Fe _<i>x</i> W _{1– <i>x</i>} O ₃ /Graphene Heterostructure: Preparation, Characterization, and Superior Performance in MB Degradation

This study reports the fabrication of pure WO3 and Fe-doped WO3 nanoparticles (NPs) exhibiting monoclinic symmetry and granular morphology through an in-situ chemical coprecipitation route. Graphene-incorporated FexW1–xO3 nanocomposites (where x = 0, 3, 5, 7, and 10 iron wt %) were subsequently prepared via an ex-situ sonication route. The resultant nanomaterials were analyzed via FTIR, XRD, SEM, EDX, TEM, DRS, and PL spectroscopy to investigate their structural, morphological, and optical properties. Rietveld refinement of XRD data confirmed the monoclinic phase and revealed alterations in the lattice parameters. The crystallite size were determined to be between 36.83 and 49.21 nm. Notably, no diffraction peak corresponding to the iron, iron oxide and the graphene phase were detected in the XRD patterns. The absence of iron and graphene peaks were further supported by FTIR spectra. Stretching vibrational modes characteristic of W–O–W, W–O (<800 cm–1) and W–O–C bonds (1000–2000 cm–1) were observed in FTIR analysis. SEM and TEM micrographs displayed granular WO3 nanoparticles (<32 nm in diameter) embedded on graphene nanosheets while EDX analysis confirmed the presence of an iron dopant. DRS and PL spectroscopy revealed significant modification in the absorption and excitation behavior. Crucially, heterojunction formation between graphene and Fe-doped WO3 have resulted in enhanced adsorption, improved photocatalytic methylene blue (MB) elimination, and excellent five-cycle photostability.