Enhanced Performance of Nanowire-Based All-TiO2 Solar Cells using Subnanometer-Thick Atomic Layer Deposited ZnO Embedded Layer

In this paper, the effect of angstrom-thick atomic layer deposited (ALD) ZnO embedded layer on photovoltaic (PV) performance of Nanowire-Based All-TiO2 solar cells has been systematically investigated. Our results indicate that by varying the thickness of ZnO layer the efficiency of the solar cell can be significantly changed. It is shown that the efficiency has its maximum for optimal thickness of 1 ALD cycle in which this ultrathin ZnO layer improves device performance through passivation of surface traps without hampering injection efficiency of photogenerated electrons. The mechanisms contributing to this unprecedented change in PV performance of the cell have been scrutinized and discussed. © 2015 Elsevier Ltd

Degradation of 4-chloro-2-methylphenol in aqueous solution by electro-Fenton and photoelectro-Fenton processes

Degradation of 4-chloro-2-methylphenol (PCOC), a refractory toxic chemical emitted to the environment from the industrial production of phenoxy herbicides was studied in aqueous solution. Electro-Fenton and photoelectro-Fenton processes were used as the degradation methods. H2O2, produced by the reduction of oxygen at carbon cathode reacted with dissolved metal ions to form hydroxyl radicals, which in turn reacted with PCOC sequentially to degrade the aromatic ring. The effects of using different [Fe2+]/[PCOC]0 and the effect of replacing Fe2+ by Mn2+ ion have been examined. It was found that degradation rate was increased with increasing [Fe2+]/[PCOC]0 ratio from 2 to 4. However, the total charge utilized during the treatment was also increased. The efficiency of PCOC degradation was observed to be higher when Mn2+ was used as the catalyst. The mineralization of aqueous solutions of PCOC, withdrawn from the reactor at certain time interval, has been followed by total organic carbon (TOC) decay and dechlorination. A fast and complete degradation of the aromatic ring was achieved in photoelectro-Fenton system. 41.7% TOC decay and complete dechlorination were observed by consuming only 141.4 C electrical charge during a 300 min photoelectron-Fenton treatment. In the case of electro-Fenton system, 280.7 C electrical charge was consumed during 450 min of electrolysis to attain a similar degradation of PCOC. 14.9% TOC removal and 89.3% dechlorination have been obtained in this system under the applied conditions. © 2005 Elsevier B.V. All rights reserved

Electrokinetic properties of biodegradable conducting polyaniline-graft-chitosan copolymer in aqueous and non-aqueous media

In this study, biodegradable and conducting polyaniline-graft-chitosan (PAni-g-CS) copolymer was synthesized by radicalic polymerization using ammonium persulfate (NH4)2S2O8 as initiator. The synthesized copolymer was characterized by using particle size, density, band gap, 1H NMR, TGA, and SEM measurements. The characterization results revealed the successful synthesis of the graft copolymer of PAni and CS. Electrokinetic properties and colloidal stabilities of PAni-g-CS dispersions were examined as a function of time, pH, electrolytes, various surfactants, and temperature by means of ?-potential measurements in polar (water) and non-polar (silicone oil) media. The ?-potential of PAni shifted to more positive region after grating with chitosan. In acidic medium, ?-potential of the copolymer was observed to increase up to +44mV. The presence of monovalent (Nacl) electrolyte had no impact on ?-potential of the copolymer dispersions whereas; divalent (BaCl2) and trivalent (AlCl3) electrolytes caused the ?-potentials of the dispersions to shift to more positive regions. The most effective surfactant on the ?-potential of the PAni-g-CS was determined to be sodium dodecyl sulfate, which reduced the value of ?-potential to -39mV. Elevated temperatures caused almost no change on the ?-potential of the copolymer dispersions. In non-aqueous media, ?-potential of PAni-g-CS was found to be in colloidally stable region. Further, PAni-g-CS was tested against Escherichia coli and showed an improved antibacterial activity when compared to that of pristine PAni and CS. © 2014 Elsevier B.V.CM1101 Firat University Scientific Research Projects Management Unit: 2224-D-10 111T637The authors thank to the Scientific Research Projects of Suleyman Demirel University (2224-D-10), COST Action CM1101 and TUBITAK (111T637) for the support of this work

Synthesis, characterization and electrorheological properties of biodegradable chitosan/bentonite composites

Biodegradable chitosan/bentonite composites with three different compositions were synthesized by the intercalation method using cetyltrimethylammonium bromide as the cationic surfactant. The composites were characterized using conductivity, density, particle size measurements, FTIR, TGA, XRD and SEM methods. Colloidal stabilities of the suspensions prepared in silicone oil (SO) were observed to increase with decreasing density. The effects of dispersed particle concentration, shear rate, electric field strength, electric field frequency and temperature on the electrorheological (ER) activities of the suspensions were investigated. The electric field viscosities of the suspensions showed typical shear thinning non-Newtonian viscoelastic behaviour. Yield stresses of the suspensions were observed to change in proportion to the square of applied electric field (E). Further, according to creep and creep-recovery analysis, reversible viscoelastic deformations were observed in the suspensions under E?0 kV mm-1. © 2013 The Mineralogical Society

