Physicochemical Properties of Tungsten Trioxide Photoanodes Fabricated by Wet Coating of Soluble, Particulate, and Mixed Precursors

Advanced oxidation processes are emerging technologies for the decomposition of organic pollutants in various types of water by harnessing solar energy. The purpose of this study is to examine the physicochemical characteristics of tungsten(VI) oxide (WO3) photoanodes, with the aim of enhancing oxidation processes in the treatment of water. The fabrication of WO3 coatings on conductive fluorine-doped tin oxide (FTO) substrates was achieved through a wet coating process that utilized three different liquid formulations: a dispersion of finely milled WO3 particles, a fully soluble WO3 precursor (acetylated peroxo tungstic acid), and a combination of both (applying a brick-and-mortar strategy). Upon subjecting the WO3 coatings to firing at a temperature of 450 °C, it was observed that their properties exhibited marked variations. The fabricated photoanodes are examined using a range of analytical techniques, including profilometry, thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), and voltammetry. The experimental data suggest that the layers generated through the combination of particulate ink and soluble precursor (referred to as the brick-and-mortar building approach) display advantageous physicochemical properties, rendering them suitable for use as photoanodes in photoelectrochemical cells.