In:
ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2014-01, No. 34 ( 2014-04-01), p. 1293-1293
Abstract:
Multi-electron transfer reactions such as the hydrogen evolution reaction, oxygen evolution reaction and carbon dioxide reduction reaction at semiconductor electrodes have been extensively studied because of the interest in solar-to-chemical energy conversion. Multi-electron transfer reactions at semiconductors are generally slow and a catalyst is required to efficiently promote these reactions. Hence, many groups have examined the modification of the semiconductor surface by catalytic metals. It was, however, found that direct contact of a metal leads to the formation of a Schottky junction and recombination center, resulting in a reduced efficiency. In this study, we constructed organic molecular layers with viologen moieties as electron transfer mediators and various metal complexes such as PtCl 4 2- , PdCl 4 2- and AuCl 4 - as catalysts for multi-electron transfer reactions on hydrogen terminated Si(111) surfaces and the modified Si(111) electrodes were utilized for photoelectrochemical hydrogen evolution and CO 2 reduction reactions. Precise structures of the metal catalysts incorporated with the molecular layers were determined by polarization-dependent total reflection fluorescence (PTRF)-XAFS. High selectivity for CO 2 reduction in preference to the hydrogen evolution reaction was achieved at the Si(111) electrodes modified by molecular layers with viologen moiety and Pd and Au complexes, which are reduced to metallic nanoparticle under operation, and, therefore, actual catalysts for CO 2 reduction were Pd and Au metal nanoparticles, which are known to be good electrocatalysts for CO 2 reduction. High selectivity for CO 2 reduction was also achieved at the Si(111) electrode modified by viologen moiety and Pt complex despite the fact that hydrogen evolution reaction is dominant at Pt metal electrode even in CO 2 saturated solution. Pt complex is not reduced to metallic nanoparticle under operation, and, therefore, Pt complex acts as a confined molecular catalyst for CO 2 reduction with high selectivity. References T. Masuda, K. Uosaki, Chem. Lett., 2004, 33, 788-789. H. Fukumitsu, T. Masuda, D. Qu, Y. Waki, H. Noguchi, K. Shimazu, K. Uosaki, Chem. Lett., 2010, 39, 768-770. Y. Sun, T. Masuda, K. Uosaki, Chem. Lett., 2012, 41, 328-330. T. Masuda, K. Shimazu, K. Uosaki, J.Phys. Chem. C, 2008, 112, 10923-10930. T. Masuda, H. Fukumitsu, S. Takakusagi, W. -J. Chun, T. Kondo, K. Asakura, K. Uosaki, Adv. Mater., 2012, 24, 268-272.
Type of Medium:
Online Resource
ISSN:
2151-2043
DOI:
10.1149/MA2014-01/34/1293
Language:
Unknown
Publisher:
The Electrochemical Society
Publication Date:
2014
detail.hit.zdb_id:
2438749-6
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