Heterostructure of NiFe@NiCr-LDH for Active and Durable Oxygen Evolution Reactions in Alkaline Media

Developing cost-effective, efficient, and durable catalysts for oxygen evolution reactions (OER) is the key for promoting large-scale H₂ production through electrochemical water splitting. Herein, we report a facile method for fabricating an NiFe@NiCr-LDH catalyst toward alkaline OER. The electronic microscopy technique revealed that it has a well-defined heterostructure at the interface between the NiFe and NiCr phases. In 1.0 M KOH, the as-prepared NiFe@NiCr-LDH catalyst shows excellent catalytic performance, evidenced by an overpotential of 266 mV at the current density of 10 mA cm^-2 and a small Tafel slope of 63 mV dec^-1; both are comparable with the RuO₂ benchmark catalyst. It also exhibits robust durability in long-term operation, manifested by a 10% current decay in 20 h, which is superior to that of the RuO₂ catalyst. Such excellent performance is attributed to the interfacial electron transfer that occurs at the interfaces of the heterostructure, and the Fe(III) species facilitate the formation of Ni(III) species as active sites in NiFe@NiCr-LDH. This study offers a feasible strategy for preparing a transition metal-based LDH catalyst for OER toward H₂ production and other electrochemical energy technologies.