Surface and functional characterization of nanostructured thin films for environmental remediation

Nowadays, the presence of pollutants in water is an urgent problem to solve. The efficient removal of these contaminants from aqueous solutions requires advanced oxidation processes (AOPs). This can be accomplished by various approaches using materials that allow the rapid removal of pollutants with high degradation rates. In this work, we focused on the surface modification of TiO₂ films for photocatalytic application in water remediation. In particular, with an appropriate surface functionalization with zirconium phosphate, we have improved the sensitivity to sunlight and the thermal stability of TiO₂. The surface functionalization of the samples was verified by using TOF-SIMS, which allows us to obtain spatially resolved chemical information. This information is very helpful for an effective engineering of the material, in order to obtain the best performances for environmental remediation. To our knowledge, this is the first time that TOF-SIMS is used to monitor the evolution of photocatalytic reactions at the photoactive surface, getting information on degradation pathways taking place at the surface of the photoactive material under solar light irradiation. In this work, as a target molecule, we chose rhodamine B, a dye widely used in textile industry, among others. The investigation of the degradation pathways occurring directly at the samples’ surface can provide relevant information about the rate determining step of the reaction and give hints for tailored functionalization of materials for improving their photocatalytic performances.