Direct growth of CuCo2S4 nanosheets on carbon fiber textile with enhanced electrochemical pseudocapacitive properties and electrocatalytic properties towards glucose oxidation

Abstract

Flexible and wearable electronic devices with excellent performance have been desired for making the next generation of electronic products. Herein, the synthesis of CuCo₂S₄ nanosheets on flexible carbon fiber textile (CFT) by a facile one-step and scalable hydrothermal procedure is reported, which is free from the sulphurization process used in the conventional synthesis of mixed metal sulphospinels. The as-prepared CuCo₂S₄ nanostructures on CFT can provide rich reaction sites and short ion diffusion paths. The CuCo₂S₄ nanosheets are employed as the free-standing electrodes for two different applications: high-performance supercapacitors and non-enzymatic glucose sensors. When employed as a flexible electrode material for supercapacitors, the electrode presents ultrahigh performance in energy storage with a specific capacitance of 3321.6 F g⁻¹ at 5 A g⁻¹, which is attributed to the suitable mass loading and special morphology of the as-prepared nanosheets. Remarkably, a specific capacitance of 2931.4 F g⁻¹ is still retained at the high current density of 30 A g⁻¹, suggesting its excellent rate capability. The specific capacitance retains 87.1% after 3000 cycles, reflecting excellent cycling performance. For real applications, a flexible symmetric supercapacitor is assembled based on CuCo₂S₄ nanosheets, which achieves a high energy density of 64.6 W h kg⁻¹ at 499.7 W kg⁻¹ and a maximum power density of 2081.5 W kg⁻¹ at 45.1 W h kg⁻¹. Besides serving as a free-standing electrode for non-enzymatic glucose sensors, CuCo₂S₄ nanosheets have remarkable electrocatalytic activity towards glucose oxidation with a high sensitivity of 3852.7 μA mM⁻¹ cm⁻² and an extraordinary linear range up to 3.67 mM. The experimental results suggest that CuCo₂S₄ nanosheets are more suitable for non-enzymatic glucose sensors than the related single/binary transition metal oxides/sulfides. Such a superior performance demonstrates that CuCo₂S₄ nanosheets hold great potential for use as flexible multifunctional electronic devices including supercapacitors and non-enzymatic glucose sensors.