Electrochemical OER/ORR Activity of Ultrathin Hexagonal Nickel-Cobalt Hydroxide Nanosheet Films with Controlled Layer Number

Our present work demonstrated electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) activities of ultrathin nickel cobalt hydroxide (NixCoy-OH, Ni/Co = x/y) nanosheet films. A Ni1Co4-OH nanosheet film showed the lowest overpotential of all Ni/Co ratios. When the layer number of Ni1Co4-OH nanosheet film was changed, the larger layer number gave the lower overpotential. However, the 1–4 layers of nanosheet showed larger decreases of the overpotentials per layer (−61 mV/layer) than the 4–12 layers (−9 mV/layer). Our present work demonstrated electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) activities of ultrathin nickel cobalt hydroxide (NixCoy-OH, Ni/Co = x/y) nanosheet films. The larger layer number of Ni1Co4-OH nanosheet film gave a lower overpotential, however, 1–4 layers of nanosheet showed larger decreases of the overpotentials per layer (−61 mV/layer) than the 4–12 layers (−9 mV/layer).