Terpyridine-functionalized polyaniline/reduced graphene oxide composites for capturing Cr3+ ions and its application in supercapacitors

Energy and environmental issues have been hot topics over the past few decades. As new energy storage conversion equipment, supercapacitor has been hindering due to their low energy density . Constructing asymmetric supercapacitors to boost energy density is considered as an effective approach. In this study, functional modification was combined with in-situ polymerization to prepare the reduced graphene oxide/polyaniline/terpyridine (RGPT) composites to capture metal ions and serve as cathode material of supercapacitor. When Cr 3+ ions are complexed with composite material, the electrochemical property of the resulting material is greatly improved. The RGPT-Cr composites display a high specific capacitance of 1499 F g −1 at 1 A g −1 with outstanding cycling stability in three-electrode systems. Asymmetric supercapacitor (ASC) devices assembled with the RGPT-Cr composites as positive electrodes present a superior energy density up to 117.5 Wh kg −1 at a power density of 915.0 W kg −1 and possess preeminent capacitance retention of 93.2% after 6000 cycles at 20 A g −1 . In addition, the theoretical calculations prove that Cr 3+ helps to enhance the surface-capacitive contribution of whole composites. This strategy has validated the fact that the incorporation of metal coordination bonds boosts the electron transfer efficiency and structural stability of the whole composite.