Interfacial electron transfer triggered reversible hydrogen spillover effect boosts high-efficient hydrogen evolution.

The mechanistic role of interfacial electron transfer in enabling reversible hydrogen spillover for enhanced hydrogen evolution reaction (HER) kinetics remains fundamentally unexplored. Herein, we report a lattice-matched PtCoNiCuZn/ WCN heterostructure electrode, where interfacial electron transfer triggers reversible hydrogen spillover, thereby achieving exceptional HER performance. Advanced characterization reveals coherent and semicoherent interfaces that induce charge redistribution, creating electron-deficient Pt sites with optimally downshifted d-band centers.