Carbon-Promoted Pt-Single Atoms Anchored on RuO2 Nanorods to Boost Electrochemical Hydrogen Evolution

While efficient for electrochemical hydrogen evolution reaction (HER), Pt is limited by its cost and rarity. Traditional Pt catalysts and Pt single-atom (aPt) catalysts (Pt-SACs) face challenges in maintaining kinetically favorable HER pathways (Volmer–Tafel) at ultralow Pt loadings. Herein, carbon-promoted aPts were deposited on RuO2 without the addition of reductants. aPts confined on carbon-supported RuO2 nanorods (aPt/RuO2NR/Carbon) promoted "inter-aPts" Tafel. aPt/RuO2NR/Carbon is the Pt-SAC that retained underpotentially deposited H; additionally, its HER onset overpotential was "negative". The aPt/RuO2NR/Carbon exhibited 260-fold higher Pt mass activity (imPt)/turnover frequency (TOF) (522.7 A mg–1/528.4 s–1) than that of commercial Pt/C (1.9 A mg–1/1.9 s–1). In an ultralow Pt loading (0.19 μg cm–2), the HER rate-determining step maintained Volmer–Tafel and the Pt utilization efficiency was 100.3%.