Boosting bifunctional and overall water splitting activity by direct fabricating bimetallic metal hydroxide catalyst on nickel foam

Abstract

Bimetallic cobalt-nickel metal nitrate hydroxide electrocatalyst fabricated on a conducting nickel foam (NF) displayed excellent bifunctional electrocatalytic activity and improved overall water splitting. X-ray photoelectron spectroscopy (XPS) analysis confirmed the presence of Co and Ni and HR-SEM suggested the formation of crystalline needle nanostructures. The individual CoNH and NiNH required overpotential of 330 and 317 mV in OER and 267 and 293 mV in HER, respectively to produce 50 mA/cm² current density. In contrast, bimetallic CoNiNH required lower overpotential (292 mV in OER and 242 mV in HER) to achieve 50 mA/cm² current density. The bifunctional activity of CoNiNH was utilized for overall water splitting, which required relatively low cell potential (1.65 V) to produce 10 mA/cm² current density. Further, the overall water splitting of CoNiNH activity was investigated in sea water also. The relatively low Tafel slope and improved charge transfer of bimetallic CoNiNH indicated the faster kinetics and supported the strong electrocatalytic activity.