Operando同步辐射技术研究光电催化剂表面水分解机理

The use of "artificial photosynthesis" of solar water splitting to convert the solar energy into the clean chemical energy of hydrogen is one of the important routes to solve the current worldwide energy and environment issues. To achieve this goal, it is firstly necessary to understand the physical and chemical mechanisms of solar water splitting..In this proposal, we aim to develop the operando synchrotron radiation experimental technique of liquid soft X-ray absorption spectroscopy (XAS) in combination of the electrochemical impedance spectroscopy (EIS) (XAS-EIS) at the Hefei Synchrotron Radiation Light Source. Moreover, we also endeavor to further develop the data analysis method of the real space multiple scattering theory for the low dimensional systems. Taking use of these experimental and theoretical methods, we will focus on the important physical and chemical process of solar water splitting at the surface of the new type of low dimensional photocatalysts of metallic single site/semiconductor nano-arrays composites under the real-time dynamic conditions. We will put emphasis on the electronic structure and geometry variation of the surface active centers, water dissociation path on the catalyst surface in the reaction process and the inherent mechanism of water photolysis reaction. By means of the first-principles calculations, we will clarify the relationship between the composition, structure and catalytic activity of the photocatalyst. The obtained results will provide some theoretical and experimental foundation for the design and synthesis of novel high-performance transition-metal based photocatalytic water decomposition materials.

通过太阳能光解水的“人工光合作用”将太阳能转换为清洁的氢能是解决当今世界能源和环境问题的重要途径之一，为此必须深入了解光解水过程的微观机理。本项目拟基于合肥同步辐射光源建立液相原位软X射线吸收谱学(XAS)与电化学阻抗谱(EIS)联用的operando实验方法。并进一步发展用于低维材料体系的实空间的多重散射理论数据分析方法，围绕过渡金属单位点负载氧化物半导体纳米阵列新型光电催化剂表面水分解这一重要的物理化学过程开展工作状态下的原位实时动态研究，重点揭示催化剂表面反应活性中心的原子和电子结构、水分子的电子结构和几何结构在水解离过程中的变化规律以及推断光生载流子在催化剂表面的分离和转移路径，从原子分子水平上认识光电解水反应的内在机理，阐明催化剂的组成、结构与活性之间的关系，为设计合成新型廉价稳定高效的光电化学水分解材料提供实验基础和理论依据。

依托同步辐射光源，研制了适合于光电化学反应测试的operando XAS-EIS实验装置，并对该原位实验装置的各项性能指标进行优化，探索了适合于金属单位点负载纳米阵列光电化学水分解过程研究的最佳参数。以金属氧化物纳米管和纳米片等纳米阵列为模板，优化光化学生长条件，在纳米阵列基底上优化制备出一系列稳定的过渡金属负载的单位点/纳米阵列结构光电催化剂材料。利用原位同步辐射技术探测工作状态下新型复合低维光电催化剂的水分解的反应过程，获取光电催化剂表面及其界面的结构信息，同时结合第一性原理计算分析水分解的反应路径，从实验和理论两方面深入认识金属单位点负载纳米阵列结构光电化学水分解反应机理。依托本项目发展原位同步辐射XAS测试平台一套，发表SCI论文19篇，申请或授权国家发明或实用新型专利3件。获得安徽省自然科学一等奖1项。依托本项目共培养五名博士研究生毕业。