Surface‐Confined Fabrication of Ultrathin Nickel Cobalt‐Layered Double Hydroxide Nanosheets for High‐Performance Supercapacitors

Abstract The design and fabrication of 2D nanostructure electrodes with desired electrochemical activities is highly demanded for electrocatalysis and supercapacitors. Herein, the tuned fabrication of ultrathin and tortuous nickel/cobalt‐layered double hydroxide (NiCo‐LDH) nanosheets via a graphene oxide (GO) surface‐confined strategy is reported, yielding nanosheets with a thickness of 1.7–1.8 nm that is duplicated from the graphene oxides in terms of both the lateral size and the shape. It has been found that the C/O functional groups on the GO surface have functioned to promote the oxidation of Co 2+ to Co 3+ , and to transform the β‐phase NiCo‐hydroxide (NiCo‐OH) into the LDH‐phase with tuned homogenous composition and geometry. The ultrathin NiCo‐LDH nanosheets mimic the morphology and size of the graphene due to the surface‐confined and/or surface‐guided growth. The as‐obtained NiCo‐LDH‐graphene (NiCo‐LDH‐G) nanosheets exhibit a superior electrocatalytic activity for oxygen evolution reaction, evidenced by a small overpotential of 0.337 V (@10 mA cm −2 in 0.1 m KOH electrolyte), and a high charge storage capability of 1489 F g −1 as electrodes for supercapacitors. This 2D surface‐confined growth strategy may pave a way for the fabrication of ultrathin 2D materials including but not limited to transition metal hydroxides for high‐performance electrochemical applications.