Electrodeposited cobalt phosphides with hierarchical nanostructure on biomass carbon for bifunctional water splitting in alkaline solution

Low cost and high-performance bifunctional catalysts for water splitting under alkaline conditions still face many challenges. CoP/C were synthesized by electrodeposition in the presence of different sodium hypophosphite concentrations with porous carbon membranes as working electrodes. The morphology of CoP/C is strongly dependent on the concentration of sodium hypophosphite. We prepared the CoP/C with varying contents of phosphorus to investigate influence of phosphorus content on the morphology of CoP/C and the corresponding catalytic capability of water splitting in alkaline conditions. When the sodium hypophosphite in the electrodeposition electrolyte reaches to 0.6 M, the malformed octahedral CoP particles appear on nanofibers of carbon membrane coated with CoP films. The CoP/C with such hierarchical structure exhibits superior electrocatalytic activities for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with the overpotential of 140 mV and 250 mV at a current density of 10 mA cm(-2), respectively in the alkaline solution. Furthermore, the CoP/C with hierarchical structure as both anode and cathode for water splitting achieves 10 mA cm(-2) only need 1.56 V. The CoP/C with hierarchical structure keeps stable catalytic performance even after 24 h. This work provides a facile strategy for designing high-efficient phosphides based catalyst for overall water splitting. (C) 2020 Elsevier B.V. All rights reserved.