Preparation method and application of composite photocatalyst for visible light catalytic hydrogen evolution

Abstract

The present invention discloses a preparation method and application of a visible light catalytic hydrogen evolution composite photocatalyst. The preparation method comprises the following steps: (1) dissolving terephthalic acid and cadmium acetate in a solvent and then performing a solvothermal reaction. After completion, a solid product is separated, washed and dried to obtain a Cd-MOF material. (2) dissolving thioacetamide (TAA) in anhydrous ethanol, then adding ammonium tridecanol molybdate and the Cd-MOF material, stirring evenly and then heating to react. After completion, a solid product is separated, washed and dried to obtain a photocatalyst Mo3S 13 / CdS@Cd‑MOF. The photocatalyst of the present invention has more active sites, higher light absorption capacity and transmission efficiency of photogenerated electrons, and improves the photocatalytic hydrogen evolution ability of the catalyst under visible light.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalyst preparation, and in particular to a preparation method and application of a visible light catalytic hydrogen evolution composite photocatalyst. Background Art

[0002] Hydrogen energy is a secondary energy source with abundant sources, green and low carbon, and wide application. It is gradually becoming one of the important carriers of global energy transformation and development. my country is the world's largest hydrogen producer and ranks first in the world in terms of installed capacity of renewable energy. It has great potential in the supply of clean and low-carbon hydrogen energy. Photocatalysis, especially the production of hydrogen from water, was developed after Fujishima and Hond discovered that ultraviolet irradiation of TiO2 can produce hydrogen in 1972. Subsequently, a large number of studies have focused on the photocatalytic hydrogen evolution using inorganic semiconductors without considering electrochemical factors. However, although 50 years have passed since the initial report of photoelectrochemical hydrogen production, and a large number of studies have been conducted in this field. But the current situation is that there is still no suitable photocatalyst and photocatalytic process that can fully convert sunlight into hydrogen. The development of an economically viable photocatalytic hydrogen production process requires consideration of multiple factors, such as photocatalysts with strong absorption capacity for all wavelengths in the visible light range, effective charge separation, appropriate adjustment of the energy of the conduction band and valence band, potentials required for water reduction and water oxidation, and sufficient lifetime of charge carriers. While most efforts in photocatalysis have been devoted to investigating the activity of various inorganic materials, most of which are semiconductors, no suitable materials have been found so far. Summary of the invention

[0003] The present invention discloses a preparation method and application of a composite photocatalyst for visible light catalytic hydrogen evolution, wherein the photocatalyst has more active sites, higher light absorption capacity and transmission efficiency of photogenerated electrons, and improves the photocatalytic hydrogen evolution capacity of the catalyst under visible light. Specifically, the technical solution of the present invention is as follows.

[0004] First, the present invention discloses a method for preparing a composite photocatalyst for visible light catalytic hydrogen evolution, comprising the steps of:

[0005] (1) Dissolve terephthalic acid and cadmium acetate in a solvent for solvothermal reaction. After completion, separate the solid product, wash it and dry it to obtain Cd-MOF material for later use.

[0006] (2) Dissolve thioacetamide (TAA) in anhydrous ethanol, then add ammonium tridecanol and the Cd-MOF material, stir evenly and heat to react. After completion, separate the solid product, wash and dry it to obtain the photocatalyst Mo3S 13 / CdS@Cd-MOF.

[0007] Furthermore, in step (1), the mass ratio of terephthalic acid to cadmium acetate is 1:2.

[0008] Furthermore, in step (1), the solvent includes any one of methanol, ethanol, water, N,N-dimethylformamide, etc.

[0009] Furthermore, in step (1), the temperature of the solvothermal reaction is 100-180°C and the time is 30-60 h. In this process, benzoic acid removes protons under solvothermal conditions to form coordination bonds with cadmium ions, further constructing a two-dimensional organic metal framework material with a rhombus microscopic morphology.

[0010] Furthermore, in step (1), the solid product is washed with ethanol and water in sequence, and then dried at 60-100° C. for 12-48 h to obtain the Cd-MOF material.

[0011] Furthermore, in step (2), the mass ratio of thioacetamide, Cd-MOF material, and ammonium tridecanethiomolybdate is 2 mg: 1 mg: 1-4 mg, and the corresponding volume of anhydrous ethanol is 50-100 mL.

