Jenny Schneider,*,† Masaya Matsuoka,‡ Masato Takeuchi,‡ Jinlong Zhang, Yu Horiuchi,‡ Masakazu Anpo,‡ and Detlef W. Bahnemann*,† †Institut fur Technische Chemie, Leibniz Universitaẗ Hannover, Callinstrasse 3, D-30167 Hannover, Germany ‡Faculty of Engineering, Osaka Prefecture University, 1 Gakuen-cho, Sakai Osaka 599-8531, Japan Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China

Understanding TiO2 photocatalysis: mechanisms and materials.

Photocatalytic water treatment using nanocrystalline titanium dioxide (NTO) is a well-known advanced oxidation process (AOP) for environmental remediation. With the in situ generation of electron-hole pairs upon irradiation with light, NTO can mineralize a wide range of organic compounds into harmless end products such as carbon dioxide, water, and inorganic ions. Photocatalytic degradation kinetics of pollutants by NTO is a topic of debate and the mostly reporting Langmuir-Hinshelwood kinetics must accompanied with proper experimental evidences. Different NTO morphologies or surface treatments on NTO can increase the photocatalytic efficiency in degradation reactions. Wisely designed photocatalytic reactors can decrease energy consumption or can avoid post-separation stages in photocatalytic water treatment processes. Doping NTO with metals or non-metals can reduce the band gap of the doped catalyst, enabling light absorption in the visible region. Coupling NTO photocatalysis with other water-treatment technologies can be more beneficial, especially in large-scale treatments. This review describes recent developments in the field of photocatalytic water treatment using NTO.

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Photocatalytic Water Treatment by Titanium Dioxide: Recent Updates

A review on research progress in the direct synthesis of hydrogen peroxide from hydrogen and oxygen: noble-metal catalytic method, fuel-cell method and plasma method

A novel method based on heating the mixture of SnCl 2 ·2H 2 O and excess S powders in air at 200–240 °C for 0–10 h ( t  = 0 h, that is, the heating of the reactants was stopped immediately once temperature reached the designed degree), coupled with a subsequent washing treatment, was proposed for the synthesis of SnS 2 nanoflakes. X-ray diffraction, transmission electron microscopy, selected area electron diffraction and Raman spectra revealed the formation of bulk-pure hexagonal phase SnS 2 nanoflakes. UV–vis diffuse reflectance spectra disclosed that the as-synthesized SnS 2 nanoflakes had optical bandgaps in the range of about 2.21–2.25 eV. Besides, the photocatalytic performances of the as-synthesized SnS 2 nanoflakes were evaluated by degrading methyl orange (MO) in deionized water under both the visible light ( λ  > 420 nm) and real sunlight irradiation. The results demonstrated that all the SnS 2 products had high visible light photocatalytic activity, and the most efficient photocatalyst among them was the one synthesized at 200 °C for 0 h, which was able to achieve a MO degradation ratio of nearly 100% after 60 min illumination in the first cycle and 86% in the fifth cycle (each cycle lasted for 120 min). Moreover, the best sample also possessed much higher photocatalytic activity than the commercial Degussa P25 TiO 2 photocatalyst under the real sunlight irradiation, and can be easily recovered from the suspension by filtration after the photocatalysis.

Novel synthesis and high visible light photocatalytic activity of SnS2 nanoflakes from SnCl2·2H2O and S powders

Silica-based micro-, meso-, macro-porous materials offer attractive routes for designing single-site photocatalysts, supporting semiconducting nanoparticles, anchoring light-responsive metal complexes, and encapsulating metal nanoparticles to drive photochemical reactions by taking advantage of their large surface area, controllable pore channels, remarkable transparency to UV/vis and tailorable physicochemical surface characteristics. This review mainly focuses on the fascinating photocatalytic properties of silica-supported Ti catalysts from single-site catalysts to nanoparticles, their surface-chemistry engineering, such as the hydrophobic modification and synthesis of thin films, and the fabrication of nanocatalysts including morphology controlled plasmonic nanostructures with localized surface plasmon resonance. The hybridization of visible-light responsive metal complexes with porous materials for the construction of functional inorganic–organic supramolecular photocatalysts is also included. In addition, the latest progress in the application of MOFs as excellent hosts for designing photocatalytic systems is described.

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Single-site and nano-confined photocatalysts designed in porous materials for environmental uses and solar fuels.

Degradation of isobutanol diluted in water over visible light sensitive vanadium doped TiO2 photocatalyst

An efficient methodology to synthesize highly active Pd nanoparticles using a single-site photocatalyst under UV-light irradiation has been developed for the synthesis of hydrogen peroxide (H2O2) from H2 and O2. By the photo-assisted deposition (PAD) method, Pd precursor can be deposited directly on the photo-excited tetrahedrally coordinated metal-oxide moiety within the silica frameworks, and subsequently transformed into Pd nanoparticles by H2 reduction. The mean diameter of the deposited Pd particles determined by CO adsorption and the catalytic activities in the direct synthesis of H2O2 were strongly dependent on the preparation method and kind and/or amount of metal-oxide moieties. Here, the use of Ti-containing mesoporous silica (Ti/Si = 0.01) acted as a most efficient support for the above reaction. The PAD method also provides PdAu bimetallic nanoparticles from an aqueous solution of mixture of PdCl2 and HAuCl4. The PdAu/Ti-MCM-41 catalyst prepared by the PAD method was shown to perform significantly better activity than the pure Pd/Ti-MCM-41.

Supported Pd and PdAu Nanoparticles on Ti-MCM-41 Prepared by a Photo-assisted Deposition Method as Efficient Catalysts for Direct Synthesis of H2O2 from H2 and O2

Preparation of hydrophobically modified single-site Ti-containing mesoporous silica (TiSBA-15) and their enhanced catalytic performances

Hydrophobic modification of Ti-containing zeolite (TS-1) was performed by using triethoxyfluorosilane (TEFS). TS-1 after modification with TEFS (w = 1%) showed higher catalytic activity for the amm...

Joji Sonoda

Papers

Degradation of isobutanol diluted in water over visible light sensitive vanadium doped TiO2 photocatalyst

Supported Pd and PdAu Nanoparticles on Ti-MCM-41 Prepared by a Photo-assisted Deposition Method as Efficient Catalysts for Direct Synthesis of H2O2 from H2 and O2

Preparation of hydrophobically modified single-site Ti-containing mesoporous silica (TiSBA-15) and their enhanced catalytic performances

Hydrophobic Modification of Ti-Containing Zeolite (TS-1) and Their Applications in Liquid-Phase Selective Catalytic Reactions