CoAs3 catalyst as well as preparation method and application thereof

Abstract

The invention discloses a CoAs3 catalyst and a preparation method and application thereof, and the method comprises the following steps: firstly, mixing Co powder and As powder, and grinding; and then under the protection of inert atmosphere, carrying out heat treatment on the ground mixture to prepare the CoAs3 catalyst, the temperature in the heat treatment process is 750-850 DEG C, and the time is 40-60 hours. The preparation method of the CoAs3 catalyst is simple, easy to operate and low in cost, and the technical problem that in the prior art, topological semimetal photocatalytic hydrogen production performance is poor is effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of the development of photocatalytic hydrogen production materials, and relates to a CoAs 3 catalyst and its preparation method and application. Background Art

[0002] As ideal catalysts in the photocatalytic hydrogen evolution system, noble metal materials such as platinum metals, alloys, oxides and their composites, although having good performance, are scarce in the earth's crust and have limited global production, resulting in high production costs, which makes it difficult to use these catalysts on a large scale industrially. In view of this, it is particularly crucial and urgent to develop non-noble metal catalysts with low cost, high performance and wide distribution to replace noble metal catalysts.

[0003] With the gradual expansion of the application scope of topological materials, topological catalysis has attracted the attention of many scientific researchers. Topological catalysis refers to the process of regulating catalytic reactions by using the special electronic structure of topological materials. Topological materials have unique surface electronic states, which are protected by symmetry and show good stability to external perturbations. This unique stability makes topological materials an ideal platform for studying the surface electronic state effects in catalytic reactions. In catalytic reactions, the surface electronic states of catalysts play a key role in processes such as the adsorption of reactants, electron transfer, and the formation of intermediates. Topological catalysis can regulate these processes by precisely "switching" the topological surface states, thereby designing catalysts with better performance. Compared with ordinary metals, topological semimetals refer to materials in which the topological characteristic bulk energy bands cross near the Fermi surface, forming gapless electronic states, and the density of states at the energy band crossing points on the Fermi surface is zero. Topological semimetals not only have topologically non-trivial surface states (boundary states), but also have conductive bulk states, and the linearly crossed energy bands on their Fermi surfaces provide extremely high Fermi velocities for the electronic states participating in the catalytic process. Therefore, topological semimetals may be potential efficient catalytic platforms. However, the existing preparation processes of topological photocatalytic hydrogen evolution materials are complex, and the photocatalytic hydrogen production performance of the materials is poor. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a CoAs 3 catalyst and its preparation method and application, so as to solve the technical problem of poor photocatalytic hydrogen production performance of topological semimetals in the prior art.

[0005] The present invention is realized through the following technical solutions: A preparation method of a CoAs 3 catalyst, comprising the following steps: S1: Mix Co powder and As powder, and then carry out grinding treatment; S2: Under the protection of an inert atmosphere, the ground mixture is heat-treated to obtain the CoAs 3 catalyst; during the heat treatment process, the temperature is 750 - 850 °C and the time is 40 - 60 h.

[0006] Preferably, during the heat treatment process, the temperature is 800 °C and the time is 50 h.

[0007] Preferably, the molar ratio of the Co powder to the As powder is 1:3.

[0008] Preferably, during the grinding process, the grinding time is 30 - 40 min.

[0009] Preferably, during the heat treatment process, the heating rate is 80 - 120 °C / h.

[0010] Preferably, the purity of the Co powder is 2N8 and the purity of the As powder is 5N.

[0011] A kind of CoAs 3 catalyst is obtained by the above method.

[0012] The above-mentioned CoAs 3 application of the catalyst in photocatalytic hydrogen production, the above-mentioned CoAs 3 catalyst is dispersed in an aqueous triethanolamine solution, and then eosin tetrabromide is added. After stirring evenly, a photocatalytic hydrogen production system is obtained; the hydrogen production rate of the photocatalytic hydrogen production system under the illumination condition of a 300 W xenon lamp at 420 nm is 2350 - 2450 μmol / g / h.

[0013] Preferably, the mass ratio of the CoAs 3 catalyst to the eosin tetrabromide is 25:(10 - 80).

[0014] Preferably, the mass ratio of the CoAs 3 catalyst to the eosin tetrabromide is 25:(40 - 80).

