How to guide photocatalytic applications of titanium dioxide co-doped with nitrogen and carbon by modulating the production of reactive oxygen species.

A carbon and nitrogen TiO 2 (C/N-TiO 2) photocatalyst has been obtained modifying a commercial TiO 2 using ammonium citrate. The photocatalyst has been tested in two photocatalytic tests under visible light, NOx abatement in gas phase and phenol degradation in liquid phase monitoring in parallel the formation of reactive oxygen species (ROS) via EPR. We achieved a deep insight about its activity, which relies on superoxide and singlet oxygen (O 2 ^−• and ¹O 2) with no role of OH^• radicals. The singlet oxygen (¹O 2) is exclusively a result of the excitation of the surface carbonaceous species and it is essential to oxidize phenol but limits the abatement of nitric oxide. The photocatalyst activity can be modulated according to its actual application tuning the carbon content. The oxidation of phenol in liquid environment is favoured by the presence of the carbonaceous phase while NO abatement is favoured by its partial removal. [Display omitted] • Carbon moieties involved in singlet oxygen generation. • Carbon moieties affect practical application of the photocatalysts. • ¹O 2 detrimental for NOx abatement. • ¹O 2 beneficial for phenol degradation. • Activity due to dioxygen based species, O 2 ^• and ¹O 2 with no role of OH^• radicals. [ABSTRACT FROM AUTHOR]