Sandwich-Type Nanocomposite of Reduced Graphene Oxide and Periodic Mesoporous Silica with Vertically Aligned Mesochannels of Tunable Pore Depth and Size

Sandwich-type nanocomposites of graphene oxide (GO) and periodic mesoporous silica (PMS) with vertically aligned mesochannels of different pore depth and size are synthesized and characterized, and their formation modes are examined. The existence of mesoscale ordered structure in the mixture of GO and surfactant solutions is confirmed for the first time by in situ small angle X-ray scattering measurement using synchrotron radiation. The mesochannel depth and pore wall ripening of PMS in the nanocomposites are controlled by the reaction time of the hydrolysis of tetraethyl orthosilicate. The pore size of PMS in the nanocomposites can be varied in the range of 1-5 nm by varying the chain length of alkyltrimethylammonium (C(n)TA(+)) template and high specific surface area (approximate to 1000 m(2) g(-1)) is achieved for all samples. Nanocomposites with vertically aligned PMS mesochannels can be synthesized by applying C(n)TA(+) templates of n >= 12, whereas with C(n)TA(+) of n <= 10, either PMS nanoparticle deposited GO structure or the structure with incomplete coverage of GO surface with imperfect PMS is found. The aggregation behaviors of surfactant molecules on GO depend on surfactant concentration relative to critical micelle concentration and reaction temperature, and result in the peculiar nanocomposites of different structural styles.