Synthesis, characterization and antimicrobial activity of biodegradable conducting polypyrrole-graft-chitosan copolymer

In this study, polypyrrole-graft-chitosan (PPy-g-CS) copolymer was chemically synthesized and its structural and morphological properties characterized by FTIR, UV-vis, SEM, XRD, TGA and zeta-potential techniques. The results revealed that there were strong interactions between PPy and CS chains. The electrical conductivity of CS increased to semiconducting range by grafting. The crystallinity and thermal stability of PPy-g-CS copolymer improved when compared to CS. The copolymer was tested against various bacterial and fungal strains at various concentrations and results obtained were compared with the reference antibiotics. The results indicated that the antibacterial activity of PPy-g-CS copolymer was stronger than CS and PPy alone. The antibacterial activity of the PPy-g-CS copolymer observed to increase with rising concentration, and showed stronger activity against bacteria than Penicillin (10 mg), Rifampicin (5 mg) and Trimethoprim (25 mg), whereas showed equipotent activity with Amikacin (30 mg) and Erythromycin (15 mg) antibiotics. © 2014 Elsevier B.V. All rights reserved

Synthesis, characterization, and enhanced antibacterial activity of chitosan-based biodegradable conducting graft copolymers

In this study, synthesis, characterization, and antibacterial activity of chitosan-based biodegradable conducting graft copolymers namely polyaniline-g-chitosan, polypyr-role- g-chitosan, and polythiophene-g-chitosan with chemical oxidation method using (NH4)2S2O8 and FeCl3 as initiators were investigated. Characterizations of the materials were carried out by means of Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, UV-vis, thermogravimetric analysis, scanning electron microscope, transmission electron microscope, and temperature-dependent electrical conductivity measurements. The grafting yield, grafting efficiency, particle sizes, dielectric constants, and densities of the conducting graft copolymers were determined. Grafting process improved the conductivities and thermal stabilities of the copolymers. The conducting polymer-g-chitosan copolymers were also tested against Klebsiella pneumoniae, Escherichia coli, Bacillus megaterium, Enterococcus faecalis, Staphylococcus aureus microorganisms and relatively higher or equipotent antibacterial activities were determined against the microorganisms compared with Penicillin, Amikacin, Erythromycin, Rifampicin, and Trimethoprim antibiotics. © 2014 Society of Plastics Engineers

Comparison of the treatment methods efficiency for decolorization and mineralization of Reactive Black 5 azo dye

PubMedID: 15752855Degradation of Reactive Black 5 (RB5), a well-known non-biodegradable disazo dye, has been studied using UV/TiO2, wet-air oxidation (WAO), electro-Fenton (EF) and UV/electro-Fenton (UV/EF) advanced oxidation processes (AOPs). The efficiency of substrate decolorization and mineralization in each process has been comparatively discussed by decreases in concentration and total organic carbon content of RB5 solutions. The most efficient method on decolorization and mineralization was observed to be WAO process. Mineralization efficiency was observed in the order of WAO > UV/TiO2 > UV/EF > EF. Final solutions of AOPs applications after 90 min treatment can be disposed safely to environment. Photocatalytic degradation kinetics of RB5 successfully fitted to Langmuir-Hinshelwood (L-H) kinetics model. The values of second order degradation rate constant (k'') and adsorption constant (K) were determined as 5.085 mg L-1 min-1 and 0.112 L mg-1, respectively. © 2004 Elsevier B.V. All rights reserved

Effect of Au nano-particles on TiO 2 nanorod electrode in dye-sensitized solar cells

Au nano particles (NPs) were deposited on vertically grown TiO 2 nanorod arrays on FTO substrate by hydrothermal process. Metal nanoparticles were loaded onto the surface of TiO 2 nanorods via photochemical reduction process under ultraviolet irradiation. X-ray diffraction (XRD), electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis were used to characterize the as-prepared Au/TiO 2 nanorod composites. Current density-voltage (J-V) measurements were obtained from a two-electrode sandwich type cell. The presence of Au nanoparticles can help the electron-hole separation by attracting photoelectrons. Addition of Au nanoparticles to the TiO 2 nanorod significantly increased the fill factor and J SC (short circuit current density). The application of Au NPs TiO 2 nanorods in improving the performance of DSSCs is promising. © 2012 Elsevier Ltd. All rights reserved

Effect of Carbon Nanotube Addition on the Superconducting Properties of BSCCO Samples Textured via Laser Floating Zone Technique

In this research, the effect of carbon nanotube (CNT) addition on the structural and superconducting properties of Bi2Sr2CaCu2Oy + x wt% CNT materials with x = 0, 0.5, 1, and 3 prepared by solid state method, followed by directional grown using the laser floating zone (LFZ) technique has been investigated. XRD measurements showed that all samples are composed of almost single Bi-2212 phase. SEM images proved that Bi-2212 phase is the major one, with minor amounts of (Sr,Ca)3BiOx, and Bi-2201 secondary phases. According to the magnetic results, carbon nanotubes decrease Tc values and significantly reduce the magnetic hysteresis loops area and the magnetic critical current density. © 2019, Springer Science+Business Media, LLC, part of Springer Nature