Ba₂SnO₄ – A New Photocatalyst for the Reduction of Chromate ions

Author： Omeiri S. Allalou N. Gharib R. Gabès Y. Bessekhouad Y. Trari M.

ISSN： 0040-5760

Source： Theoretical and Experimental Chemistry, Vol.49, Iss.5, 2013-11, pp. : 298-303

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Abstract

The photoelectrochemical properties of perovskite Ba₂SnO₄ were studied for the first time. This material has direct optical transitions with energy 3.18 eV due to electron transfer O₂–2p → Sn⁴⁺5 s. The Mott–Schottky plots obtained in acidic media (pH ≍ 2.5) indicate that this material has n-type conductivity and electron density 1.1410¹⁷ cm^–3. The conduction band potential of Ba₂SnO₄ (-0.86 V_SCE) is located in a more negative region than the reduction potential of HCrO₄^-, which permits reduction of this anion to Cr³⁺ upon the action of UV light. The photoreduction is described in the framework of the Langmuir_Hinshelwood model by a pseudo-first-order kinetic equation. Irradiation of reaction mixtures by sunlight for ~2 h leads to the conversion of 73% (50 ppm) chromate anions with 0.13% quantum yield.