碱金属与碱土金属掺杂调控WO3基钨青铜矿半导体光催化剂裂解水性能的实验与理论研究

WO3 tungsten bronze photocatalyst was used for new energy development in the past because of its visible light activity and facile preparation. Based on the larger tunnel structure and polar surface characteristic, this project will utilize alkali and alkaline-earth metals doping in tungsten bronze photocatalyst to further improve the visible light photocatalytic water splitting activity. Jahn-Teller effect induced by impurities are considered to study the change of the internal electric field and the electron-hole seperation and transport mechanism. The band structure was modified to realize the fully water splitting of tungsten bronze photocatalyst. The WO3 polar surface was studied to character of internal electric field, and the surface charge distribution was analyzed to reveal the interaction between carrier migration and polarity. The photocatalysts with different surfaces and morphology will be synthesized to study the influence of impurity ions on surface structures and surface states, and further to find out the regularity of active sites distribution on the different photocatalysts surfaces. Through the controlling of reaction condition, the photocatalytic water splitting mechanism was studied by molecule reaction dynamics simulation to seek the way to control reverse reaction of water splitting. The study of the project would help the synthesis of WO3 tungsten bronze photocatalyst with highly photocatalytic water splitting activity.

WO3基钨青铜矿光催化剂具有可见光活性、易制备等优点，在新能源开发等方面显示了潜在的应用价值。为了进一步提高其可见光催化裂解水性能，本项目拟从钨青铜矿具有大孔道空隙结构与极性面出发，利用碱金属/碱土金属离子的特性，采用实验与理论相结合的方法，对WO3基钨青铜矿光催化剂可见光裂解水性能进行改性研究。通过研究掺杂诱导Jahn-Teller效应的作用，探索调控内电场改善光生电子空穴对分离与迁移的方法；通过掺杂修饰半导体能带结构，揭示杂质改善WO3可见光全解水能力的方法与机制；分析极性面诱导内电场特征，阐明表面层电荷分布状态，揭示极性与载流子迁移之间的相互关系；制备具有不同表面、形貌的催化剂，研究杂质离子对表面结构的影响，揭示表面活性位点分布规律；通过调控光催化裂解水反应条件，结合理论模拟，阐明光催化裂解水反应动力学机理，探索抑制水裂解逆反应的方法，为制备更高活性的WO3基光催化剂提供指导。

为了进一步提高WO3基钨青铜矿光催化剂可见光催化分解水性能，推广光催化技术在能源开发领域的应用，本项目研究工作从WO3结构特点出发，采用实验和理论相结合的方法，探索和研究了WO3光催化剂的改性方法，并从微观角度阐明了改性机理。首先，通过对Na、K掺杂六方钨青铜矿WO3光催化剂的实验研究，指出光催化剂的结晶性是制约光催化性能的关键因素；进一步利用理论计算从微观角度阐明碱金属作为n型掺杂，通过提高载流子浓度改善WO3光催化性能。其次，通过调控水热反应温度实现了WO3形貌尺寸的调控，指出WO3（110）面具有最佳的光催化活性；结合理论计算研究了WO3低指数表面结构和表面态特征，探讨了H2O在WO3大孔隙和表面的吸附构象，指出H2O吸附诱导（110）表面重构是其具有最佳H2O裂解活性的主要原因。再次，利用WO3多晶相特点通过一步水热法构建了同质异相结构光催化剂，研究了同质异相结光催化剂之间的能带匹配关系，阐明了界面内电场促进光生载流子分离的微观机理，提高了WO3基光催化剂光催化裂解水的量子效率。最后，利用Au纳米助催化剂具有表面等离子体吸收和助催化作用，提高了WO3光电化学转换效率；结合理论计算，阐明了Au纳米颗粒与WO3表面相互作用原理，揭示了Au/WO3异质结界面载流子迁移规律，进而分析并指明了Au改性的最佳负载比。本项目的研究工作为WO3基光催化剂的掺杂、形貌调控、界面构建、助催化剂负载等改性手段提供了实验基础，为理解光催化剂微观结构对宏观性能作用机理提供了理论上依据，对优化改性手段、探索新型高效光催化剂有重要意义。