Insight into the synergic charge transfer on S - Mo bond-modified Z-scheme MgIn2S4/MoSe2 towards norfloxacin degradation: Mechanism, pathways and toxicity evaluation

In the semiconductor photocatalysis on heterojunctions, the charge transfer path and concomitant interfacial resistance greatly affect the carrier separation efficiency and the overall photocatalytic performance. Herein, a novel S-Mo bonded Z-scheme heterojunction of MgIn2S4/MoSe2 was successfully synthesized by a facile hydrothermal method. The photocatalytic activities on the covalently bonded MgIn2S4/MoSe2 were assessed using the norfloxacin, a typical fluoroquinolone antibiotic, under visible light. The Z-scheme charge transfer route was proposed and investigated by combining quenching tests, ESR spectroscopy and DFT calculations. Furthermore, the establishment of S-Mo bonds between MgIn2S4 and MoSe2 was verified via experimental characterizations and theoretical simulation. This chemical S-Mo linkage, acting as a distinct bridge, in collaboration with the Zscheme charge migration path synergistically promoted the transport and separation of photo-excited carriers, leading to a remarkable enhancement in the norfloxacin decomposition. Additionally, the potential degradation pathways of NOF were proposed via a complementary utilization of mass spectrometry and DFT techniques. Lastly, the computational toxicology predicted that the majority of the byproducts derived from norfloxacin degradation exhibited a progressive reduction in toxicity.