利用太阳光驱动水分解是将太阳能转化为化学能、特别是氢能的最有效策略之一。设计合成新型高效、稳定长效且宽光谱响应的光催化剂成为太阳光驱动水分解技术得以广泛应用的关键所在。作为吸收边在600nm左右的窄带隙半导体光催化材料，Ta3N5光生载流子复合率高及易发生光腐蚀等缺点极大地限制了其实际应用。本项目拟以具有丰富孔结构的g-C3N4纳米海绵为模板和氮源，可控制备高比表面积且易回收的宏观三维Cdots/Ta3N5复合纳米光催化剂，研究其太阳光分解水产氢产氧的性能。揭示C量子点在提高太阳光吸收与利用率、促进光生载流子的传递与分离、抑制Ta3N5自氧化以及促进H2O2分解历程中的作用机制，探究催化过程中电子/能量的转移/传输规律与机制，阐明Cdots/Ta3N5光催化全解水的反应机理等重要科学问题，为理性设计与可控构筑550-650nm波长范围内高量子产率的全解水光催化剂提供科学指导。

Solar-driven water splitting is one of the most promising ways to convert solar energy into chemical energy, especially hydrogen, a storable fuel. The ultimate target of photocatalytic water splitting is to explore novel efficient, stable and broad spectra response photocatalysts. Tantalum nitride (Ta3N5), as a narrow bandgap semiconductor photocatalyst with an absorption edge around 600 nm, suffers from the high recombination of the photoexcited carriers and photo-corrosion, which limits its practical applications. In this proposal, we aim to use 3D porous g-C3N4 nanosponges as both template and nitrogen source to fabricate C dots/Ta3N5 nanocomposites photocatalyst with high specific surface area and being easily recycled. Their performances of hydrogen and oxygen production from solar overall water splitting are also investigated. More significantly, the effects of C dots on the solar utilization, charge carrier migration and separation, the suppressing of self-oxidation of Ta3N5, as well as the decomposition of H2O2 will be disclosed. We will pay our great attention on the fundamental scientific events of such new-type C dots/Ta3N5 photocatalytic systems, including the electron/energy transfer/transport principles during their photocatalytic processes, the reaction mechanism of overall water splitting, etc. Our work will provide the scientific guidelines for rational design and controllable fabrication of solar water splitting photocatalyst with high apparent quantum yield in the wavelength range of 550-650 nm.