可见光持续再生氮掺杂石墨烯构筑及其催化降解有机污染物机理研究

Nitrogen-doped graphene(N-GR) becomes a promising catalyst for activating permonosulfate (PMS) due to its merits of low cost, high surface area, high electron mobility and preferential edge defects. However, N-GR stlill lags behind Co3O4 both in the catalytic efficiency and the recyclability. The major reason is thatafter the dominating basic reactive sites such as pyridine and pyrrole transfer electrons to PMS, they cannot accept electrons for timely recovery. From another hand, The increased number of acidic functional groups on graphene after repeated use makes the catalyst more negatively charged, which will remarkably reduce the PMS adsorption. Aiming at solving these key problems, a high-efficiency self site-recovery PMS catalyst will be designed and synthesized in this project by incorporating vible-light photocatalyst with N-GR. The photo-motivated electrons by solar light irradiation will be injected into the invalid reactive sites and make them in-situ recovered. Simultaneously, these electrons will reduce the acidic groups on the catalyst surface, which makes it positively charged and keeps long-term adsorption capacity for PMS. These combinative effects will lead to a breakthrough in the catalytic activity and the recyclability and be of great importance for the design of novel catalysts by band enginnering.

掺氮石墨烯具有低成本、大比表面、高电子迁移率及丰富的边缘缺陷等优点，而成为过一硫酸盐（PMS）高级氧化法的优异催化剂材料。然而，掺杂石墨烯的催化活性和循环使用性均较Co3O4有较大差距。其主要原因是掺氮石墨烯表面主导催化作用的吡啶、吡咯等碱性位点将电子转移给PMS后，无法及时有效获得电子实现再生；另一方面，催化剂多次使用后表面酸性官能团的持续增加使催化剂表面负电荷增加致使PMS吸附量锐减。针对上述关键问题，本项目在国际上首次提出采用可见光催化半导体材料与N掺杂石墨烯复合，构建可自发持续再生的高活性PMS催化剂。其主要原理是利用光催化材料在可见光激发下生成的光生电子不间断注入失效的活性位点使其持续原位再生，同时光生电子还可同步还原表面的酸性官能团，使催化剂表面带正电荷，以保持对PMS的长效吸附性。上述双重机制将实现催化剂活性及重复利用性的突破，对通过能带工程设计新型催化材料具有重要意义。

本项目建立了可见光自发再生的GR-NiO/NaClO/Vis、CuFe LDH/NaClO/Vis、TiO2-MoS2/Vis以及Ov-CuO/PMS/Vis多个污染物催化降解体系，深入揭示了可见光辅助催化产生的电子光生电子对催化剂表面电子传递、活性物种产生及位点再生的影响，从而解决了限制催化剂效率及重复实用性的关键问题；以NiO、CuO为特征体系，研究了催化剂形状及高能晶面等其催化PMS降解有机污染物性能的影响及其作用机制；以粉煤灰脱硅液为原料制备的水化硅酸钙能高效吸收铜离子，并经过简单处理转化为高效的染料及硝基苯酚降解的催化材料；制备了La/FeOOH@PAC、La/Zn/Fe3O4@PAC、Eu-MOFs等材料，对典型有机膦阻垢剂HEDP具有非常优异的吸附性能，为非均相催化降解有机膦的材料体系设计提供了基础。