Accelerating Electrochemical Water Oxidation Activity by Tailoring Morphology and Electronic Structure of Nickel Organic Framework Nanoarrays with a Fe Etching Effect

Fe-mediated nickel organic framework nanoarrays (NiFe-MOFs NAs) on carbon cloth were successfully constructed from ultrathin nanosheets via an etching effect. This strategy also combined the dissolution and coordination effect of acidic ligand (2,6-naphthalenedicarboxylic acid, NDC) to a self-sacrificial template of Ni(OH)2 NAs. Benefiting from the strong Fe etching effect, dense and thick brick-like Ni-NDC nanoplates were tailored into loose and ultrathin NiFe-NDC nanosheets with abundant squamous nanostructures, which were still tightly attached to carbon cloth. As a consequence, more coordinatively unsaturated metal sites (CUMSs) that served as active centers were exposed to accelerate oxygen production. Meanwhile, the electronic structure of active Ni centers was modulated by the incorporation of Fe atoms. The charge density redistribution between Ni and Fe ultimately optimized the energy barrier of the adsorption/desorption of oxygenated intermediates, promoting the kinetics for water oxidation.