Visible light-responsive Fe-loaded TiO₂ photocatalysts for total oxidation of acetaldehyde: Fundamental studies towards large-scale production and applications

Various Fe loadings were applied onto P25 TiO₂ using temperature-controlled vapour deposition and the resulting structures were subsequently annealed at 750 °C. As-received TiO₂ was nearly photo-catalytically inactive for acetaldehyde decomposition under visible light, but when a very small amount of Fe below the threshold was loaded, the activity became maximized. Control of Fe loading is critical to prepare high-performing Fe-TiO₂ photocatalysts since a larger amount of Fe forms larger iron oxide particles, which induces non-radiative recombination of the optically excited electron-hole pairs, thereby reducing the photocatalytic activity. Regarding the reaction mechanism, fast oxidation of acetaldehyde into CO₂ and a slower path via acetic acid to CO₂ were identified, where almost no evolution of secondary pollutant vapour was identified. A strategy towards large-scale production and stable fixation of photocatalyst powder on surfaces of construction materials for real air purification applications are discussed.