Figure 1.

Model of activated carbon based on fullerene-like elements (a) (Reproduced with permission of [2]. Copyright Royal Society of Chemistry, 2007) and schematic model of reduced graphene oxide (rGO)/carbon nanotubes (CNT) hybrid structure (b) with blue and yellow spheres corresponding to carbon atoms of rGO and CNT, respectively, as well as white and red spheres representing hydroxyl group hydrogen and oxygen atoms, respectively (Reproduced with permission of [10]. Copyright Elsevier, 2015).