新型稳定、高分散金属硫族团簇光敏剂应用于光催化产氢的研究

Light absorption and electron injection are important factors that determine the efficiency of photocatalysts in converting light energy to hydrogen energy. The development of photocatalysts with high light absorbance as well as high carrier-separation efficiency is an important challenge in the field of photocatalytic hydrogen production. The stable, highly-dispersed discrete metal chalcogenide clusters (MCCs) are found to be promising photosensitizers, because not only the MCCs have the same advantages of small size and adjustable energy level as the traditional semiconductor quantum dot photosensitizers, but also their precise structure and stability without grafting of organic ligands are more conducive to accelerating and clarifying the process of photogenerated charges transfer in the interfaces of photocatalysts. For purpose of simultaneously realizing photocatalysts of the efficient utilization of light energy and efficient transport of photongenerated carriers, in this project, we aim at synthesizing a series of stable and discrete MCCs with adjustable energy level by using the halide ionic liquids. The obtained MCCs can be highly dispersed in the common solvents, and thus can be further used as the photosensitizers to prepare high-performance composite photocatalysts. The relationships of the structures of composite photocatalysts and their photocatalytic performances will be revealed, and the corresponding mechanisms of their charge transfers and photocatalytic hydrogen generations will also be clarified. The research will shed light on developing new types of excellent photosensitizers and corresponding photocatalytic hydrogen production systems. Our preliminary research has obtained two types of stable and dispersable Tn clusters by using the ionic liquid [Bmmim]Cl, and found that the H2 generation activity of TiO2 sensitized by traces of T4 clusters was much higher than that of original TiO2 and T4 clusters, which lays a good foundation for this project.

光捕获和电子注入是决定光催化剂光能-氢能转化效率的重要因素。开发同时具有高吸光率和高载流子分离效率的催化剂是当前光催化制氢领域的重要挑战。稳定、高分散的分立金属硫族团簇（MCCs），不仅具有传统半导体量子点光敏剂粒径小、能级可调的优势，而且其结构确定、无需嫁接有机配体，将其作为光敏剂，更有利于加快并明晰光生电荷在催化剂界面的传导过程，是一类有前景的新型光敏剂。为了同时实现催化剂光能高效利用和载流子高效传输，本项目拟利用卤盐离子液体，制备系列高分散于常用溶剂中、能级可调的稳定的MCCs，并将其作为光敏剂制备复合光催化剂。研究其结构与催化性能的关系，明晰电荷传输机制以及光催化制氢机理，为构建新型高效光敏剂及其太阳能制氢体系提供重要借鉴。前期通过[Bmmim]Cl已获得两类稳定、可分散的Tn团簇，并发现微量T4簇敏化的TiO2的产氢活性远高于原始TiO2和T4簇，为项目目标的实现奠定了坚实基础。

利用卤盐离子液体制备稳定、高分散金属硫族团簇，并将其作为新型光敏剂制备复合催化剂，有望实现催化剂光能高效利用的同时载流子高效传输。本项目利用不同卤盐离子液体制备了系列稳定、高分散的分立金属硫族Tn簇、纳米介孔TiO2以及Tn簇敏化的TiO2复合光催化剂，总结了离子液体在其合成中的作用规律，并着重考察了Tn簇的晶体结构、形貌、能级结构等，以及它们对Tn/TiO2光催化产氢活性和相应光吸收、电荷分离与传导特性的影响，总结了构效关系并明晰了光催化机理。代表性研究结果如下：1）利用[Bmmim]Cl合成了三例In-Q (Q = Se/S, Se) T3簇（ChemistrySelect 2022, 7, e202200585；Dalton Trans. 2020, 49, 5020-5023）和六例Cu/Cd-In-Q (Q = S, Se/S, Se) T5簇（Chem. Eur. J. 2020, 26, 1624-1632），T3簇溶于二甲亚砜后会成为纯无机的团簇骨架，其产氢活性远高于其固相状态，而T5硒化物簇为迄今最大的分立超四面体Tn硒簇，建立了Tn簇的组成、能级结构与其光催化活性之间的关系；2）利用咪唑基离子液体制备了系列高活性的C、N共掺杂的介孔TiO2纳米晶，详细揭示了[Bmim]Cl在其形成过程的作用机制以及相应的催化机理（Chem. Eng. J. 2023, 451, 138670）；3）通过离子液体前驱体合成了高活性的小尺寸In2S3负载的介孔TiO2，发现该特殊结构会在加速光生电荷分离的同时还为催化反应提供更多位点（Nanoscale 2020, 12, 12336-12345）；利用稳定、可溶的分立Cd-In-Se T4簇敏化TiO2制备T4/TiO2复合光催化剂，发现T4簇不仅具有较好的光吸收特性还有具有快速的电子注入性能，使T4/TiO2催化剂光高效利用的同时光生载流子高效分离和传输，进而微量T4簇敏化的TiO2的产氢活性大大提高（ACS Appl. Mater. & Interfaces 2021, 13, 40562-40570）。.项目资助发表SCI论文11篇，其中2篇影响因子大于10.0，6篇影响因子大于4.0以及1篇综述性文章。申请发明专利1件。参加国内会议3人次。在本项目的部分资助下，硕士毕业5名，硕士在读1名。