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Xianzhi Fu

Bio: Xianzhi Fu is an academic researcher from University of Wisconsin-Madison. The author has contributed to research in topics: Photocatalysis & Catalysis. The author has an hindex of 8, co-authored 10 publications receiving 1191 citations.

Papers
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TL;DR: In this paper, a comparison of their catalyst compositions with literature in this area suggests that the increase in activity due to the addition of silica or zirconia may be a result of higher surface acidity.
Abstract: Sol-gel prepared mixtures of silica or zirconia with titania are shown to have significantly higher activities than pure titania for the complete photocatalytic oxidation of ethylene. These higher activities are only apparent when the respective catalysts are stabilized by sintering. The differences become even more pronounced when the catalysts are used in a tubular reactor. Optimum mixture concentrations are found to be 12 wt % zirconia and 16 wt % silica in titania. Both catalyst types exhibit activity maxima with respect to sintering temperature. It is hypothesized that the maxima arise from opposing effects of densification and phase transformation versus beneficial sintering. A comparison of our catalyst compositions with literature in this area suggests that the increase in activity due to the addition of silica or zirconia may be a result of higher surface acidity. However, isoelectric point measurements employing the unsintered and sintered catalysts show no conclusive increase in surface acidity...

647 citations

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TL;DR: In this paper, the authors used titania and platinized (0.1 wt.-%) titania photocatalysts for the degradation of benzene in oxygen-containing gaseous feed streams.
Abstract: Photocatalytic degradation of benzene in oxygen-containing gaseous feed streams was investigated using titania and platinized (0.1 wt.-%) titania photocatalysts. The titania catalyst was synthesized using sol-gel techniques. Results of this study indicate that, when using this particular photocatalyst, benzene was oxidized to carbon dioxide and water without forming any detectable organic reaction products in the reactor effluent, although only some of the benzene reacted. Both the overall conversion of benzene and its mineralization were improved by platinizing the titania. When the titania catalyst was platinized, both photocatalytic and thermocatalytic reactions were promoted. Rates of photocatalytic reactions were significantly enhanced at reaction temperatures between 70 and 90°C, while at temperatures above 90°C the rates of thermocatalytic oxidation reactions were noticeably increased. It proved possible to obtain the continuous and essentially complete mineralization of benzene by using the platinized titania catalyst and optimizing such parameters as the reaction temperature, space time, and the concentrations of oxygen and water vapor in the feed stream.

210 citations

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TL;DR: In this paper, the photocatalytic degradation of ethylene in airstreams has been studied over the temperature range 30-110 °C using a packed bed reactor containing sol-gel-derived TiO2 or platinized TiO 2 particulates.
Abstract: The photocatalytic degradation of ethylene in airstreams has been studied over the temperature range 30–110 °C using a packed bed reactor containing sol-gel-derived TiO2 or platinized TiO2 particulates. Results of this study indicate that the reactivity of ethylene is greatly enhanced at increased temperatures and that the fraction of ethylene that reacts is stoichiometrically oxidized to CO2 under all operating conditions. The effect of raising the temperature has been ascribed to decreasing adsorption of water for both types of catalysts, as well as an increase in conventional heterogeneous catalytic reactions occurring on the Pt/TiO2 catalyst. In addition, platinizing the TiO2 photocatalyst and increasing the content of water vapor in the gaseous feed streams both decrease the rate of photocatalytic oxidation of ethylene. The activation energies for the photocatalytic and heterogenous catalytic oxidation of ethylene were determined to be 13.9–16.0 kJ mol−1 and 82.8 kJ mol−1 respectively.

155 citations

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TL;DR: In this article, the results showed that the catalytic and structural properties of the sulfated TiO2 catalysts were greatly improved by sulfation, and the results indicated that surface fluorination of the catalysts during the reaction improved its activity, induced the formation of the fluorinated byproduct CFC-13, and changed such properties as its specific surface area, pore size distribution, and crystal size.

