High‐Performance Supercapacitors Based on a Zwitterionic Network of Covalently Functionalized Graphene with Iron Tetraaminophthalocyanine

Abstract Graphene derivatives are promising candidates as electrode materials in supercapacitor cells, therefore, functionalization strategies are pursued to improve their performance. A scalable approach is reported for preparing a covalently and homogenously functionalized graphene with iron tetraaminophthalocyanine (FePc‐NH₂) with a high degree of functionalization. This is achieved by exploiting fluorographene's reactivity with the diethyl bromomalonate, producing graphene‐dicarboxylic acid after hydrolysis, which is conjugated with FePc‐NH₂. The material exhibits an ultrahigh gravimetric specific capacitance of 960 F g⁻¹ at 1 A g⁻¹ and zero losses upon charging–discharging cycling. The energy density of 59 Wh kg⁻¹ is eminent among supercapacitors operating in aqueous electrolytes with graphene‐based electrode materials. This is attributed to the structural and functional synergy of the covalently bound components, giving rise to a zwitterionic surface with extensive π–π stacking, but not graphene restacking, all being very beneficial for charge and ionic transport. The safety of the proposed system, owing to the benign Na₂SO₄ aqueous electrolyte, the high capacitance, energy density, and potential of preparing the electrode material on a large‐scale and at low cost make the reported strategy very attractive for development of supercapacitors based on the covalent attachment of suitable molecules onto graphene toward high‐synergy hybrids.