阅读说明：本技术 一种复合光催化剂及其制备方法 (Composite photocatalyst and preparation method thereof ) 是由 柯勤飞 李阳 房永征 李佳佳 刘玉峰 张娜 于 2020-04-07 设计创作，主要内容包括：本发明公开了一种三元g-C<Sub>3</Sub>N<Sub>4</Sub>/MoS<Sub>2</Sub>/ZIF-8复合光催化剂及其制备方法,所述方法包括：(1)一锅法合成g-C<Sub>3</Sub>N<Sub>4</Sub>/MoS<Sub>2</Sub>二元复合物：按照质量比为1:0.625:3.3称取钼酸钠,硫代乙酰胺,尿素,混合均匀后,加入乙醇水溶液中,然后转移至反应釜中,在200℃下微波反应12-36h,自然冷却到室温。离心分离,水洗醇洗,干燥,即可得到g-C<Sub>3</Sub>N<Sub>4</Sub>/MoS<Sub>2</Sub>复合物；(2)浸渍法制备g-C<Sub>3</Sub>N<Sub>4</Sub>/MoS<Sub>2</Sub>/ZIF-8：按照质量比为1:2:(0.36～1.44)称取六水合硝酸锌、2-甲基咪唑、g-C<Sub>3</Sub>N<Sub>4</Sub>/MoS<Sub>2</Sub>复合物,分散于甲醇中,继续搅拌浸渍12h后,离心分离,洗涤,干燥得到g-C<Sub>3</Sub>N<Sub>4</Sub>/MoS<Sub>2</Sub>/ZIF-8可见光催化剂。本发明制备的复合光催化材料在水中稳定性好,催化效率高,对亚甲基蓝有很好的降解效果,90min内降解了99％。本发明所制备的光催化剂,在降解有机颜料方面具有很高的应用价值。(The invention discloses a ternary g-C 3 N 4 /MoS 2 The ZIF-8 composite photocatalyst and the preparation method thereof comprise the following steps: (1) one-pot synthesis of g-C 3 N 4 /MoS 2 Binary complex: according to the mass ratio of 1Weighing sodium molybdate, thioacetamide and urea at a ratio of 0.625:3.3, uniformly mixing, adding the mixture into an ethanol aqueous solution, transferring the mixture into a reaction kettle, carrying out microwave reaction for 12-36h at 200 ℃, and naturally cooling to room temperature. Centrifuging, washing with water, washing with alcohol, and drying to obtain g-C 3 N 4 /MoS 2 A complex; (2) preparation of g-C by impregnation 3 N 4 /MoS 2 /ZIF-8: weighing zinc nitrate hexahydrate, 2-methylimidazole and g-C according to the mass ratio of 1:2 (0.36-1.44) 3 N 4 /MoS 2 Dispersing the compound in methanol, continuously stirring and immersing for 12h, centrifuging, washing, and drying to obtain g-C 3 N 4 /MoS 2 The ZIF-8 visible light catalyst. The composite photocatalytic material prepared by the method has good stability in water, high catalytic efficiency and good degradation effect on methylene blue, and can be degraded by 99% within 90 min. The photocatalyst prepared by the invention has high application value in the aspect of degrading organic pigments.)

1. A preparation method of the composite photocatalyst is characterized by comprising the following steps:

(1) one-pot synthesis of g-C₃N₄/MoS₂Binary complex: weighing sodium molybdate, thioacetamide and urea according to the mass ratio of 1:0.625:3.3, uniformly mixing, adding into an ethanol water solution, wherein the weight ratio of ethanol: the volume ratio of water is 1:1, then the mixture is transferred into a reaction kettle, the microwave reaction is carried out for 12 to 36 hours at the temperature of 200 ℃, and the mixture is naturally cooled to the room temperature. Centrifuging, washing with water, washing with alcohol, and drying to obtain g-C₃N₄/MoS₂A complex;

(2) preparation of g-C by impregnation₃N₄/MoS₂ZIF-8, g-C obtained by subjecting the above-mentioned (1)₃N₄/MoS₂The compound is prepared by weighing zinc nitrate hexahydrate, 2-methylimidazole and g-C according to the mass ratio of 1:2 (0.36-1.44)₃N₄/MoS₂Dispersing the compound in methanol, continuously stirring and immersing for 12h, centrifuging, washing, and drying to obtain g-C₃N₄/MoS₂The ZIF-8 visible light catalyst is a composite photocatalyst.

