Ultrathin Ni-Co double hydroxide nanosheets with conformal graphene coating for highly active oxygen evolution reaction and lithium ion battery anode materials

Ultrathin graphene wrapped Ni-Co double hydroxide nanosheets (∼10 nm) were synthesized by a facile and rapid electrodeposition process, and evaluated as electrocatalysts for oxygen evolution reaction (OER) and anode materials for Li-ion batteries. The conformal graphene coating on the nanosheets significantly increased the conductivity and surface area of the Ni-Co double hydroxide electrodes. As the OER electrocatalyst, the Ni-Co graphene hybrids show a superior catalytic activity with a small Tafel slope of 67 mV per decade due to the synergy between the abundant active sites of the Ni-Co hydroxides and the conductive graphene coating, and a modest overpotential of 280 mV at a current density of 10 mA cm−2. Impressively, the electrodes exhibit an excellent stability evaluated by chronopotentiometry under a high current density of 30 mA cm−2 for 12 h. As Li-ion battery anode, the materials show a high specific capacity of 373 mA h g−1 up to 500 cycles even at a high current density of 1000 mA g−1. This study provides a new strategy to develop robust and affordable alternative OER catalyst and anode material for high-performance lithium ion batteries.