Polyaniline-Grafted Graphene Hybrid with Amide Groups and Its Use in Supercapacitors

Unlike conventional routes for preparing graphene/polyaniline (G/PANI) composites coupled by van der Waals forces, an approach to graft polyaniline (PANI) nanofibers onto graphene to acquire a polyaniline–graphene (PANI–G) hybrid connected by amide groups is described in this study. The chemical bonding between graphene and PANI is confirmed by infrared spectroscopy and X-ray photoelectron spectroscopy. The Raman spectrum of PANI–G hybrid demonstrates a close interaction between graphene and PANI. Electrochemical tests show that PANI–G hybrid has a high capacitance (623.1 F/g) at a current density of 0.3 A/g, higher than that in G/PANI composites reported previously. In addition, the retained capacitance of the PANI–G hybrid in the long term charge/discharge cycling test reached as high as 510 F/g at a current density of 50 A/g, suggesting its potential use in supercapacitors. First-principle calculations were carried out to study the electronic structures of PANI–G hybrid. The results show that the carbonyl group in the amide linkage plays a key role in the formation of π-conjugated structure, facilitates charge transfer, and consequently improves capacitance and cycling ability.