Tetra-heteroatom natural-doped activated carbon derived from cocoa leaf waste for advanced symmetric supercapacitors

The high-value utilization and sustainable development of biomass-based energy provided a feasible route to solve the energy shortage and environmental problems. Here, a facile and efficient technique to obtain activated carbon was innovatively developed in this work using a one-step physicochemical activation method combined with the tetra-heteroatom natural-doped strategy from cocoa leaf waste. The obtained activated carbon materials (CLAC₈₅₀) have a high Brunauer-Emmet-Teller surface area (S_BET) of 379 m² g⁻¹ with a maximum specific capacitance (C_s) of 202 F g⁻¹ at 1 A g⁻¹ and a significant number of heteroatoms (O: 26.42 at.%, Mg: 1.36 at.%, Si: 5.65 at.%, and Ca: 1.95 at.%). The device also delivers a high specific energy of 28.7 Wh kg⁻¹ at 535.3 W kg⁻¹. Overall, this work demonstrated that the natural heteroatom-doped strategy was beneficial for growth of heteroatom functional groups, which provide a combination of EDLC and pseudocapacitance behavior. The findings indicate a new facile and efficient route for synthesizing activated carbon with natural heteroatom-doped for symmetric and asymmetric supercapacitor applications.