Preparation, Microstructural Characterization and Photocatalysis Tests of V5+-Doped TiO2/WO3 Nanocomposites Supported on Electrospun Membranes

Abstract

Metal oxide nanocomposites (MON) have gained significant attention in the literature for the possibility of improving the optical and electronic properties of the hybrid material, compared to its pristine constituent oxides. These superior properties have been observed for TiO2 — based MON, which exhibit improved structural stability and photoactivity in environmental decontamination processes. In addition, the use of polymer membrane-supported MON is preferable to prevent further aggregation of particles, increase the surface area of the semiconductor in contact with the contaminant, and enable material reuse without considerable efficiency loss. In this work, V5+-doped TiO2/WO3 MON nanostructures were prepared by the sintering process at 500 °C and supported in electrospun fiber membranes for application as photocatalyst devices. Microstructural characterization of the samples was performed by XRD, SEM, EDS, Raman, and DSC techniques. The reflectance spectra showed that the bandgap of the MON was progressively decreased (3.20 to 2.11 eV) with the V5+ ions doping level increase. The fiber-supported MON showed photoactivity for rhodamine B dye degradation using visible light. In addition, the highest photodegradation efficiency was noted for the systems with 5 wt% vanadium oxide dispersed in the fibers (92% dye degradation in 120 min of exposure to the light source), with recyclability of the composite material for use in new photocatalysis cycles. The best results are directly related to the microstructure, lower bandgap and aggregation of metal oxide nanocomposite in the electrospun membrane, compared to the support-free MON.

A Review on the Use of Metal Oxide-Based Nanocomposites for the Remediation of Organics-Contaminated Water via Photocatalysis: Fundamentals, Bibliometric Study and Recent Advances

“…An illustrative diagram of this process is represented in Figure 2. The combined action of direct redox processes, induced by holes and photogenerated electrons on the surface of the catalysts, and of indirect redox processes, derived from reactive oxygen species, is responsible for pollutant degradation [13,42,43].…”

“…Several researchers have focused their work on the synthesis of narrow-band photocatalysts, which can be used under visible light irradiation. Various surface enhancement methods to achieve this include doping with The combined action of direct redox processes, induced by holes and photogenerated electrons on the surface of the catalysts, and of indirect redox processes, derived from reactive oxygen species, is responsible for pollutant degradation [13,42,43].…”

“…Currently, among the techniques for removing contaminants using metal oxides, heterogeneous photocatalysis stands out. These applications are directly related to metal oxide nanostructures properties, such as: high chemical and structural stability; high surface area/volume ratio; excellent electrical/electronic bulk and electric charge transfer properties (electrons (e − ) and holes (h + )); easy surface interactivity with contaminant molecules; and the possibility of reusing the material in new decontamination cycles [ 13 ].…”

“…In addition, metal oxides can form nanocomposites with other oxides and other functional materials, such as conducting polymers and carbon-based materials, in order to ensure greater surface area/volume ratio, lower electron-hole recombination and better adsorption, photocatalysis and sensing performances, when compared to results reported for pure oxides [ 13 , 14 , 15 ]. These nanostructured materials allow for a wider range of applications considered an active research object today.…”

New Advances into Nanostructured Oxides

“…Pereira et al [16] reported the preparation of V-doped titania/WO 3 (1:1 molar ratio) nanocomposites with different dopant concentrations and dispersed them in high-surfacearea fibrous polymeric membranes obtained by means of electrospinning deposition. Evidence demonstrated that: (i) V 5+ ions doped the atomic structure of titania (anatase phase), (ii) the titania crystallite sizes slightly increased by increasing the dopant concentration, and (iii) both W 6+ and V 5+ occupies Ti 4+ vacancies in the anatase crystal lattice, allowing for a greater degree of local vibrations, which favors the occurrence of photocatalytic processes.…”