Abstract
The effects of iron coprecipitated into thin film nickel oxide electrodes or introduced in the 25 weight percent 
electrolyte were studied by a combination of galvanostatic and open‐circuit decay methods. Effects on voltammetric behavior and on the oxygen overpotential were observed in thin film electrodes with as little as 0.01% iron present. The over‐potential was further lowered by 1% iron to the extent that the nickel oxide charge storage reaction was adversely affected. Higher concentrations of iron coprecipitated into a composite iron/nickel hydrous oxide dramatically catalyzed the oxygen evolution reaction by lowering the Tafel slope from about 70 mV/decade with no iron present to about 25 mV/decade with 10–50% iron. This composite oxide shows promise as an anodic electrocatalyst for alkaline electrolysis to produce hydrogen; the oxygen overpotential on thin film electrodes was over 200 mV lower than the overpotential with nickel oxide, itself, when polarized at 80 mA/cm2.