阅读说明：本技术 改性氮化碳光催化剂及其制备方法和应用 (Modified carbon nitride photocatalyst and preparation method and application thereof ) 是由 甘慧慧 易赋淘 姚志远 钱勇兴 张会宁 靳慧霞 张科锋 徐体兵 于 2019-04-11 设计创作，主要内容包括：本发明公开了一种改性氮化碳光催化剂,以石墨相氮化碳为主体,掺杂硫、卤元素,其中卤素元素的质量分数为0.1～40％；采用含硫化合物与含卤素化合物混合煅烧形成,可应用于光催化降解水中有机污染物。本发明改性氮化碳的制备方法简单易行,危险性小,对于气体氛围无特定要求,通过引入硫、卤素杂质使得石墨相氮化碳的光生空穴和电子分离能力增强,而且可以减小禁带宽度；同时引入的卤素影响价带电子电势,使得材料的光催化性能上升；所得的改性氮化碳稳定性好并作为催化剂在可见光下对于水中的有机污染物降解能力均有较大提升,因此可以被广泛应用于印染废水以及化工废水处理中。(The invention discloses a modified carbon nitride photocatalyst, which takes graphite-phase carbon nitride as a main body and is doped with sulfur and halogen elements, wherein the mass fraction of the halogen elements is 0.1-40%; the catalyst is formed by mixing and calcining a sulfur-containing compound and a halogen-containing compound, and can be applied to photocatalytic degradation of organic pollutants in water. The preparation method of the modified carbon nitride is simple and easy to implement, has small danger, has no specific requirement on gas atmosphere, enhances the separation capability of photoproduction holes and electrons of the graphite-phase carbon nitride by introducing sulfur and halogen impurities, and can reduce the forbidden bandwidth; meanwhile, the introduced halogen influences the electronic potential of a valence band, so that the photocatalytic performance of the material is improved; the obtained modified carbon nitride has good stability and can be used as a catalyst to greatly improve the degradation capability of organic pollutants in water under visible light, so that the modified carbon nitride can be widely applied to treatment of printing and dyeing wastewater and chemical wastewater.)

1. A modified carbon nitride photocatalyst is characterized in that: the graphite-phase carbon nitride is used as a main body and is doped with sulfur and halogen elements, wherein the mass fraction of the halogen elements is 0.1-40%.

2. The modified carbon nitride photocatalyst according to claim 1, wherein the halogen element is chlorine element.

3. The method for preparing a modified carbon nitride photocatalyst according to any one of claims 1 to 2, characterized by comprising the steps of:

s1, mixing and grinding a sulfur-containing compound and a halogen-containing compound;

s2, transferring the mixture obtained in the step S1 into a closed crucible, and heating and calcining.

4. The method for preparing a modified carbon nitride photocatalyst according to claim 3, wherein the mass ratio of the sulfur-containing compound to the halogen-containing compound in step S1 is 1: 0.01-0.4.

5. The method of claim 3, wherein in step S1, the sulfur-containing compound is thiourea, and the halogen-containing compound is ammonium chloride.

6. The preparation method of the modified carbon nitride photocatalyst according to claim 3, wherein the heating and calcining process of step S2 is to heat up to 450-650 ℃ at a heating rate of 2-10 ℃/min for 2-4 h.

7. Use of the modified carbon nitride photocatalyst according to any one of claims 1 to 2 for photocatalytic degradation of organic pollutants in water.

8. The use of the modified carbon nitride photocatalyst as claimed in claim 7, wherein the organic contaminant is one of rhodamine B or 4-nitrophenol.

Technical Field

The invention belongs to the field of material preparation and photocatalysis, and particularly relates to a catalytic material taking carbon nitride as a main body and application thereof in photocatalytic degradation of pollutants.

Background

With the increasing pollution in recent years, the environmental protection problem is more and more emphasized by people. Among them, photocatalytic oxidation technology is more and more favored because of its green and high-efficiency characteristics. With the development of photocatalytic materials, graphite-phase carbon nitride has received attention as a new photocatalyst. This material has the following advantages: (1) the band gap is 2.7eV, so that certain visible light response is realized; (2) the catalyst has high chemical stability and thermal stability, so the catalyst has good catalytic stability; (3) due to its non-metallic construction, it is relatively inexpensive and readily available. But at the same time, the graphite-phase carbon nitride also has the problem to be solved in the application process of photocatalysis (1) because of the forbidden bandwidth of 2.7eV, the utilization rate of visible light is extremely low, and only a small amount of visible light can excite the separation of photo-generated electrons and holes; (2) meanwhile, the photo-generated holes and electrons are easy to recombine, and the conduction efficiency of photo-generated carriers is low. In view of the above application defects, studies on modification based on carbon nitride have attracted attention of scholars, including doping modification, construction of composite heterojunction semiconductors, and the like, but the commonly reported modification methods are complicated in preparation process and high in synthesis cost, so that development of a cheap and easily available high-efficiency carbon nitride catalytic material is urgently needed.

