Efficient and Stable Degradation of Triazophos Pesticide by TiO2/WO3 Nanocomposites with S-Scheme Heterojunctions and Oxygen Defects

Abstract

The prevalent utilization of organophosphorus pesticides presents a profound risk to the global environment, necessitating the immediate development of a secure and reliable methodology to mitigate this hazard. Photocatalytic technology, through the generation of robust oxidizing free radicals by suitable catalysts, offers a viable solution by effectively oxidizing organophosphorus pesticides, thus preserving environmental well-being. In this study, we successfully synthesized TiO2/WO3 (TO/WO) nanocomposites characterized by oxygen defects and S-scheme heterojunctions, demonstrating superior photocatalytic activity in the degradation of triazophos. Notably, the 60-TO/WO nanocomposite, wherein the proportion of WO comprises 60% of the total, exhibited optimal photocatalytic degradation activity, achieving a degradation rate of 78% within 120 min, and demonstrating exceptional stability, maintaining impressive degradation activity across four cycles. This performance was notably superior to that of standalone TO and WO. The presence of oxygen defects in WO was corroborated by electron paramagnetic resonance (EPR) spectroscopy. The mechanism at the heterojunction of the 60-TO/WO nanocomposite, identified as an S-scheme, was also confirmed by EPR and theoretical computations. Oxygen defects expedite charge transfer and effectively enhance the photocatalytic reaction, while the S-scheme effectively segregates photogenerated electrons and holes, thereby optimizing the photocatalytic oxidation of triazophos. This study introduces a novel nanocomposite material, characterized by oxygen defects and the S-scheme heterojunction, capable of effectively degrading triazophos and promoting environmental health.