Z-scheme WO₃/PANI heterojunctions with enhanced photocatalytic activity under visible light: A depth experimental and...

A WO₃@PANI heterojunction photocatalyst with a various mass ratio of polyaniline to WO₃ was obtained via the in situ oxidative deposition polymerization of aniline monomer in the presence of WO₃ powder. The characterization of WO₃@PANI composites was carried via X-ray diffraction (XRD), scanning electron microscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). The photocatalytic efficiency of WO₃@PANI photocatalysts was assessed by following the decomposition of the Rhodamine B (RhB) dye under visible light irradiation (λ >420 nm). The results evidenced the high efficiency of the WO₃@PANI (0.5 wt %) nanocomposite in the photocatalytic degradation of RhB (90% within 120 min) under visible light irradiation 3.6 times compared to pure WO₃. The synergistic effect between PANI and WO₃ is the reason for the increased photogenerated carrier separation. The superior photocatalytic performance of the WO₃@PANI catalyst was ascribed to the increased visible light in the visible range and the efficient charge carrier separation. Furthermore, the Density Functional Theory study (DFT) of WO₃@PANI was performed at the molecular level, to find its internal nature for the tuning of photocatalytic efficiency. The DFT results indicated that the chemical bonds connected the solid-solid contact interfaces between WO₃ and PANI. Finally, a plausible photocatalytic mechanism of WO₃@PANI (0.5 wt %) performance under visible light illumination is suggested to guide additional photocatalytic activity development.