A green, cheap, high-performance carbonaceous catalyst derived from Chlorella pyrenoidosa for oxygen reduction reaction in microbial fuel cells

摘要

Lack of low-cost, stable, and effective catalysts for the oxygen reduction reaction (ORR) is one of the key factors limiting the practical application of microbial fuel cells (MFCs). In this paper, a non-metal high-performance ORR catalyst, prepared by directly pyrolyzing Chlorella pyrenoidosa (CP) in N-2 atmosphere, was proposed. It was found that the ORR activity of the CP catalysts was highly dependent on the carbonization temperatures. The MFC with the catalyst carbonized at 900 degrees C (CP900) delivered the highest P-max (maximum power density) value of 2068 +/- 30 mW m(-2), which was 13% higher than that with commercial 20 wt% Pt/C (1826 +/- 37 mW m(-2)) at the same catalyst loading. CP900 also showed good structural stability, maintaining 57.4% of the activity after 10,000 s operation at -0.3 V (vs. Ag/AgCl), significantly higher than 48.5% for Pt/C. The Brunauer-Emmet-Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical analyses indicated that the superior performance of CP900 was due to the high graphitization, the appropriate N and P doping, and the improved catalyst utilization due to the presence of abundant mesopores and macropores. These results demonstrated that CP900 could be a cost-efficient, stable and high performance alternative to the commercial Pt/C for MFC applications. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.