title: Revealing the adsorption mechanisms of nitroxides on ultrapure, metallicity-sorted carbon nanotubes.
abstract: Carbon nanotubes are a natural choice as gas sensor components given their high surface to volume ratio, electronic properties, and capability to mediate chemical reactions. However, a realistic assessment of the interaction of the tube wall and the adsorption processes during gas phase reactions has always been elusive. Making use of ultraclean single-walled carbon nanotubes, we have followed the adsorption kinetics of NO2 and found a physisorption mechanism. Additionally, the adsorption reaction directly depends on the metallic character of the samples. Franck-Condon satellites, hitherto undetected in nanotube-NOx systems, were resolved in the N 1s X-ray absorption signal, revealing a weak chemisorption, which is intrinsically related to NO dimer molecules. This has allowed us to identify that an additional signal observed in the higher binding energy region of the core level C 1s photoemission signal is due to the C ═ O species of ketene groups formed as reaction byproducts . This has been supported by density functional theory calculations. These results pave the way toward the optimization of nanotube-based sensors with tailored sensitivity and selectivity to different species at room temperature.
authors.affiliation: Faculty of Physics, University of Vienna , Strudlhofgasse 4, A-1090 Vienna, Austria.
authors.forename: Georgina
authors.initials: G
authors.lastname: Ruiz-Soria
authors.forename: Alejandro
authors.initials: A
authors.lastname: Pérez Paz
authors.forename: Markus
authors.initials: M
authors.lastname: Sauer
authors.forename: Duncan John
authors.initials: DJ
authors.lastname: Mowbray
authors.forename: Paolo
authors.initials: P
authors.lastname: Lacovig
authors.forename: Matteo
authors.initials: M
authors.lastname: Dalmiglio
authors.forename: Silvano
authors.initials: S
authors.lastname: Lizzit
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yanagi
authors.forename: Angel
authors.initials: A
authors.lastname: Rubio
authors.forename: Andrea
authors.initials: A
authors.lastname: Goldoni
authors.forename: Paola
authors.initials: P
authors.lastname: Ayala
authors.forename: Thomas
authors.initials: T
authors.lastname: Pichler