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Characteristics of the surface states produced on titanate photoanodes by mechanical polishing

Kutty, TRN and Devi, Gomathi L and Avudaithai, M (1990) Characteristics of the surface states produced on titanate photoanodes by mechanical polishing. In: Solar Energy Materials, 20 (4). pp. 307-321.

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Investigations using repetitive triangular potential sweeps and X-ray photo electron spectroscopy reveal that stable, surface-bound peroxotitanium species are produced without illumination on mechanically polished n-type $SrTiO_3, SrTi_3O7, BaTiO_3, BaTi_4O_9 and TiO_2$ polycrystalline photoelectrodes in alkaline media, under anodic polarization. Formation of peroxotitanium species is related to the chemical reactivity of the surface regions that incorporate the mechanically-induced crystalline defects, according to the scheme: $2OH_s^- = (O_2^{2-})_s + 2H^+ + 2e^-$. Bulk flaws present the mechanically damaged surface region allow a quasi-isoenergetic transfer of electrons from the conduction band at the bulk to empty surface states (peroxo species). At much more anodic potential [$V_{appl}$ $^>_\sim$ 0.45 V (SCE)], the Fermi level is pushed below the surface states and the electrons are transferred from ss to the CB via bulk flaws, leading to the underpotential evolution of oxygen: $(O_2^{2-})_s = O_2 + 2e^-$.

Item Type: Journal Article
Publication: Solar Energy Materials
Publisher: Elsevier Science Publishers B.V.
Additional Information: Copyright of this article belongs to Elsevier Science Publishers B.V.
Keywords: titanate photoanodes;mechanical polishing;electron spectroscopy
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 07 Feb 2008
Last Modified: 19 Sep 2010 04:41
URI: http://eprints.iisc.ac.in/id/eprint/12652

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