Journal of Applied Material Science --- 1 4 2025 12 01 Deep Eutectic Solvent-Water Solvated Synthesis of Tungsten Oxide Nanoparticles with Photochromic and Antimicrobial Properties 210152 210152 10.22034/jams.2025.210152 EN Adetola Abiola Ajayi Department of Chemistry, Faculty of Natural and Applied Sciences, Lead City University, Ibadan, Nigeria Department of Science Laboratory Technology, School of Pure and Applied Sciences, Federal Polytechnic, PMB 50, Ilaro, Nigeria 0000-0002-8437-8849 Olayinka Oderinde Department of Chemistry, Faculty of Natural and Applied Sciences, Lead City University, Ibadan, Nigeria Department of Chemistry, Nile University of Nigeria, Plot 681, Cadastral Zone C-OO, Research & Institution Area, Jabi Airport Bypass, Abuja, FCT 900001, Nigeria 0000-0002-2050-0948 Sodiq Olalekan Ogunbayo Department of Chemistry, Faculty of Natural and Applied Sciences, Lead City University, Ibadan, Nigeria Olubunmi Ayoni Ogundiran Department of Chemical Sciences, Faculty of Sciences, Taraba State University, PMB 1167, Jalingo, Nigeria Adeola Roseline Olawuyi Department of Chemistry, Faculty of Natural and Applied Sciences, Lead City University, Ibadan, Nigeria Adebobola Ololade Agbeja Department of Sustainable Forest Management, Forestry Research Institute of Nigeria, PMB 5054, Ibadan, Nigeria Journal Article 2025 09 21 Deep eutectic solvents (DESs) provide sustainable, tunable media for nanomaterial synthesis. In this work, tungsten oxide (WO₃) nanoparticles were prepared via a low-temperature green route using DES (choline chloride:ethylene glycol, 1:2) with varying water fractions to enhance solubility and reaction kinetics. Comprehensive characterization by FTIR, XRD, UV-Vis, SEM, and EDX confirmed the successful formation of WO₃ nanostructures with tunable crystallinity, morphology, and surface chemistry. FTIR spectra revealed distinct O-W-O/W-OH vibrational modes, while XRD identified monoclinic crystalline phases. SEM analysis demonstrated a morphology shift from irregular aggregates to sponge-like structures with increasing water content. Optical studies showed strong UV absorption (250-373 nm) and a rapid, reversible photochromic transition from transparent to blue within 5 s of UV exposure, fading back within 20 min under ambient conditions. Antimicrobial assays revealed dose-dependent bactericidal activity against <em>Escherichia coli </em>and <em>Staphylococcus aureus</em>, attributed to reactive oxygen species generation and oxygen-vacancy-mediated redox cycling, with the T1-D90W10 sample exhibiting the highest inhibition. This work establishes DES-water systems as versatile green platforms for fabricating multifunctional WO₃ Nanoparticles with synergistic photochromic and antimicrobial properties. https://jams.hsu.ac.ir/article_232321_4cc098a6561cf90705e5d2b5fe3e50e4.pdf