An investigation on the photo-catalytic oxidation of air pollutants via SiO2-supported TiO2

Persistence in the atmosphere of carbon dioxide (CO2) and volatile organic compounds (VOCs) represents a threat for human safety and health, both in the short and in the long term. Therefore, the removal, storage or, even better, utilization of these molecules is currently highly desirable. Photo-catalytic approaches aims to use the sunlight to afford this removal providing a limited or no further pollution. Wide band gap semiconductors are amongst the most studied and employed materials for this purpose. In this study, a crystalline (quartz) and an amorphous (SBA-15) type of silica were tested as TiO2 scaffolds in the photo-oxidation of VOCs. The photo-reduction of CO2 in presence of H2O was also considered as comparative reaction. Therefore, optical, chemical, and reflective properties of the synthesized materials were investigated. The two types of silica showed a different affinity and selectivity in both photo-reductive and photo-oxidative events. The light scattering properties of the scaffold were found to be effective as booster of the photo-catalytic performance of the active phase.