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention discloses a preparation method of a CoAs 3 catalyst. Firstly, the CoAs 3The catalyst exhibits excellent hydrogen production performance after being combined with fuel. The core reason can be attributed to the synergistic effect of a unique topological electronic structure, optimized catalytic active sites, and efficient carrier dynamics characteristics. First, during the preparation process, through fine grinding treatment, Co powder and As powder are fully mixed and the particle size is reduced. This not only increases the contact area of the reactants but also promotes the uniform diffusion and combination of Co and As elements during the subsequent heat treatment process. The subsequent heat treatment step is carried out under the protection of an inert atmosphere. Through high-temperature heat treatment (750 - 850 °C) and long-time crystallization (40 - 60 h), CoAs 3 crystalline phase has the topological semimetal characteristics of triple-degenerate fermions, which are revealed by density functional theory calculations. When considering spin-orbit coupling (SOC), the band structure of CoAs 3 shows triple-degenerate points protected by C3 rotational symmetry and mirror symmetry along the Γ - A path, resulting in non-degenerate state crossings of the conduction band and valence band near the Fermi level. This topological semimetal property endows the material with high conductivity and carriers with low effective mass, significantly improving the separation efficiency and migration rate of photo-generated electron-hole pairs, enabling the electrons generated by photoexcitation to quickly transfer to the catalyst surface to participate in the reduction reaction. At the same time, its unique electronic band structure reduces the overpotential of the hydrogen evolution reaction, providing a thermodynamic advantage for proton reduction.

[0016] Secondly, the synergistic effect of grinding and high-temperature synthesis promotes the formation of highly dispersed active sites of Co and As atoms. As a transition metal center, Co hybridizes its 3d orbitals with the 4p orbitals of As to form strong covalent bonds, constructing abundant Co-As active sites on the surface. These sites have high selectivity for the adsorption and dissociation of water molecules. Electrochemical active area tests show that its value reaches 3.25×10 -4 mF / cm², indicating that the catalyst surface has a high density of electrochemical active sites, providing an abundant interface for proton adsorption and H-H bond formation. In addition, during use, eosin tetrabromide is introduced as a photosensitizer and anchored on the catalyst surface through π-π stacking, expanding the light absorption range to the visible light region (above 420 nm), and efficiently transferring the excited-state electrons to the conduction band of CoAs 3 through the electron injection mechanism, further improving the light energy utilization rate. Triethanolamine, as a hole sacrificial agent, effectively inhibits carrier recombination, making the quantum yield reach 15.2% at 495 nm.

[0017] The CoAs 3 catalyst provided by the present invention has a simple preparation method, is easy to operate, has a low cost, and exhibits good photocatalytic hydrogen production performance.

[0018] At the same time, the present invention also discloses one kind of CoAs as described above 3Application of catalyst in photocatalytic hydrogen production, and a CoAs 3 The catalyst was dispersed in an aqueous solution of triethanolamine, and then eosin was added. After stirring evenly, a photocatalytic hydrogen production system was prepared. In this photocatalytic hydrogen production system, triethanolamine as a hole sacrificial agent effectively inhibited the carrier recombination, effectively improving the quantum yield. Eosin as a photosensitizer effectively promoted the separation of photo-generated charges, reducing the recombination probability of electrons and holes, thereby improving the photocatalytic efficiency.

[0019] Furthermore, another inventive point of the present invention lies in that the ratio of the CoAs 3 catalyst to the eosin is 25 mg:(10~80) mg, maximizing the synergistic effect between the catalyst and the photosensitizer (eosin), thereby improving the efficiency of the photocatalytic reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0021] Figure 1 X-ray diffraction pattern of CoAs 3 prepared in Example 1 of the present invention; Figure 2 Hydrogen production performance test results of the photocatalytic hydrogen production system containing CoAs 3 prepared in Example 1 of the present invention. Among them, (a) is the hydrogen production amount of the photocatalytic system with different CoAs 3 catalysts when the concentration of eosin is 0.2 mg / mL; (b) is the hydrogen production rate of the photocatalytic system with different eosin addition amounts when the addition amount of CoAs 3 catalyst is 25 mg; (c) is the test result of the hydrogen evolution cycle stability of the photocatalytic system when the ratio of eosin / catalyst is 25 mg / 70 mg; (d) is the change of the apparent quantum yield of the photocatalyst CoAs 3 with the radiation wavelength; Figure 3 The electronic energy band structure of CoAs 3 prepared by the present invention with spin-orbit coupling (SOC). DETAILED DESCRIPTION OF THE INVENTION

[0022] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art regarding the present invention. In case of conflicts, the definitions in this specification shall prevail.

