A Mn x Cd 1-x Preparation method of S / Co2SnO4 composite catalyst and application thereof in piezophotocatalytic H2 production

Abstract

The application belongs to the field of piezoelectric photocatalysis, and particularly relates to a preparation method of a Mn x Cd 1‑x S / Co2SnO4 composite catalyst and application of the Mn x Cd 1‑x S / Co2SnO4 composite catalyst in piezoelectric photocatalytic H2 production. The application prepares Mn x Cd 1‑x S / Co2SnO4 composite catalyst through a hydrothermal synthesis method, a CoSn(OH)6 precursor, high-temperature calcination to synthesize Co2SnO4, and finally a simple ultrasonic stirring method to form a heterojunction. The catalyst is used in piezoelectric photocatalytic H2 production under the synergistic action of sunlight irradiation and ultrasonic vibration. The catalyst synthesis method is simple, green, pollution-free and easy to operate. The prepared catalyst has abundant active sites, excellent stability and hydrogen production effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of piezophotocatalysis, and particularly relates to a preparation method of a Mn x Cd 1-x S / Co2SnO4 composite catalyst and application thereof in piezophotocatalytic H2 production. BACKGROUND

[0002] At present, resources such as petroleum, natural gas and coal are still the energy pillars of the world economy, but research has found that more than 80% of air pollution and more than 95% of greenhouse gases are caused by the combustion of fossil energy. Therefore, developing clean and renewable energy is an inevitable choice for sustainable development. Hydrogen, as a new green energy, has the advantages of high combustion heat value and environmental friendliness, and is favored by scientists. As early as 1972, two Japanese scientists, Fujishima and Honda, discovered that water can be decomposed to produce hydrogen by photocatalysis, which makes people see that it is possible to use photocatalytic technology to convert solar energy into chemical energy.

[0003] CdS has been the most studied metal sulfide photocatalyst in recent decades due to its suitable band gap, but the rapid recombination of photo-generated holes and photo-generated electrons makes the CdS photocatalytic hydrogen production rate very low. In order to improve this phenomenon, a Mn 1-x Cd x S solid solution with a twin structure is synthesized by a hydrothermal method, and its photocatalytic performance is much higher than that of CdS. For example, patent CN110756203A discloses a Ni2P / Mn 0.3 Cd 0.7 S photocatalytic water decomposition composite catalyst, a preparation method thereof and application thereof, and the prepared catalyst has higher catalytic activity and stability. Patent CN116832830A discloses a preparation method of a wastewater hydrogen production composite photocatalyst NiTO3 / Mn 0.4 Cd 0.6 S, and the prepared catalyst improves photocatalytic activity and quantum efficiency. However, the above catalyst preparation methods are complicated and not easy to operate. SUMMARY

[0004] The purpose of the present application is to provide a Mn x Cd 1-x S / Co2SnO4 composite catalyst, and apply it to piezophotocatalytic H2 production, which has higher catalytic activity and stronger corrosion resistance.

[0005] The Mn x Cd 1-x S / Co2SnO4 composite catalyst provided by the present application has the following steps in the preparation method:

[0006] (1) Mn xCd 1-x Preparation of S:

[0007] Mn(CH3COO)2·4H2O and Cd(CH3COO)2·2H2O were dissolved in distilled water, stirred for 30 min, and then C2H5NS (TAA) was added. The mixture was stirred until it was uniformly mixed, and then the mixture was transferred to a reaction kettle with a polytetrafluoroethylene liner. The reaction kettle was placed in an oven at 140-180°C for 22-26 h, and then cooled to room temperature. The solid was washed with deionized water and anhydrous ethanol three times, and then dried at 60°C overnight to obtain orange Mn x Cd 1-x S (referred to as MCS), wherein x is a molar ratio, 0.2≤x≤0.5.

[0008] Further, the molar ratio of Mn(CH3COO)2·4H2O and Cd(CH3COO)2·2H2O is x:1-x; and the mass ratio of C2H5NS to Mn(CH3COO)2·4H2O is 0.7513:1.2254.

