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

Abstract

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 SMo bonds between MgIn2S4 and MoSe2 was verified via experimental characterizations and theoretical simulation. This chemical SMo linkage, acting as a distinct bridge, in collaboration with the Z-scheme 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.