Electrocatalysis of N-doped Carbons in the Oxygen Reduction Reaction as a function of pH: N-sites and Scaffold Effects
Citation:
Behan, J. A.; Iannaci, A.; Domínguez, C.; Stamatin, S. N.; Hoque, M. K.; Vasconcelos, J. M.; Perova, T.; Colavita, P. E, Electrocatalysis of N-doped Carbons in the Oxygen Reduction Reaction as a function of pH: N-sites and Scaffold Effects, Carbon, 148, 2019, 224 - 230Abstract:
Metal-free nitrogenated amorphous carbon electrodes were synthesised via dc plasma
magnetron sputtering and post-deposition annealing at different temperatures. The
electrocatalytic activity of the electrodes towards the oxygen reduction reaction (ORR) was
studied as a function of pH using cyclic voltammetry with a rotating disk electrode. The
trends in onset potential were correlated to the carbon nanostructure and chemical
composition of the electrodes as determined via Raman spectroscopy and X-ray
photoelectron spectroscopy analysis. Results suggest that: 1) the ORR activity in acidic
conditions is strongly correlated to the concentration of pyridinic nitrogen sites. 2) At high
pH, the presence of graphitic nitrogen sites and a graphitized carbon scaffold are the strongest
predictors of high ORR onsets, while pyridinic nitrogen site density does not correlate to
ORR activity. An inversion region where pyridine-mediated activity competes with graphiticN mediated activity is identified in the pH region close to the value of pKa of the pyridinium
cation. The onset of the ORR is therefore determined by the activity of different sites as a
function of pH and evidence for distinct reduction reaction pathways emerges from these
results.
Sponsor
Grant Number
Irish Research Council (IRC)
GOIPG/2014/399
Marie Curie
748968 (FREMAB) and 799175 (HiBriCarbon)
Science Foundation Ireland (SFI)
13/CDA/2213
Author's Homepage:
http://people.tcd.ie/colavitpDescription:
PUBLISHED
Author: Colavita, Paula
Sponsor:
Irish Research Council (IRC)Marie Curie
Science Foundation Ireland (SFI)
Type of material:
Journal ArticleCollections
Series/Report no:
Carbon;148;
Availability:
Full text availableKeywords:
Electrocatalysis, Carbon electrodesSubject (TCD):
Nanoscience & MaterialsDOI:
https://doi.org/10.1016/j.carbon.2019.03.052Metadata
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