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Photocatalytic Oxidation of CO on TiO 2 : Chemisorption of O 2 , CO, and H 2
Author(s) -
Dai Wenxin,
Chen Xun,
Zheng Xiangping,
Ding Zhengxin,
Wang Xuxu,
Liu Ping,
Fu Xianzhi
Publication year - 2009
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200800465
Subject(s) - photocatalysis , chemisorption , oxidizing agent , adsorption , oxygen , chemistry , inorganic chemistry , catalysis , vacancy defect , photochemistry , crystallography , organic chemistry
On the surface : Adsorption of O 2 at the surface oxygen vacancy (SOV) sites of TiO 2 reconstructs the lattice oxygen (healing SOVs), resulting in a decrease of the photocatalytic activity of oxidizing CO over vacuum‐pretreated TiO 2 with increasing temperature (see scheme). Adsorption of H 2 produces new SOVs at the TiO 2 surface and stabilizes the photocatalytic activity.Photocatalytic oxidation of CO over vacuum‐pretreated TiO 2 is performed in a series of systems with the introduction of O 2 , CO, and H 2 in different orders. The photocatalytic oxidation of CO is dependent on the order of introduction of O 2 , CO, or H 2 , and introducing O 2 prior to CO promotes the oxidation of CO. Moreover, an increase of reaction temperature suppresses the oxidation of CO, but the preintroduction of H 2 reduces this suppression effect. The results of the chemisorption of O 2 , CO, and H 2 at the TiO 2 surface reveal that the adsorbed O 2 heals the surface oxygen vacancy (SOV) sites of TiO 2 , while the adsorbed CO and H 2 promote the formation of new SOVs. It is proposed that changes in the amounts of adsorbed O 2 and SOVs are mainly responsible for the differences of CO conversion in different systems.