Synergistic MOF-on-MOF S-scheme heterojunction for highly efficient peroxomonosulfate activation toward tetracycline...

The pursuit of high-performance metal organic framework (MOF) photocatalyst is fundamentally constrained by insufficient charge separation and limited redox capacity. To overcome these challenges, this study constructs a novel S-scheme heterojunction by integrating a conductive Ce MOF with ZIF67 via a facile in-situ growth approach. The designed Ce MOF/ZIF67-11 heterojunction, when synergized with peroxomonosulfate (PMS), significantly boosts visible-light absorption capacity, promotes the rapid separation and migration of photogenerated charge carriers, and strengthens redox activity. This leads to markedly promoting PMS activation, resulting in dramatically enhanced degradation efficiency of tetracycline (TC). When exposed to visible-light irradiation, Ce MOF/ZIF67-11 heterojunction achieves a TC removal efficiency of 95.62% within 50 min, substantially outperforming the individual Ce MOF and ZIF67. DFT calculations demonstrate that some sites of TC exhibit high reactivity towards electrophilic substances and free radicals. The subsequent oxidative degradation pathway and the formation of less toxic intermediates are systematically verified through integrated liquid chromatography-mass spectrometry (LC-MS) analysis and toxicity evaluation. From a practical perspective, a preliminary cost-benefit analysis underscores the promising economic feasibility of the Ce MOF/ZIF67-11 photocatalyst for potential scale-up. This study elaborates on the strategic design principles for constructing high-efficiency and stable MOF-derived S-scheme heterojunctions, contributing to the advancement of antibiotic-contamination remediation technologies.