Redox-Active Monolayers in Mesoporous Silicon

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• 作者：Simone Ciampi ; Bin Guan ; Nadim Darwish ; Peter J. Reece ; J. Justin Gooding
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：August 2, 2012
• 年：2012
• 卷：116
• 期：30
• 页码：16080-16088
• 全文大小：364K
• 年卷期：v.116,no.30(August 2, 2012)
• ISSN：1932-7455

文摘

Herein, redox reactions at chemically derivatized porous silicon (PSi) films are investigated. Passivation of the PSi matrix, by replacing metastable Si鈥揌 termini with nonpolar Si鈥擟鈺怌鈥擱 linkages, allows the electrochemical PSi device to operate in aqueous environments under oxidizing conditions (i.e., electron hole accumulation regime). Cu(I)-catalyzed alkyne鈥揳zide cycloaddition reactions are used to anchor ferrocene derivatives and probe electrochemical reactions at the exceedingly large surface area-to-volume ratio of mesoporous PSi. The forward-biased p-type PSi/electrolyte interface retains a quasi-metallic behavior throughout its entire contour, and it does so for prolonged times even when the electrode is poised at potentials at which a bare silicon electrode would rapidly oxidize. The interfacial capacitance of the PSi matrix is, however, unexpectedly low. An explanation is proposed where PSi morphology and the semiconductor space-charge layer capacitance play a significant role in determining the charging properties of the electrode. These results are important for the application of porous semiconductor electrodes in sensing, electrocatalytic, and energy-conversion devices.