Nickel-borate oxygen-evolving catalyst that functions under benign conditions.

Thin catalyst films with electrocatalytic water oxidation properties similar to those of a recently reported Co-based catalyst can be electrodeposited from dilute Ni(2+) solutions in borate electrolyte at pH 9.2 (B(i)). The Ni-B(i) films can be prepared with precise thickness control and operate at modest overpotential providing an alternative to the Co catalyst for applications in solar energy conversion.