Atomic-scale insights into the role of non-covalent interactions in electrocatalytic hydrogen evolution reaction

Understanding the non-covalent interactions occurring at electrocatalytic interfaces is important to promote the development of advanced hydrogen evolution systems. However, the exact role of non-covalent interaction in the electrode–electrolyte interface on the HER kinetics remains obscure at the molecular level, especially for non-platinum-based electrodes. This is due to the lack of an effective strategy to decouple the effect of each interaction (ΔGH, noncovalent interactions) on the HER kinetics. Accordingly, herein, we constructed a model catalyst surface (Pd,RuSOy) to decouple the influence of ΔGH and double-layer structure optimization on HER kinetics, thus exploring the role of this non-covalent interactions on the HER at the molecular level. We found that hydrated cations located in the outer Helmholtz plane (OHP) also interact directly with electrode materials and the strength of these interactions would also affect the HER activity. Consequently, Pd,RuS2−xOy exhibited remarkable electrocatalytic activity toward HER, which delivered low overpotentials of 38 and 82 mV at 10 and 100 mA cm−2, respectively. This study not only illustrates the roles of interfacial interactions, but also provides a new way for the rational design of advanced electrocatalysts.