Chlorine Incorporation Research Articles

Naphthalene diimide-based polymeric semiconductors. Effect of chlorine incorporation and n-channel transistors operating in water- CORRIGENDUM

Naphthalene diimide-based polymeric semiconductors. Effect of chlorine incorporation and n-channel transistors operating in water- CORRIGENDUM

Chloride and Indium‐Chloride‐Complex Inorganic Ligands for Efficient Stabilization of Nanocrystals in Solution and Doping of Nanocrystal Solids

Here, the surface functionalization of CdSe and CdSe/CdS core/shell nanocrystals (NCs) with compact chloride and indium‐chloride‐complex ligands is reported. The ligands provide not only short interparticle distances but additionally control doping and passivation of surface trap states, leading to enhanced electronic coupling in NC‐based arrays. The solids based on these NCs show an excellent electronic transport behavior after heat treatment at the relatively low temperature of 190 °C. Indeed, the indium‐chlorido‐capped 4.5 nm CdSe NC based thin‐film field‐effect transistor reaches a saturation mobility of μ = 4.1 cm2 (V s)−1 accompanied by a low hysteresis, while retaining the typical features of strongly quantum confined semiconductor NCs. The capping with chloride ions preserves the high photoluminescence quantum yield (≈66%) of CdSe/CdS core/shell NCs even when the CdS shell is relatively thin (six monolayers). The simplicity of the chemical incorporation of chlorine and indium species via solution ligand exchange, the efficient electronic passivation of the NC surface, as well as their high stability as dispersions make these materials especially attractive for wide‐area solution‐processable fabrication of NC‐based devices.

The synthesis of carbon nanomaterials using chlorinated hydrocarbons over a Fe-Co/CaCO3 catalyst

The effect of chlorine on the morphology of carbon nanotubes (CNTs) prepared from a Fe-Co/CaCO 3 catalyst was investigated using chlorobenzene (CB), dichlorobenzene (DCB), trichlorobenzene (TCB), dichloroethane (DCE), trichloroethane (TCE) and tetrachloroethane (TTCE) as chlorine sources using a catalytic chemical vapour deposition (CCVD) method. Toluene was used as a chlorine-free carbon source for comparison. Multi-walled carbon nanotubes (MWCNTs) were successfully synthesized. The physicochemical properties of the CNTs were studied using transmission electron microscopy (TEM), Raman spectroscopy, thermal gravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD) spectroscopy, and X-ray photoelectron spectroscopy (XPS) techniques. The inner and outer diameters of the MWCNTs increased with an increase in the number of chlorine atoms contained in the reactant. Chlorine incorporation into the MWCNTs was observed by EDS analysis for all reactants. Formation of ‘bamboo-like’ structures for the MWCNTs generated from TCE and TTCE was also observed, facilitated by the presence of the high percentage of chlorine in these reactants. Numerous MWCNTs revealed the presence of small carbon nanostructures that grew on top of the dominant CNTs, suggesting an unexpected secondary carbon growth mechanism. KEYWORDS Multi-walled carbon nanotubes, CVD, synthesis, chlorine, benzenes, ethanes.

Partitioning of Chlorine Between Nacl Brines and Ferro-Pargasite: Implications For the Formation of Chlorine-Rich Amphiboles In Mafic Rocks

