Coupling effect and electronic modulation for synergistically enhanced overall alkaline water splitting on bifunctional Fe-doped CoBi/CoP nanoneedle arrays

Designing bifunctional electrocatalysts with high efficiency and low cost for water splitting is urgently required for the production of green hydrogen. Herein, a bifunctional iron-doped cobalt borate/cobalt phosphide hybrid supported on nickel foam (Fe-CoB i /CoP/NF) was fabricated via hydrothermal and phosphating process. Benefit from the unique nanoneedle architecture for faster mass transfer, the existence of borate on CoB i for accelerating proton transfer , the moderate adsorption of H* species on CoP, Fe doping and the synergistic effect between CoB i and CoP, Fe-CoB i /CoP/NF hybrid exhibits a low overpotential of 137 mV and 260 mV at 100 mA cm −2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Moreover, Fe-CoB i /CoP/NF||Fe-CoB i /CoP/NF also presents a low cell potential of 1.65 V@100 mA cm −2 for overall alkaline water splitting and excellent durability (128 h) without decay. This work provides a new insight into the design of bifunctional electrocatalysts simultaneously through the morphological engineering and heteroatomic doping.