Carbon-modified titanium oxide materials for photocatalytic water and air decontamination

Abstract Titanium oxide-based materials with different physical and chemical features were synthetized aiming at removing organic pollutants from both water and air media. The materials were produced employing two different heating methodologies (thermal, T and hydrothermal, H) at distinct temperatures resulting in porous materials. These materials were also modified with either graphene oxide (GO) or carbon nanotubes (CNT), using an in-situ approach. All materials were tested as photocatalysts using ultra-violet (UV), visible (Vis) and solar radiation. Rhodamine B (RhB) and benzene were used as representative pollutants in water and air, respectively. The addition of carbon to the catalysts improved the removal of both pollutants. In the case of the photocatalytic degradation of rhodamine B, under both UV and Vis light, it was found that, the materials containing carbon nanostructures allowed the highest degradation degree, while the photosensitisation phenomenon became negligible. The best catalyst is the one containing CNT (2.98 wt% of C) and thermally treated at 300 °C (T300_CNT). This material showed higher degradation ability than the commercial TiO2 nanopowder Degussa P25 (P25) under Vis light. Regarding benzene removal, the samples thermally treated at 300 °C and modified with CNT and GO (T300_CNT and T300_GO, respectively) outperformed Degussa P25. The former material was successfully reused in the photocatalytic degradation of benzene over 6 consecutive cycles.