Metallic Iodine Research Articles

Controlling Lead Halide Residue in Perovskite Solar Cells: A Method to Improve the Photostability and Hysteresis

The presence of residual lead iodide phase in perovskite films, inherent to the two‐step spin‐coating method, has been reported to be beneficial for the performance of perovskite solar cells (PSCs); However, it may potentially undermine the photostability of PSCs. Herein, four distinct sets of perovskite films and devices are fabricated via the two‐step spin‐coating process, each under different processing conditions. All conditions demonstrate promising power conversion efficiency in PSCs. However, the aspect of photostability is found to be significantly influenced by unreacted PbI2 in the perovskite films. Varying degrees of residual PbI2 are detected among these films. Upon light exposure, it is observed that residual PbI2 within perovskites undergoes decomposition into metallic lead (Pb0) and mobile iodine, and these can affect the photovoltaic performance of the PSCs. The presence of mobile ions in metal–halide perovskites has generated substantial concern due to their impact on hysteresis within the J–V curve. Furthermore, the metallic lead (Pb0) containing perovskite films exhibits a prominent inverted hysteresis in the J–V curve

Managing Excess Lead Iodide with Ordered Distribution and Reduced Photoactivity via Chelating Ligands for Stable Inverted Perovskite Solar Cells.

Excess lead iodide (PbI2) aggregates distributed in perovskite photoreactive absorbers will perturb carrier collection and become a key source of instability in PSCs. Herein, a multisite heterocyclic ligand of 2-mercaptonicotinic acid (2-MNA) is introduced as a chelating agent to manage excess PbI2 in inverted PSCs. The chelating coordination of 2-MNA to Pb2+ ions through the carbonyl, sulfhydryl, and pyridinyl groups enables a high-quality perovskite film with reduced PbI2 aggregates and the formation of an ordered distribution at grain boundaries. Moreover, the coordination of 2-MNA with the [PbX6]4- octahedron effectively inhibits the photodecomposition of PbI2-rich perovskites, thus preventing the generation of metallic lead (Pb0) and iodine (I2) species in response to environmental stimuli. As a result, the inverted PSC based on a 2-MNA modified triple cation perovskite photoactive layer achieves a PCE of 21.27% and a fill factor of 82.07%, accompanied by improved thermal and photostability.

Continuous Modification of Perovskite Film by a Eu Complex to Fabricate the Thermal and UV-Light-Stable Solar Cells.

Perovskite solar cells (PSCs) with simple and low-cost processability have shown promising photovoltaic performances. However, internal defects, external UV light, and heat sensitivity are principal obstacles on their way toward commercialization. Herein, we prepare an Eu complex and directly dope it into the perovskite precursor as a UV filter to decrease the photodegradation of PSCs. The formation of hydrogen bonds between the organic cation of perovskite and the -CF3 in the Eu complex could restrain the escape of organic cations under heating. The Eu complex acts as a redox shuttle to reduce metallic lead (Pb0) and iodine (I0) defects when the PSCs have a long-time operation. Additionally, the ligand-containing aromatic rings could reduce the trace amount of I0 existing as electronic defects in perovskites and together with the long alkyl chain retard the moisture immersion into the PSCs. The best efficiency of PSCs modified by the Eu complex improves up to 20.9%. The excellent thermal stability and UV-light resistance are also realized. This strategy provides a method to design a passivator which continuously modifies the imperfections and inhibits the chemical chain reactions in perovskite film, thereby enhancing the performance and stability of PSCs.

Successful Treatment of Recalcitrant Non-genital Warts (Verruca vulgaris) with a Topical Solution Containing Two Antivirals and a Low Concentration of Salicylic Acid

