Flexible 3D hierarchical porous NiCo₂O₄/CC electrode decorated by nitrogen-doped carbon from polyaniline carbonization for high-performance supercapacitors

Atomic doping is considered as an effective method to prepare high-active conductivity-improved electrochemical materials. We report the utilization of a three-dimensional hierarchical porous nitrogen-doped carbon–NiCo₂O₄/CC as the flexible supercapacitor electrodes and recycled biosensor. In a hydrothermal process, three-dimensional hierarchical needle-like NiCo₂O₄/CC arrays were prepared by one-step, which changed to the mulberry-like morphology after in situ deposition of polyaniline nanoparticles on NiCo₂O₄/CC. Upon polyaniline carbonization at high temperature, the resulting porous nitrogen-doped carbon–NiCo₂O₄ showed uniform nanorod networks and dramatic improvements in the electrolyte affinity, penetration and ionic motion. The obtained electrodes display good flexibility and large areal specific capacitance of 3.0 F cm⁻² (2520 F g⁻¹) at the current density of 1.0 mA cm⁻², with energy density of 171.5 Wh kg⁻¹ and power density of 1118.4 W kg⁻¹. After 10000 cycles, the capacitance retention rate reaches 90.79%. The prepared NiCo₂O₄-based composites display design novelty and promising applications in the flexible supercapacitors with large capacitance and high stability.