[0012] Furthermore, in step (2), the heating reaction is carried out at a temperature of 60-100° C. and for a period of 3-6 days.

[0013] Furthermore, in step (2), the solid product is washed with ethanol and then dried at 60-100° C. for 12-48 h to obtain a final photocatalytic material.

[0014] Secondly, the present invention discloses the application of the visible light catalytic hydrogen evolution composite photocatalyst in photocatalytic hydrogen production.

[0015] Optionally, the visible light catalytic hydrogen evolution composite photocatalyst is used in a temperature range of 2-10°C in photocatalytic hydrogen production.

[0016] Furthermore, the visible light intensity wavelength of the visible light catalytic hydrogen evolution composite photocatalyst in photocatalytic hydrogen production is greater than 420 nm.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: the present invention uses thioacetamide and Cd-MOF material as raw materials to prepare CdS@Cd-MOF nanomaterials, and then uses ammonium tridecanedioic molybdate ((NH4)2Mo3S 13 ) as a co-catalyst, under certain conditions, the two samples were compounded to obtain a photocatalyst Mo3S with a special structure. 13 / CdS@Cd-MOF. The composite material not only enhances the light absorption capacity, but also increases the active sites of hydrogen evolution reaction (HER), because the photogenerated electrons and holes are easier to separate, and the transmission efficiency of the photogenerated electrons is significantly improved, thereby improving the photocatalytic hydrogen evolution capacity under visible light illumination, and more electrons combine with protons to produce hydrogen. In addition, the photocatalyst Mo3S 13 / CdS@Cd-MOF also has the characteristics of high water stability, which improves the recycling rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 The photocatalyst Mo3S prepared in Example 1 is 13 SEM image of / CdS@Cd-MOF.

[0020] Figure 2 The photocatalyst Mo3S prepared in Example 1 is 13 Infrared image of / CdS@Cd-MOF.

[0021] Figure 3 The photocatalyst Mo3S prepared in Example 1 is 13 / CdS@Cd-MOF XRD pattern. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0023] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be purchased through conventional channels. If not otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions. In addition, any method and material similar to or equivalent to the described content can be applied to the method of the present invention. The present invention is further described according to the accompanying drawings and specific embodiments of the present invention, and the preferred implementation methods and materials described in the present invention are only for demonstration purposes.

[0024] Example 1

[0025] A method for preparing a composite photocatalyst for visible light catalytic hydrogen evolution comprises the following steps:

[0026] (1) Weigh 0.84 g of terephthalic acid and dissolve it in 60 mL of N,N-dimethylformamide. Then add 0.45 g of cadmium acetate and stir for 30 min to obtain a terephthalic acid-cadmium acetate mixed solution.

[0027] (2) The mixed solution is placed in a reactor, heated to 120°C and kept warm for 48 h for solvent thermal reaction. After completion, it is cooled to room temperature, the solid product is filtered out and washed with 92% by mass ethanol and water. The obtained solid product is then vacuum dried at 60°C for 12 h to obtain Cd-MOF material for later use.

[0028] (3) Dissolve 0.4 g of ammonium heptamolybdate in water and stir evenly. Then add 120 mL of 50% by mass ammonium polysulfide solution. Stir evenly and heat in an oil bath to 96°C for five days to obtain ammonium tridecanethiomolybdate, which is set aside.

[0029] (4) Dissolve 0.8 g of thioacetamide in anhydrous ethanol and stir evenly, then add 0.2 g of the Cd-MOF and 0.02 g of the ammonium tridecanethiomolybdate of this embodiment, stir evenly, and heat in a water bath to 80°C for 5 days. After completion, filter out the solid product, wash it with ethanol three times, and then vacuum dry it at 60°C for 12 h to obtain the photocatalyst Mo3S 13 / CdS@Cd-MOF. Figure 1 , Figure 2 , Figure 3 The photocatalyst Mo3S 13 SEM image, IR spectrum and XRD pattern of / CdS@Cd-MOF.

[0030] Example 2

[0031] A method for preparing a composite photocatalyst for visible light catalytic hydrogen evolution comprises the following steps:

[0032] (1) Weigh 0.84 g of terephthalic acid and dissolve it in 60 mL of N,N-dimethylformamide. Then add 0.45 g of cadmium acetate and stir for 30 min to obtain a terephthalic acid-cadmium acetate mixed solution.

