TiO2-carbon quantum dots (CQD) nanohybrid: enhanced photocatalytic activity

In situ synthesized carbon quantum dot (CQD)-titanium dioxide (TiO2) nanostructures were found to exhibit excellent photocatalytic dye degradation properties. CQDs were synthesized by solvothermal decomposition of PEG in basic pH in presence of NaOH and their morphology and photophysical properties were studied. Nanostructures were produced by synthesizing CQDs in the presence of (a) commercial TiO2 [CQD/TiO2-P25] and (b) TiO2 precursor [CQD/TiO2] to obtain co-synthesized nanostructures. The photocatalytic properties of the hetero-structures, was also studied and compared with those of commercial TiO2-P25 and synthesized TiO2. The photocatalytic degradation rates of methylene blue were found to rise in the order of TiO2-P25 (2.00 × 10−3 min−1), synthesized TiO2 (6.7 × 10−3 min−1), CQD/TiO2-P25 (1.31 × 10−2 min−1) and CQD/TiO2 (3.6 × 10−2 min−1) respectively. The highest degradation rate for CQD/TiO2 among the samples is attributed to the superior interface between the CQDs and the TiO2, leading to higher interfacial charge transfer. The observed 18-fold increase in degradation rate for CQD/TiO2 over commercial TiO2-P25 photocatalyst and the over two-fold increase over CQD/TiO2-P25 photocatalyst, has significant techno-commercial implications, making CQD/TiO2 a promising photocatalyst.