阅读说明：本技术 一种硫化镉-磷钨酸铯复合材料的制备方法及其作为可见光催化剂制取氢的用途 (Preparation method of cadmium sulfide-cesium phosphotungstate composite material and application of composite material as visible-light-driven photocatalyst to hydrogen preparation ) 是由 李星 卿光亮 李涛海 于 2020-06-17 设计创作，主要内容包括：本发明公开了一种硫化镉-磷钨酸铯复合材料的制备方法及其作为可见光催化剂制取氢的用途,采用原位合成法制备了一种硫化镉-磷钨酸铯复合材料,将所制得的材料作为可见光催化剂,在300W的氙灯照射下进行光催化产氢实验,结果所制备的材料显示出良好的光催化性能。本发明通过将具有可见光催化性能的硫化镉纳米颗粒和具有多孔径特性的多金属氧酸盐复合,提高了该类材料的稳定性以及抗光腐蚀性能。本发明催化剂制备方法简单,易于操作,反应条件温和,反应后产物易于分离出,无腐蚀性,对环境无污染,设备投资少,成本低,适合批量生产。(The invention discloses a preparation method of a cadmium sulfide-cesium phosphotungstate composite material and application of the cadmium sulfide-cesium phosphotungstate composite material as a visible-light-driven photocatalyst for preparing hydrogen. The invention improves the stability and the anti-light corrosion performance of the material by compounding the cadmium sulfide nano-particles with visible light catalytic performance and the polyoxometallate with the porous diameter characteristic. The catalyst of the invention has simple preparation method, easy operation, mild reaction condition, easy separation of products after reaction, no corrosion, no pollution to the environment, less equipment investment and low cost, and is suitable for batch production.)

1. The preparation method of the cadmium sulfide-cesium phosphotungstate composite material is characterized by comprising the following steps of:

(1) weighing appropriate amount of cesium carbonate and phosphotungstic acid (H)₃PW₁₂O₄₀) Respectively dissolving the cesium carbonate solution and the phosphotungstic acid solution in distilled water with certain volume to obtain a cesium carbonate solution and a phosphotungstic acid solution, slowly dripping the cesium carbonate solution into the phosphotungstic acid solution under stirring at room temperature, continuing stirring for 8 hours after dripping, and standing and aging for 12 hours at room temperature; then evaporating the dry water at 60 ℃ to obtain a white solid, grinding the white solid into powder, and calcining the powder at 450 ℃ for 4 hours to obtain cesium phosphotungstate;

(2) weighing appropriate amount of the prepared cesium phosphotungstate (Cs)_2.5H_0.5PW₁₂O₄₀) Ultrasonic dispersion is carried out on the mixture with the volume ratio of 1:1, obtaining a solution A in a mixed solution of distilled water and ethanol;

(3) proper amount of hydrated cadmium acetate (Cd (Ac)₂·2H₂O) is added into the solution A, and is irradiated for 30min by a 500W xenon lamp under stirring to obtain a solution B;

(4) dissolving sodium sulfide nonahydrate in distilled water with a certain volume to obtain a solution C;

(5) slowly dripping the solution C into the solution B under the stirring condition, then stirring for 1h in a dark place, standing for 24h at room temperature, centrifugally separating and precipitating, alternately washing for three times by using distilled water and ethanol, and evaporating water at 70 ℃ to obtain a crude product;

6) grinding the obtained crude product into powder, then transferring the powder into a muffle furnace, and calcining the powder for 4 hours at 450 ℃ to obtain the cadmium sulfide-cesium phosphotungstate composite material;

the mass ratio of the cadmium acetate to the sodium sulfide is 1: 1;

the chemical expression formula of the cadmium sulfide-cesium phosphotungstate composite material is CdS/Cs_2.5H_0.5PW₁2O₄₀；

The solvents, reagents or raw materials for the reaction are all chemically pure.

2. Use of the cadmium sulfide-cesium phosphotungstate composite material obtained by the preparation method according to claim 1,the composite material is used as a visible light photocatalyst, and is irradiated with Na by simulating solar light irradiation with a 300W xenon lamp₂S/Na₂SO₃Under the condition of being used as a sacrificial agent, the hydrogen production rate can reach 286.1 mu mol/(g.h).

Technical Field

The invention belongs to the technical field of photocatalysis, and particularly relates to a preparation method of a cadmium sulfide-cesium phosphotungstate composite material and application of the cadmium sulfide-cesium phosphotungstate composite material as a visible-light-driven photocatalyst for preparing hydrogen.

Background

Hydrogen energy, as an environmentally friendly, clean and pollution-free novel energy source, can be prepared by photocatalytic water decomposition. Photocatalysis is considered as an ideal environment treatment and energy regeneration technology, and the reaction can be carried out at normal temperature and normal pressure. In order to achieve efficient water decomposition to produce hydrogen, a large number of semiconductor photocatalysts have been developed for the production of hydrogen. Cadmium sulfide is a typical type II-IV semiconductor with a Bohr radius of 2.4nm and a forbidden bandwidth of 2.42 eV. The forbidden band width of the cadmium sulfide nano material is obviously changed along with the change of the nano size and the change of the shape, and the cadmium sulfide nano material shows more excellent photocatalytic performance than a bulk material; however, cadmium sulfide is unstable, and is prone to undergo a photo-corrosion reaction, so that the catalytic reaction activity and stability of the cadmium sulfide are affected, and the application of the cadmium sulfide in photocatalysis is limited. The cesium phosphotungstate can be used as a solid acid catalyst and a carrier in application, because the cesium phosphotungstate has an acidic active center, hydrogen ions can be separated from water more conveniently and then converted into hydrogen, the efficiency of the photocatalytic hydrogen production reaction can be improved, a strip-shaped structure formed after the cesium phosphotungstate and cadmium sulfide are compounded is more favorable for charge transfer, the compounding probability of photoproduction electrons and holes is reduced, and therefore the activity of a photocatalytic machine in the photocatalytic reaction is improved.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art, aims to combine CdS with good visible light response capability and cesium phosphotungstate, overcomes respective weaknesses, enhances the photocatalytic performance of the CdS and cesium phosphotungstate, and provides a preparation method of a cadmium sulfide-cesium phosphotungstate composite material and application of the cadmium sulfide-cesium phosphotungstate composite material as a visible light catalyst to prepare hydrogen.

