High-Potential Porphyrins Supported on SnO2 and TiO2 Surfaces for Photoelectrochemical Applications

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• 作者：Jianbing Jiang ; John R. Swierk ; Kelly L. Materna ; Svante HedströmShin Hee Lee ; Robert H. Crabtree ; Charles A. Schmuttenmaer ; Victor S. Batista ; Gary W. Brudvig
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：December 29, 2016
• 年：2016
• 卷：120
• 期：51
• 页码：28971-28982
• 全文大小：747K
• ISSN：1932-7455

文摘

We report CFb>3b>-substituted porphyrins and evaluate their use as photosensitizers in water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) by characterizing interfacial electron transfer on metal oxide surfaces. By using (CFb>3b>)b>2b>Cb>6b>Hb>3b> instead of Cb>6b>Fb>5b> substituents at the meso positions, we obtain the desired high potentials while avoiding the sensitivity of Cb>6b>Fb>5b> substituents to nucleophilic substitution, a process that limits the types of synthetic reactions that can be used. Both the number of CFb>3b> groups and the central metal tune the ground and excited-state potentials. A pair of porphyrins bearing carboxylic acids as anchoring groups were deposited on SnOb>2b> and TiOb>2b> surfaces, and the interfacial charge-injection and charge-recombination kinetics were characterized by using a combination of computational modeling, terahertz measurements, and transient absorption spectroscopy. We find that both free-base and metalated porphyrins inject into SnOb>2b> and that recombination is slower for the latter case. These findings demonstrate that (CFb>3b>)b>2b>Cb>6b>Hb>3b>-substituted porphyrins are promising photosensitizers for use in WS-DSPECs.