CoOOH@COFs S−scheme heterojunction for efficient triclosan degradation in photocatalytic-peroxymonosulfate activation system: Enhanced interfacial electron transfer mechanism

Triclosan (TCS) poses harmful risks to ecosystems and human health owing to its endocrine-disrupting effects. Therefore, developing an efficient and sustainable technology to degrade TCS is urgently needed. Herein, cobalt oxyhydroxide @covalent organic frameworks (CoOOH@COFs) S−scheme heterojunction was synthesized, which combined the visible-light-driven photocatalysis and peroxymonosulfate (PMS) activation to synergistically generate abundant reactive oxygen species (ROSs) for TCS degradation. The degradation efficiency of TCS reached 100 % within 8 min in the Vis-CoOOH@COFs/PMS system, and the reaction rate constant was 0.456 min −1 , which was nearly 1.90 and 2.85 times that of single CoOOH and COFs, and 2.36 times that under dark condition, respectively. The density functional theory (DFT) calculations confirmed the energy band bending of CoOOH@COFs and S-scheme charge transport from COFs to CoOOH. Both experimental and theoretical analyses indicated that CoOOH@COFs in photocatalytic-PMS activation systems synergistically facilitated photo-generated carrier separation, enhanced interfacial electron transfer, accelerated PMS activation, and generated multiple ROSs. In particular, photogenerated electrons (e − ) accelerated the Co(III)/Co(II) redox cycle, while the PMS captured the e − , which significantly decreased the charge combination of CoOOH@COFs. Radicals (O 2 •− , • OH, and SO 4 •− ) and non-radicals (such as 1 O 2 , h + , and e − ) were both presented in the Vis-CoOOH@COFs/PMS system, with O 2 − playing a dominant role in TCS degradation. Furthermore, the pathway of TCS degradation and toxicity of intermediates were explored by DFT calculation and transformation product identification. Importantly, the environmentally friendly CoOOH@COFs S−scheme heterojunction exhibited excellent stability and reusability. In conclusion, this study innovatively designed an S−scheme heterojunction in the photocatalytic-PMS activation system, providing guidance and theoretical support for efficient and eco-friendly wastewater treatment. CoOOH@COFs S−scheme heterojunction enhanced the interfacial electron transfer and synergistically promoted the TCS degradation in the photocatalytic-PMS activation system. The photogenerated electrons accelerated the Co(III)/Co(II) redox cycle and reacted with PMS decreasing charge combination