Porous Silica as a Nanotemplate for the Solid State and Liquid Phase Synthesis of Luminescent Carbon Dots

Abstract

Sol-gel derived nanoporous silica ceramics were used as morphological template for solid-state and liquid-phase synthesis of luminescent carbon nanodots. Two kinds of porous silica with specific area of 90 m2/g and 233 m2/g were used. Solid-state process involved immobilization of phenyltrimethoxysilane molecules on the silica surface followed by pyrolysis at temperature in range of 500-600 oC. Evolution of photoluminescence from near UV range into visible spectral range was observed in solid state samples with increase of annealing time and temperature. Liquid-phase procedures were performed by thermolysis of sucrose/dimethylsulfoxide solution. Porous silica was then used for extraction of luminescent carbon nanodots from DMSO and release to water. Solutions of carbon dots demonstrated multiband nature of emission/excitation spectra. The effect of porosity on the spectral properties of emission and excitation is analyzed and discussed.