Determining the partitioning of chloride between fluid and rock has relevance to a wide range of geological processes, including high-grade metamorphism, economic deposit formation, and seawater-oceanic crust interactions. Calcium amphiboles, particularly those that are iron-rich, are a common host for chlorine and have the potential to reveal information about the ambient fluid composition, if the crystal-chemical controls on chlorine incorporation are known. In this study we investigated the incorporation of chlorine into synthetic ferro-pargasite [NaCa_2(Fe_4Al)(Al_2Si_6)O_(22)(Cl,OH)_2] formed mostly at 700 °C, 0.2 GPa, and oxygen fugacities (f_(O2)) between Co–CoO and wustite–magnetite (−20.2 < log(f_(O2)) < −17.5) for durations of 3–28 days. Starting mixtures consisted of reagent oxides and metallic iron to which chlorine was added as either a stock solution of NaCl brine up to 5 molal (m) (equivalent to mole fraction of NaCl, X_(NaCl), up to 0.082), or by mixing NaCl ± water directly with the starting mixture to achieve higher concentration brines by homogenization at elevated pressures and temperatures. Good yields of amphibole were obtained, with the most common additional phases being plagioclase, hedenbergite, and halite. At low salinities the Cl content of the amphibole, determined by electron microprobe analysis (EMPA) of individual grains, increases linearly to about 0.045 anions per formula unit (apfu) as the brine concentration increases to about 1.7 m NaCl (X_(NaCl) = 0.03). Thermodynamic modeling of the partitioning of Cl– between brine and the amphibole yields a constant value for the equilibrium constant (K_a) of 0.78 ± 0.09 at 700 °C and 0.2 GPa over the range 0.1–2.0 m NaCl with the empirically derived relationship for the activity of Cl– in amphibole (ɑ^(ɑmph)_(Cl)_-) being ɑ^(ɑmph)_(Cl)_- ═ (X^(o(3)_(Cl))^(2/3). This activity-composition relationship suggests much less random mixing of Cl^–, OH^–, and O2^– at the O(3) site. At salinities above 1.7 m NaCl, the Cl content of the amphibole is fairly insensitive to the brine concentration. Only at halite saturation (83 m NaCl, or X_(NaCl) = 0.60, at 700 °C and 0.2 GPa) is there a noticeable increase in the Cl content of the amphibole, with a bimodal distribution centered at 0.2 and 0.7 Cl apfu observed in the highest salinity synthesis. The implication of this study is that (1) amphiboles with Cl contents above about 0.1 apfu (∼0.4 wt.% Cl) require ambient brines at halite saturation, and (2) oceanic crust reacting with homogeneous seawater could incorporate 50–200 ppm Cl via the presence of 8–31 wt.% ferro-pargasite in the oceanic crust, respectively.

Chlorine Incorporation for Enhanced Performance of Planar Perovskite Solar Cell Based on Lead Acetate Precursor.

We show the effects of chlorine incorporation in the crystallization process of perovskite film based on a lead acetate precursor. We demonstrate a fabrication process for fast grain growth with highly preferred {110} orientation upon only 5 min of annealing at 100 °C. By studying the correlation between precursor composition and morphology, the growth dynamic of perovskite film in the current system is discussed. In particular, we found that both lead acetate precursor and Cl incorporation are beneficial to perovskite growth. While lead acetate allows fast crystallization process, Cl improves perovskite crystallinity. Planar perovskite solar cells with optimized parameters deliver a best power conversion efficiency of 15.0% and average efficiency of 14.0% with remarkable reproducibility and good stability.

The optoelectronic role of chlorine in CH3NH3PbI3(Cl)-based perovskite solar cells.

Perovskite photovoltaics offer a compelling combination of extremely low-cost, ease of processing and high device performance. The optoelectronic properties of the prototypical CH3NH3PbI3 can be further adjusted by introducing other extrinsic ions. Specifically, chlorine incorporation has been shown to affect the morphological development of perovksite films, which results in improved optoelectronic characteristics for high efficiency. However, it requires a deep understanding to the role of extrinsic halide, especially in the absence of unpredictable morphological influence during film growth. Here we report an effective strategy to investigate the role of the extrinsic ion in the context of optoelectronic properties, in which the morphological factors that closely correlate to device performance are mostly decoupled. The chlorine incorporation is found to mainly improve the carrier transport across the heterojunction interfaces, rather than within the perovskite crystals. Further optimization according this protocol leads to solar cells achieving power conversion efficiency of 17.91%.

