Effect of silver doping on the TiO2 for photocatalytic reduction of CO2

• Published in: Applied catalysis. B, Environmental Environmental, 2010-06, Vol.96 (3-4), p.239-244
• Main Authors: KOCI, K, MATEJU, K, OBALOVA, L, KREJCIKOVA, S, LACNY, Z, PLACHA, D, CAPEK, L, HOSPODKOVA, A, SOLCOVA, O
• Format: Article
• Language: English
• Subjects: Ag doping; Catalysis; Chemistry; CO2 reduction; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Micelles. Thin films; Photocatalysis; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; TiO2
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2010.02.030

Pure TiO2 and various silver-enriched TiO2 powders were prepared by the sol–gel process controlled in the reverse micellar environment. The catalysts were tested in CO2 photocatalytic reduction and characterized by X-ray diffraction (XRD), nitrogen adsorption measurement and UV–vis. Methane and methanol were the main reduction products. The yield of methane and methanol increases when modifying the TiO2 by silver incorporation is caused by two mechanisms: up to 5% of Ag in TiO2 the Ag impurity band inside the TiO2 bandgap decreases the absorption edge and increases so the electron–hole pair generation, above 5% of Ag in TiO2 Ag metallic clusters are formed in TiO2 crystals with Shottky barrier at the metal–semiconductor interface, which spatially separates electron and holes and increases their lifetime (decreases probability of their recombination).