Modular Assembly of High-Potential Zinc Porphyrin Photosensitizers Attached to TiO₂ with a Series of Anchoring Groups

Abstract

Efforts to improve the ease of assembly and robustness of photoanodes for light-driven water oxidation have led to the development of a modular assembly method for anchoring high-potential zinc porphyrins to TiO2 via coordination to surface-bound pyridine linkers. It is essential that the anchoring groups provide strong electronic coupling between the molecular dye and metal oxide surface for optimal electron injection and that they are robust under the operating conditions of the system. Here, four linker molecules functionalized with either carboxylate, phosphonate, acetylacetonate, or hydroxamate anchoring groups are compared for their relative water stability on TiO2. We also report the relative electron injection efficiencies, as measured by terahertz spectroscopy, for high-potential zinc porphyrins coordinated to TiO2 via pyridyl linkers with the series of anchoring groups.

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

“…Also, fast deactivation pathways may contribute to poor injection. Finally, the anchoring group can have an important effect on electron injection (41,42). This likely can explain the high photocurrents observed for DMEP and MDCE.…”

Design and photochemical study of supramolecular donor–acceptor systems assembled via metal–ligand axial coordination

“…Recently, supramolecular donor-acceptor systems possessing high oxidation potential photosensitizers have gained considerable interest primarily due to the possibility of generating high energy charge-separated states suitable for the development of water oxidation/proton reduction catalysts [118][119][120]. In this context, a series of high potential metallated porphyrins and phthalocyanines have been designed to study the photoinduced electron transfer processes.…”

A Comparative Investigation of the Role of the Anchoring Group on Perylene Monoimide Dyes in NiO‐Based Dye‐Sensitized Solar Cells

“…To assess the relative stabilities of each anchoring group, the stained electrodes were first soaked in acidic (acetic acid at 35 m m ) or basic (tetrabutylammonium hydroxide at 1 m m ) aqueous solutions, but no leaching of the dyes could be observed. This result is most certainly the consequence of the high insolubility of these hydrophobic and aromatic dyes in water, as already observed with other systems . Next, we turn to DMF as solvent, which is a good solvent for all the dyes, to determine the relative stability scale of this series of anchoring groups.…”