Enabling visible-light water photooxidation by coordinative incorporation of Co(II/III) cocatalytic sites into organic-inorganic hybrids: quantum chemical modeling and photoelectrochemical performance

Coordinative incorporation of Co(II/III) cocatalytic sites into organic-inorganic hybrids of TiO 2 and "polyheptazine" (PH, poly(aminoimino)heptazine, melon, or "graphitic carbon nitride") has been investigated both by quantum chemical calculations and experimental techniques. Sp...

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Bibliographic Details
Published in:Journal of coordination chemistry 2015-09, Vol.68 (17-18), p.3317-3327
Main Authors: Khavryuchenko, Oleksiy V., Wang, Lidong, Mitoraj, Dariusz, Peslherbe, Gilles H., Beranek, Radim
Format: Article
Language:English
Subjects:
Artificial photosynthesis
Cobalt
Hybrid materials
Incorporation
Oxygen evolution
Photoanode
Time-dependent density-functional theory
Water photooxidation
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Summary:Coordinative incorporation of Co(II/III) cocatalytic sites into organic-inorganic hybrids of TiO 2 and "polyheptazine" (PH, poly(aminoimino)heptazine, melon, or "graphitic carbon nitride") has been investigated both by quantum chemical calculations and experimental techniques. Specifically, density-functional theory (DFT) calculations (PBE/def2-TZVPP) suggest that Co(II/III) and Zn(II) ions adsorb in nanocavities at the surface of the hybrid PH-TiO 2 cluster, a prediction which can be further confirmed experimentally by 15 N nuclear magnetic resonance in the case of the Zn complex. The absorption spectra of the complexes were characterized by time-dependent DFT calculations, suggesting a change of color upon Co ion binding which can in fact be observed with the naked eye. Hybrid TiO 2 -PH photoelectrodes were impregnated with Co(II) ions from aqueous cobalt nitrate solutions. Optical absorption data suggest that Co(II) ions are predominantly present as single ions coordinated within the nitrogen cavities of TiO 2 -PH, and any undesired blocking of light absorption is negligible. The cobalt-induced cocatalytic sites can efficiently couple to the holes photogenerated by visible light in TiO 2 -PH, leading to complete oxidation of water to dioxygen. Our results indicate that coordinative incorporation of metal ions into well-designed surface sites in the light absorber is sufficient to drive complex multielectron transformations in artificial photosynthetic systems.
ISSN:0095-8972
1029-0389
DOI:10.1080/00958972.2015.1072624