Aims: Commercial formulas for the treatment of warts use salicylic acid in concentrations above 100 mg/ml, which causes skin irritation, and the results are often unsatisfactory. To address this problem, we developed a new formula with a low concentration of salicylic acid (20 mg/ml) and with the addition of virucidal compounds (metallic iodine and benzoic acid) and compared it to a formula currently on the market (Verrux®) containing 165 mg salicylic acid (0.165 g) and 145.2 mg lactic acid (0.145 g) per ml collodion.
 Study Design: A randomized double-blind study was conducted.
 Location and Duration of Study: Department of Biotechnology, UNINCOR, Chácara das Rosas, Três Corações, MG, Brazil; School of Pharmacy, Universidade Federal do Amapá - Campus Universitário Marco Zero do Equador, Rod. Juscelino Kubitschek, KM-02, Jardim Marco Zero, Macapá, AP, Brazil and School of Medicine, Universidad Politécnica y Artística del Paraguay (UPAP), Km 10, Ciudad del Este, Paraguay, between December 2004 and October 2016.
 Methodology: 95 patients were treated with the formula with salicylic acid (20mg), benzoic acid (20mg) and metallic iodine (2.5mg) per ml (group A) and 95 received treatment with Verrux® (salicylic acid 165mg, lactic acid 145.2mg per ml collodion) (group B).
 Results: All patients in Group A (100%) reported complete resolution of signs and symptoms after 13 weeks of treatment. In contrast, 67 subjects (70.5%) in group B reported regression of symptoms during the same period.
 Conclusion: There was a statistically significant difference between the groups studied here (P< 0.05). This new formulation with a low level of salicylic acid and two virucidal agents promotes healing of recalcitrant cutaneous warts without significant side effects. The price of the two formulas is virtually the same (about $8 to $10 each bottle).

Excess PbI2 Management via Multimode Supramolecular Complex Engineering Enables High‐Performance Perovskite Solar Cells

AbstractExcess PbI2 in perovskite film is an effective strategy for boosting perovskite solar cells (PSCs) performance. However, the presence of unreacted PbI2 is a critical source of intrinsic instability in perovskite under illumination, due to the photolysis of PbI2 (decomposed into metallic lead and iodine). Herein, this issue is solved by applying ionic liquids (ILs) on PSCs where the ILs can form types of stable supramolecules with residual lead iodide. The formation process and mechanism of the supramolecules are elucidated. The residual PbI2 is also revealed to cause high level lead interstitial defects and induced tensile strain which further deteriorate device performance. The self‐assembled supramolecular complex can passivate the PSCs where significant enhancements are achieved in both power conversion efficiency (PCE, from 21.9% to 23.4%) and device stability (retaining 95% of the initial PCE after 4080 h in ambient dry‐air storage, and 80% after 1400 h continuous light illumination).

Dielectric relaxation, XPS and structural studies of polyethylene oxide/iodine complex composite films

Polyethylene oxide (PEO) complexed with molecular iodine (I2) forming PEO/I2 complex composites stand‐free films were investigated using dielectric relaxation, X-ray photoelectron spectroscopy (XPS), UV–Vis spectrophotometry, structural and morphological techniques. Scanning electron microscopy was used to monitor the variation in the surface morphology and the related roughness. 2D Energy-dispersive X-ray spectroscopy (EDX) measurements enabled to observe the distribution of iodine on the film surface. High resolution XPS measurements were used to define the iodine anion types and the metallic iodine existence, as well as the relevant concentrations based on the binding energies. The dielectric relaxation measurements were carried out over the frequency range from 0.1 to 107 Hz and temperature range from 155 to 330 K. Dielectric loss (e′′) curves were fitted to the Havriliak–Negami (HN) model for one and/or two relaxation peaks (α and β), with and without the electrical conductivity contribution term, in order to deduce the relaxation time (τ) and the dielectric strengths (Δe), in addition to the electrical conductivities (σ). The temperature-dependent data of β- and σ- relaxations follow the law of Arrhenius thermal activation indicating the presence of typical glass-forming polymers. Δe of α-relaxation obeys the curvature pattern of Vogel-Tammann-Fulcher (VTF) thermal activation law. The electrical conductivity of the system increases 6000 folds by doping PEO with 5 wt% of iodine at the same temperature (293 K).

