| Summary: | A sequence of WO<sub>3</sub>/g-C<sub>3</sub>N<sub>4</sub> composites was synthesized at various % weight ratios (1, 5, 6.5, 8, 10, and 15%) of WO<sub>3</sub> into g-C<sub>3</sub>N<sub>4</sub> via electrospinning and wet-mixing method. The prepared photocatalytic materials were characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, UV–vis diffuse reflection spectroscopy (DRS), scanning electron microscopy (SEM), N<sub>2</sub> porosimetry and dynamic light scattering (DLS). Electrospun fibers of WO<sub>3</sub> with diameter 250–300 nm was prepared using polyvinylpyrrolidone (PVP) polymer and used for the synthesis of composite WO<sub>3</sub>/g-C<sub>3</sub>N<sub>4</sub> heterojunction structures. Results showed mesoporous materials with triclinic WO<sub>3</sub> crystal phase, surface areas up to 67.7 m<sup>2</sup>g<sup>−1</sup> and band gaps lower than 2.5 eV confirming the absorption to visible light region. The photocatalytic performance of the prepared photocatalysts were assessed towards the oxidation of phenol and reduction of Cr (VI), in single and binary systems using simulated solar light illumination, that followed first-order kinetics. The WO<sub>3</sub>/g-C<sub>3</sub>N<sub>4</sub> composites were found to exhibit improved photocatalytic performances compared to the pure WO<sub>3</sub> and g-C<sub>3</sub>N<sub>4</sub> with 6.5 wt% WO<sub>3</sub>/g-C<sub>3</sub>N<sub>4</sub> and 5 wt% WO<sub>3</sub>/g-C<sub>3</sub>N<sub>4</sub> composites being the most efficient catalysts for the oxidation of phenolics and reduction of Cr (VI), respectively. The improved performance was explained by a Z-scheme photocatalytic mechanism which was proposed based on scavenging experiments and the determination of the corresponding energy levels of valence and conduction bands. The study demonstrated that such composites present interesting photocatalytic properties that can be further expanded to other environmental depollution applications as well as in energy applications.
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