Three-Dimensional Ni Foam-Supported CoO Nanoparticles/N-Doped Carbon Multilayer Nanocomposite Electrode for Oxygen Evolution

Metal–organic complex (MOC) multilayers are, for the first time, conformally constructed on Ni foam (NF) via a three-component sequential layer-by-layer (LbL) self-assembly approach and converted to three-dimensional (3-D) NF-supported interconnected CoO nanoparticles (NPs)/N-doped carbon nanohybrid multilayers via calcination. The obtained nanoarchitecture delivers an overpotential of 318 mV to achieve 10 mA cm –2 and a Tafel slope of 46.1 mV dec –1 . This activity is superior to most reported oxygen evolution reaction (OER) catalysts, and even much better than those of Ir- and Ru-based ones measured under the same conditions (0.1 M KOH). Additionally, this electrode undergoes negligible potential and current change after 19.8 h chronopotentiometric measurement and 300 cyclic voltammetry cycles. The outstanding catalytic performance is mainly attributed to the ultrasmall and high-density CoO NPs embedded in N-doped carbon uniformly assembled on the 3-D substrate significantly increasing electrochemically accessible active sites and durability and the N-doped carbon greatly promoting intrinsic activity of CoO. This work not only creates 3-D highly tunable networked nanostructured electrodes with excellent durability for high-efficiency electrocatalysis but also develops a facile, economical, and extremely versatile strategy to controllably self-assemble conformal MOC-based multilayers with multifunctionality and superior performance on essentially any substrate at the molecular level for broad applications.