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A significant drawback of the traditional photocatalysts such as titanium dioxide (TiO 2) is their inability to absorb visible light from the solar spectrum due to their wide band gap energy. They are only photoactive in the ultraviolet (UV) region which is just a little fraction of the solar spectrum and could be harmful with much exposure to it. Due to its abundance in the solar spectrum, visible light needs to be harnessed for environmental applications. However, we lack visible light driven photocatalysts with long-lasting energy storage capacity for "round-the-clock photocatalytic" (RTCP) applications. For this reason, there is a growing need to find new photocatalysts that can mitigate these bottlenecks. It is evident from some carefully selected published articles (1976–2021) that tungsten oxide (WO 3) and its composites have attracted popularity in recent years because of its outstanding properties and particularly its smaller band gap energy of 2.8 eV. However, pristine WO 3 is limited due to relatively low energy density and smaller specific surface area. These drawbacks can be addressed by developing various WO 3 – based materials to improve their performance. This paper reviews and discusses their recent development in surface advancement, morphology control, modification of nanostructured WO 3 and its composites, and their RTCP energy storage for photocatalytic activities in visible light and the dark for environmental applications. Specific aspects focused on its nature, structure, properties, synthesis, coatings, deposition, approaches at modifying and enhancing its visible light photoactivity for enhanced performance and energy storage potential. [Display omitted] • Synthesis techniques for WO 3 -based photocatalysts are discussed. • Visible light enhancement strategies for WO 3 -based photocatalysts are elaborated. • WO 3 "round the clock photocatalysis" is described. • WO 3 - based photocatalytic memory for environmental applications is reviewed. • WO 3 -based catalysts are promising for continuous day and night photocatalysis. [ABSTRACT FROM AUTHOR]

This present study aims to develop a visible-light driven photocatalytic dual layer hollow fiber (DLHF) membrane for photodegradation activity. Nitrogen-doped TiO 2 DLHF membranes with different loadings of N-doped TiO 2 were successfully fabricated via a single step co-extrusion method. The fabricated membranes were characterized for their morphology and properties. The incorporation of N-doped TiO 2 into membrane matrix has shifted the absorption capability into visible light region with lowest band gap energy obtained was 2.63eV. The photocatalytic performance evaluations of the N-doped TiO 2 DLHF reported 75% and 100% of Reactive Black 5 (RB5) removal were achieved after 360 min of visible and UV light illumination respectively. Altogether, N-doped TiO 2 DLHF exhibits excellent photocatalytic degradation activity under visible and UV light irradiation, hence have a promising potential in removing RB5 and other organic contaminants for water treatment. • The fabrication of visible light driven photocatalytic dual layer hollow fiber via co-extrusion technique. • The incorporation of N-doped TiO 2 into membrane surface successfully expand the photoresponse into the visible light region. • Good photocatalytic activity with 75% and 100% removal of RB5 under visible and UV light irradiation, respectively. • Efficient photocatalytic degradation process of visible-light driven N-doped TiO 2 for contaminants present in the water. [ABSTRACT FROM AUTHOR]

Previous water treatments used are nondestructive and lead to the formation of new type of pollution. Photocatalytic reaction which induced by illumination of semiconductors in suspension was one of the most promising processes for wastewater treatment due to the ability of providing an interface with the aqueous medium and induce an advanced oxidation process. In this study, Malaysian bauxite has been selected as a new potential candidate for photocatalytic degradation. Bauxite powder was undergone heat treatment ranging from 800 to 1000 °C and then was characterized by field emission scanning electron microscope, X-ray diffraction (XRD), Brunauer–Emmett–Teller, ultraviolet–visible–near infrared spectroscopy and suspension absorbance test to determine the existing components and their composition, structure of the powder, band gap energy as well as the photocatalytic efficiency of bauxite in suspension of various concentrations of Reactive Black 5 (RB5) ranging from 5 to 20 ppm. The finding revealed that bauxite possessed slight changes in terms of XRF composition as well as particle size due to thermal process. This is supported by XRD analysis which showed that phase conversion occurred at 800 °C. Heat-treated bauxite possesses low band gap energy (2.04 eV). The photocatalytic activity of raw bauxite suspension was measured after 360 min illumination, and it proved that there was degradation of 67% and 63% from the initial 5 ppm concentration of RB5 using visible and UV lights, respectively. This finding clearly shows that bauxite exhibits good photocatalytic degradation and hence has a promising potential in removing dyes for industrial wastewater. [ABSTRACT FROM AUTHOR]