Comparison of photoactivity of nanoporous and nanostructured electrodes of W/WO₃ prepared by electrochemical anodization and electrodeposition by templates

Full text: Tungsten trioxide has been an excellent alternative material. In photoelectrocatalytic process, since presents small band gap energy (2.4 - 2.8 eV) and can to be photoexcited in the visible region [1].The modification of this material with silver nanoparticles can promote change in intrinsic properties of the semiconductor such as band structure, charge transfer, which potentiate its application in disinfection process. In this work, it was compared the properties of W/WO₃ electrodes prepared by using three different methodologies.Firstly, WO₃ thin films were grown onto tungsten substrate by electrochemical anodization, producing nanoporous electrodes. The second method nanostructured materials were obtained by using template method. The tungsten surface was coated by polystyrene spheres and submitted to direct electrodeposition of WO₃, which after templates removal, resulted in nanostructured films. The third procedure was based on deposition of silver nanoparticles by immersion method in W/WO₃ nanoporous material followed by photoirradiation to reduce Ag⁺ /Ag. All electrodes were characterized by scanning electron microscopy and showed high porosity and organization, respectively.The presence of W and O was confirmed by EDS and the monoclinic form by X-ray diffraction. The Ag modification was also diagnosed. Studies involving photocurrent vs potential has proved that silver modification presented higher influence on W/WO₃ photoactivity than the templates organization with 9.0 mA cm^-2. and 3.0 mA cm^-2 of photocurrent response, respectively. The as prepared materials were employed as photoanodes on a photoelectrochemical system for disinfection purposes.The obtained results showed that photoelectrocatalysis is a promising method for fungi disinfection under UV and visible light irradiation. References: [1] Fraga, L.E.; Zanoni, M. V. B. Journal Brazilian Chemical Society, v. 22, p. 718-725, 2011. [2 ]Brugnera, M. F. et al. Electrochimica Acta, v.85. p. 33-4, 2012. (author)