Influence of iron doping on tetravalent nickel content in catalytic oxygen evolving films

Abstract

Iron doping of nickel oxide films results in enhanced activity for promoting the oxygen evolution reaction (OER). Whereas this enhanced activity has been ascribed to a unique iron site within the nickel oxide matrix, we show here that Fe doping influences the Ni valency. The percent of Fe³⁺ doping promotes the formation of formal Ni⁴⁺, which in turn directly correlates with an enhanced activity of the catalyst in promoting OER. The role of Fe³⁺ is consistent with its behavior as a superior Lewis acid.