21世纪世界能源发展的重要方向之一是希望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化学能，为此必须深入了解太阳能水分解的过程机理。本项目拟利用水热合成法制备高度取向的Fe2O3半导体纳米片阵列光电极材料，实现光生载流子的定向转移和高效分离，提高其可见光量子转换效率。利用原位同步辐射XAFS/EIS联用技术对阵列Fe2O3纳米片光解水过程进行原位X射线吸收精细结构谱(XAFS)和电化学阻抗谱(EIS)的在线测量和监控，研究Fe2O3半导体纳米片阵列结构在光解水过程中表面态中心原子和电子结构的变化以及光生载流子的迁移路径，结合第一性原理理论计算获得水在阵列Fe2O3纳米片光电极表面的四电子羟基氧化步骤，深入探讨其光电化学水分解反应过程中的载流子转移机制和水分解反应的微观过程机理，为进一步优化设计和可控制备高性能的过渡金属元素基太阳能转化光电极材料提供实验和理论基础。

In the twenty-first century, one of the most important goals of world energy is to use the "artificial photosynthesis" of solar water splitting to convert the solar energy into chemical energy. To achieve this goal, it needs to firstly understand the physical and chemical mechanisms of solar water splitting; especially the carrier transfer mechanism and hydroxyl oxidation steps in the four-electron water oxidation process. . In this proposal, we aim to synthesize a novel type of highly ordered Fe2O3 nanosheets arrays photoanode materials with prominent photoeletrochemcial (PEC) performance, and use the self-established in-situ PEC XAFS/EIS equipment to monitor the water photolysis process under various photochemical conditions by the synthesized nanosheets arrayed photoanodes. In combination with other conventional measurement and analysis methods such as XPS/UPS and UV-vis absorption spectroscopy, the in-situ XAFS/EIS technique is used to systematically investigate the atomic and electronic structures of the central surface states and the carrier transfer path in the process of PEC water splitting on the hematite nanosheet arrayed photoanodes. By means of the first-principles calculations, the decomposition steps of water on the photoanode surface will be explored and the solar water splitting mechanism will be deeply investigated. The obtained results will provide some experimental and theoretical basis for further optimization design of electrode materials and controllable preparation of high-performance transition metal based photoelectrodes.