Owing to rapid depletion of fossil fuels and environmental concerns associated with their extraction, processing and use, intensive efforts have been devoted to proble alternative renewable resources. Production of hydrogen via electrocatalytic splitting of water provides a viable strategy to obtain hydrogen green fuel. The-state-of-the-art catalysts for water splitting, however are based on the oxides of iridium and ruthenium which are scarcely availble and possess low stability at low pH. We would like to present our recent work where we have developed electrocatalysts with earth-abundant metal cobalt and applied it for the more sluggish oxygen evolution reaction (OER) of water splitting. Graphene-supported cobalt nanoparticles (Co@G) were synthesized in a one-pot method. Mechanical exfoliation of graphite via ultrasonication produced graphene sheets, which were stabilized by the surface adsorption of a cationic surfactant (CTAB). In a subsequent step, varying amount of an –ate complex of cobalt (sodium hexanitrocobaltate(iii)) was added which binds selectively with the positively changed head of surfactant. In the last step, cobalt complex was reduced with sodium borohydride to obtain Co@G catalysts. Co@G showed lower overpotential of 280 mV at 10mA/cm<sup>2</sup>, low Tafel slope of 109 mV/dec and high turnover frequency (TOF: 0.089s<sup>-1</sup>) for oxygen evolution reaction (OER).

Catalytic water oxidation over graphene-supported cobalt catalysts

256th National Meeting (2018)

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