Novel synthesis of ZrxTi1-xOn mixed oxides using titanyl sulphate and pressurized hot and supercritical fluids, and their photocatalytic comparison with sol-gel prepared equivalents. (November 2017)

• Record Type: Journal Article
• Authors: Lang, Jaroslav; Matějová, Lenka; Troppová, Ivana; Čapek, Libor; Endres, Jan; Daniš, Stanislav
• Is Part Of: Materials research bulletin. Volume 95(2017)
• Page Start: 95
• Page End: 103
• Publication Date: 2017-11
• Subjects: TiO2-ZrO2 mixed oxides -- Titanyl sulphate -- Pressurized water crystallization -- Supercritical methanol drying -- Photoactivity; Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2017.07.023
• Languages: English
• ISSNs: 0025-5408

Abstract

Graphical abstract: Highlights: Novel preparation of Zrx Ti1-x On mixed oxides by using titanyl sulphate and pressurized hot water and supercritical methanol. Comparison of photoactivity of prepared mixed oxides with sol-gel-prepared equivalents in Acid orange 7 photodegradation. The highest photoactivity of TiO2 -H is attributed to small anatase crystallite-size. The highest photoactivity of Zr0.1 Ti0.9 On -G is attributed to the existence of anatase-brookite phase mixture and small anatase crystallite-size. The optimum Zr loading in TiO2 is below 10·mol%. Abstract: Zrx Ti1-x On mixed oxides with five various molar ratios of Zr:Ti and their parent oxides were prepared, combining thermal hydrolysis (H) with pressurized hot water crystallization and supercritical methanol drying. Their photoactivity was compared to equivalent materials prepared by sol-gel (G) method. Zr0.1 Ti0.9 On -G was the most photoactive mixed oxide, which showed significantly higher photoactivity than Zr0.1 Ti0.9 On -H. Higher photoactivity of Zr0.1 Ti0.9 On -G can be attributed to phase composition (anatase-brookite phase mixture) and smaller TiO2 anatase crystallite-size. The Zr dopation in TiO2 did not improve the photoactivity neither of sol-gel-synthetized, nor thermal hydrolysis-synthetized mixed oxides in AO7 photodegradation. Zr in higher loadings (>10 mol%) formed separate monoclinic and tetragonal ZrO2 and monoclinic zirconium titanates. Unlike Zr 4+ ions in Zr doped TiO2 the separate monoclinic and tetragonal ZrO2 and monoclinic zirconium titanates did not serve as electron trapping centres but as electron-hole recombination centres. The Zr loading in TiO2 should be below 10 mol%.