A modulated electronic state strategy designed to integrate active HER and OER components as hybrid heterostructures for efficient overall water splitting

Herein, we report a rational design of one-dimension (1D) porous hybrid heterostructures with the active HER (Mo2C) and OER (Co4S3) embedded N and S co-doped carbon (Co4S3/Mo2 C-N SC) for the effective overall water splitting. Spectroscopic characterizations reveals that modulated electronic state behaviors are generated by the strong chemical couplings at the nanointerface which triggers the charge from Co2+ to Mo4+/Mo6+ through the interfacial Mo-S-Co bond, resulting in producing the considerable amounts of the active sites (i.e., Co3+, Mo2+, and Mo3+) for the HER and OER in the hybrid heterostructures. Interestingly, Co4S3/Mo2 C-N SC shows pronounced synergistic effects in electrocatalytic activity for the HER and OER. When Co4S3/Mo2 C-N SC is used as both anode and cathode for overall water splitting, a low cell voltage of 1.62 eV is generated at 10 mA cm−2. The interesting work highlights the significance of optimization electronic structure based on transition metal-based bifunctional electrocatalysts for the HER and OER.