光电催化制氢将低密度不连续的太阳能转化为方便存储和使用的清洁化学能，是太阳能利用的重要途径之一。采用聚焦太阳光驱动的无线光电催化能够成倍提高单位面积的能量获取密度，是光电催化发展的新方向。但单一半导体材料因为光电压不足或者光利用效率太低而无法在无偏压条件下有效工作，聚光对光电极的光谱响应速度与范围提出了更高要求，且光电催化产物的存储和利用也需协同考虑。本项目拟在纳米结构p-晶体硅上沉积生长较宽带隙的氧化铁、砷化镓等n型半导体材料构建叠层光电催化薄膜，结合表面纳米结构修饰，满足高光强对捕光效率和表面反应速度的要求，通过双光子的Z-Scheme机制无偏压裂解氢溴酸制备氢气和溴单质。组合氢溴液流电池构建一体化的太阳能氢溴液流电池，利用氢溴酸与氢气/溴的可逆循环反应实现太阳能的高效转化、存储和使用。该研究有助于解析薄膜结构及其表界面特性与光电催化性能的构效关系，为太阳能高效利用提供理论和实验依据。

Photoelectrochemical (PEC) hydrogen production converses the discontinuous and low density solar energy into clean chemical fuel, which represents an important path for solar energy utilization. The energy harvesting density can be significantly improved when driven by concentrated solar radiation and by working without applied bias, which is a new direction in PEC research. A single semiconductor cannot split water efficiently without applied bias due to the low photovoltages or narrow optical adsorption spectra. The concentrated solar radiation also requires faster photo-response and wider adsorption spectrum for photoelectrodes. The storage and utilization of PEC products is also a concern. Herein, we propose the construction of tandem photoelectrode by depositing an anode thin film with a wider bandgap, such as Fe2O3 and GaAs, on the surface of nanocrystalline silicon wafer. Surface nanostructures will be further introduced to the tandem photoelectrodes to satisfy the requirements of concentrated solar radiation on optical absorption efficiency and surface reaction kinetics. The tandem photoelectrodes can provide a high photovoltage to split HBr without applied bias through a two-photon Z-scheme process. Combining the tandem photoelectrode and the H2-Br2 flow battery, solar H2-Br2 flow battery will be built by utilizing the solar splitting of HBr and the reaction of H2+Br2 for production of electricity. The solar energy conversion, storage, and utilization can thus be realized through one flexible device. This project will provide theoretical and experimental support for efficient and flexible utilization of solar energy, as well as to figure out the structure-performance relationship between the nature of surface/interface and the PEC performances of tandem photoelectrodes.