87 citations

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TL;DR: In this article, the photocatalytic degradation of trichloroethylene and tetrachloronitriouethylene in the gas phase, when porous TiO2 pellets were used, produced such undesirable chlorinated byproducts as chloroform (CHCl3) and carbon tetrACHloride (CCl4) and the formation of byproducts was reduced by increasing oxygen mole fractions in the feed gas stream and/or using the TiO 2 pellets fired at a lower temperature.
Abstract: The photocatalytic degradation of trichloroethylene and tetrachloroethylene in the gas phase, when porous TiO2 pellets were used, produced such undesirable chlorinated byproducts as chloroform (CHCl3) and carbon tetrachloride (CCl4). The formation of byproducts was reduced by increasing oxygen mole fractions in the feed gas stream and/or using the TiO2 pellets fired at a lower temperature. Theoretical calculations indicate that the Cl-radical-initiated reaction produces these byproducts. On the basis of the experimental and the theoretical results, a method to prevent the formation of the chlorinated byproducts is discussed.

59 citations


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TL;DR: For the first time, a multi-variables optimization approach is described to determine the optimum operation parameters so as to enhance process performance and photooxidation efficiency in the photocatalytic water treatment process.

4,293 citations

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TL;DR: In this paper, photo-induced superhydrophilicity was used on the surface of a wide-band gap semiconductor like titanium dioxide (TiO 2 ) for photocatalytic activity towards environmentally hazardous compounds.

4,241 citations

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TL;DR: A review of the use of the TiO 2 photocatalyst for remediation and decontamination of wastewater, report the recent work done, important achievements and problems is presented in this paper, however, a lot more is needed from engineering design and modelling for successful application of the laboratory scale techniques to large scale operation.
Abstract: Even though heterogeneous photocatalysis appeared in many forms, photodegradation of organic pollutants has recently been the most widely investigated. By far, titania has played a much larger role in this scenario compared to other semiconductor photocatalysts due to its cost effectiveness, inert nature and photostability. Extensive literature analysis has shown many possibilities of improving the efficiency of photodecomposition over titania by combining the photoprocess with either physical or chemical operations. The resulting combined processes revealed a flexible line of action for wastewater treatment technologies. The choice of treatment method usually depends upon the composition of the wastewater. However, a lot more is needed from engineering design and modelling for successful application of the laboratory scale techniques to large-scale operation. The present review paper seeks to offer an overview of the dramatic trend in the use of the TiO 2 photocatalyst for remediation and decontamination of wastewater, report the recent work done, important achievements and problems.

2,573 citations

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TL;DR: In this paper, the role of rutile in mixed-phase titania photocatalyst was investigated by EPR spectroscopy, showing that the transition points between these two phases allow for rapid electron transfer from pure-phase rutiles to anatase.
Abstract: Charge separation characteristics of a high-activity, mixed-phase titania photocatalyst (Degussa P25) are probed by EPR spectroscopy. While previous proposals consider rutile as a passive electron sink hindering recombination in anatase, this research details the critical and active role of rutile in TiO2 formulations. The inactivity of pure-phase rutile is due in part to rapid rates of recombination. Yet, in mixed-phase TiO2, charges produced on rutile by visible light are stabilized through electron transfer to lower energy anatase lattice trapping sites. These results suggest that within mixed-phase titania (P25) there is a morphology of nanoclusters containing atypically small rutile crystallites interwoven with anatase crystallites. The transition points between these two phases allow for rapid electron transfer from rutile to anatase. Thus, rutile acts as an antenna to extend the photoactivity into visible wavelengths and the structural arrangement of the similarly sized TiO2 crystallites creates ca...

1,878 citations

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TL;DR: The field of surface science provides a unique approach to understand bulk, surface and interfacial phenomena occurring during TiO2 photocatalysis as mentioned in this paper, including photon absorption, charge transport and trapping, electron transfer dynamics, adsorbed state, mechanisms, poisons and promoters, and phase and form.

1,768 citations