极性CoO二维材料表面组成、结构与光催性能的关联性及其机制研究

基于我们提出的极性晶面间电荷分离机制，本项目以极性CoO二维材料为光催化制氢和二氧化碳还原的模型结构。采用溶剂热和盐中介法制备Co(OH)2等二维材料，再在氩气中加热获得原子层厚度极性{111}表面CoO二维材料。去除(111)表面Cl-和羟基，(111)表面掺杂Ni2+、Fe2+等和负载Ag、Pt等改善其光催化活性与CO2还原选择性，获得高性能光催化剂。制备[111]取向CoO基薄膜，研究其光伏、整流和光电化学性能。采用SPM和AC-STEM等技术表征所制备材料和薄膜，结合密度泛函理论计算，确定其形貌、晶体结构、暴露晶面、晶向、(111)面及其掺杂与负载的表面组成与结构。分析(111)表面组成、结构与光催化，光伏、整流和光电化学性能的关系，基于CoO极性晶面间自发电场和肖特基结对电子迁移的影响，阐明光催化、整流、光伏和光电化学机制，为高性能光催化剂与光电器件的研究提供新策略和理论依据。

Based on the mechanism of charge separation between polar crystal facets, the polar CoO two-dimensional (2-D) materials are used as a model structure for photocatalytic H2 generation and CO2 reduction. 2-D materials of Co(OH)2 and other Co-precursors are synthesized via the solventhermal and salt-mediated methods. The CoO 2-D materials with exposed polar{111}facets are prepared by heating the 2-D materials of Co(OH)2 and other Co-precursors in an Ar atmosphere. Photocatalytic activity and CO2 reduction selectivity of the CoO 2-D materials are improved by removing the surface Cl- ions and hydroxyl groups, doping with Ni2+、Fe2+、Mn2+ or Zn2+ ions and decorating with Ag, Pt or Pd quantum dots at the (111) surface selectively, to obtain high performance photocatalysts. [001]-orientated CoO thin films are prepared, and their rectification, photovoltaic and photoelectrochemical properties are investigated. The CoO based 2-D materials and thin films are characterized by SPM and AC-STEM and other modern technologies. The morphology, crystal structure, exposed facets, crystal orientation, and (111) and doping-loading (111) surface composition and structure are confirmed by combining with density functional theory calculations. The correlation between the photocatalytic, rectification, photovoltaic and photoelectrochemical properties and the (111) surface composition and structure are analyzed. Based on the effect of Schottky junction and spontaneous electric field between polar planes of CoO on electron transfer, the mechanisms of photocatalysis, rectification, photovoltaic and photoelectrochemistry are elucidated. A new theory and a strategy are provided for design and fabrication of the high performance photocatalysts and photoelectric devices.