Graphene oxide nanoribbons grafted with thionine as versatile materials for energy storage and hydrogen evolution...

Wastewater treatment, energy storage, and green fuel generation remain among the most pressing global challenges. In this work, environmental remediation and energy conversion are addressed simultaneously by immobilizing the toxic dye thionine onto graphene oxide nanoribbons (GONRs) to create a functional composite for advanced energy applications. The GONRs/thionine materials were synthesized via hydrothermal (HT) and room-temperature (RT) routes and systematically characterized using SEM, TEM, XRD, UV-vis spectroscopy, FT-IR, Raman spectroscopy, and XPS. Their electrochemical performance for supercapacitor and hydrogen evolution reaction (HER) applications was evaluated through CV, GCD, EIS, LSV, and CP measurements. For supercapacitor applications, thionine-functionalized GONRs demonstrated a marked enhancement in capacitance in 1 M H₂SO₄ arising from thionine-induced pseudocapacitance. GONRs/Th (RT) exhibited a specific capacitance of 732 F g^-1 at 1 A g^-1 in a three-electrode setup. A symmetric two-electrode device made from GONRs/Th (RT) reached a capacitance of 141 F g^-1 at 1 A g^-1 within a 1.7 V window, delivering a maximum energy density of 57 Wh kg^-1 and a power density of 8.305 kW kg^-1 and retaining 102% after 10 000 cycles. In the HER, GONRs/Th (HT) showed an overpotential of 122 mV at 10 mA ^-1cm^-2 and a Tafel slope of 91 mV dec^-1, highlighting its potential as a versatile, eco-friendly electrode material.