Preparation And Characterization Of CDs/Silica Mesoporous Composites

Carbon dots (CDs) have attracted much attention because of their particular properties such as tunable luminescence, resistance to photobleaching, easy bio-conjugation and nontoxicity. Therefore, CDs have been widely used in bioimaging, sensing and energy conversion/storage. In many practical applications, CDs were often combined with other materials to fabricate composite structures with multi-functions. Comparing with many carrier materials, silica is a common material used in. In the present work, mesoporous multifunctional CDs and silica composites have been prepared by co-hydrolysis of silane-functionalized CDs and tetraethyl orthosilicate. The photocatalytic activity and magnetic-fluorescent properties of the CDs and silica composites have also been explored.(1) Mesoporous carbon dots/silica composites for visible-light-driven photocatalytic reduction of Cr (VI)Up to now, CDs based photocatalysts have been almost applied in the photocatalytic oxidation of organic pollutants, while barely applied in the photocatalytic reduction of heavy metal. In this study, mesoporous CDs/silica composites were prepared through co-hydrolysis of organosilane-functionalized carbon dots and tetraethyl orthosilicate. The obtained CDs/silica showed large area and blue fluorescence. More importantly, they exhibited visible-light-driven photocatalytic reduction of Cr(VI). Besides, the CDs/silica composites showed strong adsorption for both Cr2O72-and Cr3+. After the whole adsorption、adsorption and photocatalysis progress, Cr could be nearly removed by centrifugation finally.(2) Preparation and characterization of multifunctional magnetic-fluorescent Fe3O4/CDs/silica mesoporous compositesMultifunctional magnetic-fluorescent materials have been widely used in imaging due to their magnetic and fluorescent response simultaneously. Among the various luminescent components, carbon dots (CDs) have attracted particular interest as a new optical candidate due to chemical inertness, easy functionalization, high resistance to photobleaching, low toxicity and good biocompatibility. Thus, the conjugation of Fe3O4nanoparticles and CDs in a platform could serve as a fascinating bifunctional probe for simultaneously optical and magnetic detection with much enhanced sensitivity. In this study, Fe3O4/CDs/silica microspheres had been prepared with as-prepared Fe3O4nanoparticles, silane-functionalized carbon dots (CDs) and tetraethyl orthosilicate as co-precursors and cetyltrimethyl ammonium bromide as pore-directing agents. The Fe3O4/CDs/silica composites exhibited a good fluorescence and magnetic property. Moreover, they owned large surface area and mesoporous structures which could be used as building blocks for the assembly of complex nanostructures, therefore would find potentials in bimodal imaging, drug delivery, molecular targeting and so on.