Photoluminescence study of chemical bath deposited ZnIn2Se4 thin films

Thin films of ZnIn2Se4 (ZIS) have been prepared by chemical bath deposition (CBD) using a novel and water soluble Na2SeO3 as a source of selenium ion for the first time. The deposition of the films was carried out at various pH values in the range of 6–11, keeping all other bath parameters at optimised values. EDAX analysis revealed that all the grown layers were selenium deficient with trace amounts of oxygen and chlorine incorporation. FTIR spectral measurements revealed the associated symmetric and asymmetric stretching modes of bridged oxygen atoms on the surface of the films. The room temperature photoluminescence properties of these samples at different pH values are studied in detail. Further, Gaussian curve fitting was employed to deconvolute the PL spectra and the change in intensities of these peaks with respective to pH values was addressed and correlated to the role of native defects that were incorporated while deposition. The results indicate that the variation of solution pH had a noticeable effect on the photoluminescence ZIS films.

Examination of the kinetics of degradation of the antineoplastic drug 5-fluorouracil by chlorine and bromine

This study examined the degradation of the widely used antineoplastic drug 5-fluorouracil (5FU) by chlorine and bromine. 5FU was determined to interact readily with free chlorine and bromine but was stable in the presence of chloramine. The removal of 5FU followed a second-order kinetic pattern. Apparent rates (kapp) of 5FU removal by chlorine and bromine were strongly pH dependent and had maximum 14.8M−1s−1 and 1.9×103M−1s−1kapp values, respectively at pH 7. Modeling of the dependence of the kapp values vs. pH indicated the presence of a relatively acidic (pK 6.4 vs. 8.5 of 5FU per se) 5FU intermediate generated in the presence of halogen species. Spectrophotometric measurements confirmed the increased acidity of 5FU chlorination products and allowed proposing a degradation pathway of 5FU by chlorine. This pathway suggests that 5FU chlorination proceeds via chlorine incorporation at the 6th carbon in the heterocyclic ring of 5FU.

Electric field influenced ZnO growth on nanoscale etched Si surface by continuous spray pyrolysis

This work reports ZnO growth by electric field influenced continuous spray pyrolysis reactor over seed layer assisted nanoscale etched Si surface. The comparative studies of ZnO growth in the presence and absence electric field on anisotropically etched Si surface are supported by XRD, SEM, EDX, FTIR and reflectance measurements. XRD measurements confirm preferable (002) oriented ZnO growth by certain amount of etching which is reduced with further anisotropic etching. The chlorine incorporation in ZnO thin film measured by EDX and FTIR may be attributed to the seed layer effect. This present investigation show that anisotropic etch pits surface energy profile has played an important role in deciding ZnO nanorods alignment and coalescence amongst ZnO species during self assembly at nucleation sites. It is observed that additional electric field force in spray droplets is enhancing population density, homogeneous growth and surface coverage of Si surface by ZnO nanorods for particular amount of etched Si surface and improved light coupling is confirmed by reflectance measurement. The relevant growth mechanisms for ZnO nanostructure layers comprising nanorods are also discussed.

Modeling bromide effects on yields and speciation of dihaloacetonitriles formed in chlorinated drinking water

This study examined effects of bromide on yields and speciation of dihaloacetonitrile (DHAN) species that included dichloro-, bromochloro- and dibromoacetonitriles generated in chlorinated water. Experimental data obtained using two water sources, varying concentrations and characters of Natural Organic Matter (NOM), bromide concentrations, reaction times, chlorine doses, temperatures and pHs were interpreted using a semi-phenomenological model that assumed the presence of three kinetically distinct sites in NOM (denoted as sites S1, S2 and S3) and the occurrence of sequential incorporation of bromine and chlorine into them. One site was found to react very fast with the chlorine and bromine but its contribution in the DHAN generation was very low. The site with the highest contribution to the yield of DHAN (>70%) has the lowest reaction rates. The model introduced dimensionless coefficients (denoted as φ1DHAN, φ2DHAN and φ3DHAN) applicable to the initial DHAN generation sites and their monochlorinated and monobrominated products, respectively. These parameters were used to quantify the kinetic preference to bromine incorporation over that of chlorine. Values of these coefficients optimized for DHAN formation were indicative of the strongly preferential incorporation of bromine into the engaged NOM sites. The same set of φiDHAN coefficients could be used to model the speciation of DHAN released from their kinetically different precursors. The dimensionless speciation coefficients φiDHAN were determined to be site specific and dependent on the NOM content and character as well as pH. The presented model of DHAN formation and speciation can help quantify in more detail the generation of DHAN and provide more insight necessary for further assessment of their potential health effects.

