ABSTRACT
Graphene is a two-dimensional sheet of sp2-hybridized carbon atoms that form a at hexagonal lattice. Since its discovery by Geim et al. in 2004, graphene has received enormous attention due to its excellent electrical conductivity, mainly originating from the delocalized π bonds above and below the basal plane, its large surface area, and low production costs. Owing to these excellent physical and chemical properties, graphene has become an interesting alternative for the development of electrical devices, sensors, and biosensors, synthesizing nanocomposites, drug delivery, catalytic and solid-phase microextraction, energy storage materials, and transparent conducting electrodes. Because of its ultrahigh specic surface area and strong π−π electrostatic stacking property, graphene is expected to be a promising stationaryphase material for open-tubular capillary electrochromatography. Graphene-based electrochemical sensors present a better performance compared to glassy carbon, graphite, and even carbon nanotube-based sensors, mainly due to sp2like planes and edge defects that are more exposed on the graphene nanosheets than on other carbon materials. It is believed that nanoparticles can be controllably synthesized and well dispersed on the graphene surface. Additionally, the graphene nanosheets may effectively buffer the strain from the volume change of particles during cycles and also preserve a high electrical conductivity of the electrode if highly insulating metal oxides were used as anodes (e.g., Mn3O4). Recently, graphene-supported metal nanocomposites as a new class of hybrid materials combining the advantages of both graphene substrate and active metal nanoparticle components have shown extensive applications in many advanced elds such as memory electronic and optoelectronic transistors.
