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A Decaheme Cytochrome as a Molecular Electron Conduit in Dye-Sensitized Photoanodes.

Hwang ET, Sheikh K, Orchard KL, Hojo D, Radu V, Lee CY, Ainsworth E, Lockwood C, Gross MA, Adschiri T, Reisner E, Butt JN, Jeuken LJ - Adv Funct Mater (2015)

Bottom Line: The system is assembled by forming a densely packed MtrC film on an ultra-flat gold electrode, followed by the adsorption of approximately 7 nm TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP).The step-by-step construction of the MtrC/TiO2 system is monitored with (photo)electrochemistry, quartz-crystal microbalance with dissipation (QCM-D), and atomic force microscopy (AFM).Photocurrents are dependent on the redox state of the MtrC, confirming that electrons are transferred from the TiO2 nanocrystals to the surface via the MtrC conduit.

View Article: PubMed Central - PubMed

Affiliation: School of Biomedical Sciences, University of Leeds Leeds, LS2 9JT, UK E-mail: L.J.C.Jeuken@leeds.ac.uk ; The Astbury Centre for Structural Molecular Biology, University of Leeds Leeds, LS2 9JT, UK.

ABSTRACT

In nature, charge recombination in light-harvesting reaction centers is minimized by efficient charge separation. Here, it is aimed to mimic this by coupling dye-sensitized TiO2 nanocrystals to a decaheme protein, MtrC from Shewanella oneidensis MR-1, where the 10 hemes of MtrC form a ≈7-nm-long molecular wire between the TiO2 and the underlying electrode. The system is assembled by forming a densely packed MtrC film on an ultra-flat gold electrode, followed by the adsorption of approximately 7 nm TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP). The step-by-step construction of the MtrC/TiO2 system is monitored with (photo)electrochemistry, quartz-crystal microbalance with dissipation (QCM-D), and atomic force microscopy (AFM). Photocurrents are dependent on the redox state of the MtrC, confirming that electrons are transferred from the TiO2 nanocrystals to the surface via the MtrC conduit. In other words, in these TiO2/MtrC hybrid photodiodes, MtrC traps the conduction-band electrons from TiO2 before transferring them to the electrode, creating a photobioelectrochemical system in which a redox protein is used to mimic the efficient charge separation found in biological photosystems.

No MeSH data available.


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A) X-ray diffraction (XRD) pattern of 3,4-dihydroxybenzoic acid (DHBA)–TiO2 nanocrystals and bulk anatase TiO2 reference pattern (# JCPDS 84–1286) and B) transmission electron micrograph (TEM) images of oleic acid capped TiO2 nanoparticles.
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fig03: A) X-ray diffraction (XRD) pattern of 3,4-dihydroxybenzoic acid (DHBA)–TiO2 nanocrystals and bulk anatase TiO2 reference pattern (# JCPDS 84–1286) and B) transmission electron micrograph (TEM) images of oleic acid capped TiO2 nanoparticles.

Mentions: The XRD pattern of the TiO2 nanoparticles showed a crystalline pure anatase phase (Figure3A) and, by TEM, the particles were found to be truncated octahedra with diameters of 6.8 ± 0.7 nm (Figure 3B). The organic content of the dried DHBA-TiO2 particles was measured to be 7.26% by thermogravimetric analysis, equating to ≈1.4 DHBA-molecules per square nanometer on the surfaces of the TiO2 nanocrystals (Figure S1, Supporting Information). The isoelectric point of the DHBA-TiO2, determined by zeta potential measurements (Figure S2, Supporting Information), was found to be 4.49, consistent with carboxylic acid functionality on the surface. Fourier-transform infrared spectroscopy (FT-IR) spectroscopy of the dried DHBA-TiO2 particles showed characteristic resonances for the DHBA modifier; however O–Ti–O peaks absorbances were too weak to be clearly observed (Figure S3-i, Supporting Information).


