Catalysts made of CuO/Bi2O3 nanoparticles supported on g-C3N4 were synthesized using a MOF-derived strategy. The activation of CuO to CuCCCu species and stabilization of the catalyst were facilitated by the synergistic effect of the CuO/C3N4 interface and CuO nanoparticles, resulting in enhanced catalytic efficacy in the ethynylation of formaldehyde.