Synergistic Assembly of a CoS@NiFe/Ni Foam Heterostructure Electrocatalyst for Efficient Water Oxidation Catalysis at Large Current Densities.

Electrochemical water splitting is an ideal pollution-free path to generate hydrogen at large scale, however, the development of highly catalytic electrocatalysts for the water oxidation reaction at large current densities is still a fundamental challenge. Herein, we report a novel, high-wettability water-oxidation electrocatalyst composed of an amorphous NiFe layer and CoS film on commercial nickel foam via a two-step electrodeposition synthetic path. Benefiting from the strong interactions between the NiFe layer and CoS film, enlarged surface active sites and enhanced wettability, the CoS@NiFe/NF electrode exhibited an outstanding water oxidation performance at 10 mA/cm2 with an overpotential of 175 mV in 1 M KOH solution and steadily delivered a current density of 1 A/cm2 at merely 330 mV in 30 wt% KOH solution. Even at large densities, the CoS@NiFe/NF hybrids also showed excellent water oxidation stability and corrosion resistance for at least 24 h. Such a synergistic assembling approach to fabricate a CoS@NiFe/NF heterostructure together with excellent OER performance may be a promising strategy for rationally building and designing heterostructural electrocatalysts towards highly efficient water oxidation reaction.