22 research outputs found
Geodetic and geodynamic studies at Department of Geodesy and Geodetic Astronomy WUT
The article presents current issues and research work conducted in the Department of Geodesy and Geodetic Astronomy at the Faculty of Geodesy and Cartography at Warsaw University of Technology. It contains the most important directions of research in the fields of physical geodesy, satellite measurement techniques, GNSS meteorology, geodynamic studies, electronic measurement techniques and terrain information systems
From Seconds to Femtoseconds: Solar Hydrogen Production and Transient Absorption of Chalcogenorhodamine Dyes
A series
of chalcogenorhodamine dyes with oxygen, sulfur, and selenium
atoms in the xanthylium core was synthesized and used as chromophores
for solar hydrogen production with a platinized TiO<sub>2</sub> catalyst.
Solutions containing the selenorhodamine dye generate more hydrogen
[181 turnover numbers (TONs) with respect to chromophore] than its
sulfur (30 TONs) and oxygen (20 TONs) counterparts. This differs from
previous work incorporating these dyes into dye-sensitized solar cells
(DSSCs), where the oxygen- and selenium-containing species perform
similarly. Ultrafast transient absorption spectroscopy revealed an
ultrafast electron transfer under conditions for dye-sensitized solar
cells and a slower electron transfer under conditions for hydrogen
production, making the chromophore’s triplet yield an important
parameter. The selenium-containing species is the only dye for which
triplet state population is significant, which explains its superior
activity in hydrogen evolution. The discrepancy in rates of electron
transfer appears to be caused by the presence or absence of aggregation
in the system, altering the coupling between the dye and TiO<sub>2</sub>. This finding demonstrates the importance of understanding the differences
between, as well as the effects of the conditions for DSSCs and solar
hydrogen production