Charged excited state induced by ultrathin nanotip drives highly efficient hydrogen evolution

Engineering the localized electronic structure is an intriguing way to regulate the charged valence state of materials for various potential applications. Here, we show that electrocatalytic reactions relevant for water splitting can be boosted by the charged excited state generated from tip-induced localized electron. Using intentionally fabricated acicular NiCo2S4-xPx nanowire array, on which charged H2O molecules are driven to metastable excited state to efficiently reduce activation barrier and enhance carrier transfer, the overpotential at 10 mA cm(-2) required for hydrogen evolution was decreased to 75 mV and the Tafel slope was lowered to 42.3 mV per decade. This work, distinct from conventional doping and defecting strategy, provides a new insight into the underlying catalytic mechanism and functionalities of material's catalytic properties via simple structural engineering.