TY - JOUR
T1 - Reconciliation of carbon oxidation rates and activation energies based on changing nanostructure
AU - Gaddam, Chethan K.
AU - Vander Wal, Randy L.
AU - Chen, Xu
AU - Yezerets, Aleksey
AU - Kamasamudram, Krishna
N1 - Publisher Copyright:
© 2015 Elsevier Ltd. All rights reserved.
PY - 2016/3/1
Y1 - 2016/3/1
N2 - HRTEM reveals the nanostructure of the model carbons and changes therein due to oxidation. The variation in oxidation rates during the oxidation process highlights the dependence of oxidation rates on carbon nanostructure and in particular, the carbon atom site types. Changes in nanostructure necessarily occur with change in the relative proportion of site types. In turn, the oxidation rate changes accordingly. An inside-out burning mode, onion peeling, graphitization and edge site creation are behaviors observed during the course of oxidation of the model carbons. The rate for arc-generated soot falls off exponentially while that for M1300, a carbon black exhibits a parabolic increase. R250, another carbon black maintains a constant rate, lower than that for graphitized multi-walled carbon nanotubes (MWCNTs) or graphitic carbon onions. The former exhibit exclusive interior oxidation while the latter graphitic materials exhibit only edge site oxidation. XPS confirmed the interpretation of graphitic lamella that was restricting further oxidation for the arc soot, by showing an increase in the sp2/sp3 content. Raman spectra are related to oxidation induced defects in the MWCNTs and onions.
AB - HRTEM reveals the nanostructure of the model carbons and changes therein due to oxidation. The variation in oxidation rates during the oxidation process highlights the dependence of oxidation rates on carbon nanostructure and in particular, the carbon atom site types. Changes in nanostructure necessarily occur with change in the relative proportion of site types. In turn, the oxidation rate changes accordingly. An inside-out burning mode, onion peeling, graphitization and edge site creation are behaviors observed during the course of oxidation of the model carbons. The rate for arc-generated soot falls off exponentially while that for M1300, a carbon black exhibits a parabolic increase. R250, another carbon black maintains a constant rate, lower than that for graphitized multi-walled carbon nanotubes (MWCNTs) or graphitic carbon onions. The former exhibit exclusive interior oxidation while the latter graphitic materials exhibit only edge site oxidation. XPS confirmed the interpretation of graphitic lamella that was restricting further oxidation for the arc soot, by showing an increase in the sp2/sp3 content. Raman spectra are related to oxidation induced defects in the MWCNTs and onions.
UR - http://www.scopus.com/inward/record.url?scp=84955255199&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84955255199&partnerID=8YFLogxK
U2 - 10.1016/j.carbon.2015.11.035
DO - 10.1016/j.carbon.2015.11.035
M3 - Article
AN - SCOPUS:84955255199
SN - 0008-6223
VL - 98
SP - 545
EP - 556
JO - Carbon
JF - Carbon
ER -