New Approaches to Sample Preparation and Integrated Spectroscopic Methods for The Identification of Polioxyethylene Triolate Sorbitane for Pharmaceutical Examination of Drugs

Due to the fast pace of development of spectroscopic research methods in the pharmaceutical expertise of drugs presented in the United States Pharmacopeia (USP) and European Pharmacopoeia (Ph. Eur.), in this paper, we examined complex methods for the identification and preparation for analysis of polyethylene sorbitan trioleate. Two new systems were identified for purification of 98% polyoxyethylene sorbitan trioleate from organic impurities in column chromatography: acetonitrile 100% and acetonitrile/acetone 7.5/2.5. It was also revealed that a chamber with metallic iodine was the most suitable for selecting an eluent and controlling the cleaning by the TLC method. Proton NMR did not detect organic impurities. Identification of polyoxyethylene sorbitan trioleate was carried out on H1, C13, COSY, and IR spectra. These research methods are characterized by simplicity in sample preparation, the availability of reagents, the effectiveness of identification and quantification analyzes, and the efficiency in labor and material costs

Iodine Plasmonic Crystal as the Visible-Range Spectral Filter

We analyse the optical properties of the new hyperbolic metamaterial based on the one-dimensional mesoporous aluminum oxide (Al2O3) photonic crystal film doped by metallic iodine (I2) nanoparticles. The nanocomposite is a metal-dielectric hybrid and combines the classical photonic crystal features (such as photonic bandgaps, light deceleration, negative refraction etc.) with the metallic ones (low-frequency mirroring, plasmons etc.). To get this, we propose to saturate the pores (microcavities) of the periodic aluminum oxide photonic crystal matrix synthesized by the controlled acid etching at its anonization, by the iodine vapor. This way, in the photonic crystal pores, we form the cold plasma of the iodine free electrons, and make the nanocomposite the plasmonic photonic one. Note, that the iodine saturation level defines the plasma frequency which is directly affects the crystal characteristics, so we get them easy-tunable. For example, we offer the two iodine-saturated photonic crystals with various doping level in the pass-and-reflect scheme to spectral filter the optical radiation. At last, we also wish to note that simplicity of the saturation technology makes the iodine plasmonic crystals attractive for the wide commercial usage in the large-scale optic and photonic applications and devices (such as spectral filters, optical amplifiers, high-performance selective mirrors, photonic sensors etc.).

High Pressure Driven Isostructural Electronic Phase Separation in 2D BiOI

The crystal structures of BiOI under different pressures are predicted, in which the phase transformation from tetragonal BiOI into orthorhombic BiOI is observed at 100 GPa due to the appearance of Bi–I bonds (Bi‐6s2 lone pair and I‐pz obital) between interlayer Bi and I atoms. Most interestingly, for orthorhombic BiOI, an isostructural electronic phase separation is observed at 160 GPa. The electronic structure of BiOI separates into semiconductor state (contributed by intralayer O–Bi–O) and metal state, which originate from the interlayer I–I bonds. More specifically, conversion from interlayer Bi–I interaction to interlayer I–I interaction under higher pressure, results in the continuous decline of the energy band, which then crosses the Fermi‐level. In comparison, the O–Bi–O layer shows almost no change, owing to its strong covalent bonds. These results demonstrate that the dramatic variation of the interaction between the van der Waals layers can lead to the metallic iodine character in BiOI.

A Preliminary Study on the Feasibility of Copper Mesh as an Off-Gas Iodine Capturing Medium for Pyroprocessing

A commercially available copper mesh was investigated as an iodine off-gas capturing medium for pyroprocessing, with an aim to replace costly silver based adsorbents. Theoretical calculation results suggested that the reaction between metallic copper and gaseous iodine will occur spontaneously to produce copper iodide in the temperature range of 100 ~ 500℃. The effect of the reaction temperature on iodine capturing efficiency was investigated by experimentation, and it was found that 5 and 6 wt% of iodine (initial mass 2.0 g) was captured by a single copper mesh (0.26 g) at 300 and 400℃, respectively. The repeated experimental results also suggested that copper utilization can be increased with the help of the spontaneous detachment of the reaction product (CuI) from a copper mesh. The formation of the CuI phase was confirmed using the X-ray diffraction technique, and the surface morphology of the reaction product was observed using scanning electron microscopy.

Elements as Direct Feedstocks for Organic Synthesis: Fe/I2/O2 for Diamination of 2-Cyclohexenones with 2-Aminopyrimidine and 2-Aminopyridines.

Elements as feedstocks for organic synthesis, the trio of metallic iron, molecular iodine, and dioxygen, were found to be an excellent tool for oxidative regioselective diamination of conjugated enones with 2-aminopyrimidine (a guanidine surrogate) and 2-aminopyridines leading to unaromatized coupled products in moderate to good yields.

