Solvent Effects on the Microwave-Assisted Synthesis and Properties of WO3

Tungsten oxide (WO₃) is a semiconductor with a band gap of 2.4-2.8 eV and high chemical stability, making it attractive for photocatalytic applications. In this work, WO₃ was synthesized by a microwave assisted route using different solvent systems. X-ray diffraction (XRD) revealed the formation of hydrated intermediate phases after synthesis, requiring calcination to obtain monoclinic WO₃. Band gap energies ranged from 2.62 to 2.71 eV, while zeta potential showed negative values (−26 to −39 mV), which demonstrates good colloidal stability. Photoluminescence (PL) spectra suggested differences in defect concentration, particularly oxygen vacancies. Scanning electron microscopy (SEM) showed solvent-dependent morphologies, ranging from irregular aggregates to hierarchical flower-like structures. The results demonstrate that the solvent strongly influences particle growth and microstructure without significantly affecting the crystalline structure or optical properties of WO₃.