In Situ Electrochemically Activated CoMn-S@NiO/CC Nanosheets Array for Enhanced Hydrogen Evolution

The development of cost-effective hydrogen evolution reaction (HER) electrocatalysts based on 3d-transition metal is highly desired but still challenging. Herein, we report on the synthesis of the three-dimensional self-supported nickel-oxide-coated cobalt manganese sulfide nanosheets array on carbon cloth (CoMn-S@NiO/CC), which is used as an efficient electrocatalyst for HER in alkaline media. The performance of CoMn-S@NiO/CC is significantly improved through an in situ electrochemical reduction process. The electrochemically activated CoMn-S@NiO/CC (ECA CoMn-S@NiO/CC) drives 100 and 200 mA cm–2 at overpotentials of 232 and 278 mV, respectively, with long-term stability for hydrogen production in 1.0 M KOH. Such high hydrogen evolution activity for ECA CoMn-S@NiO/CC is owed to the incorporation of Co ions, increase in electrochemically active surface area, and the newly formation of amorphous regions on its surface.