Visible-Light-Driven Nitrogen-Doped Carbon Quantum Dots/CaTiO₃ Composite Catalyst with Enhanced NO Adsorption for NO Removal

Nitrogen oxides (NO_x) have attracted extensive concerns as a secondary aerosol precursor in recent years. Solar-induced photocatalytic oxidation is a promising strategy for of NO_x removal nowadays. In this contribution, nitrogen-doped carbon quantum dots (N-CQDs)/CaTiO₃ composite was synthesized using a facile hydrothermal process. The incorporation of N-CQDs to CaTiO₃ facilitates the transfer of electrons and divorce of photogenerated carriers. NO temperature-programmed desorption (NO-TPD) demonstrated that the presence of N-CQDs was conducive to the NO adsorption in comparison with the pristine CaTiO₃. The composite catalyst demonstrated much better photocatalytic performance than CaTiO₃ and P25 did in regard to gaseous NO removal and NO₂ selectivity under visible light irradiation. Both •O₂ ^- and •OH are believed to make a major contribution to NO removal. The role of N-CQDs was unraveled in the photocatalytic reaction of NO elimination over N-CQDs/CaTiO₃ samples. This study provides insight into the composite catalyst N-CQDs/CaTiO₃ in photocatalytic reactions and applications.