Flower-like copper cobaltite nanosheets on graphite paper as high-performance supercapacitor electrodes and enzymeless glucose sensors

Flower-like copper cobaltite (CuCo₂O₄) nanosheets anchored on graphite paper have been synthesized using a facile hydrothermal method followed by a postannealing treatment. Supercapacitor electrodes employing CuCo₂O₄ nanosheets exhibit an enhanced capacitance of 1131 F g^-1 at a current density of 1 A g^-1 compared with previously reported supercapacitor electrodes. The CuCo₂O₄ electrode delivers a specific capacitance of up to 409 F g^-1 at a current density of as high as 50 A g^-1, and a good long-term cycling stability, with 79.7% of its specific capacitance retained after 5000 cycles at 10 A g^-1. Furthermore, the as-prepared CuCo₂O₄ nanosheets on graphite paper can be fabricated as electrodes and used as enzymeless glucose sensors, which exhibit good sensitivity (3.625 μA μM^-1 cm^-2) and an extraordinary linear response ranging up to 320 μM with a low detection limit (5 μM).