Research strategies toward improving thin-film CdTe photovoltaic devices beyond 20% conversion efficiency

Recent studies of thin-film CdS/CdTe photovoltaic (PV) devices have suggested that a significantly higher device performance will not be achieved unless recombination in the CdTe is reduced. Although some control of CdTe recombination has been achieved historically through the careful incorporation of oxygen, chlorine, and copper, we believe a more promising avenue to higher device performance is by controlling the defects in the as-deposited CdTe. This is supported by theoretical studies that suggest much of the improvement associated with oxygen, chlorine, and copper is due to the interaction of these species with intrinsic defects related to cadmium and tellurium vacancies, interstitials, and anti-sites in the bulk as well as within the grain boundary regions. Several research projects at NREL are currently focused on altering CdTe deposition and post-deposition processes to allow for enhanced control of the as-deposited intrinsic defects. This paper discusses initial results in which process changes expected to alter the as-deposited defects are also observed to affect junction evolution and device functionality.

ChemInform Abstract: Regioselective Bromination of Fused Heterocyclic N‐Oxides.

AbstractA simple, mild, and scalable method for the title reaction is presented which can also be extended to complex molecules [e.g. the antimalarial agent (XIV)] and the incorporation of chlorine using Bu4NCl [viz.

Experimental chlorine partitioning between forsterite, enstatite and aqueous fluid at upper mantle conditions

Cl partition coefficients between forsterite, enstatite and coexisting Cl-bearing aqueous fluids were determined in a series of high pressure and temperature piston cylinder experiments at 2GPa between 900 and 1300°C in the system MgO–SiO2–H2O–NaCl–BaO–C±CaCl2±TiO2±Al2O3±F. Diamond aggregates were added to the experimental capsule set-up in order to separate the fluid from the solid residue and enable in situ analysis of the quenched solute by LA-ICP-MS. The chlorine content of forsterite and enstatite was measured by electron microprobe, and the nature of hydrous defects was investigated by infrared spectroscopy. Partition coefficients show similar incompatibility for Cl in forsterite and enstatite, with DClfo/fl=0.0012±0.0006, DClen/fl=0.0018±0.0008 and DClfo/en=1.43±0.71. The values determined for mineral/fluid partitioning are very similar to previously determined values for mineral/melt. Applying the new mineral/fluid partition coefficients to fluids in subduction zones, a contribution between 0.15% and 20% of the total chlorine from the nominally anhydrous minerals is estimated.Infrared spectra of experimental forsterite show absorption bands at 3525 and 3572cm−1 that are characteristic for hydroxyl point defects associated with trace Ti substitutions, and strongly suggest that the TiO2 content of the system can influence the chlorine and OH incorporation via the stabilization of Ti-clinohumite-like point defects. The water contents for coexisting forsterite and enstatite in some runs were determined using unpolarized IR spectra and calculated water partition coefficients DH2Ofo/en are between 0.01 and 0.5.

Atmospheric pressure chemical vapour deposition of vanadium arsenide thin films via the reaction of VCl4 or VOCl3 with tBuAsH2

Thin films of vanadium arsenide were deposited via the dual-source atmospheric pressure chemical vapour deposition reactions of VCl4 or VOCl3 with tBuAsH2. Using the vanadium precursor VCl4, films were deposited at substrate temperatures of 550–600°C, which were black-gold in appearance and were found to be metal-rich with high levels of chlorine incorporation. The use of VOCl3 as the vanadium source resulted in films being deposited between 450 and 600°C and, unlike when using VCl4, were silver in appearance. The films deposited using VOCl3 demonstrated vanadium to arsenic ratios close to 1:1, and negligible chlorine incorporation. Films deposited using either vanadium precursor were identified as VAs using powder X-ray diffraction and possessed borderline metallic/semiconductor resistivities.

