Functional utilization of biochar derived from Tenebrio molitor feces for CO2 capture and supercapacitor applications

Abstract

Biochar has attracted great interest in both CO₂ capture and supercapacitor applications due to its unique physicochemical properties and low cost. Fabrication of eco-friendly and cost-effective biochar from high potential biomass Tenebrio molitor feces can not only realize the functional application of waste, but also a potential way of future carbon capture and energy storage technology. In this study, a novel KOH activation waste-fed Tenebrio molitor feces biochar (TMFB) was developed and investigated in terms of CO₂ capture and electrochemical performance. When activated at 700 °C for 1 h, the specific surface area of the feces biochar (TMFB-700A) increased significantly from 232.1 to 2081.8 m² g⁻¹. In addition, well-developed pore distribution facilitates CO₂ capture and electrolyte diffusion. TMFB-700A can quickly adsorb a large amount of CO₂ (3.05 mol kg⁻¹) with excellent recycling performance. TMFB-700A also exhibited promising electrochemical performance (335.8 F g⁻¹ at 0.5 A g⁻¹) and was used as electrode material in a symmetrical supercapacitor. It provided a high energy density of 33.97 W h kg⁻¹ at a power density of 0.25 kW kg⁻¹ with 90.47% capacitance retention after 10 000 charge–discharge cycles. All the results demonstrated that TMFB could be a potential bifunctional material and provided valuable new insights for Tenebrio molitor feces high-value utilization.