Preparation photocatalysts

Dunkel SS, Helmich RJ, Suslick KS (2009) BiV04 as a visible-light photocatalyst prepared by ultrasonic spray pyrolysis. J Phys Chem C 113 11980-11983... 

In considering photoactivity on metal oxide and metal chalcogenide semiconductor surfaces, we must be aware that multiple sites for adsorption are accessible. On titanium dioxide, for example, there exist acidic, basic, and surface defect sites for adsorption. Adsorption isotherms will differ at each site, so that selective activation on a particular material may indeed depend on photocatalyst preparation, since this may in turn Influence the relative fraction of each type of adsorption site. The number of basic sites can be determined by titration but the total number of acidic sites is difficult to establish because of competitive water adsorption. A rough ratio of acidic to basic binding sites on several commercially available titania samples has been shown by combined surface ir and chemical titration methods to be about 2.4, with a combined acid/base site concentration of about 0.5 mmol/g . 

Studies on heterogeneous photocatalysis have been undertaken extensively worldwide, employing significantly diverse experimental conditions including illumination, photocatalyst preparation, and reactor design. To allow the comparison of experimental data between different research laboratories, a unified, unambiguous definition of the efficiencies of photocatalytic processes is compulsory. 

Anpo, M. (2000). Use of visible tight. Second-generation titanium oxide photocatalysts prepared by the application of an advanced metal ion-implantation method. Pure Appl. Chem. 72(9), 1787-1792. 

Visinescu, C. M., Sanjines, R., Levy, F., Marcu, V. and Parvulescu, V. I. (2005). Tantalum doped titania photocatalysts Preparation by dc reactive sputtering and catalytic behavior. J. Photochem. Photobiol. A-Chem. 174(2), 106-112. 

Zhou, J. K., Takeuchi, M., Zhao, X. S., Ray, A. K. and Anpo, M. (2006). Photocatalytic decomposition of formic acid under visible light irradiation over V-ion-implanted Ti02 thin film photocatalysts prepared on quartz substrate by ionized cluster beam (ICB) deposition method. Catal. Lett. 106(1-2), 67-70. 

Consistent with this idea, the photocatalyzed decarboxylation of oxalic acid was found to be controlled by surface properties and by the presence of recombination centers, which in turn depended on the photocatalyst preparation method [142]. Analogous results have been observed in the photodecarboxylation of pyruvic acid [143] and formic acid [144]. 

SerponcN., Emeline A. V., Kuznetsov V. N. and Ryabchuk V. K. (2008), Second generation visible-light-active photocatalysts preparation, optical properties and consequences of dopants on the band gap energy of TiOi , in Environmentally Benign Catalysts—Applications of Titanium Dioxide-Based Photocatalysts, Anpo M. and Kamat P. V., eds.. Springer, New York, publication date October 2008. 

Fig. 1. XRD pattern of (a) TaaOs and (b) photocatalyst prepared in this study...

Figure 2 shows SEM pictures of (a) TaaOj used in this work as starting material and (b) the photocatalyst prepared in this work. From the picture of Ta205 as shown in Fig. 2(a), the particles of Ta205 whose diameter is around several pm are observed. On the other hands, the picture of prepared photocatalyst, relatively fine primary particles whose diameter is below 100 nm... 

Figure 4 shows photocatalytic evolution of O2 in time during the photocatalytic reaction of AgNOa aqueous solution (0.01 mol/1) over the photocatalyst prepared fi om Sr nitride and Ta205 (Sr/Ta = 1) by the thermal treatment at 1023 K under the irradiation of visible light (X>420 nm). As shown in Fig. 4, O2 evolves but saturating with time by the deposition of Ag on the surface under the irradiation. This result suggests that the photocatalyst prepared in this work has ability for proceeding to the photocatalytic reaction under the visible light irradiation. The amount of evolved O2 for 1 hour in the initial stage is defined as the photocatalytic activity of the corresponding...

Figure 5 shows the dependence of the photocatalytic activity of the prepared photocatalyst upon the thermal treatment temperature and Figure 6 shows XRD pattern of the photocatalysts prepared at various temperatures. As shown in Fig. 5, the photocatalytic activity increase with increasing the thermal treatment... 

H.Y. Zhu, J.Y. Li, J.C. Zhaob, G.J. Churchman, Photocatalysts prepared from layered clays and titanium hydrate for degradation of organic pollutants in water . Applied Clay Science, 28 (1 ), 79-88, (2005). 

H. Li, Y. Zhang, S. Wang, Q. Wu, C. Liu, Study on nanomagnets supported Ti02 photocatalysts prepared by a sol-gel process in reverse microemulsion combining with solvent-thermal technique . Journal of Hazardous Materials, 169, 1045-1053, (2009). 

Ismail, A.A. and Bahnemann, D.W. (2011) Mesoporous titania photocatalysts preparation, characterization and reaction mechanisms. J. Mater. Chem., 21, 11686-11707. 

Fig. 5 SEM images of Ag AgCI photocatalyst prepared from different precursors (A, B) Agi 02sHi 852M0552O13 microrod (C, D) Ag2Mo04 microrods and cubes (E, R polyhedronlike Ag2Mo04. Reproduced from ref. 8 with permissioh. 2010 Wiley-VCH Verlag GmbH Co. KGaA, Weinheim.

Liu, H.M., Nakamura, R. and Nakato, Y. Promoted photo-oxidation reactivity ofparticulate BiV04 photocatalyst prepared by a photoassisted sol-gel method. Journal of the Electrochemical Society, 2005. 152(11) p. G856-G861. 

Lee S, Yamasue S, Okumura H, Ishihara K. Effect of oxygen and nitrogen concentration of nitrogen doped TiOx film as photocatalyst prepared by reactive sputtering. Appl Cat A 2009 371 179-90. 

In Figure 3.33b the rate constant is plotted against carbon content. The trend for photocatalysts prepared at 700 and 900°C is similar to those reported for MB and RB5 (Figure 3.32) samples prepared at 900°C show a marked maximum at approximately 8 mass% carbon, and those prepared at 700°C exhibit a gradual decrease in k with increasing carbon content. 

Nanocrystalline anatase TiOj photocatalysts prepared via a facile low temperature nonhydrolytic sol-gel reaction of TiCl4 and benzyl alcohol. 76 (2007)... 

Ag-SrTiOs photocatalysts prepared by hydrothermal method showed activity in the reduction of CO2 to methyl formate in methanol under UV irradiation [50]. Further modification with niobia led to solid (AgNb03)i (SrTi03) solutions that showed a bandgap from 3.21 to 2.65 eV when x decreased from 1 to 0 [51]. 

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