GSC  Vol.4 No.2 , May 2014
Enhancement of Photocatalytic Water Splitting Rate via Rayleigh Convection
ABSTRACT
In order to enhance photocatalytic water splitting rates with Pt/TiO2 powder, sufficient agitation of the biphasic medium is required to switch surficial reactions to volumetric reactions. Additionally, agitation is conducive to higher diffusion rates of the generated hydrogen and co-produced oxygen, hindering their ability to re-couple to water on Pt loaded to TiO2 powder. In order to create agitation without consuming any electricity, a novel technique utilizing Rayleigh convection was applied, and its ability to enhance photocatalytic water splitting rates was evaluated. Higher Rayleigh convective flow rates resulted in higher photocatalytic water splitting rates. Utilization of Rayleigh convection approximately doubled the photocatalytic water splitting rates, despite relatively low convective flow velocities (obtained through simple thermo-hydrodynamic simulations). The rate enhancement achieved through Rayleigh convection is a result of its ability to disperse the ultrafine Pt/TiO2 particles throughout the whole medium, leading to volumetric reactions.

Cite this paper
Deguchi, S. , Kariya, B. , Isu, N. , Shimasaki, S. , Banno, H. , Miwa, S. , Sawada, K. , Tsuge, J. , Imaizumi, S. , Kato, H. and Tokutake, K. (2014) Enhancement of Photocatalytic Water Splitting Rate via Rayleigh Convection. Green and Sustainable Chemistry, 4, 80-86. doi: 10.4236/gsc.2014.42012.
References
[1]   Deguchi, S., Katsuki, R., Sugiura, Y., Takeichi, T., Shibata, N. and Isu, N. (2011) Induction by Visible Light of Photocatalytic Water Decontamination by Use of Powders of Nonlinear Optic Material and Visible-Light Phosphor to Generate Dispersed Ultraviolet Light. Kagaku Kogaku Ronbunshu, 37, 38-41.
http://dx.doi.org/10.1252/kakoronbunshu.37.38

[2]   Deguchi, S., Sugiura, Y., Shibata, N., Katsuki, R., Takeichi, T. and Isu, N. (2011) Photocatalytic Water Decontamination with Dispersed Light Source of Ultraviolet Electroluminescence Powder. Kagaku Kogaku Ronbunshu, 37, 42-45.
http://dx.doi.org/10.1252/kakoronbunshu.37.42

[3]   Hong, J., Sun, S., Yang, S.G. and Liu, Y.Z. (2006) Photocatalytic Degradation of Methylene Blue in TiO2 Aqueous Suspensions Using Microwave Powered Electrodeless Discharge Lamps. Journal of Hazardous Materials, 133, 162-166. http://dx.doi.org/10.1016/j.jhazmat.2005.10.004

[4]   Horikoshi, S., Kajitani, M., Sato, S. and Serpone, N. (2007) A Novel Environmental Risk-Free Microwave Discharge Electrodeless Lamp (MDEL) in Advanced Oxidation Processes, Degradation of the 2,4-D Herbicide. Journal of Photochemistry and Photobiology A: Chemistry, 189, 355-363.
http://dx.doi.org/10.1016/j.jphotochem.2007.02.027

[5]   Mueller, P., Loupy, A. and Klan, P. (2005) The Electrodeless Discharge Lamp: A Prospective Tool for Photochemistry. Journal of Photochemistry and Photobiology A: Chemistry, 172, 146-150.
http://dx.doi.org/10.1016/j.jphotochem.2004.12.003

[6]   Deguchi, S., Shibata, N., Takeichi, T., Furukawa, Y. and Isu, N. (2010) Photocatalytic Hydrogen Production from Aqueous Solution of Various Oxidizing Sacrifice Agents. Journal of the Japan Petroleum Institute, 53, 95-100.

[7]   Deguchi, S., Takeichi, T., Shimasaki, S., Ogawa, M. and Isu, N. (2011) Photocatalytic Hydrogen Production from Water with Nonfood Hydrocarbons as Oxidizing Sacrifice Agents. AIChE Journal, 57, 2237-2243.
http://dx.doi.org/10.1002/aic.12414

[8]   Matsuoka, M., Kitano, M., Takeuchi, M., Tsujimaru, K., Anpo, M. and Thomas, J.M. (2007) Photocatalysis for New Energy Production: Recent Advances in Photocatalytic Water Splitting Reactions for Hydrogen Production. Catalysis Today, 122, 51-61. http://dx.doi.org/10.1016/j.cattod.2007.01.042

[9]   Deguchi, S., Kobayashi, N. and Kubota, M. (2008) Environmental Purifying Materials, Equipment and Method. PATENT in Japan, No. 2008-194622.

[10]   Hijikata, T. (2002) Research and Development of International Clean Energy Network Using Hydrogen Energy (WENET). International Journal of Hydrogen Energy, 27, 115-129.
http://dx.doi.org/10.1016/S0360-3199(01)00089-1

[11]   Sato, S. and White, J.M. (1980) Photoassisted Water-Gas Shift Reaction over Platinized Titanium Dioxide Catalysts. Journal of the American Chemical Society, 102, 7206-7210.
http://dx.doi.org/10.1021/ja00544a006

[12]   Chen, B., Mikami, F. and Nishikawa, N. (1999) Numerical Simulation of Natural Convection in Particle Suspensions. Transactions of the Japan Society of Mechanical Engineering B, 65, 1200-1207.
http://dx.doi.org/10.1299/kikaib.65.1200

[13]   Nakano, A., Shigechi, T. and Momoki, S. (2004) Numerical Analysis of Natural Convection from a Heated Plate Facing Downwards. Transactions of the Japan Society of Mechanical Engineering B, 70, 1797-1803.
http://dx.doi.org/10.1299/kikaib.70.1797

[14]   Matsumoto, Y. and Kameda, M. (1993) Propagation of Shock Waves in Dilute Bubbly Liquids. Transactions of the Japan Society of Mechanical Engineering B, 69, 2386-2393.
http://dx.doi.org/10.1299/kikaib.59.2386

[15]   Hernandez, R. (1995) Influence of the Heating Rate on Supercritical Rayleigh-Benard Convection. International Journal of Heat and Mass Transfer, 38, 3035-3051. http://dx.doi.org/10.1016/0017-9310(95)00023-3

 
 
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