掺杂型半导体光催化材料电子结构和性能增强机理的理论研究

Energy and environmental issues at a global level are important topics. To solve the issues, converting sunlight to usable electricity or fuel using semiconductor photocatalysts is the most viable way for producing environmentally friendly, renewable, and clean energy. For efficient conversion of sunlight to energy, these doped semiconductor photocatalysts used must have optimal band gaps. Therefore, band gap engineering via doping has been an important issue for optimizing the photocatalytic performance of semiconductors. In this project, we will carry out an extensive theoretical study of electronic structures and photocatalytic performance of semiconductors based on density functional theory calculations, molecular dynamics simulation, nonequilibrium Green's function technique as well as model transition state theory. Our activities including the following three parts: (1) Manipulate the electronic structures,separation of electron-hole pairs,and photocatalytic performance of selected semiconductor photocatalysts (i.e. BaTi4O9, MoS2 and triazine imide nanosheets, TiO2 nanotubes and arrays, CdS-graphene oxide nanocomposite) by co-doping with various metal (i.e. V, Co, Nb, Rh) cations and non-metal (i.e. C, N, F, S, P) anions, and provide new insight into the corresponding quantum mechanism. (2) Design some reasonable several hybrid nanocomposite, quantitatively characterize the layer-layer interface in these proposed nanocomposite, and explore the doping effect on their band structures and photocatalytic performance. (3) Determine the adsorption configuration of small molecules (i.e.CO,O2,H2O) on certain different crystal facets of semiconductor photocatalysts, understand and explain these related experimental measurements and observations, and then try to explore the reaction mechanism of water splitting and CO oxidation on surface of single-atom catalysts (i.e. Ir1-FeOx, Pt-Al2O3). These theoretical results and predictions will be helpful and useful for designing and applying semiconductor photocatalysts with high performance in the near future.

当今全球正面临严重的能源危机与环境问题，寻找和利用环境友好且可持续再生的清洁能源是目前我们面临的挑战。对太阳能利用具有重要应用前景的半导体光催化材料进行掺杂改性，调控其电子能带结构并优化其光反应性，具有非常重要的科学意义，是当前的一个前沿热点研究课题。本项目我们将与实验研究紧密联系，采用第一性原理计算、分子动力学模拟、非平衡格林函数方法、过渡态理论等多种理论方法，对BaTi4O9、二硫化钼和三嗪亚胺纳米片、TiO2纳米管和阵列、石墨烯氧化物-硫化镉等体系进行金属阳离子和非金属阴离子共掺，有效调控掺杂体系的电子能带结构和杂质态，增强体系光生载流子分离和光反应活性，揭示掺杂改性的微观物理图像，确定半导体光催化耦合体系的界面构型，表征掺杂型半导体光催化材料表面小分子(如O2, CO, H2O)吸附和解离特性，为合成和开发高效性能的半导体光催化材料的实验和应用研究提供一些有意义的理论依据和指导。

本项目按研究计划推进研究工作，并顺利完成预期目标。项目团队成员利用多尺度模拟方法，对半导体光催化材料的电子结构和杂质中间态进行了有效的掺杂调控，揭示了实现光反应增强导向的能带调控的微观物理图像，理论上设计出多个具有较好可见光反应活性的半导体光催化材料，这些研究结果已在Energy & Environ. Sci.、Phys. Rev. Lett.、Phys. Rev. B、Nanoscale和Phys. Chem. Chem. Phys.等国内外学术期刊发表致谢SCI论文20篇，重要研究结果或进展包括：(1) 提出金属氧化物TiO2晶面结概念，实现体系的光催化性能增强 [Energy Environ. Sci., 2018]；(2) 揭示了TiO2中n-p表面掺杂效应和共掺改性的S-O 耦合机制 [Int. J. Hydrogen Energy 2016；RSC Adv., 2017]；(3) 理论上发现双空位共掺有效调控宽能隙ZrO2的能带结构和光响应特性 [Phys. Chem. Chem. Phys., 2016]：(4) 理论表征了硅烯表面的吸附效应，发现吸附导致的局域态密度包含能带的拓扑性 [Phys. Rev. B 2016]；(5) 模拟和调控了二维体系的电子结构和磁性 [Sci. Rep., 2015]；(6) 理论预测CdX二维体系和少数层BiOI是新型且性能优异光解水材料 [RSC Adv., 2017; Phys. Chem. Chem. Phys., 2016]；(7) 揭示无序三维狄拉克半金属体系的准粒子性质和临界点标度律 [Phys. Rev. Lett. 2017]；(8) 研究了双Fe核单分子磁体的自旋输运特性 [Nanoscale 2016]等。显然，这些理论研究为合成和开发高性能的半导体光催化材料的实验和应用研究提供了一些有意义的理论依据和指导。此外，在项目执行期间，团队成员参加国内外学术研讨会9人次，培养博士2名，硕士3名，本科毕业论文设计4人，目前在读博士研究生9人。