Hierarchically porous N-doped carbon encapsulating CoO/MgO as superior cathode catalyst for microbial fuel cell

Abstract

Microbial fuel cell (MFC) has been considered a promising device to treat sewage and generate electricity. The cathode catalyst for oxygen reduction reaction is a critical factor affecting the performance of MFC. Herein, we prepared a nitrogen-doped porous carbon encapsulating CoO and MgO nanoparticles (CoO/MgO@NC) as cathode catalyst in air-cathode MFC. The maximum power density reached to 2258 ± 70 mW m−2, which was 58.3% higher than that of the control group NC (1426 ± 52 mW m−2). It was revealed that the excellent performance was partly attributed to the superior hierarchical porous structure which could provide both sufficient oxygen and more reactive sites. Besides, the multi-doping of graphitic-N, pyridinic-N, Co-Nx and Mg2+ reduced the diffusion and electron transfer resistance, promoted the H+ adsorption and electron transfer rate, and hence boosted the ORR performance. Moreover, the cost of the catalyst was only 5.4% of that of Pt/C. The porous nitrogen carbon with CoO and MgO, derived from chitosan, is an applicable cathode catalyst for its merits, such as excellent electrocatalytic activity, low cost, and ease of preparation.