Oxygen-Rich Hierarchical Porous Graphene as an Excellent Electrode for Supercapacitors, Aqueous Al-Ion Battery, and Capacitive Deionization

Abstract

In this study, we have described the synthesis of oxygen-rich hierarchical porous graphene (O-PG) using focused solar radiation on nitric acid treated graphene oxide film. This nitric acid treatment for graphene oxide helps in generating micropores on the graphene sheets and introducing oxygen-containing functional groups when solar light is focused. This unique hierarchical porous structure along with high surface area and oxygenated functional groups makes O-PG as suitable electrode in energy storage and also for capacitive deionization. The as-prepared O-PG exhibits high specific capacitance of 354 F g–1 along with energy storage of 110.6 Wh kg–1 at 1 A g–1 current density. O-PG also delivers high specific capacity of 90 mAh g–1 as high-performance cathode in aqueous Al-ion battery with an exceptionally high cyclic stability up to 10 000 cycles of charging–discharging processes at high current density of 0.5 A g–1. In addition, the electrosorption studies of salt ions were done using capacitive deioniz...