Interfacial confinement effects in MOF-derived C/CuO for peroxymonosulfate activation: Non-radical pathway-mediated thiamethoxam degradation.

Although spatial confinement in porous materials has been extensively studied in Fenton-like reactions, the localized electronic microenvironment at open interfaces remains underexplored. Herein, CuO nanoparticles embedded in a carbon matrix (C/CuO-x) were synthesized via the pyrolysis of ZIF-8(Cu) to investigate this interfacial electronic coupling during peroxymonosulfate (PMS) activation. Comprehensive experimental characterizations, including radical quenching and in-situ spectroscopy analyses, demonstrated that the C/CuO composite exhibited significantly strengthened PMS adsorption and directed the reaction toward a highly efficient non-radical pathway, driven primarily by high-valent Cu(III)=O species alongside 1O2. To elucidate the fundamental physical origin of these experimental observations, density functional theory (DFT) calculations were subsequently conducted. The computational results revealed that the carbon substrate enhanced p-d orbital hybridization and enriched Cu 3d states near the Fermi level, theoretically rationalizing the strong electronic interactions. Benefiting from this optimized non-radical pathway, the C/CuO-3 composite achieved a thiamethoxam degradation rate constant of k = 0.231 min-1, which is 2.56 and 128.39 times higher than that of the unconfined CuO/PMS and ZIF-8/PMS systems, respectively. These results provide a quantifiable understanding of how interfacial electronic coupling modulates catalytic pathways in advanced water treatment systems.