Topic
Photocatalysis
About: Photocatalysis is a research topic. Over the lifetime, 67088 publications have been published within this topic receiving 2145233 citations. The topic is also known as: photocatalyst.
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TL;DR: An important finding was that competitive adsorption between water and trace (sub-ppmv) contaminants has a significant effect on the oxidation rates of formaldehyde, toluene, and 1,3-butadiene.
Abstract: Persistent indoor air contaminants, those originating from emissions by interior furnishings, occupants, and materials of construction, typically exist in concentrations below 100 parts per billion (ppb) on an individual basis. The total of distinct contaminants may number in the hundreds with an equivalent accumulated concentration of one part per million. This study investigated the effects of humidity and trace (sub-ppmv) contaminant levels on the oxidation rates of formaldehyde, toluene, and 1,3-butadiene. The evaluation also included variations in UV intensity and flow residence time. UV intensities from inexpensive mercury fluorescent lamps, those which are expected to be employed in a practical photocatalytic purifier, are in the mW/cm 2 range. For this reason, the study included UV intensities in that range. The reactor element used in the study was a low pressure drop alumina reticulate, wash-coated with Degussa P25 titania. The data indicated that the reaction was first-order for the three reactants at the subppmv level. An important finding was that competitive adsorption between water and trace (sub-ppmv) contaminants has a significant effect on the oxidation rate. The dependencies of humidity and contaminant concentrations on the oxidation rates are explained as being the results of competitive adsorption on available hydroxyl adsorption sites and of changes in hydroxyl radical population levels
587 citations
TL;DR: In this article, the photocatalytic activity of TiO[sub 2] toward the degradation of organic compounds in aqueous solutions at low concentrations is discussed, and the increase in the catalytic activity when certain metals such as silver, gold, and palladium are deposited on the surface is also discussed.
Abstract: This paper reviews the photocatalytic activity of TiO[sub 2] toward the degradation of organic compounds in aqueous solutions at low concentrations. The photocatalytic activity of both polycrystalline samples and thin films can be related to the method of preparation of the catalyst. The increase in the catalytic activity of TiO[sub 2] when certain metals such as silver, gold, and palladium are deposited on the surface is also discussed. These catalysts have potential use in removing harmful carcinogens from water as well as possible application in reducing the harmful effects of oil spills. 45 refs., 2 figs.
585 citations
TL;DR: The results indicated that the formation rate of (·)OH on the surface of irradiated commercial Degussa P25 (P25) was much higher than that of other semiconductor.
584 citations
TL;DR: In this article, the authors used NiO as a cocatalyst for water splitting into H2 and O2 in pure water without any additives under UV irradiation, and found that NiO increased the photocatalytic activity of the NiO(0.15 wt %)/Sr2Ta2O7 photocatalyst.
Abstract: Sr2Ta2O7 and Sr2Nb2O7 with similar layered perovskite structure showed activities for water splitting into H2 and O2 in pure water without any additives under UV irradiation. The band gaps of Sr2Ta2O7 and Sr2Nb2O7 were 4.6 and 3.9 eV, respectively. Sr2Ta2O7 gave H2 and O2 from pure water under UV irradiation even in the absence of a cocatalyst. The activity of Sr2Ta2O7 was much increased by loading NiO as a cocatalyst even without pretreatment. The quantum yield of the NiO(0.15 wt %)/Sr2Ta2O7 photocatalyst was 12% at 270 nm. On the other hand, native Sr2Nb2O7 did not possess the activity. The high activity was obtained for the Sr2Nb2O7 photocatalyst when NiO was loaded and pretreated. Factors affecting the photocatalytic activities were discussed by using the Sr2Ta2O7 and Sr2Nb2O7 powder with similar layered perovskite structure. A predominant factor affecting the photocatalytic behavior of Sr2Ta2O7 and Sr2Nb2O7 is the conduction band levels formed by Ta5d and Nb4d.
583 citations
TL;DR: In this article, a series of TiO2 samples with different anatase-to-rutile ratios were prepared by calcination, and the roles of the two crystallite phases of titanium(IV) oxide (TiO2) on the photocatalytic activity in oxidation of phenol in aqueous solution were studied.
Abstract: A series of TiO2 samples with different anatase-to-rutile ratios was prepared by calcination, and the roles of the two crystallite phases of titanium(IV) oxide (TiO2) on the photocatalytic activity in oxidation of phenol in aqueous solution were studied. High dispersion of nanometer-sized anatase in the silica matrix and the possible bonding of Si−O−Ti in SiO2/TiO2 interface were found to stabilize the crystallite transformation from anatase to rutile. The temperature for this transformation was 1200 °C for the silica−titania (ST) sample, much higher than 700 °C for Degussa P25, a benchmarking photocatalyst. It is shown that samples with higher anatase-to-rutile ratios have higher activities for phenol degradation. However, the activity did not totally disappear after a complete crystallite transformation for P25 samples, indicating some activity of the rutile phase. Furthermore, the activity for the ST samples after calcination decreased significantly, even though the amount of anatase did not change muc...
582 citations