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

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 mull-doping of graphitic-N, pyridinic-N, Co-N-x 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.