Engineered flexible microsupercapacitors with MOF-derived Co₃O₄/rGO nanocomposite optimized via response surface methodology for enhanced energy storage

A promising microsupercapacitor design was achieved by printing conductive ink composed of porous Co₃O₄ nanoparticles derived from ZIF-67 with in situ reduced graphene oxide (rGO) growth via thermal reduction. The symmetric micro-supercapacitor achieved an areal capacitance of 939 mF cm⁻², an energy density of 130.4 μW h cm⁻², and a power density of 2134 mW cm⁻², optimized via response surface methodology (RSM), with peak performance at 550 °C and a composite desirability of 86.48%. Additionally, it demonstrated exceptional cyclic stability, retaining 91.7% of its initial capacitance after 10 000 cycles of charge and discharge. The asymmetric device demonstrated even higher performance, with an areal capacitance of 1220.2 mF cm⁻², an energy density of 343.51 μW h cm⁻², and a power density of 3876.6 mW cm⁻², Similarly, the Co₃O₄/rGO-550 microsupercapacitor demonstrated 94.6% cycling stability even after 10 000 charge-discharge cycles, highlighting its durability and long-term performance.