Selective reductions using visible light photocatalysts of supported gold nanoparticles

Ke, Xuebin, Zhang, Xingguang, Zhao, Jian, Sarina, Sarina, Barry, John, & Zhu, Huai Yong (2013) Selective reductions using visible light photocatalysts of supported gold nanoparticles. Green Chemistry, 15(1), pp. 236-244.

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Abstract

Photocatalytic synthesis using visible light is a desirable chemical process because of its potential to utilize sunlight. Supported gold nanoparticles (Au-NPs) were found to be efficient photocatalysts and the effects of the supports were identified including CeO2, TiO2, ZrO2, Al2O3, and zeolite Y. In particular Au/CeO2 exhibited the high catalytic activity to reduce nitroaromatics to azo compounds, hydrogenate azobenzene to hydroazobenzene, reduce ketones to alcohols, and deoxygenate epoxides to alkenes at ambient temperatures, under irradiation of visible light (or simulated sunlight). The reac-tive efficiency depends on two primary factors: one is the light adsorption of catalysts and another is the driving ability of catalysts corresponding to the reactants. The light absorption by Au-NPs is due to surface plasmon resonance effect or inter-band electron transition; this is related to the reduction ability of the photocatalysts. Irradiation with shorter wavelengths can excite the conduction electrons in Au-NPs to higher energy levels and as a result, induce reduction with more negative reduction potentials. It is known when irradiated with light the Au-NPs can abstract hydrogen from isopropanol forming Au-H species on the Au-NP surface. Hence, we proposed that the active Au-H species will react with the N=O, N=N, C=O double bonds or epoxide bonds, which are weakened by the interaction with the excited electrons in the Au-NPs, and yield the final reductive products. The reacting power of the Au-H species depends on the energy of the excited electrons in Au-NPs: the higher the electronic energy, the stronger the reduction ability of the Au-H species. This finding demonstrates that we can tune the reduction ability of the photocatalysts by manipulating the irradiation wavelength.

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ID Code: 56076
Item Type: Journal Article
Refereed: Yes
Keywords: selective reduction, visible light photocatalysis, gold nanoparticles, irradiation wavelength, light intensity
DOI: 10.1039/C2GC36542A
ISSN: 1463-9270
Subjects: Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > MACROMOLECULAR AND MATERIALS CHEMISTRY (030300) > Chemical Characterisation of Materials (030301)
Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > PHYSICAL CHEMISTRY (INCL. STRUCTURAL) (030600) > Catalysis and Mechanisms of Reactions (030601)
Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > PHYSICAL CHEMISTRY (INCL. STRUCTURAL) (030600) > Chemical Thermodynamics and Energetics (030602)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2013 RSC Publications
Deposited On: 04 Jan 2013 01:02
Last Modified: 25 Feb 2013 08:40

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