Double element co-doped carbon quantum dots (CQDs) have unique electron properties and broad prospects in photocatalysis. In this paper, the phosphorus and nitrogen co-doped CQDs (PNCQDs) were loaded on TiO2 nanosheets by in-situ synthesis method. Physical structure and chemical composition of samples were analyzed by XRD, FT-IR, XPS, SEM and TEM. UV–Vis spectra show the donor–acceptor coupling between PNCQDs and TiO2 and enhanced strong UV light absorption. Photoluminescence spectra indicate that PNCQDs effectively promote charge separation, which is different from nitrogen doped CQDs. The sample 1-PNCT with the optimal phosphorus doping amount has the highest kinetic constant for photodegradation of Methylene Blue (MB), which is 3.4 times pure TiO2. A possible Z-scheme photodegradation mechanism is proposed according to the active species scavenge experiment results in which PNCQDs can not only accept but also localize photogenerated electrons to dopant sites due to the quantum wells created by P and N doping energy barriers.
Construction of carbon quantum dots/single crystal TiO2 nanosheets with exposed {001} and {101} facets and their visible light driven catalytic activity