A Facile Electrochemical Approach to Synthesizing Stable Single Metal Atom Catalytic Centers and Clusters on N-Doped...

A new synthetic strategy is demonstrated for the facile and potentially general synthesis of single atom catalysts (SACs) on mesoporous carbon films directly from a bulk metal plate. The technique relies on electrochemical oxidation in the presence of dopamine hydrochloride and a surfactant, which simultaneously forms a Metal─Cl monolayer on the bulk metal surface and a mesoporous polydopamine layer. The Metal─Cl monolayer melts at a relatively low temperature (<350 °C), enabling migration of metal atoms directly from the bulk metal body into the porous polydopamine layer. The subsequent thermal treatment carbonizes polydopamine into (N)-doped carbon, removes chlorine from metal atoms, and fixes single metal atoms in the carbon. It is shown that this approach can prepare Au, Cu and Pt SAC, supporting the suggested mechanism and synthetic generality. Importantly, this approach avoids chelation chemistry, the prevailing principle for SAC synthesis that, however, suffers from noble-metal aggregation, a significantly higher Au loading (1.63 wt.%) is achieved compared with previous methods on carbon supports (≈0.2 wt.%), enabling the first demonstration that carbon Au SAC can actively and stably catalyze the hydrogen evolution reaction. These results raise the possibility that the commonly perceived low activity of Au SACs may not be intrinsic, but rather from the insufficient loading achieved in previous studies, suggesting Au SACs could catalyse a broader range of reactions when adequately loaded.