Synthesis of high-performance multifunctional electrode material using sweetwood lignin as a precursor

Abstract

We present a synthesis route for the highly efficient nitrogen-doped activated carbon material for ORR and supercapacitor application using a “sweetwood lignin” precursor as the carbon source via a thermochemical activation technique coupled with subsequent N-doping. The obtained nitrogen-doped activated carbon material had a high specific surface area of 2690 m² g⁻¹ and a large pore volume. The average pore size was 2.5 nm. The nitrogen content in the synthesized nitrogen-doped activated carbon material was ca. 3.9 at%. It was found that the nitrogen-doped activated carbon material based on sweetwood lignin exhibited excellent electrocatalytic activity towards the oxygen reduction reaction with onset and half-wave potentials of approximately 0.953 mV and 0.833 V, respectively, indicating a four-electron electron transport pathway in an alkaline 0.1 M KOH solution. In addition, the nitrogen-doped activated carbon material showed good durability when tested for 5000 cycles. The specific capacitance of approximately 106 F g⁻¹ was achieved in the 1 M Na₂SO₄ aqueous solution at the scan rate of 5 mV s⁻¹. Furthermore, the specific capacitance retained was 99% after 1000 cycles, indicating good electrochemical stability.