Fishnet-like superstructures constructed from ultrafine and ultralong Ni-MOF nanowire arrays directionally grown on highly rough and conductive scaffolds: synergistic activating effect for efficient and robust alkaline water oxidation activity

Abstract

The water oxidation efficiency driven by electrocatalysts is related to the energy conversion efficiency of water electrolysis and other systems. It is the key to expose active sites as possible, to fully and firmly contact with other components, and to deliver superior conductivity for the development of high-performance electrocatalysts. Herein, we have fabricated self-supporting Ni-MOF electrode containing three-dimensional (3D) fishnet-like superstructures, which are constructed from in-situ growth of amorphous or poor crystalline Ni-MOF nanowire arrays on highly rough and conductive scaffolds of metallic Ni/carbon cloth (Ni-MOF/Ni/CC). The Ni-MOF/Ni/CC electrode delivers an overpotential of 250 mV at the current density of 10 mA cm−2 (η10). The η10 is maintained at 240 mV after a constant current electrolysis for 32 h, which is much smaller than those of Ni-MOF/CC (423 mV) and Ni/CC (281 mV). The superior activity and robust durability can be attributed to the synergistic activating effect of each component in the superstructures with high density of coordination unsaturated active sites, intimate connection and excellent conductivity. This work can provide a new strategy to develop high-efficiency MOFs-based electrocatalysts for electrocatalytic water oxidation.