CoS nanosheet arrays grown on nickel foam as an excellent OER catalyst

Hydrogen is the most promising alternative energy source for many common applications because its combustion product is only water and it has a very high calorific-value. However, the overpotential in water-splitting is high due to the harsh oxygen evolution reaction (OER). Therefore, effective catalysts which are low-cost and easy to prepare are urgently needed to stimulate the reaction. Herein we constructed 3D CoS nanosheets arrays on nickel foam through a combination of electrodeposition and sulfidation. The as-prepared catalyst can catalyze OER efficiently with an overpotential of 297 mV to generate 10 mA cm−2 current density in 1 M KOH and is able to maintain excellent performance over 40 h without obvious degradation.