Regulating Hydrogen/Oxygen Species Adsorption via Built‐in Electric Field ‐Driven Electron Transfer Behavior at the Heterointerface for Efficient Water Splitting

Abstract Alkaline water electrolysis (AWE) plays a crucial role in the realization of a hydrogen economy. The design and development of efficient and stable bifunctional catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are pivotal to achieving high‐efficiency AWE. Herein, WC 1‐x /Mo 2 C nanoparticle‐embedded carbon nanofiber (WC 1‐x /Mo 2 C@CNF) with abundant interfaces is successfully designed and synthesized. Benefiting from the electron transfer behavior from Mo 2 C to WC 1‐x , the electrocatalysts of WC 1‐x /Mo 2 C@CNF exhibit superior HER and OER performance. Furthermore, when employed as anode and cathode in membrane electrode assembly devices, the WC 1‐x /Mo 2 C@CNF catalyst exhibits enhanced catalytic activity and remarkable stability for 100 hours at a high current density of 200 mA cm −2 towards overall water splitting. The experimental characterizations and theoretical simulation reveal that modulation of the d‐band center for WC 1‐x /Mo 2 C@CNF, achieved through the asymmetric charge distribution resulting from the built‐in electric field induced by work function, enables optimization of adsorption strength for hydrogen/oxygen intermediates, thereby promoting the catalytic kinetics for overall water splitting. This work provides promising strategies for designing highly active catalysts in energy conversion fields.