FACETED PHOSPHATE CRYSTALS FOR HIGHLY EFFICIENT PHOTOLYSIS OF WATER
Junwang Tang a, David Martin a, Xiaowei Chen b, Jinhua Ye c
a chemical engineering, ucl, torrington place, WC1E 7JE
b Departamento de Ciencia de los Materiales, Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Universidad de Cádiz, Campus Río San Pedro, E-11510 Puerto Real, Cádiz
c cEnvironmental Remediation Materials Unit, National Institute for Materials Sciences, Ibaraki, 305-0047, Japan
Poster, David Martin, 029
Publication date: 31st March 2013

 

Using inorganic semiconductor photocatalysts and solar radiation to perform water splitting is currently one of the most exciting ways to produce clean, renewable energy. Hydrogen fuel from dissociated water can be used directly as a fuel in fuel cells, or used in the chemical engineering industry to make more complex fuels. The current focus within the field is finding a suitable semiconductor which is robust, relatively cheap, and most importantly, offers an efficiency which would be commercially viable [1]. In order to meet the necessary overall light-to-fuel efficiency (ca. 10%), utilising the visible portion of solar radiation is crucial. Furthermore, nature demonstrates an efficient strategy to utilise solar irradiation (nearly unity quantum yield) by spatially and temporally separating electrons and holes in photosynthetic wireless reactions. Thus, artificial water splitting is can be envisaged as being two half reactions; water oxidation, and the equivalent of proton reduction to hydrogen fuel. The former of the two is much more challenging because one molecule of gaseous oxygen requires 4 holes to be produced within the semiconductor, and occurs on a timescale 5 orders of magnitude slower than H2 evolution, proven in both natural and artificial photosynthesis [2]. Therefore, finding an earth-abundant and robust water oxidation photocatalyst with a similar quantum yield to that of natural photosynthesis is widely accepted to be key to solar driven fuel synthesis, if it is to be economically viable.

   In this presentation, we demonstrate a novel surface modification to the relatively new photocatalyst, Ag3PO4[3]. Our facile synthesis method yields pure tetrahedral crystals, completely composed of {111} exposing facets. Our results show that this particular facet plane possesses a very high theoretical surface energy and exhibits nearly 100% quantum yield for water photooxiation under visible irradiation. We will futher discuss the possible reasons behind this enhancement, with particular note on the changes to the charge separation.


Tetrahedral particles lead to a high quantum yield over a wide wavelength range.
[1] K.Li, D.J. Martin, J. Tang, Chinese Journal of Catalysis, Elsevier, China, 2011 [2] J. Tang, J. R Durrant. D. R. Klug, Journal of the American Chemical Society, ACS, 2008. [3] Yi, Z.; Ye, J.; Kikugawa, N.; Kako, T.; Ouyang, S.; Stuart-Williams, H.; Yang, H.; Cao, J.; Luo, W.; Li, Z.; Liu, Y.; Withers, R. L. Nature Materials, NPG, 2010
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