铋系复合氧化物的晶面调控及其可见光完全分解水的作用机制

Photocatalytic hydrogen production has been for many years a fascinating source of inspiration for the development of model systems able to achieve efficient light-to-chemical energetic transduction. This field of research, called "artificial photosynthesis," is currently the subject of intense interest, driven by the aim of converting solar energy into the carbon-free fuel hydrogen through the visible light-driven water splitting. Some new photocatalysts were discovered to have the ability to absorb visible light. However, most of them were active to produce either H2 or O2 with sacrificial reagents. The overall water splitting without sacrificial reagent has been drawn strong attention as an ideal method to obtain sustainable H2 resource. In order to achieve this goal, the development of novel highly efficient and visible-light-responding photocatalysts is the key issue... Some bismuth based oxides, such as BiVO4, have been reported as photocatalysts for O2 production from the sacrificial reagent solution since conduction band bottoms were lower than theH2O/H2 potential. If we can effectively modify the conduction band of BiVO4, it would be a potential material for overall water splitting. In the proposal, we will change the band of BiVO4 by using solid solutions with metal or non-metal doping to meet the potential requirements of reduction and oxidation of H2O at the same time. The novel bismuth compound oxide photocatalysts with controllable exposed crystal facets will be developed by adding F and adjusting pH through a hydrothermal reaction. The directional loading of the cocatalyst is obtained on different exposed crystal facets due to difference of the electrochemical properties, which will facilitate the production of hydrogen and oxygen on different exposed crystal facets. By the design and preparation of the exposed crystal facets, the directional migration and separation of photogenerated carriers will be enhanced, and efficiently overall water splitting with visible light water will be achieved... In this proposal project, the microstructure characterization and first-principles calculation will used to reveal the migration, separation and recombination behavior of photogenerated carriers on the novel photocatalysts with specific exposed crystal facets. The relationship between half-reaction and overall water splitting will be investigated. The study will help us to understand the process and mechanism of visible-light-driven overall water splitting, and it will provide a route and method for preparing efficient visible light-driven photocatalysts.

可见光完全分解水不仅是光解水中的难点，也是人工光合作用研究的核心问题之一。至今人们已经获得了大量能响应可见光的光催化剂，而可见光下能完全分解水的光催化剂屈指可数。本研究基于具有响应可见光性能却不具产氢活性的BiVO4等铋系氧化物，通过导入新元素获得具有完全分解水能带结构的Bi系固溶体半导体材料；利用水热合成法中添加F等改变晶体表面能，实现对其暴露面的调控；利用不同暴露面的电化学性能差异，获得助催化剂的定向负载，以有利于氢气和氧气分别在特定面上产生。通过设计和制备具有特定的暴露晶面，增强光生载流子的定向迁移和分离，实现可见光高效完全分解水。本项目将结合利用微观表征和第一性原理计算等手段揭示光生载流子在特定晶面上的迁移、分离、复合行为，阐述光解水的半反应和完全分解的内在联系，该研究将有助于理解可见光完全分解水的作用过程和机制，并为构筑高效光解水制氢催化剂提供新的研究思路和理论基础。

铋系复合氧化物是一类具有很好响应可见光的催化剂。但是由于其导带主要由Bi 6p和O 2p构成，不能满足光催化分解水制氢的动力学要求。本研究基于具有响应可见光性能却不具产氢活性的BiVO4等铋系氧化物，通过导入新元素获得具有完全分解水能带结构的Bi系固溶体半导体材料。完成了水热法制备具有十二面体结构的BixY1-xVO4固溶体，通过MOF衍生法获得了具有内建电场效应的Bi0.5Y0.5VO4，提升了光解水产氢效率揭示了Y源引入增强BiVO4材料完全分解水性能的机制，提出了微结构扭曲对于催化剂光动力学层面的作用。设计和制备Bi4MO8X多元化物实现高效产氢。揭示了表面结构和助催化剂对产氢产氧半反应、以及完全分解水反应的作用，初步阐明了光生载流子在定向暴露面的迁移、分离、复合、反应等行为特征。构建了单质Bi纳米球耦合聚合物氮化碳（Bi-PCN）等光催化制氢材料体系，并以抗生素阿莫西林作为牺牲剂，构筑了产氢与污染物降解相结合的协同体系，揭示了该反应体系中H+和O2在同光生电子反应的竞争关系和作用机制。