表面缺陷调控对g-C3N4光催化去除空气中NO行为的影响研究

Nitric oxide (NO) is considered a common gaseous pollutant because it can cause problems, such as acid rain, photochemical smog, and haze. Semiconductor photocatalytic technology has recently been regarded as an attractive alternative technology for NO removal. Among various kinds of photocatalysts, graphitic carbon nitride (g-C3N4) has attracted increasing attention because of its high thermal and chemical stability, semiconductivity, and special optical features. Although it has been proven to be a promising metal-free photocatalyst to remove NO, block g-C3N4 suffers from low photoreactivity, which is caused by the fast recombination of photogenerated electrons and holes. Meanwhile, few researches focus on the mechanism and products of NO photocatalytic removal in the published literatures. Since surface defects are very important in photocatalysis, NO removal procedure over g-C3N4 may be well turned by adjusting the surface defect structure of g-C3N4. However, to the best of our knowledge, there is little research on this field. Based on our previous researches, this project will introduce a series of surface defect structures on the surface of g-C3N4 to enhance the photocatalytic NO removal activity of g-C3N4 by changing of band structure, NO adsorption modal, NO removal mechanism and NO removal products of g-C3N4. Based on the research results, we will get the basic laws and underlying causes of the fact that NO removal procedure over g-C3N4 can be well turned by adjusting the surface defect structure of g-C3N4. This project could not only enrich the basic theory of photocatalysis and NO photochemical removal, but also can promote the development of new NO removal photocatalysts.

氮氧化物(NO)是引起酸雨、雾霾、光化学烟雾等恶劣环境现象的主要成分，利用光催化剂治理NO是近年来的研究热门。在众多光催化剂中，石墨相氮化碳（g-C3N4）由于廉价、稳定、能带结构适中等优点表现出诱人的应用前景。但是，g-C3N4去除NO的能力目前还比较低，而且NO的去除机理及产物也存在争议。研究表明，表面缺陷对光催化剂去除污染物的行为有重要影响，所以通过调控g-C3N4的表面缺陷有望调控g-C3N4光催化去除NO的行为，然而这方面的研究目前非常少。在前期工作基础上，本项目拟通过在g-C3N4表面引入不同缺陷来调控g-C3N4的能带结构、NO的吸附模式、以及NO去除产物与机理，进而增强g-C3N4光催化转化NO的能力。在此基础上，获得不同表面缺陷对g-C3N4光催化去除NO行为影响的基本规律和内在根源，丰富光催化及NO光化学去除的基础理论，为促进新型NO去除光催化剂的开发提供理论依据。

氮氧化物(NO)是引起酸雨、雾霾、光化学烟雾等恶劣环境现象的主要成分，利用光催化剂治理NO是近年来的研究热门。在众多光催化剂中，石墨相氮化碳（g-C3N4）由于廉价、稳定、能带结构适中等优点表现出诱人的应用前景。但是，g-C3N4去除NO的能力之前还比较低，而且NO的去除机理及产物也存在争议。表面缺陷对光催化剂去除污染物的行为有重要影响，所以通过调控g-C3N4的表面缺陷有望调控g-C3N4光催化去除NO的行为。在前期工作基础上，本项目通过在g-C3N4表面引入不同C空位缺陷、N空位缺陷来调控g-C3N4的能带结构及其对NO的吸附模式、去除产物与机理等，进而增强g-C3N4光催化转化NO的能力。研究结果发现表面C空位和N空位在NO的去除过程中都可以作为光生电子的捕获中心，促进光生电子与空穴的分离，产生更多活性氧物种从而增强g-C3N4光催化去除NO的效果。另外，C空位缺陷还可以作为NO的吸附位点，改变NO的吸附方式，促进NO还原反应发生。除此之外，本项目还研究了杂质缺陷、杂质-空位协同缺陷等不同表面缺陷对g-C3N4光催化去除NO行为的影响。本项目获得了不同表面缺陷对g-C3N4光催化去除NO行为影响的基本规律和内在根源，丰富了光催化及NO光化学去除的基础理论，为促进新型NO去除光催化剂的开发及g-C3N4光催化去除NO的实际应用提供了理论依据。