Synthesis of three-dimensional hierarchically porous reduced graphene oxide-TiO2 nanocomposite for enhanced hydrogen storage

Three-dimensional hierarchically porous graphene-TiO2 (3D-HPGT) nanocomposites were synthesized through electrostatic assembly method. The obtained 3D-HPGT nanocomposites exhibited hierarchically porous structure with multi-level pores (macro-, meso- and micropores), high specific surface area (705 m2/g), large pore volume (0.41 cm3/g) and higher hydrogen storage capacity. At the pressure of 5 bar, 3D-HPGT nanocomposite showed a maximum hydrogen capacity of 4.11 and 1.48 wt% at 77 and 298 K, respectively, which were much higher than those of previously reported graphene-based materials. The enhanced hydrogen storage capacities were attributed to the three-dimensional hierarchically porous structure, evenly distributed TiO2 nanoparticles on the graphene nanosheets, strong attachment of TiO2 nanoparticles to the underlying graphene nanosheets, and hydrogen spillover effect originated from TiO2 nanoparticles.