Zhang Yuanzheng, Dai Yunrong, Li Huihui, Yin Lifeng, Hoffmann Michael R
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, China.
School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, P. R. China.
Commun Mater. 2020;1(1):66. doi: 10.1038/s43246-020-00068-0. Epub 2020 Sep 21.
Solar energy can be converted into chemical energy by photocatalytic water splitting to produce molecular hydrogen. Details of the photo-induced reaction mechanism occurring on the surface of a semiconductor are not fully understood, however. Herein, we employ a model photocatalytic system consisting of single atoms deposited on quantum dots that are anchored on to a primary photocatalyst to explore fundamental aspects of photolytic hydrogen generation. Single platinum atoms (Pt) are anchored onto carbon nitride quantum dots (CNQDs), which are loaded onto graphitic carbon nitride nanosheets (CNS), forming a Pt@CNQDs/CNS composite. Pt@CNQDs/CNS provides a well-defined photocatalytic system in which the electron and proton transfer processes that lead to the formation of hydrogen gas can be investigated. Results suggest that hydrogen bonding between hydrophilic surface groups of the CNQDs and interfacial water molecules facilitates both proton-assisted electron transfer and sorption/desorption pathways. Surface bound hydrogen atoms appear to diffuse from CNQDs surface sites to the deposited Pt catalytic sites leading to higher hydrogen-atom fugacity surrounding each isolated Pt site. We identify a pathway that allows for hydrogen-atom recombination into molecular hydrogen and eventually to hydrogen bubble evolution.
太阳能可以通过光催化水分解转化为化学能以产生分子氢。然而，在半导体表面发生的光诱导反应机理的细节尚未完全了解。在此，我们采用一种模型光催化系统，该系统由沉积在量子点上的单原子组成，这些量子点锚定在初级光催化剂上，以探索光解制氢的基本方面。单铂原子（Pt）锚定在氮化碳量子点（CNQDs）上，氮化碳量子点负载在石墨氮化碳纳米片（CNS）上，形成Pt@CNQDs/CNS复合材料。Pt@CNQDs/CNS提供了一个定义明确的光催化系统，在该系统中可以研究导致氢气形成的电子和质子转移过程。结果表明，CNQDs亲水性表面基团与界面水分子之间的氢键促进了质子辅助电子转移以及吸附/解吸途径。表面结合的氢原子似乎从CNQDs表面位点扩散到沉积的Pt催化位点，导致每个孤立的Pt位点周围的氢原子逸度更高。我们确定了一条允许氢原子重组为分子氢并最终产生氢气泡的途径。
