Mesoporous tungsten oxides as photocatalysts for O2 evolution under irradiation of visible light

Three-dimensionally ordered mesoporous WO3 was successfully synthesized by a hydrothermal method using mesoporous silica KIT-6 as a hard template and phosphotungstic acid as a precursor. The tungsten oxide after removal of silica template was characterized by powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Investigations of optical and photoelectrochemical properties showed that the mesoporous WO3 was a n-type semiconductor with a band gap of 2.6 eV and demonstrated prompt, steady, and reproducible photocurrent responses during repeated on/off cycles of visible light illumination (λ>420 nm). The mesoporous WO3 modified by platinum nanoparticles could be used as a stable photocatalyst for photoinducing O2 evolution. Under visible light irradiation, the average O2 evolution rate is 34.5 μmol g−1 h−1 in the presence of an electron acceptor IO3−. This work demonstrated a potential application of using mesoporous WO3 modified by platinum nanoparticles as a novel photocatalyst in the field of solar energy conversion.

► Designed and fabricated ordered mesoporous WO3 catalysts with the cubic Ia3d symmetry structure.
► Mesoporous structured WO3 catalyst exhibits strong spectral response in the visible region.
► The higher photocatalytic activity is related primarily to large effective surface area and high ordered channel, resulting in low electron-hole recombination.