Dedicated to the 80th birthday of Academician V.B. Kazanskii

O Radical Anions on Oxide Catalysts:
Formation, Properties, and Reactions

A. M. Volodin^a, *, S. E. Malykhin^a, and G. M. Zhidomirov^{a, b}

^a Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia

^b Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991 Russia

*e-mail: volodin@catalysis.ru

Received December 16, 2010

Abstract—A systematic in situ EPR study of processes yielding O^– radical anions on the surface of oxide
dielectrics (MgO, CaO), semiconductors (ZnO, TiO₂), supported systems (V/SiO₂), and zeolite FeZSM-5 is
reported. Methodological approaches to the study of O^– radical anions are considered for the cases in which
these species are directly undetectable by EPR. Particular attention is focused on the development of methods
of investigation of so-called -oxygen on the FeZSM-5 surface, which is an O^– radical anion stabilized on the
paramagnetic ion Fe³⁺. The reactions involving -oxygen and the analogous reactions known for O^– radical
anions stabilized on the oxide surface are demonstrated to occur in similar ways. The photostimulated formation of
spatially separated electron and hole centers on the surface of oxide systems is most likely due not to charge separa-
tion, but to the spatial separation of the radicals resulting from the homolytic photodissociation of chemisorbed water.
A scheme is suggested for this process on the partially hydroxylated MgO surface.

DOI: 10.1134/S0023158411040173

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