Improvement of activated carbons as oxygen reduction catalysts in neutral solutions by ammonia gas treatment and their performance in microbial fuel cells
KAUST Grant NumberKUS-I1-003-13
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AbstractCommercially available activated carbon (AC) powders from different precursor materials (peat, coconut shell, coal, and hardwood) were treated with ammonia gas at 700 C to improve their performance as oxygen reduction catalysts in neutral pH solutions used in microbial fuel cells (MFCs). The ammonia treated ACs exhibited better catalytic performance in rotating ring-disk electrode tests than their untreated precursors, with the bituminous based AC most improved, with an onset potential of Eonset = 0.12 V (untreated, Eonset = 0.08 V) and n = 3.9 electrons transferred in oxygen reduction (untreated, n = 3.6), and the hardwood based AC (treated, E onset = 0.03 V, n = 3.3; untreated, Eonset = -0.04 V, n = 3.0). Ammonia treatment decreased oxygen content by 29-58%, increased nitrogen content to 1.8 atomic %, and increased the basicity of the bituminous, peat, and hardwood ACs. The treated coal based AC cathodes had higher maximum power densities in MFCs (2450 ± 40 mW m-2) than the other AC cathodes or a Pt/C cathode (2100 ± 1 mW m-2). These results show that reduced oxygen abundance and increased nitrogen functionalities on the AC surface can increase catalytic performance for oxygen reduction in neutral media. © 2013 Elsevier B.V. All rights reserved.
CitationWatson VJ, Nieto Delgado C, Logan BE (2013) Improvement of activated carbons as oxygen reduction catalysts in neutral solutions by ammonia gas treatment and their performance in microbial fuel cells. Journal of Power Sources 242: 756–761. Available: http://dx.doi.org/10.1016/j.jpowsour.2013.05.135.
SponsorsThe authors thank Vince Bojan for assistance with XPS analysis. The authors acknowledge support from the King Abdullah University of Science and Technology (KAUST) by Award KUS-I1-003-13 and the National Science Foundation Graduate Research Fellowship Program (NSF-GRFP).
JournalJournal of Power Sources