Surface engineering of activated carbon with dopamine functionalization for sustainable screen-printed supercapacitor

Quinone-functionalized pristine activated carbon (PAC) electrode offers enhanced ion storage capabilities for SC electrodes, yet producing biocompatible, cost-effective materials with precisely controlled surface groups remains a substantial challenge. In this study, dopamine-functionalized activated carbon (DFAC) composites were synthesized using a π-π stacking approach. Notably, the DFAC electrode ink was screen-printed without the use of a drying retardant, while the PAC ink required the Texilac drying retarder to facilitate screen printing. Amine and catechol group present in dopamine enhance surface energy, improve wettability and dispersion, and promote adhesion through hydrogen bonds, ensuring smoother, more durable, and consistent printing. Redox peaks at potentials of 0.45 V and 0.5 V with respect to an Ag/AgCl reference electrode are observed, associated with the hydroquinone-quinone couple, confirming the presence of dopamine. DFAC based SCs (28 F g⁻¹) also demonstrates significantly higher specific capacitance than PAC-based SCs (10.8 F g⁻¹). At 0.5 A g⁻¹ current density, the screen-printed SCs deliver a specific capacitance of 23 F g⁻¹. A specific energy of 7.2 W h kg⁻¹ and a specific power of 1.6 kW kg⁻¹ were obtained at 1.5 A g⁻¹ current density. DFAC paves the way for biodegradable SCs, creating new opportunities for powering low-energy wireless sensors.