous structure (pore size 2-5nm, BET specific surface area >150m 2 / g), the self-assembled nanosheet structure makes the specific surface area>150m 2 / g(traditional granular materials <50m 2 / g), and the hydrogen storage capacity reaches 5.2wt% (DOE's on-board hydrogen storage system target is 6.5wt%).

[0024] (4) Production costs are greatly reduced: the utilization rate of raw materials is increased to 98% (traditional solid-phase method <70%), and the loss of red phosphorus is reduced by 40%; equipment compatibility: the existing powder metallurgy production line can be directly modified, and the modification cost is <100,000 yuan / unit (traditional CVD equipment >2 million yuan); the large-scale production cost is reduced to 80 yuan / gram (laboratory-level synthesis >500 yuan / gram).

[0025] (5) Industrial application potential: In the scenario of hydrogen production by electrolysis of water, the same hydrogen production rate can be achieved by reducing the amount of catalyst by 50%, and the annual catalyst cost of a single 100MW electrolyzer can be saved by more than 30 million yuan; in the field of hydrogen storage materials, the material's hydrogen absorption and desorption cycle life is >500 times (traditional magnesium-based materials <200 times), and the maintenance cycle of the hydrogen storage system is extended by 2.5 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of the preparation method of the present invention.

[0027] Figure 2 This is a graph showing the electrochemical performance test results of the materials measured using linear voltammetry (LSV) in Example 1, Comparative Example 1, and Comparative Example 2.

[0028] Figure 3 This is a graph showing the electrochemical performance test results of the materials measured using linear voltammetry (LSV) in Example 2 and Comparative Example 3. DETAILED DESCRIPTION

[0029] In order to help those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts should fall within the scope of protection of the present invention.

[0030] Example

[0031] The present invention is further described below with reference to specific examples and comparative examples. The following specific examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples, and are particularly not limited to the types of the various component raw materials used in the following specific examples.

[0032] The present invention provides a method for preparing a transition metal V-VI main group polynary phosphorus compound, comprising the following steps:

[0033] S1. A dual-chamber graphite boat is used as the reaction vessel, with the main reaction chamber (chamber A) loaded with a transition metal precursor and phosphorus source mixture, and the auxiliary deposition chamber (chamber B) loaded with a chalcogen precursor. The main reaction chamber (chamber A) is a boron nitride-coated graphite cylinder with a diameter of 25-35 mm and a length of 40-60 mm. The auxiliary deposition chamber (chamber B) is connected to the main reaction chamber via a porous partition with a porosity of 40-60%. The dual-chamber graphite boat can be expanded to a 4-6 chamber system, with each chamber independently temperature-controlled to an accuracy of ±10°C.

[0034] S2. Instantaneous heating and cooling using a Joule heating system: The main reaction chamber is heated to 800-1000°C within 0-10 seconds to decompose the metal precursor, while the auxiliary deposition chamber is maintained at 400-600°C to control the reduction and vaporization of the chalcogen element. The metal precursor is NiCl2, FeCl3, or a combination thereof, with a molar ratio of 1:3-5 to red phosphorus; the chalcogen element precursor is a TeO2 / Se powder mixture with a Te:Se molar ratio of 1:0.8-1.2.

[0035] S3. Periodically open the graphite rotary valve between the main reaction chamber and the auxiliary deposition chamber to achieve atomic-level doping of P, Se, and Te using the Knudsen diffusion effect; the valve opening angle is 45-75° and the frequency is 3-7 Hz. Pulse-inject H2 / Ar gas mixture is injected, with H2 accounting for 10-20%. The element ratio is adjusted to 5:2:3 P:Se:Te using mass spectrometry feedback.

[0036] S4. Gradual cooling at a rate of 50-100°C / s within 30-40 seconds to induce lattice stress and form high-density dislocation defects; wherein, the gradient cooling is divided into two stages: first, cooling to 500°C at a rate of 40-60°C / s and holding for 5-10 seconds, and then suddenly cooling at a rate of 80-120°C / s; during the cooling process, NH3 gas is introduced at a flow rate of 15-25sccm.

[0037] Example 1: Preparation of Ni-P-Se-Te nanosheets

[0038] Materials: NiCl2 powder (200 mesh) and red phosphorus in cavity A were mixed in a molar ratio of 1:4, ball milled for 2 hours and then pressed into Thin slice; 5 g of the mixture of TeO2 and Se powder (molar ratio 1:1) in cavity B was placed in a porous graphite box (to prevent powder scattering);

[0039] Parameters: Chamber A is heated to 900°C at a rate of >90°C / s, while Chamber B is maintained at 500°C for a total of 10 seconds. After the valve is opened, vapor from Chamber B is transported to Chamber A, and the co-deposition stage is maintained for 30 seconds. The temperature is then lowered to 500°C at a rate of 50°C / s, and then quenched to room temperature at a rate of 100°C / s to obtain self-supporting nanosheets, completing the defect engineering construction procedure.

