One-pot synthesis of graphene- cobalt hydroxide composite nanosheets (Co/G NSs) for electrocatalytic water oxidation

We report a one-pot method for the preparation of graphene-cobalt hydroxide nanosheets (Co/G NSs) and their use as an effective elelctrocatalyst for water oxidation. Mechanical exfoliation of graphite via sonication produced graphene sheets, which were stabilized by the surface adsorption of a cationic surfactant (CTAB). In a subsequent step, varying amount of a cobalt complex [sodium hexanitrocobaltate(III)] was added which selectively bound with the positively charged head of surfactant. In the last step, cobalt complex was reduced with sodium borohydride to obtain Co/G NSs catalyst. The catalyst showed lower overpotential (280 mV) as compared to benchmark catalysts and decent stability and turnover frequency (TOF: 0.089 s-1) for oxygen evolution reaction (OER).