Corrosion-Engineered Room-Temperature Deposition of NiMoO4/NiS/Ni(OH)2 at Nickel Foam: An Efficient Strategy and Electrocatalyst for the Oxygen Evolution Reaction

The oxygen evolution reaction (OER) tends to limit the rate of electrolysis of water. Accordingly, there is much interest in the development of electrocatalysts for this important half-reaction. Herein, a NiMoO4/NiS/Ni(OH)2 composite was nucleated directly at a nickel foam electrode at room temperature and used as an effective electrocatalyst for the OER. The NiMoO4/NiS/Ni(OH)2 composite was formed in an aqueous solution of thiomolybdate (2.5 mM) dissolved in a 0.1 M acetate solution at a pH of 7.5. Its formation was facilitated through the hydrolysis of the thiomolybdate and corrosion of the nickel foam. Highly adherent deposits of NiMoO4/NiS/Ni(OH)2 were formed at the nickel foam surface and throughout the porous foam network to give an electrochemical active surface area that was approximately 11-fold higher than that of the pristine foam. The OER activity of the NF/NiMoO4/NiS/Ni(OH)2 was studied in an alkaline 1.0 M KOH solution. An onset potential of 1.47 V vs RHE and a Tafel slope of 110 mV dec–1 were observed. The potential required to deliver a current density of 50 mA cm–2 was 1.56 V vs RHE. Finally, NiMoO4/NiS/Ni(OH)2 exhibited very good stability over a 16 h period.