Porous graphitic carbon from mangosteen peel as efficient electrocatalyst in microbial fuel cells

In this study, a low-cost and efficient strategy to synthesize nitrogen self-doped porous graphitic carbon was proposed by using mangosteen peel as both the carbon and nitrogen source, combined with molten KOH activation and Co²⁺ catalytic graphitization. The mangosteen peel carbon catalyst prepared at 800 °C (referred to as MPC-800) possessed a large specific surface area (1168 m²/g), appropriate porous structure, high graphitization degree, and high pyridinic and graphitic nitrogen content. Further, electrochemical measurements indicated that the MPC-800 catalyst showed good oxygen reduction reaction activity. Moreover, MPC-800 as cathode catalyst displays an onset potential of 0.150 V (vs. Ag/AgCl) and half-wave potential of -0.091 V (vs. Ag/AgCl) in neutral medium, which is more positive than commercial Pt/C (0.121 V and -0.113 V, respectively). The maximum power density of microbial fuel cells using MPC-800 was 240 mW/m², which was slightly superior to that of the Pt/C cathode (220 mW/m²). This work proposed a novel method, based on the low cost and wide availability of waste mangosteen peel, to synthesize an excellent oxygen reduction reaction catalyst for microbial fuel cells.