In Situ Synthesis of NiO/CuO Nanosheet Heterostructures Rich in Defects for Efficient Electrocatalytic Oxygen Evolution Reaction

Developing efficient electrocatalysts toward oxygen evolution reaction (OER) is of great significance for improving the efficiency of hydrogen production by electrolysis of water. The transition metal-based heterostructure shows superior catalytic performance toward OER due to abundant defects and a modified electronic structure of the active sites. Herein, we synthesized a NiO and CuO heterostructured nanosheet rich in defects on the Ni foam via an in situ electrochemical oxidation. The electrocatalyst showed high OER activity with an overpotential of 234 mV at 10 mA cm –2 and a small Tafel slope of 22 mV dec –1 . To our knowledge, this is the first time that the NiO and CuO heterostructure, which was obtained by a very simple preparation method, has been used in OER. The excellent catalytic performance can be attributed to electron interactions between NiO and CuO, thus modifying the adsorption energy of nickel oxide to intermediate species. Moreover, we found that the heterostructured nanosheet was composed of many very small NiO and CuO nanocrystals with abundant defects and more exposed active sites, thus improving the catalytic activity and accelerating the kinetic processes of OER.