Photocatalytic Degradation of Methylene Blue Using Au‐Decorated WO ₃ Nanoparticles and Molecular Dynamic Simulation

ABSTRACT Tungsten oxide nanoparticles (WO 3 NPs) and Au‐decorated WO 3 nanoparticles (WO 3 ‐AuNPs) were synthesized through the hydrothermal method and the biosynthesis method, respectively. Further, Both WO 3 NPs and WO 3 ‐Au NPs were characterized by Fourier transform infrared (FTIR), UV‐Vis spectroscopy, x‐ray diffraction (XRD), x‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy‐dispersive x‐ray (EDX), transmission electron microscopy (TEM), and photoluminescence (PL) analysis to confirm the surface morphological properties, elemental composition, and optical properties. The optical band gap of both WO 3 NPs and WO 3 ‐AuNPs was determined by Tauc's plot, which was found to be 2.65 eV and 1.58 eV, respectively. The photocatalytic efficiency of both WO 3 NPs and WO 3 ‐Au NPs was investigated under visible light irradiation, and it was observed that WO 3 ‐AuNPs show efficient photocatalytic properties as compared to WO 3 NPs. Pure WO 3 NPs show 88.02% photodegradation of methylene blue (MB) dye, while WO 3 ‐Au NPs achieve 98.63% degradation within 60 min. Further studies were conducted on variables such as dye concentration, catalyst dosage, and catalytic recyclability. Free radical scavenger experiments were performed to determine the role of radical species in the photodegradation process. Molecular dynamics simulations indicated that the WO 3 ‐Au surface has higher adsorption energy, reinforcing the effectiveness of these NPs in environmental remediation.