Deep eutectic solvent-assisted hydrothermal synthesis of chitosan-based nanohybrid films functionalized with silver-decorated tungsten oxide

Abstract

This study presents the fabrication and characterization of chitosan-based nanohybrid films incorporating silver-decorated tungsten oxide (Ct–AgWO₃). In this work, the deep eutectic solvent-assisted hydrothermal synthesis of WO₃ nanoparticles was combined with in situ silver decoration and chitosan reduction to synthesize a nanohybrid film. The effects of reaction time on the structural, morphological, and functional properties of the nanohybrid films were investigated over time. The resulting nanohybrid film was characterized using UV-vis spectroscopy, FESEM, EDX, FTIR, XPS, Raman spectroscopy, TGA, and photoluminescence. Morphological analysis revealed an evolution from clustered particulates at 30 min to better-dispersed nanoparticles after 6 h, with particle sizes between ca. 21 and 48 nm. XPS analysis of the nanofilm confirmed the presence of the W⁶⁺ oxidation state and the successful silver decoration. Moreover, the Raman spectra revealed a monoclinic WO₃ crystal structure and enhanced electronic properties due to the oxygen vacancies created by Ag decoration. The degree of degradation resistance was greater than that of the chitosan–WO₃ films without silver decoration, as revealed by the thermal analysis data.