光催化CO2还原制备碳氢燃料在缓解环境压力和实现碳资源的循环利用方面极具潜力。构建异质结光催化剂，能有效解决该领域中光生电子和空穴极易复合的关键科学问题。然而，传统的II型异质结虽然可以抑制光生载流子的复合，但是电子和空穴的还原氧化能力都被大幅减弱。本项目拟构建C3N4/钛酸盐二维层状梯形异质结光催化剂，并研究其CO2光还原性能。这种梯形异质结能够保持复合光催化体系的强还原和氧化能力，并且，其二维层状结构可以使两种半导体具有更大的接触面积，促进界面电荷转移，有利于提升光催化活性。研究该二维复合梯形异质结光催化剂的制备方法，探索其化学组成、形貌、能带结构、表界面性质等因素对光催化CO2还原性能的影响规律，采用原位光照光电子能谱、原位开尔文探针等原位表征手段揭示光生载流子的迁移机制，为构建高效稳定、具有强氧化还原能力的二维梯形异质结光催化材料提供新的思路。

Photocatalytic CO2 reduction into hydrocarbon fuels has great potential in alleviating environmental pressures and achieving recycling of carbon resources. The construction of heterojunction photocatalysts can effectively solve the key scientific problems in this field that photogenerated electrons and holes are easily recombined. However, the electron reduction and hole oxidation capabilities for traditional type II heterojunction are greatly weakened, although the rapid recombination of photo-generated carriers can be suppressed. This project aims to construct a C3N4/titanate two-dimensional layered step-scheme heterojunction photocatalyst, which is used for CO2 photoreduction into hydrocarbons. This step-scheme heterojunction can overcome the defects of the traditional type II heterojunction and maintain the strong reduction and oxidation ability of the composite photocatalytic system. Moreover, the two-dimensional layered structure provide a larger contact area for the two semiconductors, thus promoting interface charge transfer and photocatalytic activities. The preparation method of the two-dimensional step-scheme heterojunction composite photocatalyst will be studied. Besides, the influence of chemical composition, morphology, band structure, surface and interface properties on the photocatalytic CO2 reduction performance will be explored. In situ characterization methods such as in situ irradiated XPS and Kelvin probes will be utilized to reveal the photogenerated carrier migration mechanism. This project will provide new ideas for constructing highly efficient and stable two-dimensional step-scheme heterojunction photocatalysts with strong redox capacity.