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Surface anchored self-assembled reaction centre mimics as photoanodes consisting of a secondary electron donor, aluminium(iii) porphyrin and TiO 2 semiconductor.
- Source :
-
Physical chemistry chemical physics : PCCP [Phys Chem Chem Phys] 2019 Sep 21; Vol. 21 (35), pp. 19612-19622. Date of Electronic Publication: 2019 Aug 29. - Publication Year :
- 2019
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Abstract
- A series of vertically assembled photoanodes, consisting of 5,10,15,20-tetrakis(3,4,5-trifluorophenyl)aluminum(iii) porphyrin (AlPorF <subscript>3</subscript> ), a pyridine appended electron donor (PTZ-Py, PTZ = phenothiazine; TTF-Py, TTF = tetrathiafulvalene), and semiconductor TiO <subscript>2</subscript> , have been fabricated by exploiting the unique axial properties of AlPorF <subscript>3</subscript> . The new photoanodes were characterized by steady-state and transient spectroscopic techniques. Transient-absorption studies show that in the absence of a donor, both the photoanodes (AlPorF <subscript>3</subscript> -TiO <subscript>2</subscript> and AlPorF <subscript>3</subscript> -Ph-TiO <subscript>2</subscript> ) exhibit electron injection from AlPorF <subscript>3</subscript> into the conduction band of TiO <subscript>2</subscript> and the injection efficiencies are strongly dependent on the linker. Faster electron injection and recombination is revealed when AlPorF <subscript>3</subscript> is directly bound to TiO <subscript>2</subscript> . Although a secondary electron donor is coordinated to AlPorF <subscript>3</subscript> (viz., Donor-Py-AlPorF <subscript>3</subscript> -TiO <subscript>2</subscript> and Donor-Py-AlPorF <subscript>3</subscript> -Ph-TiO <subscript>2</subscript> ), the primary charge separation occurs in the form of electron injection from AlPorF <subscript>3</subscript> to TiO <subscript>2</subscript> followed by a secondary process involving photooxidation of the donor (PTZ and TTF) with AlPorF <subscript>3</subscript> ˙ <superscript>+</superscript> . The estimated electron injection lifetimes and the AlPorF <subscript>3</subscript> ˙ <superscript>+</superscript> decay lifetimes strongly depend on the electron richness of the donor; the higher the electron density of the donor, the faster the electron injection and photooxidation witnessed. The photoanodes with TTF (TTF-Py-AlPorF <subscript>3</subscript> -TiO <subscript>2</subscript> and TTF-Py-AlPorF <subscript>3</subscript> -Ph-TiO <subscript>2</subscript> ) show faster injection and shorter decay lifetimes of AlPorF <subscript>3</subscript> ˙ <superscript>+</superscript> over their PTZ counterparts (PTZ-Py-AlPorF <subscript>3</subscript> -TiO <subscript>2</subscript> and PTZ-Py-AlPorF <subscript>3</subscript> -Ph-TiO <subscript>2</subscript> ). The observed trends suggest that the strong secondary electron donor enhances the injection and the subsequent photooxidation processes in the investigated photoanodes. The successful mimicking of a sequential charge-separation process makes aluminum(iii) porphyrins potential sensitizers for the construction of photoanodes, especially for photocatalytic and dye-sensitized solar cells for conversion and storage of solar energy.
Details
- Language :
- English
- ISSN :
- 1463-9084
- Volume :
- 21
- Issue :
- 35
- Database :
- MEDLINE
- Journal :
- Physical chemistry chemical physics : PCCP
- Publication Type :
- Academic Journal
- Accession number :
- 31464315
- Full Text :
- https://doi.org/10.1039/c9cp03400e