Preparation of electrodeposited thin films of nickel-iron alloys on mild steel for alkaline water electrolysis. Part I: studies on oxygen evolution

• Published in: International journal of hydrogen energy 1993, Vol.18 (6), p.467-473
• Main Authors: Singh, R.N., Pandey, J.P., Anitha, K.L.
• Format: Article
• Language: English
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/0360-3199(93)90002-R

Thin films of electrodeposited nickel-iron alloys containing 15.6–38.5% Fe were obtained on mild steel at 30°C. The films were uniform, porous and p-type semiconducting. Cyclic voltammograms showed the formation of a single quasireversible redox couple, Ni(III)/Ni(II), on each film electrode in the anodic region (0–0.6 V) in 1M KOH. Oxygen evolution studies demonstrated a substantial increase in the electrocatalytic activity of Ni in the presence of 17.9% Fe additive. The Tafel slopes were 40 ± 5 mV decade −1. The reaction order with respect to OH − ion concentration was observed to be approximately 2. The results suggest that the oxygen evolution reaction occurs on the oxidized Ni(III) sites on the electrode surface with a mechanism involving an electrochemical adsorption of OH − ions in a fast step and their subsequent electrochemical desorption in the slow step.