Theoretical and experimental studies on silica-coated carbon spheres composites

In order to prepare carbon-based photonic crystals, first of all, theoretical modeling calculation was used to predict the bandgap characteristics of silica-coated carbon spheres. Then, silica-coated carbon spheres composites were synthesized using tetraethyl orthosilicate as precursor of silica by a sol-gel method combined with Stöber method. Effect of reaction conditions on surface coating of carbon spheres with silica, including the pH, the amount of precursor and reaction time, was emphasized. The morphology and structure of the composites and the effect coating of carbon spheres with silica were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy and Fourier-transform infrared spectrometry. The coating ratio of silica was investigated by thermogravimetry. The results show that pH value played an important role in coating reaction, the dosage of the precursor and reaction time had significant effect on coating layer thickness, that is, coating ratio. Carbon spheres coated with silica had good dispersibility and dispersion stability in water and ethanol, which is preconditions of reactivity of carbon spheres in liquid phase and lays the basis for the application of carbon spheres.