[0040] Results: ①CVD deposition occurred on the surface of Ni nanoparticles: Ni+P4+Se+Te→NiP2Se 0.4 Te 0.3 ②TOF-SIMS three-dimensional imaging showed that P / Se / Te was distributed in a gradient, with the surface Se concentration reaching 12 at%; the product was a quaternary doped nanosheet (thickness 3.2±0.5 nm), with a hydrogen evolution overpotential η 10 =230mV, see Figure 2 .

[0041] Similarly, in comparative sample 1, only 5 g of Se powder is loaded into the B cavity; and in comparative sample 2, only 5 g of Te powder is loaded into the B cavity.

[0042] Example 2: Preparation of Fe-PS porous spheres

[0043] Materials: FeCl3 and red phosphorus (1:3 molar ratio) in cavity A; S powder in cavity B;

[0044] Parameters: Adjust chamber B to load S powder, cancel TeO2, increase the cooling rate to 100℃ / s, and the rest are the same as case 1.

[0045] Results: Porous microspheres (200 nm in diameter) were obtained, and the hydrogen storage cycle stability reached 500 times. Figure 3 .

[0046] Similarly, comparison sample 3 is a traditional single cavity loaded with FeCl3 and red phosphorus.

[0047] Example 3: Preparation of Fe-PS@CNT core-shell materials using a four-chamber system

[0048] New cavities: C cavity: loaded with sublimated sulfur powder (purity 99.9%), temperature controlled at 200℃ (sulfur melting point 119℃); D cavity: loaded with carbon nanotubes (CNT, diameter 20-40nm) as growth carriers.

[0049] Process parameter adjustment: Chamber A: FeCl3 and red phosphorus (1:3 molar ratio); Chamber B: empty (Te / Se was not used in this example); Chamber C: 10g sublimed sulfur powder; Chamber D: 2g CNTs spread flat on a porous graphite plate.

[0050] Segmented deposition: Stage 1 (0-8s): Chamber A is heated to 850°C to generate FeP nanoparticles; Stage 2 (8-15s): Chamber C valve is opened, and sulfur vapor (S8) reacts with FeP to generate a FePS3 shell; Stage 3 (15-25s): Chamber D is heated to 600°C to allow FePS3 to grow epitaxially on the CNT surface, forming a core-shell structure.

[0051] Key parameters: Sulfur vapor transmission pressure: 0.5-1.0 kPa (controlled by the C chamber temperature and valve opening); CNT pretreatment: treatment in Ar plasma (power 50 W) for 10 minutes to increase surface defects.

[0052] Results: Element distribution uniformity: TOF-SIMS three-dimensional imaging showed a gradient distribution of P / Se / Te atoms; Industrialization indicators: The single-time output of the 6-cavity expansion system reached 30g, and the production cost was reduced to 1 / 8 of the traditional method; Catalytic performance: In a proton exchange membrane electrolyzer, the mass activity reached 12A / mg (@2V), exceeding the DOE 2025 target value.

[0053] From the data of Example 1 and Comparative Examples 1-2, and Example 2 and Comparative Example 3, it can be seen that the present invention has the following technical advantages:

[0054] (1) Precise and controllable multi-element doping: Through dual-cavity partitioning design and pulse gas path control, the four-element (P / S / Se / Te) atomic-level uniform doping with phosphorus (P) as the main body is achieved, the element ratio deviation is <5% (EDS verification), the P content is ≥50at%, the Se / Te content is 5-20at%, and the ratio can be adjusted by adjusting the loading amount of the auxiliary deposition chamber; the atomic ratio of transition metals to phosphorus elements is 1:1.5-2.5 (EDS verification), which solves the doping failure problem caused by vapor pressure differences in traditional methods (such as Te doping amount is increased to more than 15at%). Performance improvement: The hydrogen evolution overpotential (η 10 =35mV) is higher than that of single element phosphide (η 10 >120mV) is reduced by 71%, and the mass activity (12A / mg@2V) is twice the US Department of Energy (DOE) 2025 technology goal.

[0055] (2) Revolutionary breakthrough in reaction efficiency: time cost, shortening the synthesis cycle from 20h of the traditional hydrothermal method to 40s (increased by 1800 times), and the single batch production time is less than 5min; single output, the dual-chamber design enables the single output to reach 5g / batch (the traditional single-chamber method is only 1g), and after expansion to a 6-chamber system, the production capacity is increased to 30g / batch, meeting the needs of industrial continuous production; energy consumption optimization, utilizing the instantaneous temperature rise and fall characteristics of Joule heat, energy consumption is reduced to 0.3kWh / g (traditional solid-phase method>5kWh / g), and the overall energy efficiency is increased by 16 times.

