Breaking Volmer step limitation on NiO/PtNi heterojunctions via ATO-induced charge injection and interfacial modulation

Driven by the persisting poor understanding of the slow kinetics of hydrogen evolution (HER) on Pt-based alloys in alkaline media, it is necessary and challenging to explore the clear relationship between heterogeneous interface components and activity. Herein, we develop an exquisite triphasic interfacial structure featuring the Sb-doped SnO2 (ATO)-supported NiO/PtNi heterojunction with controllable heterogeneous interface. The strong electron-donating effect of the ATO carrier and the electronic coupling between PtNi and appropriate NiO components effectively optimize the adsorption of H2O* and dissociation of H*, especially the adsorption-dissociation of H2O on the NiO site (Volmer step), thus accelerating the overall alkaline HER kinetics. The resulting catalyst delivers high alkaline HER performances with a low Tafel slope (only 25.5 mV dec−1) and an ultra-long stability of 140 h operation. Our findings provide new insights into breaking the water dissociation limit of Pt-based catalysts by rational design of heterogeneous interfaces.