from first principles PP-I-1

PP-V-4Efficient Photocatalytic Decomposition of Nitric Oxideover TiO 2 -Based Nanotubes CatalystChien S.-H., Huang K.-Ch.Institute of Chemistry, Academia Sinica, Taipei 11529, TaiwanDepartment of Chemistry, National Taiwan University, Taipei 10674, Taiwanchiensh@gate.sinica.edu.twTiO 2 -based nanotubes were prepared by microwave-assisted hydrothermal procedure, withTiO 2 powder immersed in relatively concentrated (5 M) NaOH solution and treatedhydrothermally under microwave irradiation at 220°C for 30 min. The high resolutiontransmittance microscopy revealed a multi-layered open-ended nanotube morphology, withseveral hundred nanometers in length, 3 - 5 nm of inner diameter and 8 - 10 nm of outerdiameter. The XRD profile exhibited the typical diffraction peaks of titania nanutube asobtained from conventional hydrothermal method [1]. Nearly 300 m 2 /g of BET surface areaand 1.42 cm 3 /g of pore volume were obtained by nitrogen adsorption isotherm at 77 K. Theadsorption capacity and the mechanism of photocatalytic decomposition of nitric oxide (NO)were investigated by in-situ EPR spectroscopic studies and the resulted products wereanalyzed by a quadropole mass residual gas analyzer as in our previous study [2]. The resultsindicated that the catalyst activity for photodecomposition of NO was highly dependent on itspre-treatment. The hydrogen-reduced catalyst exhibited high catalytic activity for NOdecomposition under UV (300 nm) irradiation. The conversion of NO reached nearly 100% in15 min under UV irradiation with 82% of N 2 selectivity. The present study indicated that thetitania nanotubes would be a potentially efficient photocatalysts for NO reduction that leads toa direct conversion of NO into N 2, with no need of a reducing agent such as NH 3 used in theselective catalytic reduction (SCR) of NO that usually causes secondary pollution.References:[1] T. Kasuga, M. Hiramatsu, A. Hoson, T. Sekino, K. Nihara, Adv. Mater. 11 (1999) 1307.[2] S.H. Chien, K.C. Huang, M.C. Kuo, Stud. Surf. Sci. Catal. 154 (2004) 2876.313