Three-dimensional N-doped super-hydrophilic carbon electrodes with porosity tailored by Cu2O template-assisted electrochemical oxidation to improve the performance of electrical double-layer capacitors

Abstract

Three-dimensional (3D), binder-free, porous carbon-based electrodes exhibit high charge storage ability in electrical double-layer capacitors owing to their well-developed porous structures enhancing mass transfer and achieving relatively high electroconductivity. A 3D N-doped carbon electrode with abundant oxygen-containing functional groups was prepared by depositing a PDA-derived N-doped carbon layer and electrochemical oxidation using a porosity-regulating in situ generated Cu₂O sacrificial template. The optimized electrode demonstrated a high specific capacitance of 2852 mF cm⁻² at a current density of 1 mA cm⁻² and good rate capability. The material was used as an electrode in a symmetric capacitor, exhibiting an energy density of 16.4 mW h cm⁻³ at a power density of 180 mW cm⁻³, which maintained 89% of its value after 15 000 cycles. This study describes a new method of manufacturing high-performance porous electrodes suitable for practical application in electric double-layer capacitors.