Interfacial charge transfer in g-C3N4/FeVO4/AgBr nanocomposite for efficient photodegradation of tetracycline antibiotic and Victoria blue dye

Abstract

The study presents the fabrication and superior photoactivity of a ternary g-C₃N₄/FeVO₄/AgBr heterojunction nanocomposite, synthesized via a chemical precipitation method for effective degradation of tetracycline (TC) and Victoria Blue (VB) dye under light illumination. The morphology and the crystal size of the synthesized nanocomposite were characterized by using FESEM and XRD and the calculated grain size (100.39 nm) is larger than the crystal size (48.14 nm) indicating strong interparticle bonding. The heterojunction design leverages dual S-scheme interfacial charge transfer, reducing electron-hole recombination as confirmed by optoelectronic and electrochemical techniques. The composite demonstrated superior performance, achieving 82.15% degradation of TC and 97.25% degradation of VB. The study highlights density functional theory (DFT) simulations and Mott-Schottky (MS) analysis, providing insight into the electronic structure, distribution of charge, and band alignments of the g-C₃N₄/FeVO₄/AgBr nanocomposite. Electron spin resonance and radical scavenging experiments revealed holes and superoxide radicals as the primary species driving the degradation process. Furthermore, LC-MS analysis provided insights into the degradation pathways, confirming the conversion of TC and VB into non-toxic byproducts. The photocatalytic stability was confirmed through five consecutive cycles with minimal disruption in both performance and morphology, demonstrating its potential for wastewater treatment applications. Consequently, this study illustrates how the collaborative interplay of dual S-scheme charge migration and silver plasmonic effects enhances the efficiency of the g-C₃N₄/FeVO₄/AgBr nanocomposite, offering a novel and highly effective solution for the degradation of complex pollutants in environmental remediation.