MOF-derived hybrid nanoarchitectured carbons for gas discrimination of volatile aromatic hydrocarbons

Abstract

Two-dimensional layered graphene nanosheets are very interesting with regard to molecular sensing and vapor discrimination between aromatic hydrocarbons and their aliphatic analogues. However, graphene oxide (GO) suffers from stacking due to strong van der Waals forces between the adjacent nanosheets, thus reducing the surface area of exposure and limiting molecular ion transport in porous electrodes. Mixing GO with nanoporous carbon polyhedra derived from zeolitic imidazolate framework-8 (ZIF-8) generates a 3D continuous framework of hybrid nanoarchitectured hollow carbon macropores coated with reduced GO (rGO). This 3D hollow graphitic carbon framework (HGCF) synergistically combines π-rich-electron nanospaces with a high surface area and a large hierarchical pore volume, both of which are particularly beneficial as porous electrodes for selective detection of hazardous aromatic hydrocarbon vapors over their aliphatic analogues because of reinforced noncovalent π–π interactions with a π-conjugation system of aromatic rings. A designed quartz crystal microbalance (QCM) nanosensor coated with an HGCF heterostructure clearly shows the high impact of π-rich-electrons in graphene as sensing antennae on the molecular discrimination of vaporized toxic aromatic hydrocarbons as compared to carbon polyhedron shapes derived from the ZIF-8 of low sp2-graphitized carbon content.