TY - JOUR
T1 - In-situ FTIR study of adsorption and photoreactions of CH 2Cl2 on powdered TiO2
AU - Chen, Meng Tso
AU - Lien, Chen Fu
AU - Liao, Li Fen
AU - Lin, Jong Liang
N1 - Funding Information:
This work was supported in part by the National Science Foundation under EAR-0105322. Lee Slater also acknowledges support from the University of Missouri Research Board and a University of Missouri Faculty Research Grant. He is grateful for this support. Graduate students Danney Glaser and Robin Evensen provided invaluable field support, for which we extend our thanks. We also thank Maine Agricultural and Forestry Experiment Station for supporting this work. The constructive review comments of John Lane, William Sauck, Philip Carpenter, and Mark Vend1 improved the quality of this manuscript.
PY - 2003/4/24
Y1 - 2003/4/24
N2 - The adsorption and photoreactions of CH2Cl2 on powdered TiO2 have been investigated by Fourier transform infrared spectroscopy. CH2Cl2 is adsorbed molecularly or dissociatively to form chloromethoxy (CClH2O(a)) at 35 °C. CClH2O(a) decomposes into CH3Oj (a) and HCOO(a) in a vacuum at temperatures higher than ~100 °C. As TiO2 in contact with gaseous CH2Cl 2 is heated in a closed cell, HCI from Cl(a) and OH (a) recombination, CH2O from CH3O(a) decomposition, and CO and CO2 from HCOO(a) decomposition are detected. In the CH2Cl2(a) photodecomposition in the absence of O2, CO(a), CO 3(a), and HCOO(a) are generated. The TiO 2-mediated CH2Cl2(a) photodecomposition is likely initiated by surface-active oxygen species instead of direct hole transfer. In the presence of O2, CH2Cl 2(a) photodecomposition is accelerated. In addition to CO(a), CO3(a), and HCOO(a), H 2O(a) and CO2(a) are generated as well. In the case of CO(a) formation, O2 is also involved in addition to TiO2 lattice oxygen. The O2 participation may be via oxygen anion species.
AB - The adsorption and photoreactions of CH2Cl2 on powdered TiO2 have been investigated by Fourier transform infrared spectroscopy. CH2Cl2 is adsorbed molecularly or dissociatively to form chloromethoxy (CClH2O(a)) at 35 °C. CClH2O(a) decomposes into CH3Oj (a) and HCOO(a) in a vacuum at temperatures higher than ~100 °C. As TiO2 in contact with gaseous CH2Cl 2 is heated in a closed cell, HCI from Cl(a) and OH (a) recombination, CH2O from CH3O(a) decomposition, and CO and CO2 from HCOO(a) decomposition are detected. In the CH2Cl2(a) photodecomposition in the absence of O2, CO(a), CO 3(a), and HCOO(a) are generated. The TiO 2-mediated CH2Cl2(a) photodecomposition is likely initiated by surface-active oxygen species instead of direct hole transfer. In the presence of O2, CH2Cl 2(a) photodecomposition is accelerated. In addition to CO(a), CO3(a), and HCOO(a), H 2O(a) and CO2(a) are generated as well. In the case of CO(a) formation, O2 is also involved in addition to TiO2 lattice oxygen. The O2 participation may be via oxygen anion species.
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U2 - 10.1021/jp0220884
DO - 10.1021/jp0220884
M3 - Article
AN - SCOPUS:2442709984
VL - 107
SP - 3837
EP - 3843
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 16
ER -