CROSS REFERENCE TO RELATED APPLICATION

The present application is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/CN2018/097718 filed on Jul. 30, 2018. The disclosure of the above application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to the field of catalyst technologies, and in particular, to a photocatalytic composite material and a preparation method and an application thereof.

BACKGROUND

A water electrolysis method for hydrogen production is a most common hydrogen production method, but it has many disadvantages. 1. A solid polymer electrolyte membrane is a core part of water electrolysis for hydrogen production. However, currently, the development of solid polymer electrolyte membranes in China is greatly limited and depends on a few foreign companies, and consequently hydrogen production costs are relatively high. 2. The thin film as a catalyst has limited service life and a low reuse rate. 3. In an actual operation process, a large amount of electric energy needs to be consumed.

In the field of water photolysis for hydrogen production, commonly used catalysts are pure semiconductor oxides, such as cerium dioxide and titanium dioxide. Band gaps of the semiconductor oxides are approximately 3.2 eV, and can be used for photocatalytic reaction only in an ultraviolet region of sunlight. In addition, an ultraviolet part accounts for only approximately 4% of a solar spectrum, and sunlight utilization is relatively low. A transition metal sulfide semiconductor material can respond directly to visible light, but the transition metal sulfide semiconductor material has an obvious photocorrosion effect, and a capability of separating a photogenerated electron hole pair needs to be improved. This limits an application of the transition metal sulfide semiconductor material in the photocatalysis field.

SUMMARY

In view of this, an objective of the present invention is to provide a photocatalytic composite material and a preparation method and an application thereof. The photocatalytic composite material provided in the present invention can improve a capability of separating a photogenerated electron hole pair, and avoid a photocorrosion effect existing in a transition metal sulfide semiconductor material, thereby greatly improving visible light utilization of the material, and showing a wide potential application value in water decomposition for hydrogen production under an action of visible light.

To achieve the above purpose, the present invention provides the following technical solutions.

The present invention provides a preparation method of a photocatalytic composite material, including the following steps:

(1) subjecting plant leaves to soaking pretreatment to obtain template biomass;

(2) impregnating, in a molybdenum source-sulfur source aqueous solution, the template biomass obtained in step (1) to obtain a composite material precursor; and

(3) calcining the composite material precursor prepared in step (2) to obtain the photocatalytic composite material.

Preferably, the plant leaves includeSinaraundinaria nitidaleaves, salix leaves,Indocalamusleaves,Phyllostachys sulphurealeaves, orPhyllostachys nigraleaves.

Preferably, a concentration of a sulfur source in the molybdenum source-sulfur source aqueous solution is 0.05 mol/L to 1 mol/L.

Preferably, a concentration of a molybdenum source in the molybdenum source-sulfur source aqueous solution is 0.05 mol/L to 1 mol/L.

Preferably, a ratio of a volume of the molybdenum source-sulfur source aqueous solution to a mass of the template biomass is (1-3) L: 100 g.

Preferably, an impregnation time is 48 h to 72 h.

Preferably, calcination temperature is 450° C. to 700° C.

Preferably, the calcination time is 120 min to 158 min.

The present invention further provides a photocatalytic composite material obtained by using the above-described preparation method, where the photocatalytic composite material in the present invention includes acicular molybdenum sulfide and biomass carbon, the acicular molybdenum sulfide is loaded to a surface of the flake carbon, the mass content of the biomass carbon is 70% to 90%, and the mass content of the molybdenum sulfide is 10% to 30%.

The present invention further provides an application of the above-described photocatalytic composite material in water decomposition for hydrogen production.

The present invention provides a preparation method of a photocatalytic composite material, including the following steps: (1) subjecting plant leaves to soaking pretreatment to obtain template biomass; (2) impregnating, in a molybdenum source-sulfur source aqueous solution, the template biomass obtained in step (1) to obtain a composite material precursor; and (3) calcining the composite material precursor obtained in step (2) to obtain the photocatalytic composite material. In the present invention, the template biomass loaded with sulfur ions and molybdenum ions is calcined, acicular molybdenum sulfide is formed by using a carbon skeleton of an organic matter and a special microscopic structure that are of the template biomass, and the molybdenum sulfide is formed and grows on a carbon surface, forming an acicular molybdenum sulfide and biomass carbon photocatalytic composite material. The photocatalytic composite material provided in the present invention has an acicular structure, and therefore can improve a capability of separating a photogenerated electron hole pair, and avoid a photocorrosion effect existing in a transition metal sulfide semiconductor material, thereby greatly improving visible light utilization of the material, and showing a wide potential application value in water decomposition for hydrogen production under an action of visible light. It can be learned from embodiments that performance of photocatalytic hydrogen production of the photocatalytic composite material is better than that of a pure molybdenum sulfide material and has excellent photocorrosion resistance, and hydrogen production efficiency is reduced by only approximately 10% after three cycles.

