Method for preparing arsine through electro-catalysis by taking ash arsenic as arsenic source

Abstract

The invention discloses a method for preparing arsine through electro-catalysis by taking ash arsenic as an arsenic source, which comprises the following steps: taking a PdFe bimetallic alloy nanoparticle electrode loaded on a nickel foil as a working cathode, arranging a counter electrode anode, taking ash arsenic as an arsenic source, and carrying out catalytic reduction on ash arsenic in an alkaline electrolyte through a constant-current electrolysis method to prepare arsine. According to the method, efficient synthesis of arsine can be achieved within a wide current density range, ash arsenic which is common and easy to obtain is used as an arsenic source, a PdFe / NF electrode which is simply prepared through electrodeposition is used as a catalytic working cathode, reaction conditions are mild, high temperature, high pressure and chemical reducing agents are not needed, an electrocatalyst can be repeatedly used, and the method is suitable for industrial production. And a green, safe and efficient method is provided for synthesis of arsine.

Description

Technical Field

[0001] The present invention belongs to the technical field of arsine synthesis, and particularly relates to a method for electrocatalytically preparing arsine using gray arsenic as an arsenic source. Background Art

[0002] Arsine is a key dopant in the semiconductor industry and plays an important role especially in the manufacture of III-V compound semiconductors (such as gallium arsenide). By using arsine in vapor phase epitaxy and molecular beam epitaxy processes, the arsenic content in semiconductor materials can be precisely controlled, thereby adjusting their electrical properties. This control ability makes arsine play a crucial role in high-tech fields such as semiconductor manufacturing, flat panel display production, and photovoltaic cell manufacturing.

[0003] Currently, the preparation of arsine mainly relies on thermochemical reduction methods. This production process requires a large amount of chemical reducing agents and generates a large amount of waste liquid, which not only does not conform to the concept of green development but also poses a relatively large safety hazard. In recent years, electrochemical technology has become a powerful green and efficient tool in chemical synthesis. Electrochemistry realizes the reduction and oxidation of substances through electron gain and loss, avoiding the need for oxidants and reducing agents in traditional chemical reactions. The current and potential in the electrochemical process can be arbitrarily controlled, with the advantages of simple operation, environmental friendliness, and mild conditions. Therefore, the application of electrochemical methods in arsine preparation has broad prospects. Summary of the Invention

[0004] The present invention provides a method for electrocatalytically preparing arsine using gray arsenic as an arsenic source at room temperature. Currently, the preparation methods of arsine mainly include chemical reduction methods, gas phase reaction methods, etc. Although these methods can produce arsine, they have problems such as incomplete reactions, many by-products, and low safety. The present invention uses a PdFe bimetallic alloy nanoparticle electrode loaded on a nickel foil as the working cathode, uses gray arsenic as the arsenic source, and realizes the electrocatalytic reduction of gray arsenic to arsine by constant current electrolysis in an alkaline electrolyte at room temperature. High-efficiency synthesis of arsine can be achieved within a relatively wide current density range, and common and easily available gray arsenic is used as the arsenic source, and a PdFe / NF electrode prepared by simple electrodeposition is used as the catalytic working cathode. The reaction conditions are mild, without the need for high temperature, high pressure, and chemical reducing agents, and the electrocatalyst can be reused. It provides a green, safe, and efficient method for the synthesis of arsine.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] In the method for electrocatalytically preparing arsine using gray arsenic as an arsenic source, a PdFe bimetallic alloy nanoparticle electrode loaded on a nickel foil is used as the working cathode, and a counter electrode anode is set. Using gray arsenic as the arsenic source, gray arsenic is catalytically reduced by constant current electrolysis in an alkaline electrolyte to prepare arsine.

[0007] Further, the method for electrocatalytic preparation of arsine using gray arsenic as an arsenic source specifically includes the following steps:

[0008] 1) Using a PdFe bimetallic alloy nanoparticle electrode supported on a nickel foil as the working cathode, and a carbon or Pt sheet as the counter electrode anode, the cathode chamber and the anode chamber of the electrolytic cell are separated by a proton exchange membrane;

[0009] 2) Add gray arsenic and an alkaline electrolyte to the cathode chamber, and add an alkaline electrolyte to the anode chamber. Stir the electrolyte in the cathode chamber to fully disperse the gray arsenic;

[0010] 3) The working cathode and the counter electrode anode are respectively connected to an electrochemical workstation through wires, and the electrolysis system is subjected to constant current electrolysis. The current density of the constant current is 5 - 40 mA / cm 2 , and arsine is prepared.

