Low-cost adsorbent derived and in situ nitrogen/iron co-doped carbon as efficient oxygen reduction catalyst in microbial fuel cells

• In situ N/Fe co-doped carbon (N/Fe–C) is prepared from low-cost adsorbent.
• Electricity production is enhanced in MFCs with N/Fe–C compared to Pt/C.
• N/Fe–C is low-cost, environmental-friendly and makes waste profitable.

A novel low-cost adsorbent derived and in situ nitrogen/iron co-doped carbon (N/Fe–C) with three-dimensional porous structure is employed as efficient oxygen reduction catalyst in microbial fuel cells (MFCs). The electrochemical active area is significantly improved to 617.19 m2 g−1 in N/Fe–C by Fe-doping. And N/Fe–C (4.21 at.% N, 0.11 at.% Fe) exhibits excellent electrocatalytic activity with the oxygen reduction potential of −0.07 V (vs. Ag/AgCl) which is comparable to commercial Pt/C. In MFCs tests, the maximum power density and output voltage with N/Fe–C are enhanced to 745 mW m−2 and 562 mV (external resistance 1 kΩ), which are 11% and 0.72% higher than Pt/C (0.5 mg Pt cm−2), respectively. Besides, the long-term stability of N/Fe–C retains better for more than one week. Moreover, the charge transfer resistance (Rct) values are recorded by the impedance measurements, and the low Rct of N/Fe–C is also result in better catalytic activity.

Low-cost adsorbent derived N and Fe co-doped porous carbon was employed as efficient ORR catalyst in MFCs.Figure optionsDownload as PowerPoint slide