Abstract
Two different high potential Zn(II) porphyrin designs carrying either 4 or 5 meso pentafluorophenyl moieties as electron acceptor groups and a further electron withdrawing branch inserted in either the β (1) or meso (2) position were tested in photoelectrosynthetic cells for HBr splitting. Photoaction spectra in the presence of HBr showed that red photons up to 700 nm could be harvested and converted and that 2 performed better than 1, thanks to better electronic properties of the excited state, favored by the insertion of the benzothiadiazole electron withdrawing group. Photoanodic performances in the presence of HBr, however, remained low, due to inefficient regeneration of the oxidized sensitizer as a result of an insufficient driving force for Br− oxidation.
Highlights
In view of replacing traditional fossil fuels and reducing the resulting emissions of carbon dioxide, several strategies based on solar energy conversion and storage have been pursued [1,2]
Photoanodes for bromide oxidation include TiO2 or SnO2 /TiO2 core-shell nanostructures functionalized with ruthenium polypyridyl based photosensitizers [11], as well as WO3, SnO2, and Sb-doped SnO2 decorated with aggregated dyes belonging to the family of perylene diimides, reaching up to 1 mA/cm2 photocurrent [9]
We can conclude that probably neither porphyrin has optimal electron/hole spatial distribution of the excited state to perform efficient injection into the n-type semiconductor, since, as a result of the excitation, the shift of electron density on the linker arm, which connects the sensitizer to the semiconductor surface, is comparatively small with respect to that remaining on the porphyrin ring, which is relatively remote from the SnO2 surface
Summary
In view of replacing traditional fossil fuels and reducing the resulting emissions of carbon dioxide, several strategies based on solar energy conversion and storage have been pursued [1,2]. In we investigate investigate the the use use of of perfluorinated perfluorinated Zn(II) In this this work, work, we set-ups for HBr splitting, with the exploitation of two novel species 1 and set-ups for HBr splitting, with the exploitation of two novel species [18], with perfluorophenyl groups, known to increase the oxidation potential of the resulting dyes we have introduced introducedconjugated conjugatedelectron electronwithdrawing withdrawinglinkers, linkers, terminating in cyanoacrylic groups we have terminating in cyanoacrylic groups for for the anchoring to the semiconductor surface. 1 displays displays an additional acceptor unit, namely the benzothiadiazole (BTD), which contributes an additional acceptor unit, namely the benzothiadiazole (BTD), which contributes to the to the absorption of longer wavelengths. Spectroscopic properties of such species applied to the sensitization of n-type SnO2 substrates
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
