Electrodeposited Cobalt-Phosphorous-Derived Films as Competent Bifunctional Catalysts for Overall Water Splitting

One of the challenges to realize large-scale water splitting is the lack of active and low-cost electrocatalysts for its two half reactions: H-2 and O-2 evolution reactions (HER and OER). Herein, we report that cobalt-phosphorous-derived films (Co-P) can act as bifunctional catalysts for overall water splitting. The as-prepared Co-P films exhibited remarkable catalytic performance for both HER and OER in alkaline media, with a current density of 10mAcm(-2) at overpotentials of -94mV for HER and 345mV for OER and Tafel slopes of 42 and 47mV/dec, respectively. They can be employed as catalysts on both anode and cathode for overall water splitting with 100% Faradaic efficiency, rivalling the integrated performance of Pt and IrO2. The major composition of the as-prepared and post-HER films are metallic cobalt and cobalt phosphide, which partially evolved to cobalt oxide during OER.