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 (gC3N4) (NCD@BMCN) 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 NCD@BMCN 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 (center dot OH) and superoxide radicals (center dot 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 NCD@BMCN photocatalyst exhibits good stability and reusability after five consecutive cycles of photodegradation. Results have demonstrated that the NCD@BMCN is a promising Z-scheme photocatalyst for the degradation of CIP, which can be further explored to synthesize a rapid, productive and low-cost NCD@BMCN nanocomposite for the treatment of pharmaceutical-contaminated water and wastewater.

Automated summary

A novel nitrogen-doped carbon dot (NCD) decorated onto bismuth molybdate (Bi2MoO6) and carbon nitride (gC3N4) (NCD@BMCN) nanocomposite was successfully synthesized for the photodegradation of ciprofloxacin (CIP). The NCD@BMCN exhibited excellent visible-light-responsive photocatalytic activity over CIP degradation with good stability and reusability.