[0023] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not in any way limit the scope of the present invention, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0024] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0025] In this article, unless otherwise specified, the terms "comprising", "including", "containing", "having", or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0026] In this article, for the sake of concise description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered to be within the scope described in this specification.

[0027] The present invention discloses a preparation method of a CoAs 3 catalyst, comprising the following steps: S1: After mixing Co powder with a purity of 2N8 and As powder with a purity of 5N, perform grinding treatment; Preferably, during the grinding treatment, the grinding time is 30 - 40 min. The grinding treatment can significantly reduce the particle sizes of the Co powder and the As powder, enabling them to be more fully mixed. The reduction in particle size increases the contact area of the reactants, which is beneficial to the uniform diffusion and combination of Co and As elements during the subsequent heat treatment process. The grinding time of 30 - 40 min ensures the full mixing of the raw materials and the uniform reduction of particle sizes, laying a foundation for the formation of a high-quality catalyst. The synergistic effect of the grinding treatment and the high-temperature synthesis promotes the formation of highly dispersed active sites by Co and As atoms. These active sites have high selectivity for the adsorption and dissociation of water molecules and are the key to enhancing the photocatalytic hydrogen production performance. An appropriate grinding time helps to form more and more uniform active sites, thereby improving the catalytic efficiency of the catalyst.

[0028] Further preferably, the molar ratio of the Co powder to the As powder is 1:3; precisely controlling the elemental ratio of Co and As in the catalyst to ensure the formation of CoAs with a specific stoichiometry 3 phase. The specific molar ratio helps to form a highly ordered and stable crystal structure during the heat treatment process. This structure is conducive to the effective separation and migration of photo-generated electrons and holes, thereby improving the photocatalytic hydrogen production performance. When the molar ratio of the Co powder to the As powder is 1:3, the prepared CoAs 3 catalyst may have stronger topological electronic properties, such as triple degenerate fermions, etc. These properties endow the material with higher conductivity and lower effective carrier mass, which is beneficial to charge transfer and reaction kinetics in the photocatalytic process. By adjusting the ratio of Co and As, the energy band structure of the catalyst can be optimized to make it more suitable for the photocatalytic hydrogen production reaction. For example, by forming specific impurity energy levels or adjusting the band gap width, the light absorption efficiency and the utilization rate of photo-generated carriers can be improved.

[0029] In addition, the Co powder with a purity of 2N8, representing a purity of 99.8% of the Co powder, and the As powder with a purity of 5N, representing a purity of 999.99% of the As powder, can improve the purity of the product.

[0030] S2: Under the protection of an inert atmosphere, preferably argon, the ground mixture is heat-treated to obtain the CoAs 3 catalyst; During the heat treatment process, the temperature is 750 - 850 °C and the time is 40 - 60 h. Preferably, during the heat treatment process, the temperature is 800 °C and the time is 50 h. Heat treatment at 800 °C for 50 h helps the Co and As elements to fully combine to form a CoAs 3 catalyst with a specific crystal phase and topological electronic structure. The formation of this crystal phase is crucial for the photocatalytic hydrogen production performance of the catalyst. Long-time high-temperature treatment helps to reduce defects and impurities in the catalyst, improve the purity and order of the crystal, which is conducive to the effective separation and migration of photo-generated electrons and holes, reduce the recombination of carriers, and thus improve the photocatalytic efficiency. The heat treatment temperature of 800 °C can optimize the energy band structure of the catalyst to make it more suitable for the photocatalytic hydrogen production reaction. By adjusting the band gap width and energy band position, the light absorption efficiency and the utilization rate of photo-generated carriers can be improved. High-temperature treatment helps the catalyst to form stronger topological electronic properties, such as triple degenerate fermions, etc. These properties endow the material with higher conductivity and lower effective carrier mass, which is beneficial to charge transfer and reaction kinetics in the photocatalytic process.

[0031] In addition, when the heating rate is controlled to be 80 - 120 °C / h, it can ensure that the catalyst is uniformly heated during the heat treatment process, avoiding problems such as thermal stress and cracks caused by temperature gradients. An appropriate heating rate helps to optimize the heat treatment efficiency, reduce energy consumption and time costs. At the same time, it also helps to ensure that the catalyst obtains the best performance during the heat treatment process.