Microstructure and mechanical properties of carbon–carbon composites modified by reactive diffusion treatment in niobium powder

Refractory carbide coatings are primary candidate materials for improving the high-temperature performance of carbon fiber-reinforced carbon matrix composite (C/C composites). In this paper, a niobium carbide coating was grown on the C/C composite surface employing a Powder Immersion Reaction Assisted Coating (PIRAC) method. 2D C/C composite plates were immersed into Nb powder and annealed at 800 to 1200°C for up to 16h. Metallic iodine was admixed to the metal powder to allow for Nb atoms transfer onto the C/C surface and into the pores by gas transport reaction. Following PIRAC treatment, several micrometer thick uniform conformant coatings were obtained consisting of a thin Nb-rich Nb2C layer on the top surface and a thicker sub-stoichiometric NbC1−x layer underneath. The coating growth was dominated by short-circuit diffusion with the activation energy of approximately 155kJ/mol. At the lower PIRAC temperatures of 800–900°C, surface coating growth was accompanied by the infiltration of the volatile Nb iodide and filling of inter-bundle pores with niobium carbide. This resulted in the reduction of residual porosity and an increase in flexural strength and elastic modulus. The greatest increase in specific strength (30%) was measured for C/C composites PIRAC treated at 900°C, 16h. No infiltration occurred at the higher temperatures, due to the rapid sealing of surface pores by the Nb carbide layer.

Radioactive nanoparticles and their main applications: recent advances.

Selected nanoparticles and nanocomposites on the basis of radioactive elements are reviewed. Isotopes of metallic gold, iodine and technetium salts, CeO2 and other lanthanide and actinide compounds, as well as several p- (P, C, F, Te) and d- (Fe, Co, Cu, Cd, Zn) elements form most common radioactive nanoparticles. Methods for their fabrication, including dopation with radionuclides and neutron/proton/deuteron activation, are discussed. These nanocomposites possess a series of useful applications, in particular in biology and medicine, including cancer therapeutics, drug delivery systems and radiotracers, as well as in the studies of several catalytic processes and materials structure.

Metallic Interaction in Polythiophene-Ti Plasma Composites

This work presents a study about the structure and morphology of thin plasma composite films of polythiophene (PTh) with metallic particles of Ti (PTh-Ti). The objective was to study the water affinity and electric conductivity in PTh with the addition of metallic phases. The hydrophilicity was studied with the contact angles formed between water and surfaces, and the electric conductivity was calculated with the resistance measured in a two-probe device. The structure and morphology of the composites were studied with X-ray diffraction and scanning electron microscopy. The results indicated that PTh-Ti formed thin films of hybrid composites with oxidized Ti and Fe additional particles released from the electrodes used in the syntheses. The metallic fraction resulted in 2 diffraction angles at 31.6° and 66.1° product of the complex interaction among Ti, resembling orthorhombic TiO2 structures, and PTh. The metallic particles and iodine, added as a dopant to the composites to increase conductivity, reduced the hydrophilicity with water in a competition between roughness and chemical composition. In these conditions, the contact angles resulted between 46° and 75°. The electric conductivity was about 10-6 S/m increasing one order of magnitude with the metallic fraction. However, the high resistance of the polymeric fraction apparently dominates the transference of charges.

New Synthesis Method Using Magnesium Alkoxides as Carrier Materials for Ziegler-Natta Catalysts with Spherical Morphology

In this study, novel carrier materials were synthesized by addition of metal dihalide compounds in the synthesis reaction of magnesium diethoxide using metallic magnesium, ethanol and iodine. Poly(propylene) polymerizations were then investigated with the MgCl 2 -supported Ticl 4 catalysts using these carrier materials. As results, magnesium diethoxide with extremely large particle sizes and spherical shapes were obtained and the angles of repose of PP particles obtained by using their catalysts as a flowability index showed high values. Furthermore, in order to confirm key points for excellent catalyst performance from detailed characterizations, SEM images, compositions and WAXS were measured.