[0009] (2) Preparation of Co2SnO4:

[0010] Co(NO3)2·6H2O was dissolved in distilled water to obtain solution A, and then SnCl4·5H2O was dissolved in distilled water to obtain solution B. Solution A was slowly added to solution B, and stirred for 10 min to obtain solution C. Finally, 1 mol / L NaOH solution was added to solution C, and stirred for 30 min to form a blue precipitate. The mixture was transferred to a reaction kettle with a polytetrafluoroethylene liner, and placed in an oven at 160-200°C for 8-12 h. After the reaction was completed, the solid in the reaction kettle was washed with deionized water and anhydrous ethanol three times, and then dried at 60°C overnight to obtain gray CoSn(OH)6 powder. The CoSn(OH)6 was placed in a tube furnace, and heated to 480-520°C at a rate of 5°C / min, and calcined for 1-5 h to obtain black Co2SnO4 powder (referred to as CSO).

[0011] Further, the mass ratio of Co(NO3)2·6H2O to SnCl4·5H2O is 1.1641:0.7012.

[0012] (3) Preparation of Mn x Cd 1-x S / Co2SnO4 composite catalyst:

[0013] Mn x Cd 1-xS catalyst and Co2SnO4 catalyst are dissolved in a solvent, ultrasonic stirring is carried out. Filtration, washing and drying are carried out at room temperature, and finally orange powder is obtained, that is, Mn x Cd 1-x S / Co2SnO4 composite catalyst.

[0014] Further, the added mass of Co2SnO4 is 3-9% of the mass of Mn x Cd 1-x S, preferably 7-9%.

[0015] Further, the solvent includes deionized water and anhydrous ethanol.

[0016] Further, the ultrasonic power is 240W, and the time is 1h; the stirring speed is 400r / min, and the time is 4h.

[0017] The composite catalyst prepared by the above method is used for piezoelectric photocatalytic hydrogen production, and the specific application method is as follows: Mn x Cd 1- x The Mn x Cd 1-x S / Co2SnO4 composite catalyst is uniformly dispersed in water, then a sacrificial agent is added, the concentration of Na2S and Na2SO3 in the sacrificial agent solution is 0.35M and 0.25M, N2 is passed, and H2 is produced under the combined conditions of ultrasonic and light.

[0018] Further, the ultrasonic power is 240W; the power of the light is 55W.

[0019] Further, the amount of Mn x Cd 1-x S / Co2SnO4 composite catalyst used in water is 2mg / 18mL.

[0020] The beneficial effects of the present application are:

[0021] (1) The present application synthesizes Mn x Cd 1-x S with appropriate Mn doping amount by a hydrothermal method, forms a heterojunction with Co2SnO4 by ultrasonic stirring method, and prepares Mn x Cd 1-x S / Co2SnO4 composite catalyst, which has the characteristics of simple synthesis condition, easy operation, rapid and efficient, energy saving and environmental protection, etc.

[0022] (2) The introduction of the cocatalyst Co2SnO4 does not change the crystal structure of Mn x Cd 1-x S, and the crystallinity and purity of Mn x Cd 1-x S / Co2SnO4 composite catalyst are high.

[0023] (3) Mn x Cd 1-x S / Co2SnO4 composite catalyst produces H2 under the action of photocatalysis, piezoelectric catalysis and piezoelectric light synergy, wherein the catalytic performance under the piezoelectric light synergy is the best, which is 5.16 times of Mn x Cd 1-x S, 40.46 times of CdS and 42.88 times of CSO. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is Mn 0.5 Cd 0.5 S / Co2SnO4 composite catalyst synthesized in Example 1;

[0025] Figure 2 is Mn 0.5 Cd 0.5 S, Co2SnO4 and CdS catalysts synthesized in Comparative Examples 4-6;

[0026] Figure 3 is Mn 0.5 Cd 0.5 S / Co2SnO4 composite catalyst synthesized in Examples 1-4;