[0032] In addition, the present invention also discloses a CoAs prepared by the above method 3 Application of the catalyst in photocatalytic hydrogen production. Disperse the above-mentioned CoAs 3 catalyst in an aqueous triethanolamine solution, then add eosin tetrabromide, and after stirring evenly, a photocatalytic hydrogen production system is prepared; here, eosin tetrabromide is used as a photosensitizer, which can absorb light energy and transfer it to the catalyst, thereby enhancing the light absorption and utilization efficiency of the catalyst. In the photocatalytic reaction, the photosensitizer can broaden the light absorption range of the photocatalyst and improve the efficiency of converting light energy into chemical energy.

[0033] In the photocatalytic hydrogen production system, the mass ratio of the CoAs 3 catalyst to the eosin tetrabromide is 25:(10 - 80). Further preferably, in the photocatalytic hydrogen production system, the mass ratio of the CoAs 3 catalyst to the eosin tetrabromide is 25:(40 - 80). More preferably, in the photocatalytic hydrogen production system, the mass ratio of the CoAs 3 catalyst to the eosin tetrabromide is 25:70.

[0034] In the present invention, a photocatalytic activity evaluation system produced by Beijing Zhongjiao Jinyuan Technology Co., Ltd. and a gas chromatograph produced by Zhejiang Fuli Analytical Instrument Co., Ltd. were used to test the photocatalytic hydrogen evolution performance of the CoAs 3 catalyst. The photocatalytic water splitting hydrogen production reaction described in the present invention is carried out in a sealed gas-solid atmospheric pressure cylindrical glass reactor, and its light source is a 300 W xenon lamp with a 420 nm cut-off filter. During the test, first disperse 100 mg of the CoAs 3 catalyst powder in 50 - 200 mL of an aqueous triethanolamine solution, then add 0.01 - 0.03 mmol of eosin tetrabromide to the glass reactor, and then ultrasonicate for 30 - 60 min to ensure uniform dispersion of the particles. Then place the reaction vessel on a magnetic stirrer, adjust the rotation speed to 200 - 400 r / min, start the vacuum pump, and start the photocatalytic process. Subsequently, illuminate and stir the sample to initiate the reaction.

[0035] The CoAs prepared by the present invention 3The catalyst has excellent performance. Under the above test conditions, its hydrogen production rate is 2350 - 2450 μmol / g / h, and the electrochemically active area is 3.25×10 -4 mF / cm 2 . After 9 cycles of photocatalytic hydrogen production, it can still maintain a high photocatalytic activity. The H 2 production amount is 13500 μmol / g, and it has a high quantum yield. The apparent quantum yield at 495 nm is 15.2%.

[0036] The specific method for obtaining the above apparent quantum yield is as follows: The apparent quantum yield can be estimated according to the following formula:

[0037] where A represents the reaction coefficient, R represents the production rate of H 2 , N A represents Avogadro's constant, I represents the number of photons absorbed by the reaction solution. The reaction for evaluating the apparent quantum yield ( ) is carried out under the reaction conditions of the present invention above, but the light source uses monochromatic light, which is generated by a xenon lamp equipped with a band - pass filter. The center wavelengths of the band - pass filters are 380 nm, 420 nm, 450 nm, 500 nm, 550 nm and 600 nm respectively.

[0038] The present invention solves the problems existing in the current photocatalytic materials, such as complex preparation process, long preparation time, and poor photocatalytic hydrogen production performance. The CoAs 3 photocatalytic material provided by the present invention has low cost and simple preparation process. It is prepared by a solid - state reaction method in a box - type electric furnace. It not only has relatively low requirements for experimental equipment, but also is energy - efficient, environmentally friendly and has a high yield. It can be mass - produced and applied in the future new energy field, providing strong support for industry innovation and sustainable development. The CoAs 3 photocatalytic material provided by the present invention has a hydrogen production rate of 2350 - 2450 μmol / g / h and good catalytic hydrogen evolution performance. The CoAs 3 photocatalytic material provided by the present invention has good chemical stability. After 9 cycles of photocatalytic hydrogen production, it can still maintain a high photocatalytic activity. The H 2 production amount is 13500 μmol / g, and it has a persistent photocatalytic effect. The CoAs 3The photocatalytic material has a high quantum yield in the visible light range, and the apparent quantum yield at 495 nm is 15.2%, which means that most of the absorbed photons are effectively used to drive chemical reactions. The solar spectrum consists of 5% ultraviolet light, 42% - 45% visible light, and 50% near-infrared light. The CoAs provided by the present invention 3 The photocatalytic material extends the absorption wavelength, can effectively utilize sunlight, and provides a new idea for solving the problem that the current photocatalytic materials mainly absorb energy in the ultraviolet region.

