The effect of carbon particle-size on N-doped carbon catalyst for oxygen reduction reaction in microbial fuel cells

Microbial fuel cell (MFC) is a new technology that combines wastewater treatment and bioenergy production. Platinum, as a commonly used catalyst for oxygen reduction reaction (ORR) in MFC, has hindered the development of MFC as the result of its high-cost. Consequently, developing effective and low-cost catalysts for ORR has aroused extensive research interest. The particle size effect is known to play an important role for catalyst. Three kinds of carbon powders with different grain sizes were chosen to prepare nitrogen-doped carbon powder (NDCP) as a low-cost catalyst for oxygen reduction in MFCs. The result showed that particle-size effect might be attributed to morphological changes of the relative concentration of surface atoms and nitrogen functional groups. As a result, the power density of NDCP with carbon 8000 mesh (739.2 mW m ^-2) was much higher than another two catalysts by 40% (carbon 10000 mesh, 413.1 mW m^-2) and 60% (carbon 3000 mesh, 248.5 mW m-2). In addition, carbon 8000 mesh exhibited a bit higher coulombic efficiency than carbon 10000 mesh and carbon 3000 mesh.