石墨烯复合材料表界面功能层的结构调控及其催化臭氧净化有机废气的机理研究

The development of catalyst with high-catalytic activity for catalytic oxidation of VOCs with ozone is an important research area. However, the catalytic oxidation with ozone was limited in practical application of VOCs treatment, due to the decrease and inactivation of active sites on the surface of ozone catalyst, easy aggregation properties of catalysts, large steric hindrance, and the slow electron transfer in oxidation process. Recently, graphene materials prepared by chemical method are highly applied in catalytic composites owing to its significant properties such as high abundance, abundant surface functional groups, high surface area and conductivity. However, graphene is easily self-agglomeration, which leads to the activity decrease of catalyst. The self-agglomeration of graphene can be prevented by means of anchoring carbon and metal oxide quantum dots on graphene nanosheet layer, and at the same time, the metal oxide particles can be highly dispersed on the surface of graphene. This project is mainly to study on the structure control of functional layer on surface/interface of graphene composites and the mechanism of catalytic ozonation to eliminate volatile organic compounds. In this study, the cyclodextrin molecules by the pre-introduction of the metal ligand are anchored on the oxygen-contained functional groups of graphene oxide, and the self-agglomeration of graphene oxide can be refrained due to the hydrophilic properties. Thus, the nano carbon and metal oxide dots anchored on graphene (MO@C@r-GO) can be obtained after post-treatment process. The feasibility and optimal experimental conditions of MO@C@r-GO with highly efficient performance for the catalytic oxidation of VOCs with ozone is investigated. In addition, we will study the relationship between the structure and catalytic activity, the synergistic effect between metal oxide and graphene for oxidation of VOCs with ozone, distribution behavior of ozone/VOCs on interface of functional layer, and mechanism of catalytic oxidation of VOC. It is expected that this study can provide promising perspective in purification of VOCs, and enrich the fundamental theory not only for an efficient oxidation of VOCs with ozone but also for solvement of environmental pollutant problems.

臭氧催化是一项极具发展潜力的治理低浓度VOC的技术之一，但在催化过程中催化剂存在表面活性位点下降、催化剂易团聚、及空间位阻大不利于氧化过程中电子迁移等缺点。石墨烯以其来源广泛、表面官能团丰富和导电性良好的特点，在催化材料中得到广泛的研究。但石墨烯极易发生自团聚，导致催化剂活性下降。通过将碳和金属氧化物纳米量子点锚定在石墨烯纳米片层上，可防止石墨烯的自团聚，同时可使金属氧化物粒子高度分散在石墨烯表面。本项目研究石墨烯复合材料表界面功能层的构筑及催化臭氧氧化VOC的机理。通过在分子水平上构筑环糊精和氧化石墨烯的超分子体系，将预先包覆金属离子配体的环糊精锚定在氧化石墨烯含氧官能团上，避免石墨烯还原过程的自团聚，制备出高活性、表界面功能化的石墨烯复合材料；研究复合材料表界面功能层催化VOC的构效关系及反应机制；研究臭氧和VOCs在复合材料功能层表界面的分配行为，以及表界面功能层催化氧化VOC机理。

催化臭氧氧化技术，可在温和条件下实现对不同浓度S-VOCs的高效去除和深度氧化，是一种具有前景的有机含硫废气处理技术。然而，传统的负载型催化剂活性位点密度低，电子循环能力弱，抗湿性差，易硫中毒失活，限制了催化臭氧氧化技术的性能和广泛应用。石墨烯以其来源广泛、表面官能团丰富和导电性良好的特点，在催化材料中得到广泛的研究。但石墨烯极易发生自团聚，导致催化剂活性下降。通过将碳和金属氧化物纳米量子点锚定在石墨烯纳米片层上，可防止石墨烯的自团聚，同时可使金属氧化物粒子高度分散在石墨烯表面。本研究制备了原子级分散在石墨烯复合催化剂，避免石墨烯还原过程的自团聚，制备出高活性、表界面功能化、高分散活性中心、强金属-载体电子相互作用、可调控电子结构和高反应活性，解决了传统催化剂催化臭氧氧化S-VOCs中的瓶颈问题。以典型的含硫有机废气CH3SH为目标污染物，构建室温下碳基原子级分散过渡金属催化剂和杂原子掺杂非金属催化剂的催化臭氧氧化体系，系统探究了石墨烯复合催化剂的形貌结构、化学组成和电子性质对其催化臭氧去除有机废气CH3SH性能的影响，并结合理论计算深入阐明碳基复合催化剂催化臭氧化体系的构效机制。研究结果表明，通过调控碳基石墨烯复合催化剂中活性金属d带中心接近费米能级，强化活性中心和碳载体的不均匀电荷分布，可提高石墨烯复合催化剂活化O3转化为活性氧物种（ROS）的能力，诱导CH3SH的非自由基氧化路径，通过多种路径协同促进CH3SH氧化，实现高效催化臭氧氧化含硫有机废气的性能。