Carbon quantum dots (CQDs)-supported CeO2/Al2O3 with tunable band gap for the efficient degradation of plastic waste into porous carbon materials under mild conditions: experiment and DFT

A novel photocatalyst based on carbon quantum dots (CQDs)-functionalized CeO2/Al2O3 nanoparticles (NPs) was generated and applied for the oxidative degradation of polyethylene terephthalate (PET) and low-density polyethylene (LDPE). The chemical structure and morphology of Al2O3/CeO2@CQDs from the FTIR, XRD, and SEM analysis showed that the incorporation of CQDs increased the band gap value from 4.2 to 2.4 eV due to the quantum confinement effect with CQDs. The degradation of PET and LDPE was monitored through FTIR spectroscopy by registering changes in absorption bands, and the degraded products were analyzed through different analytical techniques. SEM¿EDS, XRD, HPLC, and MS spectra revealed effective conversion of PET and LDPE to highly porous carbon materials with weight losses of 98% and 91%, respectively. From the analysis of the degradation products, a suitable degradation mechanism was proposed for both plastics, which was subsequently verified with DFT molecular energy calculations. © The Author(s), under exclusive licence to Springer Nature B.V. 2025.