Constructing built-in electric field to accelerate the asymmetric local charge distribution for efficient alkaline overall water/seawater splitting

Developing efficient and durable bifunctional electrocatalysts for large-scale alkaline water/seawater electrolysis is essential but remains a challenge. Here, we have ingeniously constructed Mott-Schottky heterogeneous nanowire arrays consisting of Ru and Fe co-doped CoP with Ru nanoparticles (Ru/Ru,Fe-CoP). The incorporation of guest Ru and Fe atoms effectively increases the work function difference between the CoP region and the Ru region, leading to the enhancement of the built-in electric field, which accelerates the induction of electron transfer at the Mott-Schottky interface and promotes the formation of local electrophilic/nucleophilic region. Theoretical calculations revealed that the asymmetric charge distribution effectively modulated the free energy of hydrogen adsorption as well as the formation energy of oxygen intermediates. Benefiting from the regulation of local charge distribution, the constructed Ru/Ru,Fe-CoP exhibits a remarkable catalytic activity for HER and OER in 1 M KOH with overpotentials of only 146 and 345 mV at 1000 mA cm−2, respectively. This innovative manipulation of charge asymmetric distribution by modulating Schottky heterojunctions provides an avenue for rational design of efficient bifunctional electrocatalysts. [Display omitted] •A Mott-Schottky heterojunction consisting of Ru/Fe co-doped CoP with Ru nanoparticles (Ru/Ru,Fe-CoP) was constructed.•The enhanced built-in electric field accelerates the formation of localized electrophilic/nucleophilic regions.•The Ru/Ru,Fe-CoP exhibits high bifunctional activities and stabilities in both freshwater and seawater.