二维过渡金属硫族化合物(TMDCs)基纳米复合光催化材料的设计合成及其可见光催化机理

This project aims to improve the photocatalytic performance of two-dimensional (2D) graphene-like transition metal dichalcogenides (TMDCs) based composite photocatalysts, and to explore the intrinsic relationship among the synthesis technology, microstructures and the photocatalytic activities of the as-prepared composite photocatalysts. The modification and regulation of microstructures, phase structures and energy band structures will be included. Several TMDCs-based composites photocatalysts (such as g-C3N4/MoSe2 and g-C3N4/Ag/WSe2) are fabricated via solvothermal method and wet chemical synthesis using metal, oxide, carbon materials as carriers. Molecular modeling and density functional theory (DFT) calculations are performed to simulate the crystal structure, electronic band structures and density of states (DOS) of TMDCs nanosheets and their composites. The controllable adjustment regulation of TMDCs based heterojunction on crystal structure, electronic band structures and DOS of the composite photocatalysts are explored. Photoluminescence (PL), X-ray photoelectron spectra (XPS), electron spin resonance (ESR), photo-electrochemical measurements, electrochemical impedances spectroscopy (EIS) and active species trapping experiments are employed to investigate the migration path of photo-generated carriers in TMDCs-based heterojunction composite photocatalysts and the synergy effect between/among main catalysts and co-catalysts. Based on type II heterojunction-based charge carrier separation and Z-scheme-based charge carrier separation, the photocatalytic mechanisms for the TMDCs-based heterojunction composite photocatalysts will be explored. According, the composite photocatalysts with high photocatalytic activities and wide solar spectrum absorption are designed and synthesized based on atomic and molecular levels.

本课题旨在调控TMDCs、g-C3N4及复合物的微/纳结构、相结构及能带结构，提高其光催化性能，探索催化剂制备工艺、微观结构和光催化性能之间关系的规律。采用溶剂热法和液相沉淀法等制备金属、氧化物及碳材料负载TMDCs基复合光催化剂(如g-C3N4/MoSe2和g-C3N4/Ag/WSe2)。采用DFT模拟计算TMDCs纳米片以及复合光催化剂的晶体结构与电子能带结构及电子态密度，探索TMDCs基异质结对光催化剂结构和电子态密度的调控规律。通过PL、XPS、ESR、光电化学测试和自由基捕获实验探索TMDCs基异质结复合光催化剂的光生载流子迁移规律、主催化剂与共催化剂组分之间协同效应，以及异质结电子转移、Z型电子转移、助催化剂在复合体系中的作用等光催化机理，从原子分子层次设计合成高催化活性、宽太阳光谱吸收、稳定的复合光催化材料。

光催化技术作为一种环境友好型的绿色高级氧化技术，具有能在室温下深度反应和可直接利用太阳能等特点，既能将低密度的太阳能转化为氢能，也能利用太阳能光催化降解和矿化环境中的有机和无机污染物。因此，设计和发展高效宽光谱响应异质结光催化材料，提高太阳能利用率，具有重要的科学意义和潜在的应用价值。本项目通过调控g-C3N4、TMDCs、BiOIO3基复合物的微/纳结构、相结构及能带结构，探索复合光催化剂制备工艺、微观结构和光催化性能之间关系的规律。分别采用溶剂热法和液相沉淀法等设计构建了几类g-C3N4、TMDCs、BiOIO3基复合光催化剂，如rGO-MoSe2/g-C3N4、1T/2H MoSe2/pg-C3N4、AgI/BiOBr/rGO、Bi4O5Br2/AgCl/Ag、BiOIO3/MoS2、BiOIO3/BiOI/Bi2S3和BiOIO3/Bi-MOF等。通过PL、XPS、ESR、光电化学测试和自由基捕获实验，探索异质结复合光催化剂的光生载流子迁移规律，以及光催化降解染料和抗生素等（如罗丹明B、盐酸四环素）水体中有机污染物的作用机理。课题的研究成果为从原子分子层次设计合成高催化活性、宽太阳光谱吸收、稳定的复合光催化材料提供了坚实的理论基础与有力的实验依据。