MOF-derived AgCl/ZnO heterojunction photocatalysts: Enhanced degradation of tetracycline via promoted charge carrier separation.

With the widespread application of tetracycline (TC) in pharmaceuticals and aquaculture, the ecological and health risks caused by its residues have become increasingly prominent. The construction of heterojunction systems exhibiting high-efficiency carrier separation has emerged as a highly promising approach for the photocatalytic degradation of TC. This study adopts the metal organic framework (MOF) template method to prepare Zn-HMT precursors. By innovatively adding silver nitrate, Ag+ ions underwent in-situ "silver-chlorine" reactions with Cl- ions in the precursor, forming AgCl/Zn-HMT composite materials. Subsequent one-step pyrolysis in air yields a series of AgCl/ZnO-X (AgCl loading 1.0, 1.5, 2.0, 5 wt%) heterojunction catalysts. XRD, SEM, Raman and XPS characterizations confirm the formation of tight heterojunctions. Photocatalytic degradation experiments demonstrate that AgCl/ZnO-1.5 (1.5 wt% AgCl loading) achieves a 79 % degradation efficiency, and the degradation rate of AgCl/ZnO-1.5 is 1.49 times than that of ZnO. The enhanced catalytic performance is primarily attributed to the formation of heterojunction. PL spectroscopy, photocurrent measurements, electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) collectively confirm that the construction of heterojunction significantly reduces photogenerated carrier recombination rates. Further trapping experiment proves that superoxide radicals (•O2-) and photogenerated holes (h+) are the dominant reactive species in reaction system. This study provides novel technical approaches and theoretical foundations for designing high-efficiency photocatalysts for antibiotic degradation through MOF template-based heterojunction engineering.