Interfacial synergies between single-atomic Pt and CoS for enhancing hydrogen evolution reaction catalysis

Despite the significant role of single atoms during the hydrogen evolution reaction (HER), the underlying nature of the synergetic effect between substrates and single atom is still unclear. Herein, through anchoring Pt single atoms on cobalt sulfide support (Pt@CoS), the roles of Pt single atoms and the substrate for alkaline HER catalysis are unfolded. Electrochemical studies demonstrate the remarkable catalytic performance of Pt @CoS catalysts with a 45-fold increase in mass current density compared to the benchmark Pt/C at 100 mV. The DFT calculation unravels that the anchored Pt SAs on CoS enable more unhybridized d z 2 orbitals of surrounding cobalt sites through the interfacial synergetic effect, which benefits the water dissociation kinetics. Likewise, the Pt sites can also act as active sites to facilitate the subsequent H 2 formation, thus synergistically promoting the alkaline HER catalysis. This work highlights the importance of the synergies effect between single atoms and substrate for rational catalyst design. Pt single atom anchored on CoS could enable more unhybridized d z 2 orbitals of surrounding cobalt sites for water dissociation, while the Pt single atoms facilitate H 2 generation, thereby synergistically promoting the catalytic kinetics of alkaline HER. • Pt@CoS displays a 45-time increase in Pt mass current density compared to the benchmark Pt/C at 100 mA cm −2 . • Theoretical analysis unravels the synergistic effect resulting in more unhybridized d z 2 orbitals of Pt surrounded cobalt atoms. • Pt@CoS improves both the water dissociation and recombination step via an interfacial synergy.