Ultrafast Carrier Dynamics in Exfoliated and Functionalized Calcium Niobate Nanosheets in Water and Methanol

详细信息    查看全文

• 作者：Elizabeth C. Carroll ; Owen C. Compton ; Dorte Madsen ; Frank E. Osterloh ; Delmar S. Larsen
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：February 21, 2008
• 年：2008
• 卷：112
• 期：7
• 页码：2394 - 2403
• 全文大小：575K
• 年卷期：v.112,no.7(February 21, 2008)
• ISSN：1932-7455

文摘

We have characterized the initial charge carrier trapping and recombination processes in suspensions ofexfoliated calcium niobate nanosheets derived from the Dion Jacobsen phase KCa₂Nb₃O₁₀. Niobate nanosheetshave previously been found to catalyze hydrogen generation in photochemical water-splitting reactions. Photo-generated charge carriers relaxed with second-order kinetics on a sub-nanosecond time scale that dependedon the nanosheet size. Methanol was used as a sacrificial electron donor to separate the electron and holedynamics, and the photo-oxidation dynamics was found to directly compete with electron-hole recombination.Absorption spectra for trapped carriers were determined and used to separately analyze the trapped electronand hole dynamics in [H_1-xCa₂Nb₃O₁₀]^x- (x = 0.15-0.20) sheets in water. Surface modification by 3-amino-propyl(trimethoxy)silane was found to quench trapped carrier absorptions, resulting in an observed opticalgain.