RuO2 nanoclusters embedded bunch-like Co3O4 nanowire array on nickel foam for high performance asymmetric supercapacitors

The progression of efficient electrode materials with higher electrochemical characteristics and better intrinsic activity, conductivity and stability is key to the development of supercapacitors. In this study, ultra-small RuO₂ nanoclusters are embedded into bunch-like Co₃O₄ nanowire array prepared by an impregnation-calcination process. A self-supported Co₃O₄ nanowire array on nickel foam is firstly synthesized by a hydrothermal-calcination way and utilized as a carrier for anchoring the RuO₂ nanoclusters. A bunch-like Co₃O₄ nanowire array is formed during the formation of RuO₂. In a three-electrode system at 1 A g⁻¹, the charge storage capacity of the as prepared RuO₂-Co₃O₄/NF (950.4 F g⁻¹) is 2.5 times higher than that observed in pristine Co₃O₄ (381.4 F g⁻¹). Additionally, an asymmetric supercapacitor (ASC) utilizing RuO₂-Co₃O₄/NF as cathode and activated carbon (AC) as anode exhibits good endurance, maintaining 89.7 % of its capacitance after 10,000 cycles, as well as excellent energy density (749.8 W kg⁻¹, 40.3 Wh kg⁻¹). Furthermore, it can keep a light-emitting diode rated at 2.5 V illuminating for 8 min. The investigation suggests that the RuO₂-Co₃O₄/NF composite material holds potential for the production of electrochemical supercapacitors.