Carbon quantum dots decorated on ZnO nanoparticles: An efficient visible‐light responsive antibacterial agents

Zinc oxide@carbon quantum dots (ZnO@CQDs) nanocomposite was prepared via a facile hydrothermal method. Characterization of the obtained samples was carried out by Scanning electron microscopy‐EDX(SEM–EDX), Transmission electron microscopy (TEM), X‐ray diffraction (XRD), Photoluminescence (PL), and Fourier transformed infrared spectroscopy (FT‐IR). These results revealed that we have prepared ZnO@CQDs nanocomposite successfully. Our study revealed that the antibacterial efficiency (against S.aureus and E.coli ) under visible light irradiation of as prepared ZnO@CQDs nanocomposite was higher than pure ZnO nanoparticles. The ZnO@CQDs nanocomposite showed excellent antibacterial activity against Gram‐negative and Gram‐positive bacteria with a minimal inhibitory concentration (6–8 mg/mL) against to E.coli and S.aureus. We also tested the light response of ZnO@CQDs under UV–vis light, by calculating its band gap data, after decorated with CQDs, the band gap of the pure ZnO can significantly decreased from 2.57 eV to 2.50 eV. The ZnO decorated by CQDs can both enhance the light absorption and suppress photogenerated electron–hole's recombination which results in the enhancement of antibacterial properties.