Sustainable ternary conductive inks incorporating reduced graphene oxide derived from steel industry waste for screen-printed flexible supercapacitors

Flexible supercapacitors (FSCs) emerge as promising candidates for powering wearable electronics but encounter limitations in fabrication efficiency, capacitance, and energy density. This study presents a reduced graphene oxide/Multiwalled Carbon nanotube and copper oxide (rGO/MWCNT/CuO) composite ink, combining electric double-layer capacitance (EDLC) from rGO/MWCNT and pseudo capacitance (PC) from CuO, to enhance FSC performance. rGO is synthesized from Kish graphite, a steel industry waste, offering a sustainable material source. The FSCs demonstrate an outstanding areal capacitance of 324.2 mF cm −2 (at 0.1 mA cm −2 ) and an energy density of 35.6 μWh cm −2 at a power density of 0.04 mW cm −2 . Moreover, the rGO/MWCNT/CuO-based FSC exhibits excellent cycling stability, retaining its performance without noticeable degradation for 3000 charge–discharge cycles.