Ball-milling preparation of titanium/graphene composites and its enhanced hydrogen storage ability

Mass pure Ti/graphene (GE) composites have been synthesized by direct ball-milling Ti powders and GE nanosheets. Through adjusting the reaction conditions, Ti–C bonding in Ti/GE composites was constructed on the interface between Ti nanoparticles and GE nanosheets, which was also confirmed by the following Raman and XPS measurements. Pressure-composition-isotherm (PCT) curves showed that the Ti/GE composites exhibited a higher hydrogen storage capacity (4.3 wt% for H₂ at 300 °C, 0.08 bar) and lower equilibrium pressure compared with that of simply physically mixed sample. In addition, the hydrogen adsorption process and the mechanism for the Ti/GE composites have also been investigated, in which a Kubas-enhanced adsorption process was found in the composites. In this Kubas-type adsorption process, hydrogen was adsorbed firstly by Ti atoms with a formation of Ti–H bonding and then the bonded hydrogen was spilled over to graphene, forming a C–H interaction.