Dual S-scheme g-C3N4/Fe3O4/In2O3/MoS2 magnetic nanocomposite for enhanced visible-light-driven tetracycline degradation

A novel quaternary nanocomposite (g-C3N4/Fe3O4/In2O3/MoS2) was synthesized via a synergistic hydrothermal-ultrasonic wet chemistry route. Various advanced characterization techniques were employed to comprehensively characterize the nanocomposite. The photocatalytic efficiency of the nanocomposite was investigated by using tetracycline antibiotic as a model pollutant. The quaternary nanocomposite showed remarkable photocatalytic degradation efficiency of tetracycline (94.1 % in 240 min visible-light illumination) under natural pH (6.17) and low catalyst dosage (0.2 g/L) with k = 0.0106 min−1. Critical variables include catalyst type, dosage (0.05–0.5 g/L), tetracycline concentration (5–40 mg/L), and pH (5−9) were systematically investigated to maximize tetracycline mineralization efficiency. Quenching experiments indicated •O2- served as the main active radical. Furthermore, the g-C3N4/Fe3O4/In2O3/MoS2 nanocomposite demonstrated robust stability and rapid magnetic separation over five cycles. The degradation pathways were deduced based on possible degradation intermediates. The excellent performance of the quaternary nanocomposite can be ascribed to expanded visible-light absorption and suppressed charge-carrier recombination via a dual S-scheme heterojunction. Consequently, this novel nanocomposite shows great potential for efficiently removing emerging organic contaminants from aqueous solutions.