Nitrogen-enriched activated carbons from waste particleboard used as electrode materials for supercapacitors: effects of activating agent on surface characteristics

Abstract

Nitrogen-enriched activated carbon was prepared from waste particleboard by a chemical activation method, where partially carbonized waste particleboard was treated with KOH in different ratio. The porosity and nitrogen content of the nitrogen-enriched activated carbons depend strongly on the weight ratio of KOH/carbonization. As the weight ratio of KOH/carbonization increases from 2 to 5, the specific surface area increases from 1498 to 1826 m² g⁻¹, while the nitrogen content decreases from 2.86 to 1.32 wt%. These nitrogen-enriched activated carbons are tested as electrode material in two-electrode symmetric supercapacitor system in 7 M KOH electrolyte and found to exhibit high specific capacitance with excellent retention of it at high current density and for long term operation. In particular, the nitrogen-enriched activated carbon prepared with a moderate KOH/carbonization weight ratio of 3, which possesses a balanced specific surface area (1758 m² g⁻¹) and nitrogen content (2.38 wt%) exhibits the largest specific capacitance of 263 F g⁻¹ at 0.05 A g⁻¹, attributed to the co-contribution of double-layer capacitance and pseudo-capacitance. Moreover, it shows excellent rate capability (228 F g⁻¹ at 10 A g⁻¹) and good cycling stability (over 95% capacitance retention over 3000 cycles), making it a promising electrode material for supercapacitors.