Issue 4, 2020

Pomelo peel-derived, N-doped biochar microspheres as an efficient and durable metal-free ORR catalyst in microbial fuel cells

Abstract

Microbial fuel cells (MFCs) are widely explored for promising green and renewable energy generation; however, their strong reliance on noble metal-based catalysts causes high fabrication costs and thus limits their widespread applications. Herein, metal-free alternatives derived from naturally abundant, renewable pomelo peels are explored. Two kinds of pomelo peel-derived novel N-doped carbocatalysts are presented, i.e., biochar microspheres (BCMs) and their activated porous counterpart (a-BCMs). In comparison with BCMs, the thermal activation processing endowed a-BCMs with significantly enhanced porosity, an elevated N doping content (2.41 vs. 0.51 at%), a 5-fold increased specific surface area (314.3 vs. 62.8 m2 g−1), and a much improved electrical conductivity (0.13 vs. 0.006 S cm−1). This metal-free a-BCM catalyst is subsequently employed to construct an MFC cathode for the oxygen reduction reaction (ORR), and an impressive electrocatalytic activity is achieved in 0.1 mol L−1 phosphate-buffered saline (PBS) buffer. The maximum power density reaches as high as 907.2 mW m−2, comparable to that of the costly Pt/C counterpart (1022.9 mW m−2). The long-term durability of the a-BCM electrocatalyst is also demonstrated by continuous running for 90 days, even superior to that of Pt/C. The origin of this excellent electrocatalytic performance of a-BCMs is deeply analyzed and discussed. Furthermore, the 4e reduction pathway is also unraveled for the efficient and durable carbocatalysis of the ORR over a-BCMs in MFCs.

Graphical abstract: Pomelo peel-derived, N-doped biochar microspheres as an efficient and durable metal-free ORR catalyst in microbial fuel cells

Supplementary files

Article information

Article type
Paper
Submitted
21 sept. 2019
Accepted
11 nov. 2019
First published
12 nov. 2019

Sustainable Energy Fuels, 2020,4, 1642-1653

Pomelo peel-derived, N-doped biochar microspheres as an efficient and durable metal-free ORR catalyst in microbial fuel cells

Y. Zhang, L. Deng, H. Hu, Y. Qiao, H. Yuan, D. Chen, M. Chang and H. Wei, Sustainable Energy Fuels, 2020, 4, 1642 DOI: 10.1039/C9SE00834A

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