InP-QD/TiO2异质结光裂解H2O的第一性原理研究

半导体/TiO2异质结材料具有良好的可见光区的光催化活性，在光催化分解有机物、光裂解H2O制氢等领域受到广泛关注。然而，由于TiO2的导带能级很高，很难找到电子结构与之匹配的半导体光敏化剂与其构成高性能的半导体/TiO2异质结，制约了半导体/TiO2异质结光催化材料的发展。本项目拟选用InP量子点（InP-QD）替代传统的半导体光敏化材料，利用InP-QD的尺寸效应实现对InP-QD/TiO2异质结光催化性能的调控。采用密度泛函理论方法研究InP-QD/TiO2异质结的电子结构，探讨光生载流子的产生与分离的机理，揭示该体系光催化裂解H2O的反应过程。在此基础上，从理论上建立对半导体-QD/TiO2异质结材料光催化性能的评价标准，并预测新的半导体-QD/TiO2异质结材料体系。相关的研究成果为新型基于TiO2的异质结光催化材料的设计与制备提供理论指导。

Semiconductor/TiO2 heterojunctions present high photocatalytic activities under visible-light irradiation, and they are widely utilized in fields of solar energy conversion and environmental purification. However, because of the high conduction band level of TiO2, it is very difficult to find the proper semiconductor photo-sensitizer that has matched electronic structure in semiconductor/TiO2 heterojunctions. In this project, we use InP (quantum dot, QD) as the photo-sensitizer to modulate the photocatalytic activity of InP-QD/TiO2 heterojunction through the size effect of InP-QD. We perform density functional theory calculations to investigate the electronic structure of InP-QD/TiO2 heterojunction to reveal the mechanism of the generation and the separation of photoexcited carriers, and the process of photocatalytic H2O splitting on InP-QD/TiO2 heterojunction. As a result, criteria for the evaluation of the photocatalytic activity of semiconductor-QD/TiO2 heterojunctions will be proposed. It is expected that our theoretical results could provide useful information for the development of new TiO2-based heterojunction photocatalysts.