Photocatalytic Performances and Antifouling Efficacies of Alternative Marine Coatings Derived from Polymer/Metal Oxides (WO3@TiO2)-Based Composites

This work concerns development of alternative antifouling paints for marine applications using composite metal oxides derived from TiO2 and WO3. Composite metal oxides with a variety of tungsten content were prepared via a sol-gel process using titanium isopropoxide and sodium tungstate dihydrate as the precursors. The crystalline phase, bandgap energy, morphology, surface structure, and electronic states of the synthesized products were then characterized and confirmed by XPS, XRD, UV/Vis spectroscopy, SEM-EDX, and TEM techniques. Photocatalytic performance polymer film loaded with composite metal oxides containing 10% by mole of WO3 (10%WO3@TiO2) was confirmed both under UV irradiation and in the dark. The results are discussed in light of oxygen vacancies and the presence of heterojunctions between the TiO2 and WO3 domains in the composites, which eventually lead to suppression of charges recombination. Finally, antifouling and the antimicrobial efficacy of the polymer film loaded with composite metal oxide particles (10%WO3@TiO2) were evaluated under static marine immersion conditions using Zobell Marine agar. After 30 days, the percentage fouling coverage (16.35%), colonies number (CFU value 12 x 10(3)), and percentage reduction of colonies (92.94%), were obtained, which significantly outperformed those of the control (the bare substrate).