Indirect Z-scheme nitrogen-doped carbon dot decorated Bi2MoO6/g-C3N4 photocatalyst for enhanced visible-light-driven degradation of ciprofloxacin

A novel nitrogen-doped carbon dot (NCD) decorated onto bismuth molybdate (Bi2MoO6) and carbon nitride (g-C3N4) ([email protected]) nanocomposite was successfully synthesized for the photodegradation of ciprofloxacin (CIP) under the visible light irradiation. The homogeneous deposition of 10–20 nm NCD onto the surface of BMCN increases the specific surface area and photocurrent density, which can facilitate the good charge transfer efficiency for the enhanced photodegradation of CIP. The [email protected] exhibits excellent visible-light-responsive photocatalytic activity over CIP degradation and the pseudo-first-order rate constants are in the range of 0.036–0.13 min−1, which are dependent on initial pH, photocatalyst dosage and existence of anions. The indirect Z-scheme mechanism for CIP photodegradation with hydroxyl radicals (•OH) and superoxide radicals (•O2−) as the dominant reactive species is also proposed, in which NCD plays a role as the mediator to transfer electrons from the conduction band of Bi2MoO6 to the valence band of g-C3N4. Moreover, the [email protected] photocatalyst exhibits good stability and reusability after five consecutive cycles of photodegradation. Results have demonstrated that the [email protected] is a promising Z-scheme photocatalyst for the degradation of CIP, which can be further explored to synthesize a rapid, productive and low-cost [email protected] nanocomposite for the treatment of pharmaceutical-contaminated water and wastewater.