2-Methylimidazole-induced synthesis of ZIF-67/CuO composite catalysts for enhanced oxygen evolution reaction activity

Developing high-efficient Cu-based catalysts for oxygen evolution reaction (OER) remains challenging under alkaline conditions. Herein, a series of ZIF-67/CuO composite catalysts on Cu foam (CF) were synthesized under controlling the molar ratio of Co2+ to 2-Methylimidazole. The formation of CuO nanobelts (NBTs) from CF and subsequent epitaxial growth of ZIF-67 particles facilitate the synergistic effect between components, which could enhance the charge/mass transfer in the electrocatalytic water oxidation process to achieve excellent OER activity. The optimal ZIF-67(R48)/CuO/CF composite sample obtained current densities of 50 and 200 mA cm–2 in 1.0 mol L–1 KOH with an overpotential of only 295 and 344 mV. Especially, the composite catalyst showed good stability on running 50 h at 20 mA cm–2 without obvious decay. The Cu-ZIF layer at the interface of ZIF-67 and CuO enabled fast electronic transfer between Cu and Co sites during the OER process, which is the key issue for excellent OER activity of the composite catalysts.