Photoinduced decomposition of acetaldehyde on a reduced TiO2(110) surface: involvement of lattice oxygen.
We have investigated the photo-induced decomposition of acetaldehyde (CH3CHO) on TiO2(110) at 400 nm using temperature programmed desorption (TPD) and time of flight (TOF) methods. Formate (HCOO-) and acetate (CH3COO-) products have been detected. The initial step in the decomposition of CH3CHO on TiO2(110) is the formation of a CH3CHO bidentate intermediate in which the carbonyl O atom of CH3CHO is bound to the five-fold-coordinated Ti4+lattice site (Ti5c) and the carbonyl C atom is bound to a nearby bridge-bonded oxygen (BBO) atom. During 400 nm irradiation, the decomposition of the CH3CHO bidentate mainly occurs through two parallel pathways. Part of the CH3CHO bidentate on the surface undergoes a facile photoreaction to form formate by ejecting the methyl radical of CH3CHO into gas phase. The remaining CH3CHO bidentate reacts on the surface to produce acetate by transferring the H atom of -CHO to a BBO site or by ejecting the H atom into the vacuum. Thus we have found that BBO atoms are intimately involved in the photo-induced decomposition of CH3CHO on TiO2(110).
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, Liaoning, P. R. China. guoqing@dicp.ac.cn xmyang@dicp.ac.cn.
Chenbiao
C
Xu
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, Liaoning, P. R. China. guoqing@dicp.ac.cn xmyang@dicp.ac.cn.
Wenshao
W
Yang
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, Liaoning, P. R. China. guoqing@dicp.ac.cn xmyang@dicp.ac.cn.
Qing
Q
Guo
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, Liaoning, P. R. China. guoqing@dicp.ac.cn xmyang@dicp.ac.cn.
Dongxu
D
Dai
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, Liaoning, P. R. China. guoqing@dicp.ac.cn xmyang@dicp.ac.cn.
Xueming
X
Yang