Photocurrent generated on a carotenoid-sensitized TiO2 nanocrystalline mesoporous electrode |
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| Institution: | 1. Department of Chemistry & Biochemistry, University of Texas, Austin, TX 78712, USA;2. Department of Chemistry, University of Alabama, Tuscaloosa, AL 35487-0336, USA;1. Department of Food Science, Faculty of Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark;2. Department of Biomedical Sciences, Building 4.5, Panum Institute, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200, Denmark;3. Heart Research Institute, 7 Eliza Street, Newtown, NSW 2042, Australia;4. Faculty of Medicine, University of Sydney, Sydney, NSW 2006, Australia;1. Department of Physics, Center of Excellent for Advanced Materials Research, Faculty of Science, King Khalid University, PO Box 9004, Abha, Saudi Arabia;2. Nano-Science Lab., Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt;3. Semiconductor Lab., Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt;4. Environmental Studies and Research Institute (ESRI), University of Sadat City, Sadat Branch, Egypt;5. Physics Department, Faculty of Science, Firat University, Elazig, Turkey;1. Department of Physics, University of the Free State, Bloemfontein ZA9300, South Africa;2. Department of Physics, University of Khartoum, Khartoum, Sudan;1. Department of Applied Chemistry, University of Johannesburg, P. O. Box 17011, Doornfontein Campus, 2028 Johannesburg, South Africa;2. Department of Chemistry, Faculty of Science, Obafemi Awolowo University, Ile-Ife 220005, Nigeria;3. Council for Scientific and Industrial Research, Meraka Institute, Centre for High Performance Computing, 15 Lower Hope Road, Rosebank, Cape Town 7700, South Africa |
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| Abstract: | Photocurrent was observed upon monochromatic illumination of an ITO electrode coated with a TiO2 nanocrystalline mesoporous membrane with carotenoid 8′-apo-β-caroten-8′-oic acid (ACOA) deposited as a sensitizer (illuminated area 0.25 cm2) and immersed in an aqueous 10 mM hydroquinone (H2Q), 0.1 M NaH2PO4 solution (pH = 7.4) purged with argon, using a platinum flag counter electrode (area 3.3 cm2) and a SCE reference electrode. The carotenoid-sensitized short-circuit photocurrent reached 4.6 μA/cm2 upon a 40 μW/cm2 incident light beam at 426 nm, with an IPCE (%, incident monochromatic photon-to-photocurrent conversion efficiency) as high as 34%. The short-circuit photocurrent was stable during 1 h of continuous illumination with only a 10% decrease. An open-circuit voltage of 0.15 V was obtained (upon 426 nm, 40 μW/cm2 illumination) which remained at a constant value for hours. The observed open-circuit voltage is close to the theoretical value (0.22 V) expected in such a system. The action spectrum resembled the absorption spectrum of ACOA bound on the TiO2 membrane with a maximum near 426 nm. No decay of the ACOA on the TiO2 surface was observed after 12 h, presumably because of rapid regeneration of ACOA from ACOA + at the surface by electron transfer from H2Q. |
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