Anodic chlorine/nitrogen co-doping of reduced graphene oxide films at room temperature

Room temperature simultaneous doping of reduced graphene oxide films with oxygen, nitrogen and chlorine was performed through anodic polarization in a neutral nitrogen-deaerated KCl electrolyte. The thermodynamic electrochemical windows of water, dissolved nitrogen and chlorine anions were analyzed on the basis of the Pourbaix diagram. Anode polarization demonstrated that the nitrogen, water and chlorine anions can be oxidized at an applied potential of 1.7V vs. NHE. The oxidative products, i.e. oxygen, nitrate anion and hypochlorous acid, can react with the reduced graphene oxide surface. X-ray photoelectron spectroscopy proved the chlorine–nitrogen co-doping of the treated film, along with an increase of oxygen groups. Surface structure evolution was also confirmed by Raman and Fourier-transform infrared spectroscopies. The anodic doping can be hindered by covering the reduced graphene oxide surface with sulfate anions or forming stable carbon–nitrogen bonds. Incorporation of oxygen, nitrogen and chlorine also helps to enhance the supercapacitance of the doped film.

Synthesis and Pharmacological Evaluation of Some DL-Dichlorophenyl Alcohol Amides Anticonvulsants

The anticonvulsant activity of a homologous series of DL-dichlorophenyl alcohol amides is described. The compounds DL-2-hydroxy-2-(3',4'-dichlorophenyl) butyramide (4, CAS 620950-11-0), DL-3-hydroxy-3-(3',4'-dichlorophenyl) pentanamide (5, CAS 620950-15-4) and DL-4-hydroxy-4-(3',4'-dichlorophenyl) hexanamide (6, CAS 620950-17-6 ) were prepared and tested. Compounds 4, 5 and 6 exhibited a significant activity in seizures induced by pentetrazol. Incorporation of chlorine in the phenyl ring increased their potency. Compound 4 exhibited a slightly lower activity than the reference drug phenobarbital (CAS 50-06-6).

SolEx: A model for mixed COHSCl-volatile solubilities and exsolved gas compositions in basalt

We present a software application, SolEx, to calculate basaltic melt and coexisting vapour compositions in the system C–O–H–S–Cl. Such a model has great utility in interpreting emitted gas and melt inclusion compositions, especially through the incorporation of sulphur and chlorine, the most commonly measured volcanic gas species. We assume that the behaviour of the fluid phase is controlled by the volumetrically dominant volatile species, H2Oand CO2, whereas sulphur and chlorine partition between the melt and fluid phases. Melt–fluid partition coefficients for S and Cl were parameterised from measurements by Lesne et al. (2011a, p. 1737). The model of Churakov and Gottschalk (2003a, p. 2415) was applied to calculate fugacity coefficients and the equilibrium constants for the reaction imelt→ifluid were thereby deduced. SO2dominates at oxidation states of ΔNNO>0.5 (Jugo et al., 2010, p. 5926), where this model is applicable.In the forward model, total volatile inventories and melt composition are specified by the user. The parameterisation of Dixon (1997, p. 368) is used to predict the partitioning of CO2and H2Obetween vapour and melt phases. An iterative procedure is employed to predict the partitioning of S and Cl components between fluid and melt phases. Melt and gas compositions and gas volume fraction are thereby modelled over pressures in the range 5–4000bar. This approach satisfactorily reproduces independent literature data on S and Cl behaviour in basalt. SolEx is a user-friendly software package available for OS X and Windows, facilitating modelling of closed- and open-system C–O–H–S–Cl degassing in basalts.

