Anchoring CuO Nanoparticles On C, N-Codoped G-C₃N₄ Nanosheets from Melamine-Entrapped MOF Gel for High-Efficiency Oxygen Evolution

Facile engineering of transitional metal oxide nanoparticles (NPs) homogeneously anchored on graphitic carbon nitride (g-C₃N₄) is very important. Herein, we develop a rapid and facile route to synthesize CuO NPs- and C, N-codoped g-C₃N₄ nanosheets grown on Ni foil (CuO/CN−C₃N₄/Ni-f), derived from the oxidation-pyrolysis of melamine-entrapped Cu(II)-MOF gel in the air. A detailed growth process for the hierarchical structure is studied. The obtained hierarchical structure without any binders used directly as an electrode only needs an overpotential of 223 mV to achieve a current density of 50 mA cm⁻² in 0.5 M KOH, implying its highly efficient electrocatalytic activity. Notably, this material also exhibits strong long-term durability. Free energy calculations show that the intrinsic origin of the outstanding activity is derived from sufficient exposure of active sites for CuO NPs anchored on the nanosheets and high N content.