One-Step Synthesis of Bifunctional TiO₂Catalysts and Their Photocatalytic Activity

Abstract

In this paper, we have investigated in detail the preparation of anatase TiO 2 catalysts by the controlled thermal decomposition of ammonium titanyl sulfate ((NH 4 ) 2 TiO(SO 4 ) 2 ) and their catalytic activity. The structures of anatase TiO 2 catalysts have been characterized by powder X-ray diffraction, N 2 adsorption-desorption isotherms, diffuse reflectance UV-vis spectroscopy, infrared spectroscopy, X-ray photoemission spectroscopy, NH 3 temperature-programmed desorption, and solid-state MAS NMR spectrometer. We report for the first time that the anatase TiO 2 catalyst prepared by calcination of (NH 4 ) 2 TiO(SO 4 ) 2 at 600 °C (TiO 2 -600) is a very active bifunctional catalyst. TiO 2 -600 is doped with N and S and thus very active in the photodegradation of methyl orange under visible light illumination (λ > 420 nm); meanwhile, it also has a large number of Bro ¨nsted acid sites arising from the covalently bonded sulfuric acid groups and thus is active in the esterification of ethanol and acetic acid to ethyl acetate. The Pt/TiO 2 -600 photocatalysts with different Pt loadings were prepared via the incipient wetness impregnation method and their photocatalytic activity for the H 2 production from water splitting was evaluated with methanol as a sacrificial electron donor under both all-wavelength light and visible light (λ > 400 nm) irradiation. All Pt/TiO 2 -600 photocatalysts show considerable photocatalytic activity of water splitting. The optimum Pt loading on TiO 2 -600 is 1 and 0.1 wt % for the all-wavelength light and visible light photocatalytic reaction, respectively. Our results demonstrate a facile method to prepare highly active bifunctional TiO 2 catalysts promising in both visible-light-driven photocatalysis and acid catalysis.

One‐Step Preparation of Efficient and Reusable SO42−/ZrO2‐Based Hybrid Solid Catalysts Functionalized by Alkyl‐Bridged Organosilica Moieties for Biodiesel Production

“…The O 1s XPS line of the SO 4 2À /ZrO 2 sample shows two signals centered at 531.6 (denoted O 1s (1)) and 532.6 eV (denoted O 1s(2)), respectively, originating from oxygen species in the ZrÀOÀZr and ZrÀOÀS bonds, respectively. [25] After the introduction of ethane-or phenylene-bridged organosilica fragments into the framework of SO 4 2À /ZrO 2 , the binding energies of O 1s (1) …”

Effect of sacrificial electron donors on hydrogen generation over visible light–irradiated nonmetal-doped TiO2 photocatalysts

“…It had been reported by Fujishima et al [2] that TiO 2 semiconductor particles can be used as a photocatalyst for decomposition of water to oxygen and hydrogen. Since then, light-assisted cleavage of water on the surface of semiconductor particles to produce oxygen and hydrogen has been of continued interest [3][4][5][6][7]. In a couple of very recent reviews [3,4], the prospects for visible light-driven hydrogen generation over semiconductor photocatalysts in the presence of a sacrificial electron donor (SED) have been discussed.…”

Synthesis and Catalytic Applications of Non-Metal Doped Mesoporous Titania

“…Hartmann et al showed the effectiveness of sol-gel derived mp-TiO2 in the water splitting reaction, but its large bandgap limits visible light absorption [229]. To improve hydrogen production from water splitting using visible light, non-metal elements have been doped into mp-TiO2 [33,152,181,190,191,230]. First, Sreethawong et al prepared N-mp-TiO2 and assemblies of TiO2 nanocrystals [190].…”

“…An increase in Pt loading of more than 1.3 wt % decreased the hydrogen production due to increased Pt agglomeration, excessive coverage of the titania surface by the Pt nanoparticles, and an increased probability of charge recombination by the excess electrons on the Pt surface. Fang et al also showed the efficacy of Pt loading in N/S-mp-TiO 2 in water splitting [230]. The co-doped samples were prepared by controlled thermal decomposition of a single source, ammonium titanyl sulfate ((NH 4 ) 2 TiO(SO 4 ) 2 ).…”