@article { ISI:000264647800005,
	title = {Physico-chemical, photo-catalytic and O-2-adsorption properties of TiO2 nanotubes coated with gold nanoparticles},
	journal = {Journal of Photochemistry and Photobiology A-Chemistry},
	volume = {203},
	number = {1},
	year = {2009},
	month = {MAR},
	pages = {24-31},
	publisher = {ELSEVIER SCIENCE SA},
	address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND},
	abstract = {<p>Gold-containing titania nanotubes (Au/NT) were found to display higher activity for photooxidation of acetaldehyde, as compared to corresponding gold-free nanotubes and also a Degussa P-25 catalyst. Besides CO2 as a major reaction product, small amounts of H-2, CH4, CO, H2O and CH3COOH were also formed, irrespective of the catalyst employed. High-resolution TEM examination showed that most of the gold particles in Au/NT were of 1.5-5 nm size, distributed both within and at outside surface of the nanotubes. Some larger size (10-70 run) clusters were also seen at the external surfaces, particularly in the samples calcined at an elevated temperature. The temperature-programmed desorption measurements revealed that, compared to P-25 TiO2, a significant entrapment of O-2 occurred at two distinct tubular sites of NT samples, corresponding activation energy of desorption (E,) being around 36 and 41 kcal mol(-1). On the other hand, gold nanoparticles in Au/NT served as independent low-energy (E-a = 26 kcal mol(-1)) sites for adsorption/activation of O-2. These adsorptive properties of TiO2 and Au were lost completely on calcination, thus revealing a crucial role played by the particle size. In situ IR spectroscopy results showed that room-temperature exposure to acetaldehyde + air gave rise to a molecularly bound state, i.e. CH3CHOad, over both NT and Au/NTsamples, which in turn transformed quickly to yield certain acetate (CH3COOad-) and formate (HCOOad-) type transient species with the involvement of the surface OH groups. The decomposition and oxidation of these surface species with the help of O-2(-), O-ad and hydroxyl ion radicals (OH-) formed at photo-excited Au/NT interfaces led to the reaction products mentioned above. We conclude that, besides electron-hole charge separation, the adsorptive properties of host matrix and nanosize gold may together play a significant role in deciding the photo-catalytic properties of Au/TiO2. (C) 2008 Elsevier B.V. All rights reserved.</p>},
	keywords = {Acetaldehyde oxidation, Gold co-catalyst, O-2-adsorption, Photo-catalytic activity, TiO2 nanotubes},
	issn = {1010-6030},
	doi = {10.1016/j.jphotochem.2008.12.013},
	author = {Malwadkar, Sachin S. and Gholap, Ramkrishna S. and Awate, Shobhana V. and Korake, Prakash V. and Chaskar, Manohar G. and Gupta, Narendra M.}
}
