Interfacial engineering of Bi2S3 QD on FeTiO3 p-n heterojunction for enhanced photocatalytic degradation of ciprofloxacin: Insights into morphological transition, mechanism and by-products toxicity evaluation

Abstract

Background

Rapid surge in population in recent years and a mismanagement of water resources have resulted in their pollution and scarcity. Depleting freshwater resources has not only impacted human life (human health) but also threatened aquatic biodiversity.

Methods

The present study involves the green synthesis of FeTiO₃/Bi₂S₃ p-n nano heterojunction by using the leaf extract of D. erecta L to enhance the photocatalytic mineralization of ciprofloxacin (CIP). The comprehensive structure and optical properties were thoroughly evaluated through SEM, TEM, XRD, XPS, BET, EIS, ESR, PL and DRS studies.

Significant findings

The fabricated nanocomposite (NC) displayed high catalytic performance under visible light irradiation degrading 96.4 % of CIP in 120 min. SEM images revealed unusual morphological transition of FeTiO₃ from nanosphere clusters to nanoflowers during the coupling process of Bi₂S₃ quantum dots (QDs). Furthermore, the prominent radical species were identified to be O₂^.- and ^.OH through ESR and radical scavenging studies. The reusability of the material was evaluated by testing through six consecutive photocatalytic cycle and was calculated to be 94.9 %, and the stability was further confirmed by XRD and XPS analysis of used catalyst. The intermediates produced during photodegradation were identified through GC-MS analysis and a possible degradation pathway was proposed. Subsequently, the toxicity of the resulting by-product was evaluated through ECOSAR tool. The study presents FeTiO₃/Bi₂S₃ as a promising candidate in terms of improved photocatalytic activity for wastewater treatment and environmental applications.