极性半导体光催化性能的结构本质与高效宽光谱响应的材料研究

Development of high performance photoelectrodes or photocatalysts that directly convert sunlight into chemical energy is of great scientific and practical significance. The key scientific issue in this research field is how to improve quantumn yield and stability of the semiconductors under visible light illumination. The core underlying this challenging issue lies in migration and reaction of the photogenerated electrons and holes. To solve the problem, it is required to have deep understanding of the relationship between materials structure and property. This project aims to disclose the structural origin of excellent photo-electrochemical properties of the known polar semiconductor photoelectrodes by investigating the separation, transportation and reaction of the photo-excited electrons and holes in conjunction with fine characterization of domain states and local chemical structures. Then design novel photoelectrochemical devices with broad solar spectral response by modifying crystal structure, domain state, particle morphology and orientation of polar semiconductors, especially the ferroelectric semiconductors, in conjunction with cocatalysts loading as well as carbon/polar composites making. Further, investigate the relationship and controlling rules between physical structure, interface state, and photoelectrochemical performance of the so made materials and devices, with a willing to provide knowledge as well as critical materials toward realizing the photochemical application of solar energy.

发展高性能光电极或光催化剂以实现太阳能的光化学转换具有重要的科学和现实意义。该领域的关键科学问题在于如何提高半导体材料在可见光区的量子效率和稳定性，其核心就是电子和空穴的迁移和反应。对这一问题的解决需要对材料结构与性能关系有深刻的理解。本项目通过研究已知极性半导体光电极材料中光激发电子和空穴的分离、传输和反应机制，结合电畴状态和局域化学结构的精细表征，揭示其优异光电化学性能的结构基础; 进而通过调控极性半导体特别是铁电半导体的晶体结构、电畴状态、晶粒形貌和晶面取向，结合碳材料添加和助催化剂担载，设计新的宽光谱响应的光电化学器件，探明所制材料和器件的物理结构、界面状态和光电化学性能的关系与调控规律, 争取为实现太阳能的光化学利用提供知识储备和关键材料。

发展高性能光催化材料以实现太阳能的高效利用与转换对于解决能源环境问题具有重要意义。在本项目执行期内，我们围绕极性半导体光催化性能的结构本质与高效宽光谱响应的材料研究这一主题，设计合成了系列极性纳米光催化材料，研究了其形貌调控规律、微结构特点、光电响应与光催化性能，获得了若干创新成果：例如，针对如何降低光生载流子复合这一关键科学问题提出了利用极性半导体内嵌电场助力光生电子空穴分离与传输的学术研究新思路，相关成果获国际同行专家好评。采用熔盐法生长了若干具有催化活性的铁电晶体，研究了其光电响应特性与机制，发现快的光电响应速率是该类材料具有优异催化性能的原因之一，相关成果入选期刊封面和背封面。发现负载有少量碳酸锶的钛酸锶纳米复合材料能够在室温条件下催化氧化甲烷并揭示出二者之间的协同催化效应机制，该工作突破了甲烷不吸附或难吸附的常规认识，提供了一个通过两种无活性材料的合作实现新功能的范例，相关成果入选期刊封面。针对温和条件下小分子碳氢的催化氧化这一关键科学问题，通过极性半导体光催化材料的多尺度设计在负载有纳米银颗粒的氧化锌表面实现了对包括甲烷在内的多种小分子碳氢的高效氧化，相关成果不仅获同行专家好评，而且引起媒体的广泛关注和报道。