新型自偏压光电化学池分解水同时产氢、产氧、产电的性能与机制

Solar-driven photocatalytic water splitting is becoming a hotspot as a new sustainable technology. Currently, it cannot realize the simultaneous production of hydrogen and oxygen, and it often needs additional sacrificial agents or external bias potential to keep continual reaction, resulting in a great limitation for water splitting. In this project, TiO2 nanotubes are used as substrate of photoanode for their highly ordered nanostructure and excellent electron mobility. After coupled with BiVO4, a visible-light responded BiVO4/TNA photoanode is prepared, exhibiting visible response and significantly expanded life time of carriers and faster electron transportation. In particular, the photoanode would have an improved water oxidation kinetics by modification with Co-P catalyst. On the other hand, visible light response p-SiNW nanowires obtained by etching p-type silicon wafer is chosen as photocathode due to their large surface area and good electron mobility. After modification by NiOx, the NiOx/p-SiNW photocathode is formed, showing larger photocurrent, better stability and higher hydrogen production rate. This project will investigate the characteristics of both photoelctrodes and finally establish a novel visible-light responded and self-biasing photoelectrochemical cell based on the energy level matching between photoanode and photocathode. The new photoelectrochemical cell would realize spontaneously photocatalytic splitting water into hydrogen and oxygen as well as electricity generation.

太阳光催化分解水产氢属于可持续发展新技术，但现有光催化分解水产氢，不能完全利用太阳能同时产氢、产氧，常需添加外来牺牲剂或施加偏电压。本项目以结构高度有序、光生电荷迁移快的钛基TiO2纳米管阵列（TNA）为光阳极基底材料，通过与BiVO4构成异质结，形成可见光响应、能延长BiVO4光生电子寿命、促进载流子快速迁移的BiVO4/TNA光阳极，并通过钴-磷酸盐修饰，提升电极的氧气释放速率；以p-型硅晶片为光阴极基底材料，通过化学刻蚀制备比表面积大、光生电荷迁移快的p-型硅纳米线（p-SiNW）光阴极，通过电极表面修饰NiOx，形成稳定性好、光电流高、氢气释放反应速率快的NiOx/p-SiNW光阴极。在此基础上，研究新型光阳极和光阴极材料的性能与机制，并基于阳、阴极半导体能级匹配特征，构建新型可见光响应的高效自偏压光电化学池，实现光催化自发分解水同时产氢、产氧和对外发电的目的，并研究性能和机制。

利用太阳能降解有机污染物同时产电是废水资源化利用的重要途径，而开发高效的光电催化体系是实现太阳能高效利用的关键。传统的光电催化体系通过外加偏压，从而促进光电极中光生电荷的分离与传输以提高光电催化体系的效率。此外传统的光电催化降解有机物过程，不仅耗能高，而且损失了有机污染物本身储存的丰富化学能。因此，开发高效的自驱动、能回收有机物化学能的光电催化体系具有重要的应用价值。本研究从结构设计，表面修饰以及异质结构建等方面优化了可见光响应的钒酸铋和二氧化钛等系列光阳极材料的光电化学性能。基于阳、阴极半导体能级匹配特征，构建了系列新型高效稳定的自偏压光电化学池，成功地实现了难降解有机物的处理与发电和分解水产氢产氧，并研究性能和机制。. 项目发表高水平SCI论文18篇，包括环境/能源领域顶级期刊Water Research，Applied Catalysis B: Environmental等；授权专利3项；培养博士生3人，硕士生3人。