Spectroscopic Study of Tetradecyltrimethylammonium Bromide Pt−C14TAB Nanoparticles: Structure and Stability

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• 作者：Yuri Borodko ; Louis Jones ; Hyunjoo Lee ; Heinz Frei ; Gabor Somorjai
• 刊名：Langmuir
• 出版年：2009
• 出版时间：June 16, 2009
• 年：2009
• 卷：25
• 期：12
• 页码：6665-6671
• 全文大小：928K
• 年卷期：v.25,no.12(June 16, 2009)
• ISSN：1520-5827

文摘

The vibrational spectra of platinum nanoparticles (12 nm) capped with tetradecyltrimethylammonium bromide, C₁₄TAB, were investigated by Fourier transform infrared (FTIR) spectroscopy. We have shown that the thermal decay of Pt−C₁₄TAB nanoparticles in N₂, H₂, and O₂ atmospheres leads to the release of the hydrocarbon chain of the surfactant and the formation of a strongly bonded layer of ammonium cations on the platinum surface. The platinum atoms accessible to CO chemisorption were not reducible by hydrogen in the temperature range from 30 to 200 °C. A FTIR spectrum of C₁₄TAB adsorbed on Pt nanoparticles was dramatically perturbed as compared with pure C₁₄TAB. New intense and broad bands centered at 1450 cm⁻¹ and 760 cm⁻¹ are making their appearance in Pt−C₁₄TAB. It may be speculated that new bands are the result of coupling between conducting electrons of Pt and molecular vibrations of adsorbed C₁₄TAB, and as a consequence, specific vibrational modes of ammonium cation are transformed into electron-vibrational modes.