Subnano Ruthenium Species Anchored on Tin Dioxide Surface for Efficient Alkaline Hydrogen Evolution Reaction

Single-atom catalysts with unique electronic structures are drawing increasing attention as compared with nano-catalysts. However, subnano-catalysts, falling between the two categories, may match the demands of catalytic reactions better due to their tunable electronic structure, but they have rarely been studied. Here, we report a subnano-ruthenium species anchored on nano-SnO2 (Ru@SnO2). Although rutile SnO2 and RuO2 are isostructural and tend to form a spinodal structure in bulk materials, the Ru@SnO2 nano-structure is successfully prepared by our newly developed micro-etching technique. The optimized sample displays high activity for alkaline hydrogen evolution reaction with low overpotential and flat Tafel slope, superior to commercial Pt/C (20 wt%), while density functional theory investigations on the hydrogen-binding energy and Gibbs free energy are consistent with these results. The inherent design and synthesis strategies reported herein may open a new avenue for further catalyst development.