Enhanced synergistic catalysis by a novel triple-phase interface design of NiO/Ru@Ni for the hydrogen evolution reaction

Electrolysis of water needs high-efficiency catalysts to accelerate the kinetics of the hydrogen evolution reaction (HER). A single catalyst is usually unable to simultaneously and effectively enhance all elementary steps of the HER. In this study, we demonstrate a novel triple-phase interface design that includes NiO and Ru nanoparticles on a porous nickel scaffold (PNS) to promote the Volmer and Heyrovsky steps, respectively. An in situ electro-oxidation route is developed to enable two catalysts along the interfaces to be directly wired with the metallic PNS. Because the hydrogen intermediates and electrons can be easily transported through the triple-phase interfaces, such a triple-phase interface structure exhibits highly efficient synergistic catalysis that is not observed in a conventional combination of two catalysts. The resultant electrocatalyst shows an overpotential of 39 mV at −10 mA cm−2 and a low Tafel slope of 75 mV dec−1 in 1 M KOH electrolyte, which are comparable to Pt/C and superior to other non-Pt electrocatalysts. Our studies demonstrated that interface construction of bifunctional catalysts can serve as an effective approach to promote the activities of non-Pt catalysts.