[0033] (2) The mixed solution is placed in a reactor, heated to 120°C and kept warm for 48 h for solvent thermal reaction. After completion, it is cooled to room temperature, the solid product is filtered out and washed with 92% by mass ethanol and water. The obtained solid product is then vacuum dried at 60°C for 12 h to obtain Cd-MOF material for later use.

[0034] (3) Dissolve 0.4 g of ammonium heptamolybdate in water and stir evenly. Then add 120 mL of 50% by mass ammonium polysulfide solution. Stir evenly and heat in an oil bath to 96°C for five days to obtain ammonium tridecanethiomolybdate, which is set aside.

[0035] (4) Dissolve 0.8 g of thioacetamide in anhydrous ethanol and stir evenly, then add 0.2 g of the Cd-MOF and 0.04 g of the ammonium tridecanethiomolybdate of this embodiment, stir evenly, and heat in a water bath to 60°C for 6 days. After completion, filter out the solid product, wash it with ethanol three times, and then vacuum dry it at 70°C for 48 h to obtain the photocatalyst Mo3S 13 / CdS@Cd-MOF.

[0036] Example 3

[0037] A method for preparing a composite photocatalyst for visible light catalytic hydrogen evolution comprises the following steps:

[0038] (1) Weigh 0.84 g of terephthalic acid and dissolve it in 60 mL of N,N-dimethylformamide. Then add 0.45 g of cadmium acetate and stir for 30 min to obtain a terephthalic acid-cadmium acetate mixed solution.

[0039] (2) The mixed solution is placed in a reactor, heated to 120°C and kept warm for 48 h for solvent thermal reaction. After completion, it is cooled to room temperature, the solid product is filtered out and washed with 92% by mass ethanol and water. The obtained solid product is then vacuum dried at 60°C for 12 h to obtain Cd-MOF material for later use.

[0040] (3) Dissolve 0.4 g of ammonium heptamolybdate in water and stir evenly. Then add 120 mL of 50% by mass ammonium polysulfide solution. Stir evenly and heat in an oil bath to 96°C for five days to obtain ammonium tridecanethiomolybdate, which is set aside.

[0041] (4) Dissolve 0.8 g of thioacetamide in anhydrous ethanol and stir evenly, then add 0.2 g of the Cd-MOF and 0.08 g of the ammonium tridecanethiomolybdate of this embodiment, stir evenly, and heat in a water bath to 100°C for 3 days. After completion, filter out the solid product, wash it with ethanol 3 times, and then vacuum dry it at 70°C for 48 h to obtain the photocatalyst Mo3S 13 / CdS@Cd-MOF.

[0042] Example 4

[0043] A method for preparing a composite photocatalyst for visible light catalytic hydrogen evolution comprises the following steps:

[0044] (1) Weigh 0.84 g of terephthalic acid and dissolve it in 60 mL of N,N-dimethylformamide. Then add 0.45 g of cadmium acetate and stir for 30 min to obtain a terephthalic acid-cadmium acetate mixed solution.

[0045] (2) The mixed solution is placed in a reaction kettle, heated to 120°C and kept warm for 48 hours for solvent thermal reaction. After completion, it is cooled to room temperature, and the solid product is filtered out and washed with 92% by mass ethanol and water. The obtained solid product is then vacuum dried at 60°C for 12 hours to obtain Cd-MOF material for later use.

[0046] (3) 0.8 g of thioacetamide was dissolved in anhydrous ethanol and stirred evenly, and then 0.2 g of the Cd-MOF of this example was added, stirred evenly, and heated in a water bath to 80°C for 5 days. After completion, the solid product was filtered out, washed with ethanol three times, and then vacuum dried at 60°C for 12 hours to obtain the comparative photocatalyst CdS@Cd-MOF.

[0047] Example 5

[0048] A method for preparing a composite photocatalyst for visible light catalytic hydrogen evolution comprises the following steps:

[0049] (1) Weigh 0.84 g of terephthalic acid and dissolve it in 60 mL of N,N-dimethylformamide. Then add 0.45 g of cadmium acetate and stir for 30 min to obtain a terephthalic acid-cadmium acetate mixed solution.