[0027] Figure 4 is the H2 production performance graph of the catalyst synthesized in Examples 1-4 and Comparative Examples 3-4 under the piezoelectric light condition;

[0028] Figure 5 is the H2 production performance graph of the catalyst synthesized in Examples 1-4 and Comparative Examples 3-4 under the piezoelectric condition only;

[0029] Figure 6 is the H2 production performance graph of the catalyst synthesized in Examples 1-4 and Comparative Examples 3-4 under the light condition only. DETAILED DESCRIPTION

[0030] The present application is not limited to the following detailed description, and those skilled in the art can implement the present application in other various embodiments according to the disclosure of the present application, or any simple changes or modifications made by using the design structure and ideas of the present application, all fall within the protection scope of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The H2 production efficiency is calculated according to the following formula:

[0031]

[0032] R: H2 production rate, unit: pmol / (g h), V: hydrogen volume, unit: pL, m: catalyst mass, unit: g, t: reaction time, unit: h.

[0033] Example 1

[0034] (1) 1.2254 g of Mn(CH3COO)2·4H2O and 1.3326 g of Cd(CH3COO)2·2H2O were dissolved in distilled water, stirred for 30 min to fully dissolve, and then 0.7513 g of C2H5NS (TAA) was added and stirred to mix evenly. The mixture was then transferred to a reaction kettle lined with polytetrafluoroethylene, and the reaction kettle was placed in an oven at 160°C for 24 h. After the reaction was completed, the reaction kettle was cooled to room temperature, and the solid was washed with deionized water and anhydrous ethanol three times and dried at 60°C overnight to obtain orange Mn 0.5 Cd 0.5 S.

[0035] (2) 1.1641 g of Co(NO3)2·6H2O was dissolved in 30 mL of distilled water to obtain solution A, and then 0.7012 g of SnCl4·5H2O was dissolved in 30 mL of distilled water to obtain solution B. Solution A was slowly added to solution B, stirred for 10 min to obtain solution C, and then 20 mL of 1 mol / L NaOH solution was added to solution C and stirred for 30 min to form a blue precipitate. The mixture was then transferred to a reaction kettle with a polytetrafluoroethylene lining, and the reaction kettle was placed in an oven at 180°C for 10 h. After the reaction was completed, the reaction kettle was cooled to room temperature, and the solid in the reaction kettle was washed with deionized water and anhydrous ethanol three times and dried at 60°C overnight to obtain gray CoSn(OH)6 powder. 0.1 g of CoSn(OH)6 was weighed into a tube furnace and heated to 500°C at a rate of 5°C / min, and calcined for 3 h to obtain black Co2SnO4 powder.

[0036] (3) Mn 0.5 Cd 0.5 S, Co2SnO4 was dissolved in deionized water, ultrasonicated at 240 W for 1 h and stirred at a stirring speed of 400 r / min for 4 h; filtered, washed, and dried at room temperature to finally obtain orange powder, which was Mn 0.5 Cd 0.5 S / Co2SnO4 composite catalyst, denoted as Mn 0.5 Cd 0.5 S-7% Co2SnO4. The mass of Co2SnO4 is 7% of the mass of Mn 0.5 Cd 0.5 S.

[0037] Mn 0.5 Cd0.5 S-7% Co2SnO4 applied to piezophotocatalytic H2 production:

[0038] 2 mg Mn 0.5 Cd 0.5 S-7% Co2SnO4, 18 mL of water were mixed and ultrasonically dispersed for 0.5 h to make the catalyst uniformly dispersed in water, then 2 mL of a sacrificial agent was added, the concentrations of Na2S and Na2SO3 in the sacrificial agent solution were 0.35 M and 0.25 M respectively, then N2 was passed for 30 min, finally, under the conditions of ultrasonic (240 W) and light (55 W xenon lamp simulating sunlight), it was sealed for 2 h. After the experiment was completed, 0.5 mL of gas in a tube was extracted, the peak area was detected by a gas chromatograph, and the H2 production rate was calculated. The analysis and calculation showed that the H2 production rate was 28.73 mmol / (g·h).