[0011] Further, in step 2), the alkaline electrolyte is an aqueous solution of one or more of sodium carbonate, potassium carbonate, potassium hydroxide, and sodium hydroxide, and its concentration is 0.1 - 1.5 M, preferably 0.5 - 1 M.

[0012] Further, in step 2), the amount of gray arsenic added to the electrolyte in the cathode chamber is 300 - 800 g / L, preferably 600 - 700 g / L.

[0013] Further, the electrocatalytic reaction time is 5 - 100 h, preferably 10 - 20 h.

[0014] Further, the PdFe bimetallic alloy nanoparticle electrode supported on a nickel foil is labeled as the PdFe / NF electrode, and its preparation method includes the following steps:

[0015] S1: Pretreat the nickel foil to remove the surface oxide layer and impurities;

[0016] S2: Place the nickel foil obtained in step S1 in a mixed aqueous solution containing Fe salts and Pd salts, and perform electrodeposition in a standard three - electrode system. The nickel foil serves as the working cathode, the Pt sheet serves as the counter electrode, and the saturated calomel electrode serves as the reference electrode. During the electrodeposition process, Pd and Fe elements are deposited onto the nickel foil. After completion, rinse and dry for standby;

[0017] S3: Bake the electrode obtained in step S2 in an inert gas atmosphere at 400 - 600 °C for 1 - 4 h, and cool to room temperature to obtain the PdFe / NF electrode.

[0018] Further, the pretreatment steps in step S1 are as follows: Place the nickel foil in a 2 - 4M hydrochloric acid solution and ultrasonicate for 2 - 20 minutes to remove the surface oxide layer. Subsequently, rinse the surface acidic solution with deionized water, then place it in acetone and ultrasonicate to remove the residual organic matter on the surface. Finally, rinse it with deionized water and dry it, and the treatment is completed.

[0019] Further, in step S2, the Pd salt is one of K 2 PdCl 4 , Na 2 PdCl 4 , PdCl 2 and K 2 PdCl 6 . Its concentration in the mixed aqueous solution is 0.1 - 1M; the Fe salt is one of FeCl 3 , Fe 2 (SO 4 ) 3 and Fe(NO 3 ) 3 . Its concentration in the mixed aqueous solution is 0.1 - 1M, preferably 0.5M.

[0020] Further, in step S2, the concentration of the Pd salt in the mixed aqueous solution is 0.1 - 0.3M, preferably 0.2M. When performing electrodeposition, stop the deposition when the charge reaches 300 - 1500C, preferably stop the deposition when the charge reaches 400 - 500C.

[0021] Further, a Co salt is added to the mixed aqueous solution in step S2. The Co salt is one of the chlorides, sulfates or nitrates of Co. Its concentration in the mixed aqueous solution is 0.1 - 1M, preferably 0.5M. The finally prepared catalyst is a Co - doped PdFeCo / NF multi - metal electrode.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1) The present invention realizes the electrocatalytic preparation of arsine using gray arsenic as the arsenic source at room temperature. In a relatively wide current density range, the efficient synthesis of arsine is achieved, and the arsine concentration can reach 43.1% in a relatively wide current density range.

[0024] 2) The present invention uses PdFe bimetallic alloy nanoparticles loaded on nickel foil as the electrocatalyst, without high temperature, high pressure and chemical reducing agents. The reaction conditions are mild, the operation is simple, the catalyst can be reused and easily recovered, effectively avoiding the problems of complex process, low safety and large waste liquid pollution in other synthesis methods.

[0025] 3) The working electrode of the present invention has good durability and stability and can be recycled multiple times. Description of the Drawings

[0026] Figure 1 This is the TEM image of the cathode working electrode PdFe / NF in Example 1 of the present invention. Detailed implementation manners

[0027] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0028] In the embodiment of the present invention, the size of the nickel foil is 10×10 cm 2 .

