ZnO CVD 检测.pptVIP

VI Convegno Nazionale sulla Scienza e Tecnologia dei Materiali – Perugia 12-15 Giugno 2007 CVD SYNTHESIS AND PHOTOCATALYTIC ACTIVITY OF ZnO NANOPLATELETS PHOTOCATALYSIS Photocatalytic Activity depends on: Zn(hfa)2?TMEDA (Hhfa=1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA=N,N,N’,N’-tetramethyilethylendiamine) ZnO(001) Surface  Zn(hfa)2?TMEDA - CARATTERIZZAZIONE * VI Convegno Nazionale sulla Scienza e Tecnologia dei Materiali – Perugia 12-15 Giugno 2007 C. Maccato*2, D. Barreca1, A. P. Ferrucci2, A. Gasparotto2, C. Maragno2, E. Tondello2 1 ISTM-CNR and INSTM - Padova, Italy 2 Department of Chemistry - Padova University and INSTM - Padova, Italy *chiara.maccato@unipd.it Padova University ISTM-CNR INSTM Zinc oxide (ZnO) Wurtzite (hexagonal lattice) n-type semiconductor EG?3.4 eV Main interests: ? Optoelectronics ? Gas Sensing ? Energetics ? Photocatalysis O Zn A? ˉ Valence Band + Conduction Band h? Eg Reduction A Oxidation D- D? The aim of semiconductor photocatalysis is to effectively decompose organic pollutants. Photons are used to create electron – hole pairs in the semiconductor. e- + O2 → O2- h+ + OH- → OH? The competition between separation and recombination processes of charge carriers (e-, h+). Surface catalysts-dye charge transfer and efficient surface adsorption/desorption processes. AIM: Synthesis of nanosystems characterized by a high surface/volume ratio using a bottom-up CVD approach . Zn(NO)3·xH2O + 1,1,1,5,5,5-hexafluoro-2,4-pentanedione + N,N,N’,N’-tetramethylethylendiamine Zn(hfa)2(TMEDA) Yield = 63% Tobin J. Marks et al., J. Am. Chem. Soc., (2005) 127, 5613. Zn O H F N C 2nd Generation precursor high volatility and thermal stability one-pot synthesis ZnO NANOSYSTEMS Zn(hfa)2(TMEDA) CVD Si(100) ZnO F(O2+H2O) = 40 sccm F(N2) = 40 sccm 10 mbar, 60’ T[Zn(hfa)2(TMEDA)] = 60°C Tsub. = 250-500°C Thickness [Φ(O2+H2O)] Tsub. 250 300 350 400 450 111 128 256 209 128 64 nm 500 °C