Accumulation of Multiple Oxidative Equivalents at a Single Site by Cross-Surface Electron Transfer on TiO2

详细信息    查看全文

• 作者：Wenjing Song ; Akitaka Ito ; Robert A. Binstead ; Kenneth Hanson ; Hanlin Luo ; M. Kyle Brennaman ; Javier J. Concepcion ; Thomas J. Meyer
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：August 7, 2013
• 年：2013
• 卷：135
• 期：31
• 页码：11587-11594
• 全文大小：510K
• 年卷期：v.135,no.31(August 7, 2013)
• ISSN：1520-5126

文摘

The photodriven accumulation of two oxidative equivalents at a single site was investigated on TiO₂ coloaded with a ruthenium polypyridyl chromophore [Ru(bpy)₂((4,4鈥?(OH)₂PO)₂bpy)]²⁺ (Ru^IIP²⁺, bpy = 2,2鈥?bipyridine, ((OH)₂PO)₂-bpy = 2,2鈥?bipyridine-4,4鈥?diyldiphosphonic acid) and a water oxidation catalyst [Ru(Mebimpy) ((4,4鈥?(OH)₂PO鈥揅H₂)₂bpy)(OH₂)]²⁺ (Ru^IIOH₂²⁺, Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine, (4,4鈥?(OH)₂PO鈥揅H₂)₂bpy) = 4,4鈥?bis-methlylenephosphonato-2,2鈥?bipyridine). Electron injection from the metal-to-ligand charge transfer (MLCT) excited state of 鈭扲u^IIP²⁺ (鈭扲u^IIP²⁺*) to give 鈭扲u^IIIP³⁺ and TiO₂(e^{鈥?/sup>) was followed by rapid (<20 ns) nearest-neighbor 鈭扲uIIOH₂2+ to 鈭扲uIIIP3+ electron transfer. On surfaces containing both 鈭扲uIIP2+ and 鈭扲uIIIOH₂3+ (or 鈭扲uIIIOH2+), 鈭扲uIIOH₂2+ was formed by random migration of the injected electron inside the TiO₂ nanoparticle and recombination with the preoxidized catalyst, followed by relatively slow (渭s-ms) non-nearest neighbor cross-surface electron transfer from 鈭扲uIIOH₂2+ to 鈭扲uIIIP3+. Steady state illumination of coloaded TiO₂ photoanodes in a dye sensitized photoelectrosynthesis cell (DSPEC) configuration resulted in the buildup of 鈭扲uIIIP3+, 鈭扲uIIIOH2+, and 鈭扲uIV鈺怬2+, with 鈭扲uIV鈺怬2+ formation favored at high chromophore to catalyst ratios.}