Stable and Highly Active Single Atom Configurations for Photocatalytic H 2 Generation

The employment of single atoms (SAs), especially Pt SAs, as co-catalysts in photocatalytic H$_2$ generation has gained significant attention due to their exceptional efficiency. However, a major challenge in their application is the light-induced agglomeration of these SAs into less active nanosized particles under photocatalytic conditions. This study addresses the stability and reactivity of Pt SAs on TiO$_2$ surfaces by investigating various post-deposition annealing treatments in air, Ar, and Ar-H$_2$ environments at different
temperatures. It is described that annealing in an Ar-H$_2$ atmosphere optimally stabilizes SA configurations, forming stable 2D rafts of assembled SAs ≈0.5–1 nm in diameter. These rafts not only resist light-induced agglomeration but also exhibit significantly enhanced H$_2$ production efficiency. The findings reveal a promising approach to maintaining the high reactivity of Pt SAs while overcoming the critical challenge of their stability under photocatalytic conditions.