Simultaneous growth of graphene/mesoporous silica composites using liquid precursor for HPLC separations

Abstract

Silica intercalated graphene-silica composites (G/SiO2) were prepared by one-step hydrothermal method. In the previously reported one-step method for synthesizing G/SiO2 composites (eg. Bull. Mater. Sci., 37 (2014), 589–595; Applied Surface Science 259 (2012), 566–573), graphene needs to be synthesized first and then used to prepare G/SiO2 composites. In this work, neither the preparation of graphene nor the use of graphite as a carbon source is required for the preparation of G/SiO2 composites. Instead, organic solvent (such as toluene, xylene, mesitylene, n-hexane, n-heptane, and cyclohexane) was directly used as the carbon source, and the growth and recombination of graphene and SiO2 were achieved simultaneously through a one-step hydrothermal method. In a hydrothermal reaction vessel, the mixture consisting of organic solvent, TEOS, H2O, and surfactant was uniformly stirred, and then reacted at 160 °C for 4 h to prepare G/SiO2 composite. The influence of the type of organic solvent, hydrothermal reaction temperature, and calcination temperature on the structure of G/SiO2 composites were studied. The morphology and structure of G/SiO2 composites were characterized by FESEM, TEM, and Raman. The formation mechanism of G/SiO2 composite was proposed. G/SiO2 composite was then grown directly on the SiO2 spheres and used as stationary phase for high performance liquid chromatograph separation. Mixture of hydrocarbons was well separated under reversed phase condition.