Selectivity Control of CO2 Reduction in an Inorganic Artificial Photosynthesis System

We demonstrated that the selectivity of photo electrochemical CO 2 reduction can be controlled in an inorganic artificial photosynthesis system using an AlGaN/GaN photo electrode. By increasing input light intensity and the use of a gold cathode, the Faradaic efficiency of CO dramatically increases...

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Published inApplied physics express Vol. 6; no. 9; pp. 097102 - 097102-4
Main Authors Hashiba, Hiroshi, Yotsuhashi, Satoshi, Deguchi, Masahiro, Yamada, Yuka, Ohkawa, Kazuhiro
Format Journal Article
LanguageEnglish
Published The Japan Society of Applied Physics 01.09.2013
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Summary:We demonstrated that the selectivity of photo electrochemical CO 2 reduction can be controlled in an inorganic artificial photosynthesis system using an AlGaN/GaN photo electrode. By increasing input light intensity and the use of a gold cathode, the Faradaic efficiency of CO dramatically increases from 30% to over 80% while that of H 2 decreases. We observed that the cathode potential resulting from illumination determines the ratio of CO and H 2 . With this system, it is possible to switch the main reaction product from CO to HCOOH, which is also effective even under intense illumination.
Bibliography:Schematic illustration of photo electrochemical system. Electrons and holes created by light illumination contribute to CO 2 reduction on cathode and water oxidation on anode, respectively. Photocurrent and cathode potential on changing light intensity from 1 to 10 SUN. Blue triangles represent photocurrent and red squares represent cathode potential. Photocurrent is normalized by an illuminated area to the photo electrode. Faradaic efficiency of CO, HCOOH, and H 2 plotted against input light intensity. The pink diamonds, purple squares, and green triangles represent the Faradaic efficiency of CO, HCOOH, and H 2 , respectively. (a) Schematic band diagram before photo illumination. A gray region represents the energy level filled with electrons. The photo electrode and the cathode are electrically connected (expressed by a line in this figure). (b) Schematic band diagram after photo illumination. The raised conduction band due to excited electrons leads to an increase in cathode potential. Faradaic efficiency of CO, HCOOH, and H 2 for different cathodes with illumination of 10 SUN. The pink, purple, and green regions represent the Faradaic efficiency of CO, HCOOH, and H 2 , respectively.
ISSN:1882-0778
1882-0786
DOI:10.7567/APEX.6.097102