Ionizing radiation induced degradation of poly (2-methoxy-5-(2’-ethyl-hexyloxy) -1,4-phenylene vinylene) in solution

In this paper we investigate the causes of the chromatic alteration observed in chloroform solutions of poly (2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) after gamma ray irradiation. Structural and chemical changes were analyzed by gel permeation chromatography, fourier transform infrared spectroscopy, and proton nuclear magnetic resonance techniques and complemented by electronic structure calculations. The results indicate chlorine incorporation in the polymer structure and main chain scission after irradiation. Based on our findings we propose that the main mechanism for the blue-shifts, observed in the UV-Vis absorption spectra of MEH-PPV after irradiation, is the result of a radical attack on the polymer main chain. Gamma rays generate radicals, •Cl and •CHCl2 from chloroform radiolysis that attack preferentially the vinyl double bonds of the polymer backbone, breaking the electronic conjugation and eventually the chain. Our results indicate that oxygen does not play a major role in the effect. Electronic spectra simulations were performed based on these assumptions reproducing the UV-Vis experimental results.

Pulsed Plasma Enhanced Chemical Vapor Deposition of Alumina Thin Films: Influence of the Duty Cycle on Structure and Elastic Properties

In this study, the duty cycle (Δ) has been systematically modified during the pulsed plasma enhanced chemical vapor deposition (PECVD) of alumina (Al2O3) coatings. This deposition method is prone to chlorine incorporation during growth as AlCl3 is used as precursor. Here, we show that the incorporation of chlorine can be reduced from 2.4 ± 0.1 to 1.2 ± 0.1 at.-% by increasing Δ from 62% to 91%. The film grown at Δ = 88% has a density of 3.85 ± 0.12 g cm−3 (96% of α-alumina bulk density) and an elastic modulus of 365 ± 50 GPa (∼83% of the bulk α-alumina value). Δ affects the normalized ion flux (NIF), which is the ratio between the flux of bombarding ions and the flux of deposited material. By increasing Δ, the formation of α-rich alumina is promoted at 560 °C, the chlorine content is reduced, and the film is densified. An increased Δ and hence NIF results in enhanced ion bombardment of the film surface during growth, promoting chlorine desorption. Furthermore, it is reasonable to assume that the deposition rate decrease measured is a consequence of increasing Δ and hence NIF. Both the density as well as the elastic modulus increase measured is consistent with the increased NIF caused by increasing the duty cycle.

Permeability and chemical analysis of aromatic polyamide based membranes exposed to sodium hypochlorite

In this study, a cross-linked aromatic polyamide based reverse osmosis membrane was exposed to variable sodium hypochlorite ageing conditions (free chlorine concentration, solution pH) and the resulting evolutions of membrane surface chemical and structural properties were monitored. Elemental and surface chemical analysis performed using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), showed that chlorine is essentially incorporated on the polyamide layer of a commercially available composite RO membrane, when soaked in chlorine baths, presumably through a two step electrophilic substitution reaction governed by the concentration of hypochlorous acid (HOCl), at pH values above 5. Deconvolution of the FTIR vibrational amide I band experimentally confirmed previous assumptions stated in the literature regarding the weakening of polyamide intermolecular hydrogen bond interactions with the incorporation of chlorine. An increase in the fraction of non associated C O groups (1680 cm −1) and a decrease of hydrogen bonded C O groups (1660 cm −1) were observed with an increase in the concentration of the free chlorine active specie. The relative evolution of pure water permeability was assessed during lab-scale filtration of MilliQ water of a membrane before and after exposure to chlorine. Filtration results indicate polyamide conformational order changes, associated with the weakening of polyamide intermolecular H bonds, as observed with the increase in the packing propensity of the membrane, dominant for HOCl doses above 400 ppm h. In addition, water–sodium chloride selectivity capabilities permanently decreased above this HOCl concentration threshold, further suggesting polyamide chain mobility. However, under controlled exposure conditions, i.e., HOCl concentration, operating conditions (applied pressure or permeation flux) can be improved while maintaining similar RO membrane separation performance.