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

Abstract 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, NiB 0.45 -250/Cu, which forms a NiB 0.45 /NiO x core-shell heterostructured nanoparticulate film during anodic electrolysis. The performance of NiB 0.45 -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 IrO 2 -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 NiB x films. Optimal combination of these factors can evidently enhance the catalytic activity of nickel boride electrocatalysts.