[0039] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0040] Conventional instrument equipment in the art is used in the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0041] Example 1 This example discloses a preparation method of a CoAs 3 catalyst, which includes the following steps: S1: Mix Co powder with a purity of 2N8 and As powder with a purity of 5N in a molar ratio of 1:3, and then grind for 30 min; S2: Under the protection of an argon atmosphere, heat the system to 800°C at a heating rate of 100°C / h, and heat-treat the ground mixture at 800°C for 50 h to obtain the CoAs 3 catalyst.

[0042] Figure 1 For the CoAs prepared in Example 1 of the present invention 3 The X-ray diffraction pattern shows that the half-height width of the diffraction peak is small, the intensity is high, and there are no impurity peaks, and all diffraction peaks are consistent with the XRD data in the literature, which indicates that high-quality CoAs has been successfully synthesized in this application 3 .

[0043] Then, 25 mg of a CoAs prepared in this example 3The catalyst was dispersed in 100 mL of aqueous triethanolamine solution, and then 70 mg of eosin was added. After ultrasonic treatment for 40 min, CoAs 3 the catalyst was evenly dispersed to prepare a photocatalytic hydrogen production system.

[0044] Figure 2 Figure 1 is the test result of the hydrogen production performance of the photocatalytic hydrogen production system containing CoAs prepared in Example 1 of the present invention. Among them, (a) is the hydrogen production amount of the photocatalytic system with the concentration of eosin being 0.2 mg / mL and different CoAs 3 catalysts added; (b) is the hydrogen production rate of the photocatalytic system with the addition amount of CoAs 3 catalyst being 25 mg and different addition amounts of eosin; (c) is the test result of the hydrogen evolution cycle stability of the photocatalytic system when the ratio of eosin / catalyst is 25 mg / 70 mg; (d) is the change of the apparent quantum yield of the photocatalyst CoAs 3 with the radiation wavelength. As can be seen from the figure, the hydrogen production rate of the CoAs 3 photocatalytic material provided by the present invention can reach up to 2400 μmol / g / h at most. After 9 times of repeated photocatalytic hydrogen production, it can still maintain a high photocatalytic activity. The H 3 production amount is 13500 μmol / g, with a lasting photocatalytic effect, and a high quantum yield in the visible light range. The apparent quantum yield at 495 nm is 15.2%, which means that most of the absorbed photons are effectively used to drive chemical reactions. 2 Figure 2 is the electronic band structure of the spin-orbit coupling (SOC) of the CoAs

[0045] Figure 3 photocatalyst prepared in Example 1 of the present invention. As can be seen from the figure, CoAs 3 is a topological semimetal material containing triple degenerate fermions. The present invention uses a first-principles calculation software package based on density functional theory - the VASP software package to study the topological properties and electronic band structures of CoAs 3 materials with spin-orbit coupling (SOC) and without considering spin-orbit coupling. From the theoretical calculated band diagram, it can be found that when considering spin-orbit coupling, due to the protection of crystal symmetry (mainly C3 rotation symmetry and mirror protection), two triple degenerate points formed by the crossing of two spin-degenerate bands and non-spin-degenerate bands will appear on the Γ-A path. Therefore, CoAs 3 is a topological semimetal material containing triple degenerate fermions. 3 Figure 3 is the X-ray photoelectron spectroscopy (XPS) spectrum of the CoAs

[0046] Example 2 This example discloses a CoAs3 The preparation method of the catalyst comprises the following steps: S1: Mix Co powder with a purity of 2N8 and As powder with a purity of 5N in a molar ratio of 1:3, and then grind for 40 min; S2: Under the protection of an argon atmosphere, heat the system to 750 °C at a heating rate of 80 °C / h, and perform heat treatment on the ground mixture at 750 °C for 60 h to obtain the CoAs x catalyst.

