Photoelectrochemistry of Photosystem I Bound in Nafion

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• 作者：David R. Baker ; Richard F. Simmerman ; James J. Sumner ; Barry D. Bruce ; Cynthia A. Lundgren
• 刊名：Langmuir
• 出版年：2014
• 出版时间：November 18, 2014
• 年：2014
• 卷：30
• 期：45
• 页码：13650-13655
• 全文大小：344K
• ISSN：1520-5827

文摘

Developing a solid state Photosystem I (PSI) modified electrode is attractive for photoelectrochemical applications because of the quantum yield of PSI, which approaches unity in the visible spectrum. Electrodes are constructed using a Nafion film to encapsulate PSI as well as the hole-scavenging redox mediator Os(bpy)₂Cl₂. The photoactive electrodes generate photocurrents of 4 渭A/cm² when illuminated with 1.4 mW/cm² of 676 nm band-pass filtered light. Methyl viologen (MV²⁺) is present in the electrolyte to scavenge photoelectrons from PSI in the Nafion film and transport charges to the counter electrode. Because MV²⁺ is positively charged in both reduced and oxidized states, it is able to diffuse through the cation permeable channels of Nafion. Photocurrent is produced when the working electrode is set to voltages negative of the Os³⁺/Os²⁺ redox potential. Charge transfer through the Nafion film and photohole scavenging at the PSI luminal surface by Os(bpy)₂Cl₂ depends on the reduction of Os redox centers to Os²⁺ via hole scavenging from PSI. The optimal film densities of Nafion (10 渭g/cm² Nafion) and PSI (100 渭g/cm² PSI) are determined to provide the highest photocurrents. These optimal film densities force films to be thin to allow the majority of PSI to have productive electrical contact with the backing electrode.