Semiconductor photocatalysis. ZnS-catalyzed photoreaction of aldehydes and related derivatives: Two-electron-transfer reduction and relationship with spectroscopic properties

Journal Article · Thu Mar 23 04:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100343a066· OSTI ID:5038600

Yanagida, Shozo; Ishimaru, Yoshiteru; Miyake, Yoshio; Shiragami, Tsutomu; Pac, Chyongjin ^[1]; Hashimoto, Kazuhito; Sakata, Tadayoshi ^[2]

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1. Osaka Univ., Suita (Japan)
2. Institute for Molecular Science, Myodaiji (Japan)

Photocatalytic activity and spectroscopic properties of ZnS suspensions for the two-electron reduction of aldehydes or related compounds in aqueous medium are described. The ZnS suspension (ZnS-O) prepared by cooling from aqueous ZnSO{sub 4} and Na{sub 2}S solutions catalyzes photoredox reactions of acetaldehyde, giving ethanol without much H{sub 2} evolution as a two-electron-reduction product, and acetic acid, biacetyl, and acetoin as oxidation products. When the ZnS-O suspension is refluxed (giving ZnS-100) or dried to powder, the resulting ZnS shows an increased activity for H{sub 2} evolution but a decreased activity for the two-electron reduction. The two-electron photoreduction is ascribed to the sequential transfer of active electrons in the conduction band of defect-free aggregates of ZnS microcrystallites (quantized ZnS). This mechanism is supported by product analysis, energetics at ZnS interfaces, the sharp and blue-shifted onset of absorption and excitation spectra, and the long-life band gap emission of the active ZnS-O suspension. UV, emission, and ESR spectra, as well as the enhancement of the particle size and crystallinity, suggest that the activity change observed after heating or drying to powder is due to the formation of surface states which may trap active electrons. This interpretation is also supported by the generated activity of ZnS-100 for the H{sub 2} photoevolution under >350-nm irradiation. ZnS photocatalysis under >350-nm irradiation relationship with spectroscopic properties are also discussed.

• OSTI ID: 5038600
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:6; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ABSORPTION SPECTROSCOPY
ALDEHYDES
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
EMISSION SPECTROSCOPY
EXPERIMENTAL DATA
INFORMATION
INORGANIC PHOSPHORS
LUMINESCENCE
MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOSPHORS
PHOTOCHEMICAL REACTIONS
QUANTITY RATIO
REDUCTION
RESONANCE
SPECTROSCOPY
SULFIDES
SULFUR COMPOUNDS
ZINC COMPOUNDS
ZINC SULFIDES