[0056] (3) Product structural advantages: Crystal purity, XRD half-peak width reduced from 1.2° to 0.3° by traditional methods, lattice distortion rate <0.5% (HRTEM statistics); surface active sites, lattice defects induced by gradient cooling, dislocation density >10 12 / cm 2(Verified by geometric phase analysis), the active site exposure rate increased by 8 times; specific surface area, nanosheet thickness <5nm (AFM measurement), interlayer spacing 0.6-0.9nm (XRD corresponding to (002) crystal plane); surface porous structure (pore size 2-5nm, BET specific surface area >150m 2 / g), the self-assembled nanosheet structure makes the specific surface area>150m 2 / g(traditional granular materials <50m 2 / g), and the hydrogen storage capacity reaches 5.2wt% (DOE's on-board hydrogen storage system target is 6.5wt%).

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a transition metal V-VI main group polynary phosphorus compound, characterized in that: The following steps are involved: S1. A dual-chamber graphite boat is used as a reaction vessel, wherein the main reaction chamber is loaded with a mixture of a transition metal precursor and a phosphorus source, and the auxiliary deposition chamber is loaded with a chalcogen precursor; S2. Instantaneous heating and cooling using a Joule heating system: The main reaction chamber is heated to 800-1000°C within 0-10 seconds to decompose the metal precursor, while the auxiliary deposition chamber is maintained at 400-600°C to control the reduction and vaporization of the chalcogenide elements. S3. Periodically open the graphite rotary valve between the main reaction chamber and the auxiliary deposition chamber to achieve P / Se / Te atomic-level doping using the Knudsen diffusion effect; S4. Gradual cooling at a rate of 50-100°C / s within 30-40 seconds to induce lattice stress to form high-density dislocation defects.

2. The preparation method according to claim 1, characterized in that The double-cavity graphite boat comprises: a main reaction chamber which is a boron nitride coated graphite cylinder with a diameter of 25-35 mm and a length of 40-60 mm; and an auxiliary deposition chamber connected to the main reaction chamber through a porous partition with a porosity of 40-60%.

3. The preparation method according to claim 1, characterized in that In step S2: the metal precursor is NiCl2, FeCl3 or a combination thereof, and the molar ratio of the metal precursor to red phosphorus is 1:3-5; the chalcogen element precursor is a TeO2 / Se powder mixture, and the molar ratio of Te:Se is 1:0.8-1.

2.

4. The preparation method according to claim 1, characterized in that In step S3: the valve opening angle is 45-75°, the frequency is 3-7 Hz; the H2 / Ar mixed gas is pulse-injected, with the H2 accounting for 10-20%; and the element ratio is adjusted to P:Se:Te=5:2:3 through mass spectrometry feedback.

5. The preparation method according to claim 1, characterized in that In step S4: gradient cooling is divided into two stages: first, cooling at 40-60°C / s to 500°C and holding for 5-10s, and then quenching at 80-120°C / s; NH3 gas is introduced during the cooling process with a flow rate of 15-25sccm.

6. A transition metal pnictogen compound, characterized in that: Prepared by the preparation method according to any one of claims 1 to 5, comprising a multi-element system such as Ni-P-Se-Te or Fe-PS; the nanosheet thickness is less than 5 nm, the interlayer spacing is 0.6-0.9 nm; the surface dislocation density is greater than 1012 / cm 2 , BET specific surface area>150m 2 / g.

7. A core-shell structure material, characterized in that: The transition metal pnictide compound prepared by the preparation method according to any one of claims 1-5, wherein a FePS3 shell is epitaxially grown on the surface of carbon nanotubes as a carrier; the shell thickness is 10-30 nm, and the interface lattice mismatch is <2%.

8. Application of a transition metal pnictogen compound in hydrogen production by water electrolysis, characterized in that: The transition metal pnictogen compound according to claim 6 is used in the production of hydrogen by electrolysis of water.

9. Use of a transition metal pnictogen compound in the preparation of a hydrogen storage material, characterized in that: The transition metal pnictogen compound according to claim 6 is used in a hydrogen storage material.

10. Use of a transition metal pnictogen compound in electrochemical oxygen evolution reaction and hydrogen evolution reaction, characterized in that: The transition metal pnictogen compound of claim 6 is used in electrochemical oxygen evolution reaction and hydrogen evolution reaction.

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