4 research outputs found
Effect of Side Groups for Ruthenium Bipyridyl Dye on the Interactions with Iodine in Dye-Sensitized Solar Cells
A density functional theory (DFT) study was performed to elucidate the effect of the side group (X) in Ru(H<sub>2</sub>dcbpy)(X<sub>2</sub>bpy)(NCS)<sub>2</sub> dye on the interactions with iodide ions (I<sup>–</sup> and I<sub>3</sub><sup>–</sup>) and iodine molecule (I<sub>2</sub>), where X is a carboxyl, nonyl, amino, or 1-pyrrolyl group, and dcbpy and X<sub>2</sub>bpy represent 4,4′-dicarboxy-2,2′-bipyridine and 4,4′-X<sub>2</sub>-2,2′-bipyridine, respectively. Oxidized dyes interact with I<sup>–</sup> via the S atom of the NCS ligand perpendicular to the H<sub>2</sub>dcbpy ligand. The relative interaction strength between the dye and I<sup>–</sup> is amino < nonyl <1-pyrrolyl < carboxyl group. Except for dye possessing amino groups, a second I<sup>–</sup> bonds to the first I<sup>–</sup>, and the iodides weakly interact with the C–H bond of X<sub>2</sub>dcbpy ligand. Additionally, I<sub>2</sub> interacts via the S atom of the NCS ligand perpendicular to H<sub>2</sub>dcbpy of the neutral dye, and this interaction becomes stronger in the order of carboxyl < 1-pyrrolyl < nonyl < amino group dye. Only the neutral dye possessing amino groups interacts with I<sub>3</sub><sup>–</sup> via N–H···I bonds. On the basis of theoretical results, the effect of side groups for Ru bipyridyl dye on both regeneration of oxidized dye with I<sup>–</sup> species and recombination related to the interactions with I<sub>2</sub> and I<sub>3</sub><sup>–</sup> species in the dye-sensitized solar cells is discussed
Theoretical Study on the Intermolecular Interactions of Black Dye Dimers and Black Dye–Deoxycholic Acid Complexes in Dye-Sensitized Solar Cells
Herein the intermolecular interactions in RuÂ(H<sub>3</sub>tcterpy)Â(NCS)<sub>3</sub> (black dye) dimers, where tcterpy is 4,4′,4″-tricarboxy-2,2′:6′,2″-terpyridine,
deoxycholic acid (3α,12α-dihydroxy-5β-cholan-24-oic
acid, DCA) dimers, and black dye–DCA complexes in acetonitrile
were investigated using density functional theory (DFT) and time-dependent
DFT (TD-DFT). Among the five resulting black dye dimers, the most
preferable species (<b>BB1</b>) forms intermolecular hydrogen
bonds via the carboxyl groups and has a centrosymmetric structure
similar to that reported for a black dye crystal. Theoretical calculations
indicate six black dye–DCA complexes, and the most stable configuration
(<b>BC1</b>) has three intermolecular hydrogen bonds between
the two carboxyl groups of the dye ligand and one carboxyl and two
hydroxyl groups of DCA. <b>BC1</b> has a higher intermolecular
interaction energy than <b>BB1</b>. On the basis of these theoretical
results, the structure of black dye aggregation and the aggregation
suppression mechanism by DCA during the immersion process to prepare
for dye-sensitized solar cell (DSSC) are discussed
Discovery of Overcoating Metal Oxides on Photoelectrode for Water Splitting by Automated Screening
We applied an automated semiconductor
synthesis and screen system
to discover overcoating film materials and optimize coating conditions
on the BiVO<sub>4</sub>/WO<sub>3</sub> composite photoelectrode to
enhance stability and photocurrent. Thirteen metallic elements for
overcoating oxides were examined with various coating amounts. The
stability of the BiVO<sub>4</sub>/WO<sub>3</sub> photoelectrode in
a highly concentrated carbonate electrolyte aqueous solution was significantly
improved by overcoating with Ta<sub>2</sub>O<sub>5</sub> film, which
was amorphous and porous when calcined at 550 °C. The photocurrent
for the water oxidation reaction was only minimally inhibited by the
presence of the Ta<sub>2</sub>O<sub>5</sub> film on the BiVO<sub>4</sub>/WO<sub>3</sub> photoelectrode
Cs-Modified WO<sub>3</sub> Photocatalyst Showing Efficient Solar Energy Conversion for O<sub>2</sub> Production and Fe (III) Ion Reduction under Visible Light
Cs-modification effects of WO<sub>3</sub> on photocatalytic O<sub>2</sub> evolution and Fe (III) ion reduction over WO<sub>3</sub> under visible light irradiation were investigated. WO<sub>3</sub> having cation-exchange ability at the surface was successfully prepared by hydrothermal and impregnation methods using cesium aqueous solutions. The photocatalytic activity of Cs-modified WO<sub>3</sub> was partially improved by the ion-exchange of Cs<sup>+</sup> for H<sup>+</sup> and Fe<sup>2+</sup>, and more than 10 times higher than that of WO<sub>3</sub> without any treatment. The optimized WO<sub>3</sub> showed 48 times higher quantum efficiency (19% at 420 nm) than that reported previously under visible light, and showed a high solar-to-chemical energy conversion efficiency (η<sub>sun</sub> = 0.3%). This η<sub>sun</sub> value is comparable to the solar-to-product energy conversion efficiencies of natural plant photosynthesis for biomass energy