石墨烯/银系半导体复合光催化材料的构筑及其可见光催化性能

The development of highly efficient photocatalysts with visible light response is vital to the industrial application of photocatalytic technology. In the project, silver-based semiconductors with excellent visible light photocatalytic performance will be combined with graphene to harness their synergistic effect, thereby suppressing the recombination of photogenerated electron-hole pairs, extending the excitation wavelength and improving the stability of the catalysts. First, graphene/silver-based semiconductor bi-/multi-component photocatalysts with various architectures including graphene-supported structure, graphene-encapsulated structure, and the arrays on graphene, will be designed and constructed through in situ growth and self-assembly methods. The key factor that affects the size, shape and distribution of the silver-based semiconductors in the graphene-based composites will be systematically investigated on the basis of the graphene structure (surface functional groups, defects and doping) and the reaction medium, so as to realize the controllable synthesis of the composite photocatalytic materials. Secondly, the photocatalytic performance of the as-synthesized graphene/silver-based semiconductor composites will be systematically researched for degradation of environmental pollutants such as phenol, chlorobenzene, etc. The influence of the semiconductors (composition, size, and shape), the graphene (reduction degree, surface functional groups, and doping), and the microstructure and interface of the graphene/silver-based semiconductor composites on the photocatalytic performance will be investigated in detail. Thirdly, the energy band structure of graphene/silver-based semiconductor composites and the transfer process of photoinduced electrons will be theoretically studied by density functional theory, thereby revealing the mechanism of the influence of the graphene on the catalytic activity. It is expected that the study in the project can lay experimental and theoretical basis for the development and application of high-performance graphene/silver-based semiconductor composite photocatalysts with visible light response.

开发具有可见光响应的高性能光催化材料是光催化技术实用化的关键。本项目拟将具有优异可见光催化活性的银系半导体与石墨烯复合，发挥二者的协同优势，以促进光生电荷分离、拓宽光响应范围、提高催化剂的稳定性。首先采用原位合成和自组装的方法构筑各种结构类型（负载型,包裹型,阵列型）的石墨烯/银系半导体二元或多元复合光催化体系，从石墨烯结构（包括功能团、缺陷、掺杂等）和溶液性质入手系统地研究影响银系半导体粒子尺寸、形状及与石墨烯复合方式的关键因素，实现复合体系的可控合成。在此基础上，系统考察石墨烯/银系半导体复合材料对苯酚、氯苯等有机污染物的光催化降解作用，探讨复合体系和异质界面的结构类型、半导体粒子的组成和状态、石墨烯的结构等对催化性能的影响。利用密度泛函理论研究复合体系的能带结构和光生电子转移方式，揭示石墨烯影响光催化活性的机理,为高性能石墨烯/银系半导体可见光催化材料的开发和应用奠定理论和技术基础。

开发可见光响应的高性能光催化剂是光催化技术实用化的关键。本项目在研究具有良好可见光催化活性的银系半导体化合物的可控合成及其光催化性能的基础上，以性能优异的石墨烯复合光催化活性组份，通过原位合成或用预制的半导体微纳单元修饰石墨烯（RGO）或氧化石墨烯（GO）薄片，构建了各种新颖的石墨烯基二元和三元复合光催化材料。用元素分析、ICP、XRD、SEM、TEM、Raman光谱、 UV-Vis光谱、XPS等手段对合成材料进行了表征。系统研究了石墨烯（或氧化石墨烯）存在条件下无机纳米粒子的成核和生长规律及影响纳米粒子在石墨烯薄片上均匀分布的各种因素。发现反应溶剂、反应物浓度和有机添加剂等因素对形成高度均一的石墨烯基复合材料具有重要的影响，发现利用多组份复合体系中各组元之间的相互作用可以调控粒子的成核和生长。总结出了各类石墨烯基复合材料可控合成的初步规律。发现利用负电性的氧化石墨烯与带正电的阳离子或胶粒之间的静电作用是合成石墨烯基复合材料的一条行之有效的途径。系统考察了石墨烯基复合光催化材料对有机污染物（如罗丹明B、甲基橙、亚甲基蓝、苯酚等）的光催化降解作用，研究了复合体系组成、结构等因素对催化性能的影响，探讨了光催化作用机理。发现石墨烯与功能组份间有着强烈的耦合效应，其协同作用能促进光生电子-空穴对的有效分离、增强催化剂对可见光的吸收能力及对染料分子的吸附富集能力、阻止催化剂活性组份的团聚，对复合材料的光催化及相关性能具有显著的促进作用。如 Ag2O/GO, Ag3PO4/GO, N-RGO/Ag3PO4, BiPO4/GO, RGO/PrPO4, GO/AgIO4, S,N-RGO@Ag2CO3 等均表现出了比对应单组份催化剂更强的光催化活性和更好的循环稳定性。发现通过多组份复合，发挥各组元之间的协同作用，既能增强材料的催化性能，又能赋予材料以多功能特性。如制得了具有磁分离特性的催化剂Ag3PO4/Fe3O4/GO 和 RGO/Ag/Fe3O4，具有增强的可见光光催化性能的新型全固态Z 型光催化材料 g-C3N4/GO/AgBr 和 g-C3N4/Ag/Ag3VO4等。初步阐明了催化剂的组成、结构与催化性能的关系。本项目研究为石墨烯/（银系）半导体复合光催化材料的开发和应用奠定了科学基础。