[0029] Example 1: Synthesis of arsine

[0030] 1) Preparation of the cathode working electrode

[0031] Step 1: Place the nickel foil in a 3M hydrochloric acid solution and ultrasonicate for 10 min to remove the surface oxide layer; then rinse the surface acidic solution with deionized water, and then place it in acetone and ultrasonicate for 10 min to remove the residual organic matter on the surface; finally, rinse it with deionized water and dry it for standby;

[0032] Step 2: Place the nickel foil obtained in Step 1 in a mixed aqueous solution containing 0.5M Fe(NO 3 ) 3 and 0.2M K 2 PdCl 4 , and perform electrodeposition at a current of 20 mA in a standard three-electrode system. The nickel foil serves as the cathode working electrode, the Pt sheet serves as the counter electrode, and the saturated calomel electrode serves as the reference electrode. During the electrodeposition process, Pd and Fe elements are deposited onto the nickel foil. When the charge reaches 500 C, stop the deposition, rinse it and dry it for standby;

[0033] Step 3: Bake the electrode obtained in Step 2 in an Ar atmosphere at 500 °C for 3 h. After cooling to room temperature, rinse it with deionized water and dry it to obtain the PdFe / NF electrode. The TEM image of the PdFe / NF electrode is as Figure 1 shown, and there are uniformly dispersed PdFe nanoparticles on the surface of the nickel foil substrate.

[0034] 2) Catalytic reduction of gray arsenic to prepare arsine by constant current electrolysis

[0035] Using a 10×10 cm 2The double-chamber standard flow electrolytic cell with an effective area serves as the container. The cathode chamber and the anode chamber are separated by a proton exchange membrane (Nafion 117). 1 L of an alkaline aqueous solution of 1 M KOH is added to the cathode chamber, and 1 L of an alkaline aqueous solution of 1 M KOH is added to the anode chamber. Then, 700 g of gray arsenic is added to the cathode chamber, a magnetic stirrer bar is added to the cathode chamber, and the cathode chamber is placed on a magnetic stirrer to stir the electrolyte in the cathode chamber. PdFe / NF is used as the cathode working electrode, a Pt sheet is used as the counter electrode, and a Hg / HgO (1.0 M KOH) electrode is used as the reference electrode. The cathode and anode electrodes are respectively connected to an electrochemical workstation through wires. A constant current of 1 A - 5 A is selected for the reaction, and the arsine concentration is analyzed by gas chromatography after 5 hours / 10 hours of reaction.

[0036] According to the above operation process, tests are carried out at different constant currents, and the results are shown in Table 1.

[0037] In the experiment of catalytic reduction of gray arsenic to prepare arsine by the constant current electrolysis method of the present invention, there are only two cathode products, namely the arsenic hydrogenation product (arsine AsH 3 ), and hydrogen. The arsine concentration in Table 1 refers to the volume fraction of arsine in the mixed system of arsine and hydrogen. In the experiment of the present invention, the gas outlet of the cathode chamber is connected to a tail gas treatment device (multiple series-connected absorption tanks filled with saturated potassium permanganate aqueous solution). When sampling and analyzing, the valve at the gas outlet is switched to connect to the gas chromatography to measure the arsine concentration in the mixed gas.

[0038] Table 1. Arsine concentration (%) at different currents

[0039]

[0040]

[0041] As shown in Table 1, under different current test conditions, the arsine concentration generated at the cathode can exceed 20%. Especially under the action of a 3 A current, after 10 hours of testing, the arsine concentration reaches 43.1%. When the current is low, the conversion rate of gray arsenic is slow; as the current further increases, due to the competitive effect of the hydrogen evolution reaction, the arsine concentration decreases.

[0042] Example 2: Regulating the electrolyte concentration

[0043] The experimental conditions of Example 2 are repeated in Example 1, with the difference only being that "in step 2), the concentration of the alkaline aqueous solution of KOH is replaced with 0.5 M, 1 M, 1.5 M, 2 M, 2.5 M, or 3 M, and the concentration of the alkaline aqueous solution of KOH in the cathode chamber and the anode chamber is the same. A constant current of 3 A is selected for the reaction", and other conditions remain unchanged. The arsine concentration is analyzed by gas chromatography after 5 h / 10 h of reaction.

[0044] According to the above operation process, tests were carried out at different electrolyte concentrations, and the results are shown in Table 2.

