金属配合物/半导体杂化人工光合体系太阳能全分解水的研究

Solar water splitting to produce hydrogen is considered to be the "Holy Grail" in the field of chemical science. Photocatalytic systems based on heterogeneous semiconductors or homogeneous complexes have been developed for many years, but the efficiencies of charge separation and utilization are still low, resulting in the difficulty of overall water splitting. In this project, one-step and two-step photoexcitation strategies are used to construct artificial photosynthesis systems composed of heterogeneous semiconductors and homogeneous complexes for photocatalytic overall water splitting. The following studies are carried out: (1) elucidating the structure-activity relationship between the particle morphology, size, band structure and the performance, (2) revealing the influence of the structural characteristics of metal complexes on the water-splitting activity, (3) clarifying the relation of energy level match between semiconductors and metal complexes. Based on these experimental results and spectral characterizations, we aim to investigate the thermodynamic and kinetic studies of multi-electron transfer and the effect of electron transfer driving force between semiconductors and metal complexes on the photocatalytic activity. These prospective results will provide the theoretical support and experimental basis for the rational design and assembly of highly efficient artificial photosynthesis systems for solar fuel conversion.

太阳能分解水制氢被认为是化学科学领域的“圣杯”式研究。基于多相半导体或均相分子的光催化体系经过多年发展已取得诸多进展，但由于体系的电荷分离和利用效率较低，导致分解纯水十分困难。本项目拟以均相的金属配合物与多相的半导体杂化材料为研究对象，分别采用一步法和两步法光激发策略，构筑人工光合太阳能全分解水体系，同时开展如下研究：（1）阐明半导体材料的颗粒形貌、尺寸和能带结构与光解水性能之间的构效关系；（2）研究配合物催化剂的结构特征对光解水反应速率的影响；（3）揭示吸光半导体与配合物分子之间的能级匹配关系。在此实验基础上，采用先进光谱技术表征，对光解水反应中多电子转移的热力学和动力学过程进行深入探索，弄清吸光半导体与配合物催化剂之间电子转移驱动力对光解水性能的影响等关键科学问题，为合理地设计及开发新型、高效的人工光合体系用于太阳能燃料的转化提供了理论支撑和实验基础。

金属配合物/半导体杂化体系在光催化分解水过程中的光稳定性以及吸光半导体与金属配合物之间电子转移的驱动力大小是影响光解水性能的关键因素。为解决上述关键科学问题，本项目构筑均相/多相杂化人工光合太阳能全分解水体系并对其电荷传输机理进行深入探索。其中主要包括以下三部分工作：（1）采用半导体作为捕光材料，金属配合物作为分解水催化剂，构筑金属配合物/半导体杂化体系。通过界面调控，耦合光吸收互补的两种半导体材料，极大程度提升了太阳能的利用率，促进了光生电荷分离和传输，实现高效光催化全分解水，太阳能到氢气转化效率高达4.3%。（2）利用聚合物光催化剂作为基元材料，通过缺陷工程、分子掺杂以及复合体系的构筑等方式。有效的促进了聚合物光催化剂的电荷分离能力，实现高效的光催化氧还原反应生产过氧化氢，太阳能到化学能的转化率高达1.2%。（3）通过一系列的改性方法例如创建缺陷，掺杂金属或非金属元素，锚定单原子催化剂构筑高效的电催化剂，为开发高效光解水助催化剂的开发提供了材料基础。项目执行期间以第一作者和通讯作者在Joule, J. Am. Chem. Soc., Angew. Chem. Int. Ed., Adv. Funct. Mater.等期刊发表论文16篇。本研究项目顺利完成了计划书上规定的任务及预期研究目标。