In-situ formation of Ni (oxy)hydroxide on Ni foam as an efficient electrocatalyst for oxygen evolution reaction.

A binder-free Ni (oxy)hydroxide on Ni foam was prepared through an in-situ electrochemical activation method. Ni (oxy)hydroxide is active for the oxygen evolution reaction. The Ni (oxy)hydroxide directly formed on the surface of Ni foam as a binder-free catalyst not only exhibited large electrochemically active area, but also displayed low interfacial electronic resistance and low charge transfer resistance. Therefore, the optimized Ni (oxy)hydroxide exhibits an overpotential of 288 and 370 mV at 10 and 500 mA cm−2, respectively, in 1.0 M KOH for the oxygen evolution reaction, as well as favorable during 240 h at 100 mA cm−2. • Electrochemical activation method is a time and energy-saving method. • Strong electronic interaction between NiOOH and Ni favors electron transfer. • High valence Ni in NiOOH enhances the chemisorption of OH− during OER. • In situ formation of NiOOH layer reduces the interfacial electronic resistance. [ABSTRACT FROM AUTHOR]