The sluggish hydrogen evolution reaction (HER) in alkaline media is fundamentally limited by the high energy barrier of H2O dissociation, which is strongly governed by the orientation and hydrogen-bond environment of interfacial H2O molecules. Here, we reported a heterostructured electrocatalyst comprising PtOx nanoclusters anchored on NiO (PtOx/NiO) that overcomes this limitation by regulating the interfacial H2O configuration. Combined in-situ experimental and theoretical investigations revealed that PtOx/NiO established a strengthened dipole field, which induced a preferential H-down orientation of interfacial H2O, thereby lowering the H2O dissociation barrier. Meanwhile, partially oxidized Pt sites optimize hydrogen intermediate binding, increasing surface proton availability and facilitating subsequent HER. As a result, the PtOx/NiO delivered outstanding HER performance in alkaline electrolyte, requiring only 27 mV overpotential at 10 mA cm-2. This work establishes interfacial dipole engineering as an effective strategy for accelerating H2O activation, offering new mechanistic insight and a generalizable framework for designing high-efficiency alkaline HER electrocatalysts.
Yuan et al. (Wed,) studied this question.