[0039] Example 2

[0040] Compared with Example 1, the difference lies in that in step (3), Co2SnO4 with a mass of 3% of Mn 0.5 Cd 0.5 S was added, and the rest was the same as in Example 1. The prepared composite catalyst was denoted as Mn 0.5 Cd 0.5 S-3% Co2SnO4.

[0041] The Mn 0.5 Cd 0.5 S-3% Co2SnO4 prepared in Example 2 was applied to piezophotocatalytic H2 production, and the application method was the same as in Example 1. The H2 production rate was 16.76 mmol / (g·h).

[0042] Example 3

[0043] Compared with Example 1, the difference lies in that in step (3), Co2SnO4 with a mass of 5% of Mn 0.5 Cd 0.5 S was added, and the rest was the same as in Example 1. The prepared composite catalyst was denoted as Mn 0.5 Cd 0.5 S-5% Co2SnO4.

[0044] The Mn 0.5 Cd 0.5 S-5% Co2SnO4 prepared in Example 3 was applied to piezophotocatalytic H2 production, and the application method was the same as in Example 1. The H2 production rate was 18.64 mmol / (g·h).

[0045] Example 4

[0046] Compared with Example 1, the difference lies in that in step (3), Co2SnO4 with a mass of 5% of Mn0.5 Cd 0.5 S 9%, others same as example 1, the prepared composite catalyst is denoted as Mn 0.5 Cd 0.5 S-9%Co2SnO4.

[0047] The Mn 0.5 Cd 0.5 S-9%Co2SnO4 prepared in example 4 is applied to piezophotocatalytic production of H2, and the application method is the same as that in example 1, and the H2 production rate is 24.97 mmol / (g·h).

[0048] Example 5

[0049] Compared with example 1, the difference lies in that in step (3), Mn 0.5 Cd 0.5 S and Co2SnO4 are dissolved in anhydrous ethanol, and others are the same as in example 1.

[0050] The Mn 0.5 Cd 0.5 S-7%Co2SnO4 prepared in example 5 is applied to piezophotocatalytic production of H2, and the application method is the same as that in example 1, and the H2 production rate is 9.57 mmol / (g·h).

[0051] Example 6

[0052] Compared with example 1, the difference lies in that in step (1), the addition amount of Mn(CH3COO)2·4H2O and Cd(CH3COO)2·2H2O is 0.4912 g and 2.1322 g, and others are the same as in example 1, and Mn 0.2 Cd 0.8 S / Co2SnO4 composite catalyst is prepared, denoted as Mn 0.2 Cd 0.8 S-7%Co2SnO4.

[0053] The Mn 0.2 Cd 0.8 S-7%Co2SnO4 prepared in example 6 is applied to piezophotocatalytic production of H2, and the application method is the same as that in example 1, and the H2 production rate is 0.37 mmol / (g·h).

[0054] Example 7

[0055] Compared with example 1, the difference lies in that in step (1), the addition amount of Mn(CH3COO)2·4H2O and Cd(CH3COO)2·2H2O is 0.7353 g and 1.8657 g, and others are the same as in example 1, and Mn 0.3 Cd 0.7 S / Co2SnO4 composite catalyst is prepared, denoted as Mn0.3 Cd 0.7 S-7% Co2SnO4.

[0056] Mn 0.3 Cd 0.7 S-7% Co2SnO4 was applied to the piezophotocatalytic production of H2, and the application method was the same as that in Example 1, and the H2 production rate was 0.97 mmol / (g·h).

[0057] Example 8

[0058] Compared with Example 1, the difference lies in that in step (1), the added amount of Mn(CH3COO)2·4H2O and Cd(CH3COO)2·2H2O is 0.9804 g and 1.5992 g, respectively, and the others are the same as in Example 1, and Mn 0.4 Cd 0.6 S / Co2SnO4 composite catalyst, denoted as Mn 0.4 Cd 0.6 S-7% Co2SnO4.

