(316h) An Experimental and Computational Study of the Surface Chemistry Effects in the TiO2 Grafting of Graphene Oxide

Titanium dioxide (TiO₂) and its nanocomposite films are increasingly being used in the making of supercapacitors and photocatalytic decontamination applications. In this work, we have synthesized graphene oxide (GO) platelets with three different surface oxygen densities using the modified Hummerâ??s method. The GO platelets were further dispersed in a 2:1 water/ethanol mixture using a bath sonicator for 30 min. Then we added the TiO₂ nanopowder to the mixture and maintained it at 120°C for 3 h in a Teflon-sealed autoclave. Finally, we recovered the TiO₂-grafted GO powder by filtration and drying and investigated the covalent bond formation between the TiO₂ and GO by the FT-IR method. The unique aspect of our work is to elucidate the effect of GO surface oxygen density on the TiO₂ grafting process. Furthermore, to gain a molecular insight into the kinetics and thermodynamics of the TiO₂ grafting reaction onto the GO sheet, we performed a reactive molecular dynamics simulation of the TiO₂/GO system in the water/ethanol solution at the prescribed reaction condition. We used the ReaxFF force field with a time step of 0.05 fs to first equilibrate the system at room temperature and then increased the temperature to 120°C. We have analyzed the surface assembly of the TiO₂ particles on the GO sheet and quantified the reaction kinetics as a function of GO surface oxygen density.