[0045] Table 2. Arsine concentration (%) at different electrolyte concentrations

[0046]

[0047]

[0048] As shown in Table 2, tests were carried out at different electrolyte concentrations, and the results show that the electrolyte concentration has a great influence on arsine, showing a volcano-shaped curve. Specifically, when the electrolyte concentration is 1 M or less, the arsine concentration can reach more than 30%; when the electrolyte concentration is increased (1.5 - 3 M), the arsine concentration decreases rapidly. This is because the ion transport flux in the electrolyte becomes larger, the rate of the competing hydrogen evolution reaction is faster, and the active hydrogen present in the solution is not sufficient to be converted into arsine.

[0049] Example 3: Preparation of a cathode electrode by regulating the Pd salt concentration

[0050] In this Example 3, the Pd salt concentration in the PdFe / NF electrode was regulated to control the ratio of Pd and Fe. The preparation steps of the PdFe / NF electrode were repeated as in Example 1, with the only difference being that "in the preparation step of the cathode working electrode, the concentration of K 2 PdCl 4 was replaced with X M (X refers to the concentration of K 2 PdCl 4 ", and other conditions remained unchanged, and finally the PdFe / NF electrode was prepared.

[0051] The PdFe / NF electrode of Example 3 was used for the catalytic reduction of gray arsenic to prepare arsine by constant current electrolysis. The experimental steps were repeated as in Example 1, a constant current of 3 A was selected for the reaction, and other conditions remained unchanged. After 5 hours / 10 hours of reaction, the arsine concentration was analyzed by gas chromatography, and the test results are shown in Table 3.

[0052] Table 3. Arsine production at different Pd salt concentrations

[0053]

[0054] As shown in Table 3, the content of Pd has a significant influence on the efficiency of the conversion of gray arsenic to arsine. By regulating the content of the Pd precursor, the content of Pd in the cathode working electrode can be controlled; specifically, as the content of Pd increases, the arsine concentration first increases and then decreases (at 0.2 M K 2 PdCl 4When it reaches the best), this phenomenon may stem from the fact that Pd has good adsorption capacity for the active hydrogen generated by cathode electrolysis. When the content of adsorbed hydrogen reaches a certain level, it is more likely to be converted into hydrogen gas, thus affecting the production of arsine.

[0055] Example 4: Optimization of multi-metal doped electrode

[0056] In Example 4, the electronic state of the active component Pd was further regulated by multi-metal doping to optimize the electrode. The specific steps for preparing the cathode working electrode in Example 4 are as follows:

[0057] Step 1: Place the nickel foil in 3M hydrochloric acid solution and ultrasonicate for 10 min to remove the surface oxide layer; then rinse the surface acidic solution with deionized water, and place it in acetone and ultrasonicate for 10 min to remove the residual organic matter on the surface; finally, rinse it with deionized water and dry it for later use;

[0058] Step 2: Place the nickel foil obtained in Step 1 in a mixed aqueous solution containing 0.5M Fe(NO 3 ) 3 , 0.5M Z (where Z refers to another nitrate) and 0.2M K 2 PdCl 4 , and perform electrodeposition at a current of 20 mA in a standard three-electrode system. The nickel foil serves as the cathode working electrode, the Pt sheet serves as the counter electrode, and the saturated calomel electrode serves as the reference electrode. Stop deposition when the charge reaches 500 C, rinse it and dry it for later use;

[0059] Step 3: Bake the electrode obtained in Step 2 in an Ar atmosphere at 500 °C for 3 h. After cooling to room temperature, rinse it with deionized water and dry it to obtain the PdFeZ / NF multi-metal electrode.

[0060] In Example 4, the PdFeZ / NF electrode doped with multiple metals was used for the catalytic reduction of gray arsenic to prepare arsine by constant current electrolysis. The experimental steps were repeated as in Example 1, and a constant current of 3 A was selected for the reaction. Other conditions remained unchanged. After 5 hours / 10 hours of reaction, the arsine concentration was analyzed by gas chromatography. The test results are shown in Table 4.

[0061] Table 4. Arsine concentration (%) synthesized by multi-metal doped electrodes

[0062]

[0063]

[0064] As shown in Table 4, the performance test results of the multi-metal doped electrodes indicate that the Co element has a significant electronic regulation effect on Pd. Specifically, for the PdFeCo / NF electrode synthesized by adding a Co precursor to the deposition solution, the arsine concentration reaches 48.8%, which is significantly better than that of the pure PdFe / NF electrode. This result shows that the doping of the Co element significantly promotes the arsine synthesis reaction and improves the catalytic performance of the electrode.

