▎ 摘　　要

Capacitive energy storage is one of the electrochemical energy storage systems with a short charging moment giving power density. The electrochemical aqueous hydrogen storage capability of graphene and functionalized graphene with the study of structural, capacitive and faradaic energy contribution is explored specifically at the earliest. The functionalized (nitrogen) graphene shows excellent electrochemical hydrogen storage. The graphene and nitrogen functionalized graphene showed discharge capacity of 52 mAh g(-1) and 38 mAh g(-1) and maximum specific capacitance of 273 F g(-1) and 374 F g(-1). Understanding the contribution can provide suggestions for building high capacitance, specific energy and power of energy storage devices. (C) 2020 Elsevier B.V. All rights reserved.