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

Highlights: • Silica-graphene composites were prepared in one step. • Graphene and silica are simultaneously formed and overlapped to form intercalation composites. • Ordinary organic solvents are used as carbon sources. • The preparation process does not need to use graphite as a carbon source. 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.