[0059] Mn 0.4 Cd 0.6 S-7% Co2SnO4 was applied to the piezophotocatalytic production of H2, and the application method was the same as that in Example 1, and the H2 production rate was 1.25 mmol / (g·h).

[0060] Comparative Example 1

[0061] Compared with Example 1, the difference lies in that in the application method, the ultrasonic wave (240 W) and the light (55 W xenon lamp simulating sunlight) are replaced by only ultrasonic wave (240 W), and the others are the same as in Example 1. Mn 0.5 Cd 0.5 The H2 production rate of the Mn

[0062] Comparative Example 2

[0063] Compared with Example 1, the difference lies in that in the application method, the ultrasonic wave (240 W) and the light (55 W xenon lamp simulating sunlight) are replaced by only light (55 W xenon lamp simulating sunlight), and the others are the same as in Example 1. Mn 0.5 Cd 0.5 The H2 production rate of the Mn

[0064] Comparative Example 3

[0065] Dissolve 1.2254 g Mn(CH3COO)2·4H2O, 1.3326 g Cd(CH3COO)2·2H2O in 40 mL distilled water, stir for 30 min, then add 0.7513 g C2H5NS, continue stirring for 30 min, then transfer into a Teflon-lined autoclave, and place in an oven at 160 °C for 24 h. After completion, cool to room temperature, wash with deionized water and anhydrous ethanol three times, and dry at 60 °C under vacuum for 24 h to obtain an orange powder, which is Mn 0.5 Cd 0.5 S catalyst.

[0066] The Mn 0.5 Cd 0.5 S catalyst prepared in Comparative Example 3 is applied to piezophotocatalytic H2 production:

[0067] Weigh 2 mg Mn 0.5 Cd 0.5 S catalyst, 18 mL water, ultrasonic dispersion for 0.5 h, then add 2 mL of sacrificial agent solution, the concentration of Na2S, Na2SO3 in the sacrificial agent solution is 0.35 M, 0.25 M, then pass 30 min N2, finally under ultrasonic (240 W) and light (55 W xenon lamp simulating sunlight) for 2 h. After the experiment is completed, 0.5 mL of gas is extracted, and the peak area is detected by gas chromatograph to calculate the production rate of H2. The analysis and calculation show that the production rate of H2 is 5.57 mmol / (g·h).

[0068] Comparative Example 4

[0069] Dissolve 1.1641 g Co(NO3)2·6H2O in 30 mL distilled water to obtain solution A, then dissolve 0.7012 g SnCl4·5H2O in 30 mL distilled water to obtain solution B, slowly add solution A to solution B, stir for 10 min to obtain solution C, finally add 20 mL of 1 mol / L NaOH solution to solution C, stir for 30 min to form a blue precipitate, then transfer the mixture into a reaction kettle with a Teflon liner, and place in an oven at 180 °C for 10 h. After the reaction is completed, cool to room temperature, wash the solid in the reaction kettle with deionized water and anhydrous ethanol three times, and dry at 60 °C overnight to obtain a gray CoSn(OH)6 powder. Weigh 0.1 g of CoSn(OH)6 and place it in a tube furnace, and calcine at 500 °C for 3 h to obtain a black Co2SnO4 catalyst.

[0070] The Co2SnO4 catalyst prepared in Comparative Example 4 is applied to piezophotocatalytic H2 production:

[0071] 2 mg of Co2SnO4 catalyst, 18 mL of water were mixed and ultrasonically dispersed for 0.5 h. Then 2 mL of the sacrificial agent was added, the concentrations of Na2S and Na2SO3 in the sacrificial agent solution were 0.35 M and 0.25 M respectively, then N2 was passed for 30 min, and finally the system was sealed and subjected to ultrasonic irradiation (240 W) and light irradiation (55 W xenon lamp simulating sunlight) for 2 h. After the experiment was completed, the gas in a 0.5 mL tube was extracted and the peak area was detected by a gas chromatograph to calculate the H2 production rate. The calculated H2 production rate was 0.67 mmol / (g·h).