Disclosure of Invention

In order to solve the technical problems, the invention provides a modified carbon nitride photocatalyst with higher electron and hole separation capability.

The technical scheme provided by the invention is to provide a modified carbon nitride photocatalyst, which takes graphite-phase carbon nitride as a main body and is doped with sulfur and halogen elements, wherein the mass fraction of the halogen elements is 0.1-40%.

Preferably, the halogen element is chlorine element.

The invention further provides a preparation method of the modified carbon nitride, which comprises the following steps:

s1, mixing and grinding a sulfur-containing compound and a halogen-containing compound;

s2, transferring the mixture obtained in the step S1 into a closed crucible, and heating and calcining.

Wherein the mass ratio of the sulfur-containing compound to the halogen-containing compound in step S1 is 1: 0.01-0.4; preferably, the sulfur-containing compound is thiourea and the halogen-containing compound is ammonium chloride.

In the step S2, the heating and calcining process is to heat up to 450-650 ℃ at a heating rate of 2-10 ℃/min and calcine for 2-4 h.

The invention also aims to provide the application of the modified carbon nitride in photocatalytic degradation of organic pollutants in water, wherein the organic pollutants comprise rhodamine B, 4-nitrophenol and the like.

The invention has the advantages and beneficial effects that:

1, the separation capability of photoproduction holes and electrons of graphite-phase carbon nitride is enhanced by introducing sulfur and halogen impurities, and the forbidden bandwidth can be reduced; meanwhile, the introduced halogen influences the electronic potential of a valence band, so that the photocatalytic performance of the material is improved;

2, the method successfully carries out doping modification on graphite-like phase carbon nitride by adopting a sulfur-halogen co-doping technology which is simple and easy to implement and low in raw material, and prepares and synthesizes the carbon nitride catalytic material with high visible light catalytic activity efficiency; the preparation method is simple and easy to implement, has small danger, has no specific requirements on gas atmosphere, and the obtained material has good photocatalytic effect, so the method is a synthesis method with application prospect;

3 under visible light, the degradation capability of the modified carbon nitride as a catalyst on organic pollutants in water, such as rhodamine B and 4-nitrophenol, is greatly improved, so that the modified carbon nitride can be widely applied to printing and dyeing wastewater and chemical wastewater treatment.

Drawings

FIG. 1 is an X-ray powder diffraction pattern of undoped modified carbon nitride (labeled as carbon nitride in the figure) and modified carbon nitride (labeled as sulfur-halogen co-doped carbon nitride in the figure) prepared in example 1.

Fig. 2 is a graph of the uv-vis diffuse reflectance spectra of undoped modified carbon nitride (labeled as carbon nitride in the figure) and modified carbon nitride (labeled as sulfur-halogen co-doped carbon nitride in the figure) obtained in example 1.

FIG. 3 is a graph of time-degradation of undoped modified carbon nitride (labeled as carbon nitride in the figure) and modified carbon nitride (labeled as sulfur-halogen co-doped carbon nitride in the figure) prepared in example 1 for rhodamine B in water.

Figure 4 is a graph of the time-degradation of undoped modified carbon nitride (labeled carbon nitride in the figure) and the modified carbon nitride prepared in example 1 (labeled sulfur-halogen co-doped carbon nitride in the figure) for 4-nitrophenol in water.

FIG. 5 is a graph of the cyclic degradation of undoped modified carbon nitride (labeled as carbon nitride in the figure) and modified carbon nitride (labeled as sulfur-halogen co-doped carbon nitride in the figure) prepared in example 1 for rhodamine B in water.

FIG. 6 is a graph of the cyclic degradation of undoped modified carbon nitride (labeled carbon nitride in the figure) with the modified carbon nitride prepared in example 1 (labeled sulfur-halogen co-doped carbon nitride in the figure) versus 4-nitrophenol in water.

Detailed Description

The present invention will be further described with reference to the following embodiments.