[0065] Comparative Example 1: Using other metals doped with Pd to prepare the cathode working electrode

[0066] Step 1: Place the nickel foil in 3M hydrochloric acid solution and ultrasonicate for 10 min to remove the surface oxide layer; then rinse the surface acidic solution with deionized water, and place it in acetone and ultrasonicate for 10 min to remove the residual organic matter on the surface; finally, rinse it with deionized water and dry it for later use.

[0067] Step 2: Place the nickel foil obtained in Step 1 in a mixed aqueous solution containing 0.5M Y (Y refers to other nitrates) and 0.2M K 2 PdCl 4 and perform electrodeposition at a current of 20 mA in a standard three-electrode system. The nickel foil serves as the cathode working electrode, the Pt sheet serves as the counter electrode, and the saturated calomel electrode serves as the reference electrode. Stop the deposition when the charge reaches 500 C, rinse it and dry it for later use.

[0068] Step 3: Bake the electrode obtained in Step 2 in an Ar atmosphere at 500 °C for 3 h. After cooling to room temperature, rinse it with deionized water and dry it to obtain the PdY / NF electrode.

[0069] Use the constant current electrolysis method to catalytically reduce gray arsenic to prepare arsine for the PdY / NF electrodes doped with different metals in Comparative Example 1. Repeat the experimental steps of Example 1, select a constant current of 3 A for the reaction, keep other conditions unchanged, and analyze the arsine concentration by gas chromatography after 5 h / 10 h of reaction. The test results are shown in Table 5.

[0070] Table 5. Arsine concentration (%) synthesized by electrodes doped with different metals and Pd

[0071]

[0072] As shown in Table 5, the performance test results of different metals doped with Pd indicate that the Fe element has a unique electronic regulation effect on Pd and can inhibit the hydrogen evolution reaction to a certain extent.

[0073] Comparative Example 2: Using different substrate materials for electrodeposition to prepare PdFe / Z electrodes

[0074] The preparation steps of the cathode working electrode in Comparative Example 2 were repeated as in Example 1, except that "the nickel foil was replaced with a substrate material Z of the same size (Z refers to other substrate materials, selected from nickel foam, titanium foam, copper foil, nickel foil or platinum sheet)", and other conditions remained unchanged. Finally, the PdFe / Z electrode was obtained.

[0075] In Comparative Example 2, the PdFe / Z electrode was prepared using different substrate materials for the catalytic reduction of gray arsenic to prepare arsine by constant current electrolysis. The experimental steps were repeated as in Example 1, and a constant current of 3 A was selected for the reaction. Other conditions remained unchanged. After the reaction for 5 h / 10 h, the arsine concentration was analyzed by gas chromatography. The test results are shown in Table 6.

[0076] Table 6. Arsine concentration (%) synthesized by electrodes prepared with different substrate materials

[0077]

[0078] As shown in Table 6, the performance test results of the PdFe / Z electrodes prepared by electrodeposition using different substrate materials show that the nickel substrate material has outstanding performance in the synthesis of arsine due to its good weak hydrogen evolution property, and the nickel foil is the best as the substrate.

[0079] Comparative Example 3: Synthesis of arsine using different arsenic sources

[0080] Using a 10×10 cm 2 A two-chamber standard flow electrolytic cell with an effective area was used as the container. The cathode chamber and the anode chamber were separated by a proton exchange membrane (Nafion 117). 1 L of an alkaline aqueous solution of 1 M KOH was added to the cathode chamber, and 1 L of an alkaline aqueous solution of 1 M KOH was added to the anode chamber. Then, 700 g of different arsenic sources (see Table 7 in detail) were added to the cathode and stirred by a magnetic stirrer. The PdFe / NF prepared in Example 1 was used as the cathode working electrode, a Pt sheet was used as the counter electrode, and a Hg / HgO (1.0 M KOH) electrode was used as the reference electrode. The cathode and anode electrodes were respectively connected to an electrochemical workstation by wires. A constant current of 3 A was selected for the reaction. After the reaction for 5 hours / 10 hours, the arsine concentration was analyzed by gas chromatography. The test results are shown in Table 7.