A Decaheme Cytochrome as a Molecular Electron Conduit in Dye-Sensitized Photoanodes.

Hwang ET, Sheikh K, Orchard KL, Hojo D, Radu V, Lee CY, Ainsworth E, Lockwood C, Gross MA, Adschiri T, Reisner E, Butt JN, Jeuken LJ - Adv Funct Mater (2015)

A) X-ray diffraction (XRD) pattern of 3,4-dihydroxybenzoic acid (DHBA)–TiO2 nanocrystals and bulk anatase TiO2 reference pattern (# JCPDS 84–1286) and B) transmission electron micrograph (TEM) images of oleic acid capped TiO2 nanoparticles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493899&req=5

fig03: A) X-ray diffraction (XRD) pattern of 3,4-dihydroxybenzoic acid (DHBA)–TiO2 nanocrystals and bulk anatase TiO2 reference pattern (# JCPDS 84–1286) and B) transmission electron micrograph (TEM) images of oleic acid capped TiO2 nanoparticles.
Mentions: The XRD pattern of the TiO2 nanoparticles showed a crystalline pure anatase phase (Figure3A) and, by TEM, the particles were found to be truncated octahedra with diameters of 6.8 ± 0.7 nm (Figure 3B). The organic content of the dried DHBA-TiO2 particles was measured to be 7.26% by thermogravimetric analysis, equating to ≈1.4 DHBA-molecules per square nanometer on the surfaces of the TiO2 nanocrystals (Figure S1, Supporting Information). The isoelectric point of the DHBA-TiO2, determined by zeta potential measurements (Figure S2, Supporting Information), was found to be 4.49, consistent with carboxylic acid functionality on the surface. Fourier-transform infrared spectroscopy (FT-IR) spectroscopy of the dried DHBA-TiO2 particles showed characteristic resonances for the DHBA modifier; however O–Ti–O peaks absorbances were too weak to be clearly observed (Figure S3-i, Supporting Information).

Bottom Line: The system is assembled by forming a densely packed MtrC film on an ultra-flat gold electrode, followed by the adsorption of approximately 7 nm TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP).The step-by-step construction of the MtrC/TiO2 system is monitored with (photo)electrochemistry, quartz-crystal microbalance with dissipation (QCM-D), and atomic force microscopy (AFM).Photocurrents are dependent on the redox state of the MtrC, confirming that electrons are transferred from the TiO2 nanocrystals to the surface via the MtrC conduit.

View Article: PubMed Central - PubMed

Affiliation: School of Biomedical Sciences, University of Leeds Leeds, LS2 9JT, UK E-mail: L.J.C.Jeuken@leeds.ac.uk ; The Astbury Centre for Structural Molecular Biology, University of Leeds Leeds, LS2 9JT, UK.

ABSTRACT

In nature, charge recombination in light-harvesting reaction centers is minimized by efficient charge separation. Here, it is aimed to mimic this by coupling dye-sensitized TiO2 nanocrystals to a decaheme protein, MtrC from Shewanella oneidensis MR-1, where the 10 hemes of MtrC form a ≈7-nm-long molecular wire between the TiO2 and the underlying electrode. The system is assembled by forming a densely packed MtrC film on an ultra-flat gold electrode, followed by the adsorption of approximately 7 nm TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP). The step-by-step construction of the MtrC/TiO2 system is monitored with (photo)electrochemistry, quartz-crystal microbalance with dissipation (QCM-D), and atomic force microscopy (AFM). Photocurrents are dependent on the redox state of the MtrC, confirming that electrons are transferred from the TiO2 nanocrystals to the surface via the MtrC conduit. In other words, in these TiO2/MtrC hybrid photodiodes, MtrC traps the conduction-band electrons from TiO2 before transferring them to the electrode, creating a photobioelectrochemical system in which a redox protein is used to mimic the efficient charge separation found in biological photosystems.

No MeSH data available.


Related in: MedlinePlus