Hierarchical porous carbon derived from recycled waste filter paper as high-performance supercapacitor electrodes

Abstract

Hierarchical activated porous carbon (APC) was synthesized through convenient chemical activation with ZnCl₂ using recycled waste filter paper as the carbon precursor. The micro/mesopore ratio, pore volume and specific surface area of these APC materials could be controlled by adjusting the dosage of the ZnCl₂ chemical agent and the activation temperature. The optimal sample, APC-7-4, was activated at 700 °C with a ZnCl₂/carbon precursor mass ratio of 4 : 1, and exhibited a large surface area of 2169.8 m² g⁻¹, a suitable pore size and prominent porosity. Remarkably, when the resultant APC-7-4 material acted as the electrode material for a supercapacitor, APC-7-4 displayed an outstanding charge storage capacity with a satisfactory specific capacitance of 302.3 F g⁻¹ in 6 M KOH at a current density of 1 A g⁻¹. Moreover, the APC-7-4 electrode possessed good long-term cycling stability, and ca. 95.4% of its initial specific capacitance at 5 A g⁻¹ was retained even after 10 000 cycles. Based on these electrochemical test results, the approach proposed in this work provides a new view of converting waste products to design high-performance carbon-based electrode materials for great and promising applications in electric double-layer capacitors.