Ionic liquid-assisted synthesis of a novel PANI/ZnWO4/WO3 ternary nanocomposite: a facile double electron transfer photocatalyst for efficient degradation of a herbicide

Abstract

This study reports a novel, efficient, and non-toxic polyaniline–ZnWO₄–WO₃ (PZW) ternary nanocomposite, synthesized following an ionic liquid (IL)-assisted in situ oxidative polymerization method. The as-prepared nanocomposite was utilized towards improved photocatalytic wastewater treatment and toxicity removal. Initially, individual ZnWO₄ and WO₃ nanostructures were synthesized using an IL-assisted solvothermal method. Thereafter, the subsequent modification of the ZnWO₄ and WO₃ nanostructures with the polyaniline (PANI) conducting polymer was done by in situ oxidative polymerization of PANI. Comprehensive analysis of the structural and morphological properties of the nanocomposite revealed high structural integrity and close contact between the individual components. The optical and photo-electrochemical investigations suggested rapid charge carrier separation, suitable band arrangement, and a superior lifetime of the nanocomposite. Afterward, the recyclable ternary nanocomposite demonstrated a higher solar light-mediated photocatalytic degradation of the toxic glyphosate (GLP) herbicide (K_app = 0.0707 min⁻¹). Additionally, the non-toxic nature of the nanocomposite (after a catalytic cycle) and treated GLP solutions were assessed via the standard TBE (trypan blue dye exclusion) assay. Furthermore, the XPS analysis, radical trapping experiment, and reactive oxygen species quantification (HO˙ and O₂˙⁻) study suggested a possible double electron transfer type Z-scheme mechanism, which accounts for superior solar light-assisted N–C bond cleavage of GLP herbicide.