EPFR Formation from Phenol adsorption on Al2O3 and TiO2: EPR and EELS studies

View/ Open
Date
2012Author
Kiruri, L.W.
Patterson, Matthew C.
Keilbart, Nathan D.
Thibodeaux, Chad A.
Lomnicki, Slawo
Kurtz, Richard L.
Poliakoff, E. D.
Dellinger, Barry
Sprunger, Phillip T.
Metadata
Show full item recordAbstract
We have examined the formation of environmentally persistent free radicals (EPFRs) from phenol over alumina and titania using both powder and single-crystal samples. Electron paramagnetic resonance (EPR) studies of phenol adsorbed on metal oxide powders indicates radical formation on both titania and alumina, with both oxides forming one faster-decaying species (lifetime on the order of 50-100 hours) and one slower-decayng species (lifetimes on the order of 1000 hours or more). Electron energy loss spectroscopy (EELS) measurements comparing physisorbed phenol on single-crystal TiO2(110) to phenoxyl radicals on the same substrate indicate distinct changes in the π-π* transitions from phenol after radical formation. The identical shifts are observed from EELS studies of phenoxyl radicals on ultrathin alumina grown on NiAl(110), indicating that this shift in the π-π* transition may be taken as a general hallmark of phenoxyl radical formation.
URI
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3891583/http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3891583/pdf/nihms-432146.pdf
http://ir-library.ku.ac.ke/handle/123456789/11476