Constructing interfacial electric field with rich oxygen vacancy modulated heterojunction FeVO4-MgZnAl LDH for enhanced photocatalytic degradation of doxycycline

Abstract

FeVO4 nanorods were synthesized and integrated with plate-like MgZnAl layered double hydroxide (MZA LDH) using a combination of sonochemical coprecipitation and hydrothermal methods. The resulting FeVO4-MgZnAl LDH nanocomposites (NCs) were engineered to enhance photocatalytic performance through an S-scheme charge transfer mechanism. These NCs exhibited exceptional photocatalytic activity, achieving 93.7 % degradation of doxycycline (DXY) which is significantly outperforming its counterparts, FeVO4 (29.8 %) and MgZnAl LDH (49.8 %). Detailed analysis using scavenging tests and electron spin resonance (ESR) analysis confirmed that the photoexcited charges follow the S-scheme pathway, leading to the generation of hydroxyl (•OH) and superoxide (O2•⁻) radicals. This mechanism remarkedly improves the catalytic efficiency of FeVO4-MZA NCs with a kinetic rate constant of 4–9 times higher than those of its individual components. The photocatalyst's were comprehensively characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV–vis-DRS), photoluminescence (PL) spectroscopy, and electrochemical impedance spectroscopy (EIS). The FeVO₄-MZA NCs demonstrated remarkable stability and reusability, indicating their suitability for large-scale water treatment applications. Additionally, the non-toxic nature of FeVO4-MZA NCs, coupled with effective charge carrier separation and reduced recombination rates, establishes them as highly efficient photocatalysts for the removal of pharmaceutical contaminants from aquatic systems and paves a way for manufacturing innovation.