Highly active and durable electrocatalytic water oxidation by a NiB0.45/NiOx core-shell heterostructured nanoparticulate film

On the way to energy-efficient and cost-effective hydrogen production by electrochemical or photoelectrochemical water splitting, it is of primary importance to develop highly active and durable water oxidation electrocatalysts based on earth-abundant elements. Here we report a highly active, robust, cheap, and facilely fabricated O-2-evolving catalyst on a Cu foil, NiB0.45-250/Cu, which forms a NiB0.45/NiOx core-shell hetero-structured nanoparticulate film during anodic electrolysis. The performance of NiB0.45-250/Cu, to produce 10 mA cm(-2) at 296 mV overpotential in 1 M KOH over 60 h, is at par with the best efficiency of earth-abundant electrocatalysts reported to date and surpasses that of IrO2-loaded copper electrode under identical conditions. Experimental evidence and theoretical calculations reveal the correlations of B/Ni atomic ratio and annealing temperature with the morphology, surface microtexture, electrochemical active surface area, and electrical conductivity of NiBx films. Optimal combination of these factors can evidently enhance the catalytic activity of nickel boride electrocatalysts.