[0072] Comparative Example 5

[0073] 1.3326 g of Cd(CH3COO)2·2H2O was dissolved in 40 mL of distilled water and stirred for 30 min. Then 0.7513 g of C2H5NS was added and stirred for another 30 min. The mixture was then transferred into a polytetrafluoroethylene-lined autoclave and kept at a temperature of 160 ℃ for 24 h. After cooling to room temperature, the solid was washed with deionized water and anhydrous ethanol, and dried at 60 ℃ under vacuum for 24 h to obtain a yellow powder, which was CdS catalyst.

[0074] The CdS catalyst prepared in Comparative Example 5 was applied to piezophotocatalytic H2 production:

[0075] 2 mg of CdS catalyst, 18 mL of water were mixed and ultrasonically dispersed for 30 min. Then 2 mL of the sacrificial agent was added, the concentrations of Na2S and Na2SO3 in the sacrificial agent solution were 0.35 M and 0.25 M respectively, then N2 was passed for 30 min, and finally the system was sealed and subjected to ultrasonic irradiation (240 W) and light irradiation (55 W xenon lamp simulating sunlight) for 2 h. After the experiment was completed, the gas in a 0.5 mL tube was extracted and the peak area was detected by a gas chromatograph to calculate the H2 production rate. The calculated H2 production rate was 0.71 mmol / (g·h).

[0076] Comparative Example 6

[0077] 1.2254 g of Mn(CH3COO)2·4H2O and 1.3326 g of Cd(CH3COO)2·2H2O were dissolved in distilled water and stirred for 30 min to ensure complete dissolution. Then 0.7513 g of C2H5NS was added and stirred to mix uniformly. The mixture was then transferred into a polytetrafluoroethylene-lined autoclave and kept in an oven at 160 ℃ for 24 h. After the reaction was completed, the solid in the autoclave was washed with deionized water and anhydrous ethanol three times and dried at 60 ℃ overnight to obtain orange Mn 0.5 Cd 0.5 S.

[0078] Co(NO3)2.6H2O was dissolved in 30 mL of distilled water to obtain solution A, and then 0.7012 g of SnCl4.5H2O was dissolved in 30 mL of distilled water to obtain solution B, solution A was slowly added to solution B, stirred for 10 min to obtain solution C, and finally 20 mL of 1 mol / L NaOH solution was added to solution C, stirred for 30 min to form a blue precipitate, and finally the mixture was transferred to a reaction kettle with a polytetrafluoroethylene liner, placed in an oven at 180°C for 10 h, after the reaction was completed, cooled to room temperature, and the solid in the reaction kettle was washed with deionized water and anhydrous ethanol three times, and dried at 60°C overnight to obtain gray CoSn(OH)6.

[0079] Mn 0.5 Cd 0.5 S, CoSn(OH)6 was dissolved in deionized water, ultrasonic at 240 W for 1 h, and stirred at a stirring speed of 400 r / min for 4 h; filtered, washed, and dried at room temperature, and finally orange powder was obtained, which was Mn 0.5 Cd 0.5 S / Co2SnO4 composite catalyst, denoted as Mn 0.5 Cd 0.5 S-7% CoSn(OH)6. The mass of CoSn(OH)6 is 7% of the mass of Mn 0.5 Cd 0.5 S.

[0080] Mn 0.5 Cd 0.5 S-7% CoSn(OH)6 prepared in Comparative Example 6 was applied to piezophotocatalytic H2 production:

[0081] 2 mg of Mn 0.5 Cd 0.5 S-7% CoSn(OH)6 was mixed with 18 mL of water and ultrasonically dispersed for 30 min. Then 2 mL of a sacrificial agent was added, the concentration of Na2S and Na2SO3 in the sacrificial agent solution was 0.35 M and 0.25 M, then N2 was passed for 30 min, and finally it was sealed and ultrasonically treated (240 W) and light irradiated (55 W xenon lamp simulating sunlight) for 2 h. After the experiment was completed, 0.5 mL of gas was drawn into a tube, the peak area was detected by a gas chromatograph, and the H2 production rate was calculated, which was 9.94 mmol / (g.h) by analysis and calculation.

