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

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)NO/NiS) prepared by coupling NiS and a bimetallic metal-organic framework (MOF) of NiFe(CN)NO on nickel foam (NF) via a simple two-step route. The NiFe(CN)NO/NiS electrocatalyst displays an interesting rod-like hierarchical architecture assembled by ultrathin nanosheets. The combination of NiFe(CN)NO and NiS optimizes the electronic structure of the metal active sites and increases the electron transfer capability. Benefitting from the synergistic effect between NiS and the NiFe-MOF as well as the unique hierarchical architecture, the NiFe(CN)NO/NiS/NF electrode exhibits excellent electrocatalytic OER activity with ultralow overpotentials of 162/197 mV at 10/100 mA cm and an ultrasmall Tafel slope of 26 mV dec in 1.0 M KOH, which are far superior to those of the individual NiFe(CN)NO, NiS and commercial IrO catalysts. In particular, unlike common metal sulfide-based electrocatalysts, the composition, morphology and microstructure of the NiFe-MOF/NiS 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.