Decorated ZnO nanorods with Bi2S3 nanosheets for enhanced photocatalytic removal of antibiotics and analgesics: Degradation mechanism and pathway

Novel nanorods (NRs) of Bi2S3-ZnO (BZ) heterojunction have been prepared using a microwave-assisted hydrothermal approach. The photocatalytic behavior of BZ heterojunction NRs has been investigated under simulated solar irradiation against the mineralization of meloxicam (MX) analgesics, sulfamethoxazole (SMX), trimethoprim (TMP) antibiotics, as well as crystal violet (CV) and malachite green (MG) dyes. XRD, FTIR, SEM, EDX, TEM, UV–Vis, BET, Zeta potential, and Pl techniques are used to characterize the prepared samples. The TEM results showed that the ZnO NRs are wrapped with Bi2S3 NSHs. For SMX and MX, the degradation rate of BZ PC is 2.46 and 1.6 fold greater than that for pristine ZnO NRs, respectively. Furthermore, the BZ NRs heterojunction demonstrated 100% degradation efficiency for SMX, SM, TMP, and CV after 120 min, and after 60 min for MG. The enhanced photodegradation activity of BZ NRs photocatalyst (PC) is assigned to its high absorption ability for visible light, increased surface area, adsorption capability, as well as inhibition of the hole-electron recombination process according to the PL study. Furthermore, the quenching experiment exposed that hydroxyl radicals (·OH) exhibit a significant role in the photodegradation process. Moreover, after 5 cycles, the photocatalytic degradation efficiency of the BZ PC remained constant, confirming its high stability and reusability. The special charge transfer pathway over the BZ PC has been investigated, which will assist in the design of systems with superior photocatalytic properties. The degraded products and pathways is also proposed. Conclusively, BZ is considered stable, efficient, and non-selective PC for green solar-driven photocatalytic degradation.