Oxygen reduction reaction (ORR) on a cathode is a key factor that limits the power generation and application of air-cathode microbial fuel cells. Tubular nitrogen-doped carbon materials synthesized by thermally annealing green foxtail with melamine were investigated as a metal-free electrocatalyst for efficient cathode ORR. Owing to the high specific surface area, tubular and porous structure, and abundant active centers of the pyridinic and graphite nitrogen incorporated carbon matrix, the nitrogen-doped carbon materials showed excellent activity toward ORR in a neutral electrolyte. Oxygen was reduced to water in a four electron reaction on the three-phase boundary of the as-prepared materials. The microbial fuel cell with the nitrogen-doped carbon electrocatalyst prepared at 800 °C had a satisfactory power density and better stability than commercial Pt/C due to its metal-free property and porous structure. Thus, nitrogen-doped carbon materials derived from economical and sustainable biomass could be a potential alternative for the metal-free ORR catalyst in microbial fuel cells with low cost and high electricity generation efficiency.

阴极上的氧还原反应（ORR）是限制空气阴极微生物燃料电池发电和应用的关键因素。研究了将绿色狐尾与三聚氰胺热退火合成的管状氮掺杂碳材料，作为有效阴极ORR的无金属电催化剂。由于高比表面积，管状和多孔结构以及吡啶和石墨氮结合的碳基质的丰富的活性中心，因此掺杂氮的碳材料在中性电解质中对ORR表现出优异的活性。在所制备材料的三相边界上，通过四电子反应，氧气被还原为水。具有商业化的Pt / C的，在800°C制备的掺氮碳电催化剂的微生物燃料电池，由于其无金属性能和多孔结构，具有令人满意的功率密度和更好的稳定性。因此，源自经济且可持续的生物质的氮掺杂碳材料可能以低成本和高发电效率成为微生物燃料电池中无金属ORR催化剂的潜在替代品。