MIL-88A(Fe)-derived Co9S8/Fe2O3 nanotubes: Construction of Schottky junction for enhanced pesticide removal.

The extensive use of pesticides poses serious risks to the environment and human health. Developing advanced technology for pesticide degradation is a key demand in modern agriculture. In this work, we fabricated a unique Co9S8/Fe2O3 Schottky junction via in situ growth of Co9S8 onto MIL-88A(Fe) derived Fe2O3 nanotubes, and applied it for degrading a typical neonicotinoid pesticide, thiamethoxam, by photocatalytic peroxymonosulfate (PMS) activation. The established heterojunction enables rapid electron transfer from Fe2O3 to Co9S8, thereby increasing the excitation-deexcitation cycle efficiency by 20-fold and prolonging the photogenerated electron lifetime by 3-fold compared to pure Fe2O3. Remarkably, ultrafast charge transfer from Fe2O3 to Co9S8 contributes over 70% of total photogenerated charges, which significantly promotes the Co(III)/Co(II) redox cycle and enhances PMS activation for radical generation. Co9S8/Fe2O3 composites exhibit superior degradation activity in diverse natural waters and maintain stability in continuous-flow reactors. Wheat growth experiments were used to examine purification capability. The study introduces a robust, efficient photo-Fenton catalyst for removing neonicotinoid pesticides from water and reducing ecological toxicity, with impressive stability and practical application potential.