Photostability of Phosphonate-Derivatized, RuII Polypyridyl Complexes on Metal Oxide Surfaces

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• 作者：Kenneth Hanson ; M. Kyle Brennaman ; Hanlin Luo ; Christopher R. K. Glasson ; Javier J. Concepcion ; Wenjing Song ; Thomas J. Meyer
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2012
• 出版时间：March 28, 2012
• 年：2012
• 卷：4
• 期：3
• 页码：1462-1469
• 全文大小：351K
• 年卷期：v.4,no.3(March 28, 2012)
• ISSN：1944-8252

文摘

The photostability of [Ru^II(bpy)₂(4,4鈥?(PO₃H₂)₂bpy)]Cl₂ (bpy = 4,4鈥?bipyridine) on nanocrystalline TiO₂ and ZrO₂ films was investigated using a standard measurement protocol. Stability was evaluated by monitoring visible light absorbance spectral changes, in real time, during 455 nm photolysis (30 nm fwhm, 475 mW/cm²) in a variety of conditions relevant to dye-sensitized solar cells and dye-sensitized photoelectrosynthesis cells. Desorption (k_des) and photochemical (k_chem) processes were observed and found to be dependent upon solvent, anion, semiconductor, and presence of oxygen. Both processes are affected by oxygen with k_des and k_photo noticeably smaller in argon saturated solution. Desorption was strongly solvent and pH dependent with desorption rates increasing in the order: methanol (MeOH) 鈮?acetonitrile (MeCN) < propylene carbonate (PC) < pH 1 pH 7. Photochemistry occurred in MeOH and PC but not in aqueous, 0.1 M HClO₄ and MeCN. The anion and solvent dependence of k_photo strongly suggests the photoreaction involves ligand substitution initiated by population of metal centered d-d states. The relative stability of 鈭扨O₃H₂- versus 鈭扖OOH-substituted [Ru^II(bpy)₃]²⁺ was also quantitatively established.

Keywords:

dye-sensitized solar cell (DSSC); dye-sensitized photoelectrosynthesis cell (DSPEC); ruthenium polypyridine; photostability; desorption; photochemistry