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

Abstract

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 highefficiency MOF-based composite electrocatalysts for energy applications.