Graphene Oxide Nanoribbons Grafted with Thionine as Versatile Materials for Energy Storage and Hydrogen Evolution Electrocatalysis

Abstract

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, 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 at 1 A/g in a three-electrode setup. A symmetric two-electrode device made from GONRs/Th (RT) reached a capacitance of 141 F/g at 1 A/g within a 1.7 V window, delivering a maximum energy density of 57 Wh/kg, a power density of 8.305 kW/kg, and maintaining 102% after 10,000 cycles. In HER, GONRs/Th (HT) showed an overpotential of 122 mV at 10 mA/cm2 and a Tafel slope of 91 mV/dec, highlighting its potential as a versatile, eco-friendly electrode material.