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[en] This special issue on Solar energy and nano materials for clean energy development is composed of selected, full-length versions of papers presented during the international Solar 09 conference that was held in the fascinating historical city of Luxon. The conference gathered scientists from 26 countries, to discuss outstanding research on a multitude of topics and disciplines. As was pointed out by Professor Paul Barbara from the University of Texas in Austin at the opening session of the conference, this medium-sized conference offered the unique opportunity to learn and exchange scientific issues from distinct disciplines that have one main thing in common, solar photons. This exceptional opportunity to learn about other fields of research not only required particular didactic skills form the speakers, but also demanded special attention and openness from the audience.
[en] The effect of γ-radiation on the electronic absorption spectra of the negatively solvatochromic dyestuff 1, namely, 4-(4'-N,N,-dimethylaminostyryl)-pyridinium methiodide in water and dimethylsulphoxide solvents is investigated. Ionizing radiation at different absorbed doses brought about gradual bleaching of aerated dye solutions. The γ-radiation induced degradation and the consequent changes in the electronic absorption spectrum of dye 1 are discussed in the light of the theoretically calculated spectrum. The linear response range of dye 1 in the case of DMSO solution is wider than that in H2O. The results demonstrate that the radiochromic dye solutions offer dosimetry in the low dose range by means of visible spectrophotometric analysis. (author)
[en] Pure and Gd3+ doped titanate nano tubes (TNTs) materials were synthesized by a hydrothermal method. Their morphology, optical properties, thermal stability, and magnetic properties were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis spectroscopy, thermal analysis, and magnetic measurements. It was found that doping renders Gd3+ TNT visible light active and results in smaller crystallite size and larger surface area as well as higher thermal stability compared to pure titanate nano tubes. The estimated magnetic moments point to presence of weak antiferromagnetic interaction. Application of the prepared Gd3+ TNT for modifying conventional photoanodes in polymer solar cells was attempted. Preliminary results show slightly improved photovoltaic energy conversion efficiency in the devices containing the newly designed Gd3+ doped nano tubes.
[en] Highly luminescent complexes of Eu and Tb ions with norfloxacin (NFLX) and gatifloxacin (GFLX) were prepared in sol–gel matrix. The red and green emissions of Eu and Tb ions were obtained by the energy transfer from the triplet state of (NFLX) and (GFLX) to the excited emitting states (5D0 and 5D4) of Eu and Tb, respectively. The intensity of the electric field emission bands (5D0→7F2, 617 nm and 5D4→7F5, 545 nm) of Eu and Tb ions were proportional to the concentration of (NFLX at pH 6.0) and (GFLX at pH 3.5) in acetonitrile with excitation wavelengths (λex) (340 and 395) and (370 and 350 nm) for Eu and Tb ions, respectively. The monitored luminescence intensity of the system showed a good linear relationship with the concentration of NFLX within a range of 5×10−9–5.8×10−6 and 5×10−8–1.0×10−6 mol L−1 with a correlation coefficient of 0.990, and for GFLX within a range of 2.4×10−9–3.2×10−5 and 5×10−8–8.0×10−6 mol L−1 with a correlation coefficient of 0.995. The detection limit (LOD) was determined as 3.0×10−9 and 1.0×10−8 mol L−1 for NFLX and 1.6×10−10 and 2.0×10−8mol L−1 for GFLX. The limit of quantification (LOQ) is 9×10−9 and 3.0×10−8 and 4.8×10−10 and 6.0×10−8 in case of Eu and Tb, respectively. - Highlights: ► A simultaneous determination of (NFLX) and (GFLX) in their mixture was developed. ► High luminescence intensity of the Eu3+ –NFLX or GFLX was observed in acetonitrile. ► The Eu3+ more sensitive than Tb3+ as a sensor for the determination of NFLX or GFLX.
[en] Novel low density polyethylene-grafted-poly(4-vinylpyridine-co-acrylamide) (LDPE-g-P(4-VP/AAm)) films were prepared by means of γ-radiation-induced graft copolymerization as support for photocatalytic application. Nanometer-sized TiO2 particles were immobilized to the grafted LDPE via dip coating technique. The efficiency of immobilized photocatalyst is tested on two target pollutants (textile azo dyes: Remazol red RB-133 (RR RB 133) and reactive blue 2 (RB2)). The efficient photocatalytic ability as reflected in determined photobleaching rate of both dyes was observed and is comparable to that for the non-supported TiO2 used in a typical slurry photoreactor. The LDPE-g-(4-VP/AAm) copolymers supported TiO2 photocatalyst has the practical advantages of easy separation and removal from the polluted environment. It could be a viable technique for the safe disposal of textile wastewater into the water streams
[en] Graphical abstract: (a) A highly ordered, vertically oriented TiO2 nanorods compared with TiO2 nanopaticles and (b) Dye sensitized solar cell fabricated using sealing technique. Highlights: ► TiO2 nanorods particles size of 3–5 nm was synthesized hydrothermally at 100 °C. ► SBET was 78.14 m2/g and the band gap energy was 3.2 eV. ► (Jsc) and (Voc) of the DSSC were in the range 10.84–13.23 mA cm−2 and 0.71–0.78 V. ► Conversion efficiency of DSSCs was 7.2%. ► IPCE analyses of the DSSC showed two peaks, at ∼350 and 520 nm. -- Abstract: A low temperature hydrothermal process have been developed to synthesize titania nanorods (NRs) and nanoparticles (NPs) with controlled size for dye sensitized solar cells (DSSCs). Effect of calcination temperature on the performance of TiO2 nanoparticles for solar cells was investigated and discussed. The crystallite size and the relative crystallinity of the anatase phase were increased with increasing the calcination temperature. The structures and morphologies of both (TiO2 nanorods and nanoparticles) were characterized using XRD, SEM, TEM/HRTEM, UV–vis Spectroscopy, FTIR and BET specific surface area (SBET) as well as pore-size distribution by BJH. The size of the titania nanorods was 6.7 nm width and 22 nm length while it was 13 nm for nanoparticles. Efficiency of dye-sensitized solar cells (DSSCs) fabricated with oriented TiO2 nanorods was reported to be more superior compared to DSSC based on mesoporous TiO2 nanoparticles due to their high surface area, hierarchically mesoporous structures, low charge recombination and fast electron-transfer rate. With increasing calcination temperature of the prepared nanopowders, the light-electricity conversion efficiency (η) decreased. The efficiency of the assembly solar cells was decreased due to the agglomeration of the particles and difficulty of electron movement. The power efficiency was enhanced from 1.7% for TiO2 nanoparticles cells at hydrothermally temperature 500 °C and 5.2% for TiO2 nanoparticles cells at hydrothermally temperature 100 °C to 7.2% for TiO2 nanorods cells under AM1.5 illumination (100 mW cm−2)