[0081] Table 7. Arsine concentration (%) synthesized using different arsenic sources

[0082]

[0083] As shown in Table 7, the performance test results of synthesizing arsine using different arsenic sources show that gray arsenic has the best performance in producing arsine, which is attributed to the zero-valent chemical state of gray arsenic; in addition, gray arsenic has better electrical conductivity than other arsenic sources, and this good electron transport ability has a significant impact on the production of arsine.

[0084] The content described in this specification is only an enumeration of the implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments.

Claims

1. A method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source, characterized in that: A PdFe bimetallic alloy nanoparticle electrode loaded on a nickel foil is used as a working cathode, a counter electrode anode is set, and gray arsenic is used as an arsenic source. Arsine is prepared by catalytic reduction of gray arsenic in an alkaline electrolyte through constant current electrolysis.

2. The method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source according to claim 1, characterized in that: The specific steps include: 1) A PdFe bimetallic alloy nanoparticle electrode loaded on a nickel foil is used as a working cathode, a carbon or Pt sheet is used as a counter electrode anode, and the cathode chamber and the anode chamber of the electrolytic cell are separated by a proton membrane; 2) adding gray arsenic and alkaline electrolyte into the cathode chamber, adding alkaline electrolyte into the anode chamber, and stirring the electrolyte in the cathode chamber to fully disperse the gray arsenic; 3) The working cathode and the counter electrode anode are connected to the electrochemical workstation through wires, and the electrolysis system performs constant current electrolysis with a current density of 5-40 mA / cm 2 , to prepare arsine.

3. The method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source according to claim 2, characterized in that: In step 2), the alkaline electrolyte is an aqueous solution of one or more of sodium carbonate, potassium carbonate, potassium hydroxide, and sodium hydroxide, and its concentration is 0.1-1.5M, preferably 0.5-1M.

4. The method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source according to claim 2, characterized in that: In step 2), the amount of gray arsenic added to the cathode chamber electrolyte is 300-800 g / L, preferably 600-700 g / L.

5. The method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source according to claim 2, characterized in that: The electrocatalytic reaction time is 5-100 hours, preferably 10-20 hours.

6. The method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source according to claim 1, characterized in that: The PdFe bimetallic alloy nanoparticle electrode loaded on nickel foil is marked as PdFe / NF electrode, and its preparation method comprises the following steps: S1: Pre-treating the nickel foil to remove the surface oxide layer and impurities; S2: placing the nickel foil obtained in step S1 in a mixed aqueous solution containing Fe salt and Pd salt, and performing electrodeposition in a standard three-electrode system, wherein the nickel foil is used as a cathode working electrode, the Pt sheet is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode. During the electrodeposition process, Pd and Fe elements are deposited on the nickel foil, and then the nickel foil is rinsed and dried for later use; S3: calcining the electrode obtained in step S2 at 400-600° C. for 1-4 h in an inert gas atmosphere, and cooling to room temperature to obtain the PdFe / NF electrode.

7. The method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source according to claim 6, characterized in that: The pretreatment steps in step S1 are: placing the nickel foil in a 2-4M hydrochloric acid solution and ultrasonically treating it for 2-20 minutes to remove the surface oxide layer, then rinsing the surface acid solution with deionized water, and then placing it in acetone and ultrasonically removing the residual organic matter on the surface, and finally rinsing it with deionized water and drying it, and the treatment is completed.

8. The method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source according to claim 6, characterized in that: In step S2, the Pd salt is one of K2PdCl4, Na2PdCl4, PdCl2 and K2PdCl6, and its concentration in the mixed aqueous solution is 0.1-1M; the Fe salt is one of FeCl3, Fe2(SO4)3 and Fe(NO3)3, and its concentration in the mixed aqueous solution is 0.1-1M, preferably 0.5M; In step S2, the concentration of the Pd salt in the mixed aqueous solution is 0.1-0.3M, preferably 0.2M.

9. The method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source according to claim 6, characterized in that: A Co salt is also added to the mixed aqueous solution of step S2. The Co salt is a chloride, sulfate or nitrate of Co. The concentration of the Co salt in the mixed aqueous solution is 0.1-1M, preferably 0.5M. The final catalyst is a Co-doped PdFeCo / NF multi-metal electrode.

10. The method for preparing arsine by electrocatalysis using gray arsenic as an arsenic source according to claim 6, characterized in that: During the electrodeposition, the deposition is stopped when the charge reaches 300-1500C, preferably when the charge reaches 400-500C.

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