2. A composite photocatalyst prepared by the process of claim 1.

3. The composite photocatalyst of claim 2, wherein g-C in the composite photocatalyst₃N₄、MoS₂And the mass ratio of ZIF-8 is 1:0.2 (2.5-10).

Technical Field

The invention relates to a catalyst, in particular to a composite photocatalyst.

Background

Energy and environmental problems are two serious problems faced by the current society, and the development of the society is seriously restricted. Among the technical means, photocatalysis is considered as the most promising method for solving the energy and environmental problems due to the characteristics of low energy consumption, environmental friendliness and high efficiency. Metal-organic frameworks (MOFs) are three-dimensional, reticulated porous materials formed by self-assembly of Metal central ions and organic ligands. The nano-porous silicon dioxide has the advantages of large specific surface area, high porosity, good stability, adjustable topological structure and the like, so that the nano-porous silicon dioxide is widely researched and applied to the fields of gas separation and storage, drug delivery, catalysis, luminescent materials and the like. The photocatalysis technology is a new technology for high-efficiency pollutant degradation, can promote the formation of non-spontaneous reaction by the power of sunlight, is safe and non-toxic, has the unique advantages of mild reaction conditions, unlimited treatment load, no selectivity in pollutant treatment and the like, and plays a great charm in the field of environmental protection. However, in the aspect of water treatment, the effective catalytic degradation process of the photocatalytic material can only be performed under ultraviolet light, so that the application of the photocatalytic material is greatly restricted, and the catalytic degradation cost is increased. Most MOFs have a wide energy band gap, which results in absorption of only about 5% of the total sunlight, and this has a significant limitation in practical applications. In fact, of the solar radiation, infrared and near-infrared radiation account for 53%. Therefore, in photocatalysis, how to fully utilize infrared light and near infrared light in sunlight has great research value.

Graphite phase carbon nitride (g-C)₃N₄) As a carbon-based material, the material has the characteristics of wide sources of preparation raw materials, low price, simple preparation method, easy industrialization and the like. The photocatalyst has adjustable electronic structure and good physical and chemical stability. The forbidden band width of the material is 2.70eV, so that the material can be excited by visible light and can absorb the visible light to decompose water to prepare hydrogen. However, g-C₃N₄Also has many disadvantages to improve the photocatalytic performance, especially higher electron hole recombination rate, seriously reducing the photocatalytic efficiency, and improving g-C₃N₄The photocatalytic performance and the improvement of the electron hole separation rate are always the key points of research in the field.

MoS₂Is a two-dimensional ferrous metal sulfide with metallic luster. It consists of two S atoms and one Mo atom layer as the middle layer₂The special structure has extremely high transmission rate of carriers in the structure, and the energy band width range of the structure is 1.2-1.9eV, so that the structure can absorb more sunlight and has extremely high utilization rate of the sunlight. The material has excellent electrical and optical characteristics, and is widely applied to the fields of microelectronic devices, solar cells and the like at present. MoS₂The active sites for the photocatalytic reaction are located at the edges of the exposed S-Mo-S layer in the layered structure. MoS₂Less conductive and prone to layer-by-layer stacking with reduced edge exposure to active sitesThereby reducing its photocatalytic activity. One solution to this problem is to use MoS as a solution₂Dispersed on a suitable template material to prepare high-sulfur multi-edge MoS₂A material.

A modified MoS is disclosed in patent CN 106975511A₂/g-C₃N₄The photocatalyst disclosed by the patent can be used for carrying out catalytic degradation on rhodamine B under the irradiation of near infrared light, but the catalytic efficiency is lower. In patent CN 107115880A, a MoS is disclosed₂/CNTs/g-C₃N₄The composite photocatalytic material and the preparation method thereof, but new pollution is introduced by residual metal ions of nickel and chromium of the carbon nano tube while rhodamine B is degraded, and the problem of recovery is difficult to solve. In is disclosed In patent CN 103990486A₂S₃/g-C₃N₄The preparation method of the composite nano material is that In the experiment of degrading Methylene Blue (MB), the composite photocatalyst has a single In ratio₂S₃Has better catalytic effect, but g-C₃N₄The preparation of the urea is obtained by calcining urea at the high temperature of 550 ℃, and the preparation process is complex, has high cost and is not beneficial to energy conservation and environmental protection.

Disclosure of Invention

The invention aims to provide a composite photocatalyst and a preparation method thereof.

