Visible active N-doped TiO2/reduced graphene oxide for the degradation of tetracycline hydrochloride

Highlights: • N-TiO₂/rGO was successfully prepared by a photoreduction method. • N-TiO₂/rGO composites exhibited an enhanced visible-light photocatalytic activity. • Superoxide radicals (O₂⁻) was chiefly responsible for the degradation process. • The N-TiO₂/rGO catalyst was highly stable during the photodegradation of TC. • A mechanism for enhanced photodegradation activity of N-TiO₂/rGO was proposed. N-doped TiO₂ nanoparticles deposited on reduced graphene oxide sheets were successfully prepared by a photoreduction method. The synthesized N-TiO₂/rGO composite was characterized by XRD, SERS, XPS, TEM, UV–vis DRS and PL, and its visible-light photocatalytic activity was evaluated by degradation of tetracycline hydrochloride (TC). The results showed that N-TiO₂/rGO composites exhibited a more enhanced photodegradation activity compared to pure TiO₂ and N-doped TiO₂. Trapping tests indicated that not OH and h⁺ but O₂⁻ was chiefly responsible for the photodegradation process. The reusable experiments showed that the prepared N-TiO₂/rGO catalyst was stable during the photodegradation of TC.