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 (Pt₁) are anchored onto carbon nitride quantum dots (CNQDs), which are loaded onto graphitic carbon nitride nanosheets (CNS), forming a Pt₁@CNQDs/CNS composite. Pt₁@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 Pt₁ catalytic sites leading to higher hydrogen-atom fugacity surrounding each isolated Pt₁ site. We identify a pathway that allows for hydrogen-atom recombination into molecular hydrogen and eventually to hydrogen bubble evolution.

通过光催化水分解产生分子氢可以将太阳能转化为化学能。然而，还没有完全理解在半导体表面上发生的光致反应机理的细节。在本文中，我们采用模型光催化系统，该系统由沉积在量子点上的单个原子组成，该量子点固定在主要光催化剂上，以探索光解氢生成的基本方面。将单个铂原子（Pt ₁）锚定到氮化碳量子点（CNQDs）上，然后将其加载到石墨化碳氮化物纳米片（CNS）上，形成Pt ₁ @ CNQDs / CNS复合材料。铂₁@ CNQDs / CNS提供了一个定义明确的光催化系统，其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的亲水表面基团与界面水分子之间的氢键促进了质子辅助的电子转移和吸附/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 ₁催化位点，导致每个分离的Pt ₁ 位点周围的氢原子逸度更高。我们确定了一种途径，该途径允许氢原子重组为分子氢，最终达到氢气泡的演化。