In order to achieve the above object, the present invention provides a preparation method of a composite photocatalyst, which is characterized by comprising the following steps:

(1) one-pot synthesis of g-C₃N₄/MoS₂Binary complex: weighing sodium molybdate, thioacetamide and urea according to the mass ratio of 1:0.625:3.3, uniformly mixing, adding into an ethanol water solution, wherein the weight ratio of ethanol: the volume ratio of water is 1:1, then the mixture is transferred into a reaction kettle, the microwave reaction is carried out for 12 to 36 hours at the temperature of 200 ℃, and the mixture is naturally cooled to the room temperature. Centrifuging, washing with water, washing with alcohol, and drying to obtain g-C₃N₄/MoS₂A complex;

(2) preparation of g-C by impregnation₃N₄/MoS₂/ZIF-8g-C obtained in the above (1)₃N₄/MoS₂The compound is prepared by weighing zinc nitrate hexahydrate, 2-methylimidazole and g-C according to the mass ratio of 1:2 (0.36-1.44)₃N₄/MoS₂Dispersing the compound in methanol, continuously stirring and immersing for 12h, centrifuging, washing, and drying to obtain g-C₃N₄/MoS₂The ZIF-8 visible light catalyst is a composite photocatalyst.

The invention also provides the composite photocatalyst prepared by the method.

Preferably, g-C in the composite photocatalyst₃N₄、MoS₂And the mass ratio of ZIF-8 is 1:0.2 (2.5-10).

The invention innovatively provides that ammonium thioacetate is used as MoS₂The sulfur source is simultaneously used for synthesizing the sulfurated C together with the urea₃N₄(g-C₃N₄) One-pot synthesis of g-C₃N₄/MoS₂And (c) a complex. The compound is bonded through S-S, has a compact interface and improves the electron conduction rate; meanwhile, the two components form a heterogeneous result, charge is transferred, and the photoproduction electron-hole separation efficiency is easy to improve. In addition, in the present specification, in order to improve the adsorption performance of the catalyst material, g-C₃N₄/MoS₂ZIF-8 is introduced into the compound to form the ternary composite photocatalyst. The catalyst can greatly improve the utilization rate of visible light in sunlight and has high catalytic activity.

Compared with the prior art, the invention has the beneficial effects that:

(1) g-C prepared by the invention₃N₄/MoS₂the/ZIF-8 visible light catalyst can effectively reduce the recombination of photo-generated electron-hole pairs through the formation of a heterojunction, and improve the photocatalytic activity. It effectively retains MoS₂The wide absorption property and the wide light response range can greatly improve the utilization rate of light. And the structural integrity of the ZIF-8 is well reserved, so that the composite photocatalytic material has a higher specific surface area, can have good adsorption performance, provides enough active sites for photocatalytic reaction, and effectively improves the photocatalytic effect of the photocatalystAnd (4) rate. When g-C₃N₄And MoS₂When the light is irradiated by visible light, electrons on the valence band are excited and jump to the conduction band, so that photo-generated electron-hole pairs are generated. And because of g-C₃N₄The conduction band potential of (A) is more negative, so that photogenerated electrons on the conduction band can be transferred to the MoS₂And ZIF-8 conductive band, the transferred electrons react with dissolved oxygen in the reaction system to generate active substance of superoxide radical (. O)₂ ^-) The superoxide radicals can react with MB dye molecules adsorbed on the surface of the composite photocatalyst, and play a role in degrading MB through photocatalysis. And MoS₂So that its hole can migrate to g-C₃N₄The holes are able to directly degrade MB.

(2) The preparation method of the invention fully uses microwave heating to accelerate the nucleation rate and the crystal growth rate. The microwave method has the advantages of short reaction time, high yield, simple equipment, low pollution, no temperature gradient, small size of the synthesized product and uniform particle size distribution. Using thioacetamide and urea as g-C₃N₄The synthetic universality is that an S-S coupling bond is formed on the interface, which is beneficial to improving the interface combination degree and improving the electron conduction rate. Therefore, compared with the room-temperature self-assembly method and the hydrothermal method, the method has greater innovation in theory and technology.

Drawings

FIG. 1 shows g-C obtained in examples 1, 2 and 3 of the present invention₃N₄/MoS₂XRD patterns of/ZIF-8 visible-light-driven photocatalyst and each component;

FIG. 2 shows g-C obtained in examples 1, 2 and 3 of the present invention₃N₄/MoS₂A ZIF-8 visible light catalyst and a photocatalytic degradation diagram of each component to methylene blue;

FIG. 3 shows g-C obtained in example 1 of the present invention₃N₄/MoS₂SEM image of/ZIF-8 visible light catalyst.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.