Chemisorbed Oxygen Species over the (110) Face of SnO2

The electronic states of chemisorbed oxygen species on the (110) face of SnO2 and their variations caused by heat treatments and/or O2 exposure have been investigated. The reactivities of the chemisorbed oxygen species for methane oxidations were also examined.Four different chemisorbed oxygen species (O22-, O2-, O-, Ob) were observed, in addition to the lattice oxygen (O2-), on the surface of the stabilized (110) surface of SnO2 after O2 exposure. The Ob species was assumed to be the bridging oxygen at the topmost layer of the SnO2 (110) surface having no neighboring oxygen vacancies. The electronic state of Ob was converted to O- upon CH4 exposure at 473 K by coupling with newly produced vacancies at the bridging site of the SnO2 (110) surface.