Oxygen-functionalized Ti3C2 MXene/exfoliated montmorillonite supported S-scheme BiOBr/Bi2MoO6 heterostructures for efficient photocatalytic quinolone antibiotics degradation

Abstract

Exploiting an excellent photocatalyst system with sufficient photogenerated charge separation and strong redox ability for efficient degradation of multiple fluoroquinolones (FQs) antibiotics was crucial but still a big challenge. The significant impacts of novel oxygen-functionalized Ti3C2 MXene/exfoliated montmorillonite (Ti3C2/MMTex) severed as a superior co-catalyst to boost the catalytic activity of single semiconductor was verified in our previous work. Based on that, the Bi2MoO6 particles/BiOBr nanosheets were ingeniously anchored onto multilayer O-functionalized Ti3C2/MMTex by the form of in-situ self-assembly via facile two-step microwave-assisted solvothermal process. Representative characterizations confirmed that Ti3C2/MMTex exhibited chemical stability and achieved transformation from surface F-terminal to O-terminal owing to the introduction of MMTex. Moreover, Ti3C2/MMTex supporter greatly decreased the accumulation and improved the morphology of Bi2MoO6/BiOBr S-scheme heterojunction. With extensive Bi2MoO6/BiOBr sheets embedding onto Ti3C2/MMTex, the quaternary BiOBr/Bi2MoO6/Ti3C2/MMTex catalyst displayed extraordinary coral reef-like structure, followed by abundantly exposing high-active {001} facets of BiOBr. Furthermore, owing to the Schottky/S-scheme double heterojunction linkage system, the multiple electrons transfer pathways formed over the quaternary composite effectively facilitated the separation of photogenerated charge carriers, thereby leading to the enhanced generation of •O2− and •OH. Hence, multiple FQs antibiotics degradation efficiency over BiOBr/Bi2MoO6/Ti3C2/MMTex all up to 90%, especially for levofloxacin (LEV), 99% LEV could be eliminated within 120 min. Besides, superior recyclability and stability were revealed in this quaternary composite. Notably, demethylation and piperazine ring-opening dominated LEV degradation pathway and the generated intermediates possessed lower toxicity and ecological risks. Our study further excavates multiple positive effects of Ti3C2/MMTex co-catalyst in constructing the efficient catalytic system, and supplies novelty tactics to engineer a stable non-noble meta/Bi-based semiconductor Schottky/S-scheme double heterojunction linkage system with compact interface contact.