The technical scheme adopted by the invention for solving the technical problems is as follows: a preparation method of a cadmium sulfide-cesium phosphotungstate composite material comprises the following steps of firstly synthesizing cesium phosphotungstate, then synthesizing a crude product by using cesium phosphotungstate, cadmium acetate and sodium sulfide as main raw materials through an in-situ synthesis method, and then calcining at a high temperature to obtain the cadmium sulfide-cesium phosphotungstate composite material:

(1) weighing a proper amount of cesium carbonate and phosphotungstic acid, respectively dissolving in distilled water with a certain volume to obtain a cesium carbonate solution and a phosphotungstic acid solution, slowly dripping the cesium carbonate solution into the phosphotungstic acid solution under stirring at room temperature, continuing stirring for 8 hours after dripping, and standing and aging for 12 hours at room temperature; then evaporating the dry water at 60 ℃ to obtain a white solid, grinding the white solid into powder, and calcining the powder at 450 ℃ for 4 hours to obtain cesium phosphotungstate;

(2) weighing a proper amount of the prepared cesium phosphotungstate, and ultrasonically dispersing the cesium phosphotungstate in a volume ratio of 1:1, obtaining a solution A in a mixed solution of distilled water and ethanol;

(3) adding a proper amount of hydrated cadmium acetate into the solution A, and irradiating for 30min by using a 500W xenon lamp under stirring to obtain a solution B;

(4) dissolving sodium sulfide nonahydrate in distilled water with a certain volume to obtain a solution C;

(5) slowly dripping the solution C into the solution B under the stirring condition, then stirring for 1h in a dark place, standing for 24h at room temperature, centrifugally separating and precipitating, alternately washing for three times by using distilled water and ethanol, and evaporating water at 70 ℃ to obtain a crude product;

(6) grinding the obtained crude product into powder, then transferring the powder into a muffle furnace, and calcining the powder for 4 hours at 450 ℃ to obtain the cadmium sulfide-cesium phosphotungstate composite material;

the mass ratio of the cadmium acetate to the sodium sulfide is 1: 1;

the chemical formula of the hydrated cadmium acetate is Cd (Ac)₂·2H₂O；

The chemical formula of the phosphotungstic acid is H₃PW₁₂O₄₀；

The chemical formula of the cesium phosphotungstate is Cs_2.5H_0.5PW₁₂O₄₀；

The chemical expression formula of the cadmium sulfide-cesium phosphotungstate composite material is CdS/Cs_2.5H_0.5PW₁2O₄₀；

The solvents, reagents or raw materials for the reaction are all chemically pure.

Furthermore, the invention also provides application of the cadmium sulfide-cesium phosphotungstate composite material, wherein the composite material is used as a visible light catalyst, a 300W xenon lamp is used for simulating solar light irradiation, and Na is used₂S/Na₂SO₃As sacrificial agentsUnder the condition of (1), the hydrogen production rate can reach 286.1 mu mol/(g.h).

Compared with the prior art, the invention has the following characteristics:

1. the chemical reagents used in the invention are all common reagents, and are cheap and easy to obtain; the synthesis preparation process is simple, the generated pollution is little, and the synthesized photocatalyst has good stability and high activity;

2. the in-situ synthesis method adopted by the invention effectively prevents the cesium phosphotungstate salt from losing, well maintains the Keggin structure of the cesium phosphotungstate salt, and the characteristics of the cesium phosphotungstate salt are unchanged after being loaded, thereby ensuring that the catalyst has higher catalytic activity;

3. in the prepared cadmium sulfide/cesium phosphotungstate composite material photocatalyst, cadmium sulfide is stably and uniformly attached to the surface of cesium phosphotungstate salt, and the cesium phosphotungstate salt can effectively reduce the recombination rate of photo-generated electrons and holes, and improve the photo-corrosion resistance of cadmium sulfide, so that the cadmium sulfide/cesium phosphotungstate composite material photocatalyst has more excellent photocatalytic performance.

Drawings

FIG. 1 is an XRD pattern of the cadmium sulfide-cesium phosphotungstate composite material prepared by the invention.

FIG. 2 is an IR diagram of the cadmium sulfide-cesium phosphotungstate composite material prepared by the invention.

FIG. 3a is an SEM image of cesium phosphotungstate prepared by the invention, and FIG. 3b is an SEM image of cadmium sulfide-cesium phosphotungstate composite material prepared by the invention.

FIG. 4 is a graph showing the catalytic hydrogen production of the cadmium sulfide-cesium phosphotungstate composite material prepared by the present invention as a visible light catalyst.

Detailed Description

The present invention is further described in detail with reference to the following examples, and the technical solution of the present invention is not limited to the specific embodiments listed below, but includes any combination of the specific embodiments.