[0050] (2) The mixed solution is placed in a reactor, heated to 120°C and kept warm for 48 h for solvent thermal reaction. After completion, it is cooled to room temperature, the solid product is filtered out and washed with 92% by mass ethanol and water. The obtained solid product is then vacuum dried at 60°C for 12 h to obtain Cd-MOF material for later use.

[0051] (3) Dissolve 0.4 g of ammonium heptamolybdate in water and stir evenly. Then add 120 mL of 50% by mass ammonium polysulfide solution. Stir evenly and heat in an oil bath to 96°C for five days to obtain ammonium tridecanethiomolybdate, which is set aside.

[0052] (4) 0.2 g of the Cd-MOF and 0.02 g of the ammonium tridecanethiomolybdate were stirred evenly and then heated in a water bath to 80°C for 5 days. After completion, the solid product was filtered out, washed with ethanol three times, and then vacuum dried at 60°C for 12 hours to obtain the photocatalyst Mo3S 13 / Cd-MOF.

[0053] Example 6

[0054] A method for preparing a composite photocatalyst for visible light catalytic hydrogen evolution comprises the following steps:

[0055] (1) Weigh 0.84 g of terephthalic acid and dissolve it in 60 mL of N,N-dimethylformamide. Then add 0.45 g of cadmium acetate and stir for 30 min to obtain a terephthalic acid-cadmium acetate mixed solution.

[0056] (2) The mixed solution is placed in a reactor, heated to 120°C and kept warm for 48 hours for solvent thermal reaction. After completion, it is cooled to room temperature, and the solid product is filtered out and washed with 92% by mass ethanol and water. The obtained solid product is then vacuum dried at 60°C for 12 hours to obtain Cd-MOF material for later use.

[0057] Performance Test:

[0058] .

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a composite photocatalyst for hydrogen evolution catalyzed by visible light, characterized in that: Includes steps: (1) dissolving terephthalic acid and cadmium acetate in a solvent and performing a solvothermal reaction, separating a solid product after completion, washing and drying to obtain a Cd-MOF material for later use; (2) dissolving thioacetamide in anhydrous ethanol, then adding ammonium tridecanediomolybdate and the Cd-MOF material, stirring evenly and heating to react; after completion, separating the solid product, washing and drying, and obtaining the photocatalyst Mo3S 13 / CdS@Cd-MOF; In step (1), the mass ratio of terephthalic acid to cadmium acetate is 1:2; In step (2), the mass ratio of thioacetamide, Cd-MOF material, and ammonium tridecanediomolybdate is 2 mg: 1 mg: 1-4 mg, and the corresponding volume of anhydrous ethanol is 50-100 mL.

2. The method for preparing the composite photocatalyst for visible light catalytic hydrogen evolution according to claim 1, characterized in that: In step (1), the solvent includes any one of methanol, ethanol, water, and N,N-dimethylformamide.

3. The method for preparing the composite photocatalyst for visible light catalytic hydrogen evolution according to claim 1, characterized in that: In step (1), the temperature of the solvent thermal reaction is 100-180°C and the time is 30-60 h.

4. The method for preparing the composite photocatalyst for visible light catalytic hydrogen evolution according to claim 1, characterized in that: In step (1), the solid product is washed with ethanol and water in sequence; and then dried at 60-100° C. for 12-48 h to obtain the Cd-MOF material.

5. The method for preparing the composite photocatalyst for visible light catalytic hydrogen evolution according to claim 1, characterized in that: In step (2), the heating reaction temperature is 60-100° C. and the time is 3-6 days.

6. The method for preparing the composite photocatalyst for hydrogen evolution catalyzed by visible light according to any one of claims 1 to 5, characterized in that: In step (2), the solid product is washed with ethanol and then dried at 60-100° C. for 12-48 h.

7. Use of the visible light catalytic hydrogen evolution composite photocatalyst obtained by the preparation method according to any one of claims 1 to 6 in photocatalytic hydrogen production.

8. The use according to claim 7, characterized in that: The use temperature of the visible light catalytic hydrogen evolution composite photocatalyst in photocatalytic hydrogen production is 2-10°C.

9. The use according to claim 7 or 8, characterized in that: The visible light wavelength of the visible light catalytic hydrogen evolution composite photocatalyst in photocatalytic hydrogen production is greater than 420 nm.

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