Zn-Driven AgI Anchoring on Ti-MOF for Photocatalytic Singlet Oxygen Generation in Imidacloprid Removal

Utilizing metal-organic frameworks (MOFs) to facilitate the formation of AgI and construct novel heterojunction material is a promising strategy for water remediation. However, achieving strong connections at the active sites of MOFs and improving charge transfer processes remain a challenge. Herein, we proposed a Zn-driven approach to anchor AgI on Zn-doped NH₂-MIL-125(Ti) (ZTNML), which exhibited 6.7 times and 5.3 times higher imidacloprid degradation efficiencies than that of AgI and NH₂-MIL-125(Ti), respectively. Density functional theory calculations revealed that the Zn sites in ZTNML played a critical role in anchoring AgI, facilitated by strong I^- adsorption and Ag⁺ binding. This unique Zn-I interaction significantly enhanced charge transfer from ZTNML to AgI, promoting the separation of photogenerated electron-hole pairs through a Z-scheme mechanism, induced by both the difference in work functions and strong interfacial interactions. As derived from Fukui function analysis and liquid chromatography-mass spectrometry (LC-MS) data, a potential degradation pathway for imidacloprid driven by superoxide radicals and singlet oxygen species was proposed. Furthermore, QSAR modeling was employed to predict the toxicity of degradation intermediates, providing an assessment of environmental safety. Our work converts heavy metal ions while constructing heterojunctions and efficiently eliminating organic pollutants, providing a sustainable approach to environmental protection.