Kimfung Li a, Albertus Handoko a, Junwang Tang a
a chemical engineering, ucl, torrington place, WC1E 7JE
Poster, Kimfung Li, 030
Publication date: 31st March 2013


The concern of rising CO2 emissions and the increasing demand of clean energy have drawn much attention to the utilization and minimization of CO2[1]. Promoting CO2 into other useful organic compounds is one of the most challenging reactions in chemistry, since CO2 is extremely stable in its gaseous phase. Photocatalytic CO2 reduction is a promising clean energy alternative that converts and stores solar energy in a chemical form. Very recently, great success in CO2 photoreduction to CO by photocatalysis has been achieved, either in a homogeneous or heterogeneous system, (e.g. rhenium-complexes or RuP dye-modified TiO2 coupled with the reducing enzyme CODH). However, most of the reported photocatalysts require an efficient hole scavenger. On the other hand, some materials can photoreduce CO2 in the absence of a hole scavenger; the corresponding oxygen evolution from water oxidation by photogenerated hole was not detected which brings up concerns about the function of photogenerated holes in photocatalyst and subsequently stability of the inorganic photocatalysts. Water is the ideal hole acceptor since it has to be used in the CO2 reduction as a proton source and it is earth-abundant.     Unlike other organic hole scavengers, the water oxidation process is extremely slow and requires high energy potential [2, 3]. Only a very few wide band-gap materials can perform CO2 reduction accompanied by water oxidation. Therefore, finding a photocatalyst within solar spectrum region that can simultaneously oxidize water and reduce CO2 is the key for CO2 photoredcution technology.

Herein, we present potassium tantalate, which has a bandgap within the solar spectrum, achieving photocatalytic CO2 conversion using water as sole electron donor. Both reduction products (CO and hydrogen) and oxidation product (oxygen) were simultaneous detected. Furthermore KTaO3 with different morphologies was synthesised. The effects of particle size and morphology were studied. Nanoflake-structured KTaO3 shows more than 7 times higher activity for both CO2 and proton reduction compared with spherical particles.

KTaO3 acting as a photocatalyst for CO2 conversion
[1] K.Li, D.J. Martin, J. Tang, Chinese Journal of Catalysis, Elsevier, China, 2011 [2] J. W. Tang, J. R. Durrant and D. R. Klug, J. Am. Chem. Soc., 2008, 130, 13885-13891 [3] J. Tang, A. J. Cowan, J. R. Durrant and D. R. Klug, Journal of physical Chemistry C, 2011, 115, 3143-3150 [4] K.Li, A. D. Handoko, M. Khraisheh, J. Tang, Energy & Environmental Science, in revision.
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