Molecular sensing of useful or toxic substances has been extensively investigated and has revealed that well-designed host structures are essential for high sensitivities and selectivities. In addition to organic supramolecular hosts, structure-controlled inorganic nanomaterials have become
increasingly important in this area. In particular, graphene
has emerged as an important compound because of its
homogeneous thickness and extended conjugated p-elec-
tronic structure. [3] Control of the spacing between graphene
layers upon their reassembly should result in 2D cavities that
are ideal for molecular discrimination, although this approach
remains challenging. Fortunately, the high affinity between
nanocarbons and certain kinds of ionic liquids has been
previously reported [4] and guided us in our formulation of a
solution to this problem. Consequently, we now introduce a
method for the formation of graphene layers that are
intercalated by ionic liquids. The layered structures are
formed by in situ reduction of graphene oxide layers in the
presence of nonvolatile ionic liquids, and subsequent electrostatic layer-by-layer (LbL) assembly (Figure 1). We further
demonstrate the use of layered graphene/ionic liquid (G–IL)
composites on quartz crystal microbalances (QCM) for
selective gas sensing. The nanospace formed between sp 2 -hybridized carbon nanosheets has a higher affinity for toxic
aromatic hydrocarbons than for their aliphatic analogues.