Pseudocapacitive organic catechol derivative-functionalized three-dimensional graphene aerogel hybrid electrodes for high-performance supercapacitors

Bio-inspired and environmentally friendly chemical functionalization is a successful way to a new class of hybrid electrode materials for applications in energy storage. Quinone (Q)-hydroquinone (QH ₂ ) couples, a prototypical example of organic redox systems, provide fast and reversible proton-coupled electron-transfer reactions which lead to increased capacity. To achieve high capacitance and rate performance, constructing three-dimensional (3D) continuous porous structure is highly desirable. Here we report the hybrid electrodes (GA-C) consisting of 3D graphene aerogel (GA) functionalized with organic redox-active material, catechol derivative, for application to high-performance supercapacitors. The catechol derivative is adsorbed on the surface of GA through non-covalent interactions and promotes fast and reversible Q/QH ₂ faradaic reactions, providing large specific capacitance of 188 F g ⁻¹ at a current of 1 A g ⁻¹ and a specific energy of ∼25 Wh kg ⁻¹ at a specific power of ∼18,000 W kg ⁻¹ . 3D continuous porous structure of GA electrode facilitates ion and electron transports, resulting in high rate performance (∼140 F g ⁻¹ at a current of 10 A g ⁻¹ ).