H2 Generation with (Mixed) Plasmonic Cu/Au‐TiO2 Photocatalysts: Structure–Reactivity Relationships Assessed by in situ Spectroscopy

Monometallic Cu and bimetallic Cu/Au‐TiO2 catalysts were prepared by impregnation (IM) and reductive precipitation (RP) methods in sequential (SP) and simultaneous mode (CP) and tested for photocatalytic H2 generation from H2O/methanol mixtures with visible (400–700 nm) and UV/Vis light (320–500 nm)...

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Bibliographic Details
Published in:ChemCatChem 2017-03, Vol.9 (6), p.1025-1031
Main Authors: Priebe, Jacqueline B., Radnik, Jörg, Kreyenschulte, Carsten, Lennox, Alastair J. J., Junge, Henrik, Beller, Matthias, Brückner, Angelika
Format: Article
Language:English
Subjects:
bimetallic catalysts
hydrogen generation
in situ spectroscopy
photocatalysis
Spectrum analysis
surface plasmon resonance
X-rays
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Summary:Monometallic Cu and bimetallic Cu/Au‐TiO2 catalysts were prepared by impregnation (IM) and reductive precipitation (RP) methods in sequential (SP) and simultaneous mode (CP) and tested for photocatalytic H2 generation from H2O/methanol mixtures with visible (400–700 nm) and UV/Vis light (320–500 nm). Comprehensive studies by high‐resolution (HR)‐STEM, X‐ray photoelectron spectroscopy (XPS), and different in situ methods (X‐ray absorption near‐edge structure (XANES), UV/Vis, and EPR spectroscopy) revealed that IM leads to dispersed surface Cu species with no clear particle formation, which is poorly active under visible light, whereas plasmonic Cu0 nanoparticles formed by RP are about three times more active under the same conditions. In Cu/Au‐TiO2 catalysts prepared by RP‐SP, highly dispersed Cu surface species boost H2 production under UV/Vis light, owing to the effective separation within TiO2 and electron trapping by Cu, whereas small Cu0 and Au0 particles remain widely separated. When Cu/Au‐TiO2 catalysts are prepared by RP‐CP, mixed Cu/Au particles of uniform size (4–8 nm) provide the highest H2 evolution rates under visible light, owing to effective surface plasmon resonance absorption. All that glitters isn't gold: The impact of different metal deposition methods on light‐driven H2 production is studied. Au/Cu alloy particles formed by coprecipitation evolve much more H2 under visible light than separate Au0 and Cu0 particles formed by stepwise precipitation. The opposite is true under UV light.
ISSN:1867-3880
1867-3899
DOI:10.1002/cctc.201601361