[0082] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the contents in the specification, and must be determined according to the scope of claims.

Claims

1. A Mn x Cd 1-x S / Co2SnO4 composite catalyst characterized by, The catalyst is formed by Mn x Cd 1-x S and Co2SnO4 form a heterojunction structure, wherein 0.2≤x≤0.5; Co2SnO4 is Mn x Cd 1-x 3-9% of the mass of S; The preparation method of the composite catalyst is: Mn x Cd 1-x S and Co2SnO4 are dissolved in a solvent, after ultrasonic, stirring, filtering, washing, drying, Mn x Cd 1-x S / Co2SnO4 composite catalyst; The solvent is deionized water.

2. The Mn of claim 1 x Cd 1-x S / Co2SnO4 composite catalyst characterized in that, The preparation method of the Co2SnO4 is: Co(NO3)2.6H2O is dissolved in distilled water to obtain solution A, SnCl4.5H2O is dissolved in distilled water to obtain solution B, solution A is added dropwise into solution B, stirring for 10 min to obtain solution C; NaOH solution is added into solution C, stirring for 30 min to form blue precipitate, then the mixture is transferred into a reaction kettle with a polytetrafluoroethylene lining, and placed in an oven at 160-200 DEG C for 8-12 h, after the reaction is completed, cooling to room temperature, the solid in the reaction kettle is washed and dried to obtain gray CoSn(OH)6; CoSn(OH)6 is placed in a tube furnace, heated to 480-520 DEG C at a rate of 5 DEG C / min, and calcined for 1-5 h to obtain black Co2SnO4.

3. The Mn of claim 2 x Cd 1-x S / Co2SnO4 composite catalyst characterized in that, The mass ratio of Co(NO3)2.6H2O and SnCl4.5H2O is 1.1641:0.7012; And / or, the concentration of the NaOH solution is 1 mol / L.

4. The Mn of claim 1 x Cd 1-x S / Co2SnO4 composite catalyst characterized in that, The Mn x Cd 1-x The method for preparing S is: Mn(CH3COO)2-4H2O, Cd(CH3COO)2-2H2O were mixed in a molar ratio of x:(1-x), dissolved in distilled water, stirred for 30 min, C2H5NS was added and stirred to mix uniformly, then the mixture was transferred to a reaction kettle with a polytetrafluoroethylene lining, placed in an oven at 140-180 °C for 22-26 h, after the reaction was completed, cooled to room temperature, the solid in the reaction kettle was washed and dried to obtain orange Mn x Cd 1-x S.

5. The Mn of claim 4 x Cd 1-x S / Co2SnO4 composite catalyst characterized in that, The mass ratio of C2H5NS and Mn(CH3COO)2.4H2O is 0.7513:1.2254.

6. A Mn as claimed in claim 1 x Cd 1-x A method for preparing a S / Co2SnO4 composite catalyst, characterized by, The preparation method is: Mn x Cd 1-x S and Co2SnO4 are dissolved in a solvent, after ultrasonic, stirring, filtering, washing, drying, Mn x Cd 1-x S / Co2SnO4 composite catalyst; the solvent is deionized water.

7. The Mn of claim 6 x Cd 1-x A method for preparing a S / Co2SnO4 composite catalyst, characterized in that, The ultrasonic power is 240 W, and the ultrasonic time is 1 h.

8. A Mn as claimed in claim 1 x Cd 1-x The application of the S / Co2SnO4 composite catalyst in photocatalytic H2 production, characterized in that, Mn x Cd 1-x S / Co2SnO4 composite catalyst was added to water, uniformly dispersed, then added to the sacrificial agent, followed by N2 under ultrasonic and light conditions for photocatalytic H2 production.

9. The Mn of claim 8 x Cd 1-x The application of the S / Co2SnO4 composite catalyst in photocatalytic H2 production is characterized in that, The ultrasonic power in the ultrasonic and light irradiation conditions is 240 W; the light irradiation adopts sunlight simulated by a 55 W xenon lamp.

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