Construction of NiFe(CN)₅NO/Ni₃S₂ hierarchical submicro-rods on nickel foam as advanced oxygen evolution...

The development of cheap, abundant, and highly efficient electrocatalysts for the oxygen evolution reaction (OER) is urgently needed for hydrogen production from water splitting. Herein, we demonstrate a novel OER electrocatalyst (NiFe(CN)₅NO/Ni₃S₂) prepared by coupling Ni₃S₂ and a bimetallic metal-organic framework (MOF) of NiFe(CN)₅NO on nickel foam (NF) via a simple two-step route. The NiFe(CN)₅NO/Ni₃S₂ electrocatalyst displays an interesting rod-like hierarchical architecture assembled by ultrathin nanosheets. The combination of NiFe(CN)₅NO and Ni₃S₂ optimizes the electronic structure of the metal active sites and increases the electron transfer capability. Benefitting from the synergistic effect between Ni₃S₂ and the NiFe-MOF as well as the unique hierarchical architecture, the NiFe(CN)₅NO/Ni₃S₂/NF electrode exhibits excellent electrocatalytic OER activity with ultralow overpotentials of 162/197 mV at 10/100 mA cm^-2 and an ultrasmall Tafel slope of 26 mV dec^-1 in 1.0 M KOH, which are far superior to those of the individual NiFe(CN)₅NO, Ni₃S₂ and commercial IrO₂ catalysts. In particular, unlike common metal sulfide-based electrocatalysts, the composition, morphology and microstructure of the NiFe-MOF/Ni₃S₂ composite electrocatalyst can be well retained after the OER, which endows it with fantastic long-term durability. This work offers a new strategy for the construction of novel and high-efficiency MOF-based composite electrocatalysts for energy applications.