Journal ArticleDOI
Chemical Role of Holes and Electrons in ZnO Photocatalysis
S. R. Morrison,T. Freund +1 more
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In this paper, the role of the electronic properties of a semiconductor in heterogeneous catalysis and electrochemistry was experimentally investigated on single-crystal ZnO, and it was shown quantitatively that the availability of electrons and holes at the surface is dominant in the mechanism of a heterogeneously catalyzed reaction.Abstract:
The role of the electronic properties of a semiconductor in heterogeneous catalysis and electrochemistry was experimentally investigated on single‐crystal ZnO. It was shown quantitatively that the availability of electrons and holes at the surface is dominant in the mechanism of a heterogeneously catalyzed reaction. Chemical rate measurements as well as in situ solid‐state measurements were carried out in an aqueous medium for the reaction: HCOOH+O2→H2O2+CO2, photocatalyzed by ZnO. Two new experimental electrochemical methods for semiconductor surface reactions were developed: ``current doubling'' and measurement of ``unfilled'' electronic surface states by the capacitance. They were devised to characterize reactive sorbed species. The detailed catalytic mechanism was based on studies of individual reaction steps under three solid‐state surface conditions: (1) only holes reacting, (2) only electrons reacting, and (3) both holes and electrons reacting. The first two correspond to the ZnO being an electroch...read more
Citations
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Journal ArticleDOI
TiO2 photocatalysis and related surface phenomena
TL;DR: The field of photocatalysis can be traced back more than 80 years to early observations of the chalking of titania-based paints and to studies of the darkening of metal oxides in contact with organic compounds in sunlight as discussed by the authors.
Journal ArticleDOI
Development of alternative photocatalysts to TiO2: Challenges and opportunities
TL;DR: In this article, the main achievements obtained with photocatalyst alternatives to TiO2 in the three main niches for this technology are summarized, with an historical perspective, in order to assess which of the photoactive materials are best for each particular application.
Journal ArticleDOI
Physical Chemistry of Semiconductor−Liquid Interfaces
Arthur J. Nozik,Rüdiger Memming +1 more
TL;DR: A review of the basic physicochemical principles of semiconductor−liquid interfaces, including their historical development, and describe the major technological applications that are based on these scientific principles can be found in this paper.
Journal ArticleDOI
Mechanism for Visible Light Responses in Anodic Photocurrents at N-Doped TiO2 Film Electrodes
TL;DR: In this paper, the effect of reductants such as methanol, SCN, Br-, I-, and hydroquinone on the photocurrent action spectrum of anatase TiO2 powder was investigated.
Journal ArticleDOI
Photoelectrochemical Properties of Nanostructured Tungsten Trioxide Films
TL;DR: In this article, the photoelectrochemical characteristics of highly transparent nanoporous WO3 films are described and the photocurrent versus excitation wavelength spectra exhibit a maximum close to 400 nm and a significant photoresponse to the blue part of the visible spectrum.
References
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Journal ArticleDOI
Crystallographic Polarity of ZnO Crystals
A. N. Mariano,R. E. Hanneman +1 more
TL;DR: The crystallographic polarity of the noncentrosymmetric material zincite (ZnO) has been determined by a rapid x-ray absorption edge method as discussed by the authors.
Journal ArticleDOI
Photoconduction and Surface Effects with Zinc Oxide Crystals
R. J. Collins,D. G. Thomas +1 more
TL;DR: In this article, it is proposed that holes from hole electron pairs discharge lattice oxygen ions at the surface, producing a surface excess of zinc and an electron enrichment layer in which conduction occurs.
Journal ArticleDOI
The charge distribution at the zinc oxide-electrolyte interface
TL;DR: Capacitance measurements made on single crystal zinc oxide electrodes in contact with aqueous electrolytes are reported in this paper, and the results are in almost quantitative accord with predictions of the simple Poisson-Boltzmann (Poisson-Fermi in the degenerate case) equation.
Book ChapterDOI
Surface Barrier Effects in Adsorption, Illustrated by Zinc Oxide
TL;DR: In this paper, the surface barrier effects in adsorption were discussed, including the role played by the potential barrier associated with a double layer between adsorbed ions on the surface and ionized impurities of opposite charge in the semiconductor.
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