Luminescent properties and sensing performance of a carbon quantum dot encapsulated mesoporous silica/polyacrylonitrile electrospun nanofibrous membrane

A novel turn-off and label-free fluorescent sensor based on a carbon quantum dot encapsulated mesoporous silica/polyacrylonitrile (CDs/mesoSiO2/PAN) electrospun nanofibrous membrane for the determination of Fe(III) was evaluated. Compared with that of the free-state CDs, the fluorescent behavior of the embedded CDs was altered because of the involvement of mesoSiO2/PAN electrospun nanofibers as a supporting matrix. On the basis of previously reported understandings, the photoluminescent (PL) mechanism of the CDs had been further studied. It is evident that the fixed blue emission of CDs occurs from the carbon defect states, whereas the excitation-dependent emission at longer wavelengths is related to confinement effects of the CDs. Moreover, compared with the free-state CDs, the CDs/mesoSiO2/PAN nanofibrous membrane exhibits a more stable PL signal, improved anti-photobleaching performance, and better pH adaptability because of the possible hydrogen bonding between the SiOH groups in nanofibers and the surface oxygen-containing groups of the CDs, which create an adequate chemical environment for the preservation of the carbon defect states in luminescence generation as well as the active sites for Fe(III) binding. Applying the CDs/mesoSiO2/PAN membrane for the determination of Fe(III) in tap water samples indicates that it can work efficiently as a PL sensor.