Improvement of TiO₂ photocatalytic properties under visible light by WO₃/TiO₂ and MoO₃/TiO₂ composites

Graphical abstract: The WO₃/TiO₂ or MoO₃/TiO₂ composites with different compositions have been prepared by a facile sol–gel method, and 5 wt% WO₃/TiO₂ or 2 wt% MoO₃/TiO₂ composites possess higher photocatalytic activity than pure TiO₂ for the degradation of Rhodamine B (RhB) under visible light irradiation. - Highlights: • WO₃/TiO₂ and MoO₃/TiO₂ composites were synthesized by a facile sol–gel method. • Heterostructure coupling improved TiO₂ photocatalytic activity under visible-light. • Photocatalytic activity arises from separation of photogenerated charge carriers. • The order of photocatalytic activity is 5 wt% WO₃/TiO₂ > 2 wt% MoO₃/TiO₂ > TiO₂. - Abstract: The WO₃/TiO₂ or MoO₃/TiO₂ composites with different compositions have been prepared by a facile sol–gel method. The obtained composites were characterized using X-ray diffraction (XRD), BET surface area analysis, electron dispersion spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) emission spectrum. The research results show that BET specific surface areas of the composites are significantly enhanced and the composites possess higher photocatalytic activity than pure TiO₂ for the degradation of Rhodamine B (RhB) under visible light irradiation. It has been demonstrated that the photocatalytic activity depends on the composition and calcination temperature of composites, and degradation conditions for RhB. The improvement of photocatalytic activity can be attributed to the reduction of the electron–hole recombination rate due to the formation of WO₃/TiO₂ or MoO₃/TiO₂ heterostructures, which have been confirmed by XPS and PL spectra