Synthesis and characterization of battery waste-derived graphene oxide toward green energy applications

Graphene oxide (GO) nanosheets were produced from graphite rods recovered from spent AA batteries through surface plasma-assisted electrochemical exfoliation in 3.0 M KOH, followed by ultrasonic dispersion. Applied biases of 55–70 V were investigated, with GO-65 showing the best overall performance. Physicochemical characterization confirmed the formation of oxygen-functionalized, defect-rich, multilayered nanosheets containing retained or restacked graphitic domains. In 1 M KOH, GO-65 required an overpotential of 350 mV to reach 10 mA cm⁻ 2 and exhibited a Tafel slope of 52 mV dec⁻ 1 . Its higher double-layer capacitance and lower interfacial impedance indicated a larger electrochemically accessible interface and more favorable charge transfer. GO-65 retained approximately 95% of its initial current after 24 h, while its overpotential increased by only 10 mV. The rapid and simple process produced approximately 5 g of dry GO per batch, while the plasma and ultrasonication steps consumed a combined 0.113 kWh, highlighting its potential for higher-throughput production. Although GO alone showed moderate HER activity, its accessible surface, oxygen-containing anchoring groups, and stable graphitic framework make it a promising scaffold for composite electrocatalysts. This approach provides a practical basis for upcycling carbon-rich waste into functional materials for green hydrogen production and circular resource use.