Ordered mesoporous silica encapsulated carbon quantum dots and its application in Fe3+detection

The nanocomposites prepared by the combination of SiO2 and carbon quantum dots (CQDs) have the advantages of low toxicity, high fluorescence intensity, high biocompatibility and good water solubility, which greatly broaden its application range. Nevertheless, if only SiO2 and CQDs are simply combined without any structural design, the stability of the nanocomposites will be poor, which will affect its practical application value. In this work, we first synthesized ordered mesoporous silica (OMS) rapidly in aqueous solution by a facile method (30 min), and then generated CQDs in situ in the mesoporous channels of OMS by hydrothermal method to obtain CQDs@OMS fluorescent nanocomposites. The chemical structure and morphology of OMS and CQDs@ OMS were characterized by FT-IR, XRD, SAXRD and TEM, indicating that CQDs was successfully encapsulated in OMS. The stability test results of CQDs@OMS indicate that CQDs can be stably present in the mesoporous channels of OMS, and the fluorescence intensity of CQDs@OMS nanocomposites is almost independent of ionic strength, pH and storage time. The optical performance results show that the optimal excitation wavelength of CQDs@OMS nanocomposites is about 340 nm, the emission wavelength is about 440 nm. Using CQDs@OMS nanocomposites as fluorescent probes to detect Fe3+, it was found that CQDs@OMS responded very quickly to Fe3+. The fluorescence quenching intensity of CQDs@OMS has a good linear relationship with the concentration of Fe3+ in the range of 25-750 mu M. Therefore, the trace amount of Fe3+ in solution can be calculated by measuring the relative magnitude of fluorescence intensity.