Photocatalytic H2 Production from Ethanol–Water Mixtures Over Pt/TiO2 and Au/TiO2 Photocatalysts: A Comparative Study
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文摘
Pt/TiO2 (Pt loadings 0-?wt%) and Au/TiO2 (Au loadings 0-?wt%) photocatalysts were synthesized, characterized and tested for H2 production from ethanol–water mixtures (80?vol% ethanol, 20?vol% H2O) under UV excitation. Average metal nanoparticle sizes determined by TEM were 1-?nm for Pt in the Pt/TiO2 photocatalysts and 5-?nm for Au in the Au/TiO2 photocatalysts. Au/TiO2 showed an intense localized surface plasmon resonance feature at ~570?nm, typical for metallic Au nanoparticles of diameter ~5?nm supported on TiO2. X-ray photoelectron spectroscopy and X-ray diffraction analyses established that Pt and Au were present in metallic form on the TiO2 support. X-ray fluorescence revealed close accord between nominal and actual Pt and Au loadings. The Au/TiO2 and Pt/TiO2 photocatalysts both displayed very high activities for H2 production under UV irradiation, with the Au/TiO2 samples affording slightly superior rates of H2 production at most metal loadings. The 2?wt% Au/TiO2 and 1?wt% Pt/TiO2 photocatalysts showed the highest H2 production rates (32-4 mmol?g??h?). Photoluminescence studies confirmed that Pt and Au nanoparticles positively enhance the photocatalytic properties of P25 TiO2 for H2 production by acting as electron acceptors and thereby suppressing electron–hole pair recombination in TiO2.

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