Highly active N-doped non-precious transition metal Fe@N-C catalysts for efficient oxygen reduction reaction in microbial fuel cells

In this study, highly active and stable N-doped porous carbon Fe(x)@N-C (x stands for the Fe/terephthalic acid molar ratio) catalysts were prepared from MIL-53(Fe) using inexpensive acetonitrile as N source and their electrochemical performances were also tested. The Fe(x)@N-C showed mainly zero-valent iron phase with small amount of Fe3C phase. Among all the prepared composites, Fe(0.3)@N-C possessed the largest surface area and pore volume, and largest number of Fe-Nx active sites. The MFC with Fe(0.3)@N-C presented the greatest open voltage of 0.60 V among Fe(x)@N-C, which is closer to the MFC with Pt/C (0.61 V). The power density of Fe(0.3)@N-C in MFC was 604.6 mW center dot m(-2). The MFC output voltage of Fe(0.3)@N-C was stabilized at 0.58 +/- 0.01 V and maintained at this value for 75 days. The Fe(0.3)@N-C had comparable MFC output voltage as Pt/C and possessed much superior stability to Pt/C, showing a great potential for industrial application in MFC.