Advanced Functional Materials, Vol.20, No.17, 2867-2873, 2010
Self-Propagating Domino-like Reactions in Oxidized Graphite
Graphite oxide (GO) has received extensive interest as a precursor for the bulk production of graphene-based materials. Here, the highly energetic nature of GO, noted from the self-propagating thermal deoxygenating reaction observed in solid state, is explored. Although the resulting graphene product is quite stable against combustion even in a natural gas flame, its thermal stability is significantly reduced when contaminated with potassium salt by-products left from GO synthesis. In particular, the contaminated GO becomes highly flammable. A gentle touch with a hot soldering iron can trigger violent, catastrophic, total combustion of such GO films, which poses a serious fire hazard. This highlights the need for efficient sample purification methods. Typically, purification of GO is hindered by its tendency to gelate as the pH value increases during rinsing. A two-step, acid-acetone washing procedure is found to be effective for suppressing gelation and thus facilitating purification. Salt-induced flammability is alarming for the fire safety of large-scale manufacturing, processing, and storage of GO materials. However, the energy released from the deoxygenation of GO can also be harnessed to drive new reactions for creating graphene-based hybrid materials. Through such domino-like reactions, graphene sheets decorated with metal and metal oxide particles are synthesized using GO as the in situ power source. Enhanced electrochemical capacitance is observed for graphene sheets loaded with RuO2 nanoparticles.