Khanderi, Jayaprakash ; Hoffmann, Rudolf C. ; Engstler, Jörg ; Schneider, Jörg J. ; Arras, Jürgen ; Claus, Peter ; Cherkashinin, Gennady (2010)
Binary Au/MWCNT and Ternary Au/ZnO/MWCNT Nanocomposites: Synthesis, Characterisation and Catalytic Performance.
In: Chemistry – A European Journal, 16 (7)
doi: 10.1002/chem.200901987
Article, Bibliographie

Abstract

Gold nanoparticles of 10-24 and 5-8 nm in size were obtained by chemical citrate reduction and UV photoreduction, respectively, on acid-treated multiwalled carbon nanotubes (MWCNTs) and on ZnO/MWCNT composites. The shape and size of the deposited Au nanoparticles were found to be dependent upon the synthetic method used. Single-crystalline, hexagonal gold particles were produced in the case of UV photoreduction on ZnO/MWCNT, whereas spherical Au particles were deposited on MWCNT when the chemical citrate reduction method was used. In the UV photoreduction route, n-doped ZnO serves as the e- donor, whereas the solvent is the hole trap. All materials were fully characterised by UV/Vis spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and BET surface analysis. The catalytic activity of the composites was studied for the selective hydrogenation of α,β-unsaturated carbonyl compound 3,7-dimethyl-2,6-octadienal (citral). The Au/ZnO/MWCNT composite favours the formation of unsaturated alcohols (selectivity=50 % at a citral conversion of 20 %) due to the presence of single-crystalline, hexagonal gold particles, whereas saturated aldehyde formation is favoured in the case of the Au/MWCNT nanocomposite that contains spherical gold particles.

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