[0047] Disperse 25 mg of a CoAs 3 catalyst prepared in this example in 50 mL of triethanolamine aqueous solution, then add 60 mg of eosin tetrabromide, and ultrasonicate for 30 min to ensure that the CoAs 3 catalyst is evenly dispersed to obtain a photocatalytic hydrogen production system.

[0048] After testing the hydrogen production performance of the above photocatalytic hydrogen production system, the hydrogen production rate of the photocatalytic hydrogen production system is 2350 μmol / g / h.

[0049] Example 3 This example discloses a preparation method of a CoAs 3 catalyst, which comprises the following steps: S1: Mix Co powder with a purity of 2N8 and As powder with a purity of 5N in a molar ratio of 1:3, and then grind for 35 min; S2: Under the protection of an inert atmosphere, heat the system to 850 °C at a heating rate of 120 °C / h, and perform heat treatment on the ground mixture at 850 °C for 40 h to obtain the CoAs 3 catalyst.

[0050] Disperse 25 mg of a CoAs 3 catalyst prepared in this example in 200 mL of triethanolamine aqueous solution, then add 10 mg of eosin tetrabromide, and ultrasonicate for 60 min to ensure that the CoAs 3 catalyst is evenly dispersed to obtain a photocatalytic hydrogen production system.

[0051] After testing the hydrogen production performance of the above photocatalytic hydrogen production system, the hydrogen production rate of the photocatalytic hydrogen production system is 1275 μmol / g / h.

[0052] Example 4 This example discloses a preparation method of a CoAs 3 catalyst, which comprises the following steps: S1: Mix Co powder with a purity of 2N8 and As powder with a purity of 5N in a molar ratio of 1:3, and then grind for 30 min; S2: Under the protection of an inert atmosphere, heat the system to 820 °C at a heating rate of 80 °C / h, and heat-treat the ground mixture at 820 °C for 44 h to obtain the CoAs 3 catalyst.

[0053] Disperse 25 mg of a CoAs 3 catalyst prepared in this example in 80 mL of an aqueous triethanolamine solution, then add 20 mg of eosin tetrabromide, and ultrasonicate for 40 min to ensure that the CoAs 3 catalyst is evenly dispersed to obtain a photocatalytic hydrogen production system.

[0054] After testing the hydrogen production performance of the above photocatalytic hydrogen production system, the hydrogen production rate of the photocatalytic hydrogen production system is 1780 μmol / g / h.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a CoAs3 catalyst, characterized in that: The following steps are involved: S1: Mix Co powder and As powder and grind them; S2: Under the protection of an inert atmosphere, heat-treating the ground mixture to obtain the CoAs3 catalyst; the temperature during the heat treatment is 750-850°C and the time is 40-60h.

2. The method for preparing a CoAs3 catalyst according to claim 1, characterized in that: The temperature during the heat treatment is 800°C and the time is 50h.

3. The method for preparing a CoAs3 catalyst according to claim 1, characterized in that: The molar ratio of the Co powder to the As powder is 1:

3.

4. The method for preparing a CoAs3 catalyst according to claim 1, characterized in that: During the grinding process, the grinding time is 30 to 40 minutes.

5. The method for preparing a CoAs3 catalyst according to claim 1, characterized in that: During the heat treatment process, the heating rate is 80-120°C / h.

6. The method for preparing a CoAs3 catalyst according to claim 1, characterized in that: The purity of the Co powder is 2N8, and the purity of the As powder is 5N.

7. A CoAs3 catalyst, characterized in that Prepared by the method according to any one of claims 1 to 6.

8. The use of a CoAs3 catalyst in photocatalytic hydrogen production as claimed in claim 7, characterized in that: The CoAs3 catalyst is dispersed in a triethanolamine aqueous solution, and then tetrabromofluorescein is added and stirred evenly to obtain a photocatalytic hydrogen production system; the photocatalytic hydrogen production system has a hydrogen production rate of 2350~2450 μmol / g / h under the illumination conditions of a 420 nm, 300 W xenon lamp.

9. The use of a CoAs3 catalyst in photocatalytic hydrogen production according to claim 8, characterized in that: The mass ratio of the CoAs3 catalyst to the tetrabromofluorescein is 25:(10~80).

10. The use of a CoAs3 catalyst in photocatalytic hydrogen production according to claim 8, characterized in that: The mass ratio of the CoAs3 catalyst to the tetrabromofluorescein is 25:(40~80).

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