Metallic samarium and iodine promoted facile and efficient syntheses of trisubstituted alkenes from the acetates of Baylis–Hillman adducts

Promoted by samarium metal in the presence of a catalytic amount of iodine, the Baylis–Hillman adducts underwent reductive elimination to form ( E)-methylcinnamic ester derivatives. When the iodine was used in 1:1 ratio with metallic samarium, stereospecific syntheses of allylic iodide derivatives, (2 Z)-2-(iodomethyl)alk-2-enoates, were achieved. Thus, this gives a new approach to the selective construction of stereo-defined trisubstituted alkenes with the simple Sm/I 2 system.

Reductive carbonylation of nitrobenzene over Pd/Fe/I2/Py and Pd/C/Fe/I2/Py catalytic systems

A simple catalytic system containing metallic palladium, iron and iodine has been shown to be very active in the carbonylation of nitrobenzene to carbamate. The influence of the components of the catalytic system studied on its selectivity and activity has been established. It has been found that the catalytic activity of palladium supported on carbon (using both lignite coal and bituminous coal) was not lower than the activity of metallic palladium.

Recycle transmutation of MA and LLFP using BWR for sustaining geologic disposal

The actinides and fission products produced in nuclear fuels constitute an important part of the HLW. Therefore, methods for reducing the radiotoxicity of the MA and LLFP in HLW are presently under investigation. The purposes of this study are to evaluate the effectiveness of MA transmutation by taking advantage of neutron spectrum hardening due to void fraction along BWR axial direction; to understand the effectiveness of LLFP transmutation in BWR considering the large capture cross section of FP in thermal region; and to evaluate the macroscopic characteristics of longer residential period of LLFP target in the high burnup BWR core. Conceptual B/T BWR supposed in this study was reactor which the performance comparable to the current BWR. In MA transmutation case, the calculation was focused on varying the void fraction of 0 to 40% along the axial direction, which were directly associated to the lower and upper region of the BWR core. The performance of B/T BWR was evaluated in which four components of MA ( 237Np, 241Am, 243Am, and 244Cm) with fixed fraction were blended with UO 2 in B/T fuel. While, for LLFP transmutation, the B/T BWR was assumed to have two homogeneous regions: {1} the region for UO 2 driver fuel (99% of fuel weight), and {2} the region for LLFP ( 99Tc and 129I) target capsules (1% of fuel weight), in which metallic Tc rods and iodine in the form of CeI 3 was contained in cylindrical target capsules. The evaluation functions are {1} fission-to-transmutation ratio, [F/T ratio] MA, and {2} transmutation fraction, Tf LLFP. Results show that the hardening neutron spectrum due to increase of void fraction in B/T BWR would result a higher [F/T ratio] of MA transmutation performance. Np and Am would be effectively loaded in the upper region of the core, while Cm could be loaded in any region of the core. At the EOC of equal or more than 50 GWd/Mg(HM), technetium has a higher transmutation fraction compared to iodine. To obtain higher LLFP transmutation fraction, the residential time in the LLFP targets in the core, should be kept for long time, for instance about 10 to 30 years. For that purpose, it was proposed that the number of B/T BWR system for LLFP treatment corresponds to the residential time of the LLFP target, i.e. 10 to 30 units.

Reduction of Nitrobenzene to Aniline with Carbon Monoxide and Water in the Presence of the PdCl2/Fe/I2 System

A study of modified catalyst systems composed of palladium or its chloride and a co-catalyst such as metallic Fe-powder, iodine, and pyridine was used in the reduction of nitrobenzene to aniline with carbon monoxide and water at 180°C and 2.5-4 MPa pressure. The reaction is complete in 2 h with a nitrobenzene conversion of 98-100% and a 100% selectivity with respect to aniline.

A model of silver–iodine reactions in a light water reactor containment sump under severe accident conditions

Metallic silver and iodine form insoluble AgI in the containment sump which has a major impact on iodine volatility and hence on the source term to the environment. Resistance-in-series models are developed and validated against separate-effects tests. The reaction between I 2 and Ag is limited by mass transfer in the liquid. The rate does not follow a parabolic law for the duration of the experiments. The extent of oxidation of the silver sample seems to play a decisive role for reactions with I − which proceed via a two-step process. The initial, rapid step is controlled by the reaction with the surface silver oxide with a contribution of mass transfer in the liquid. The subsequent, slow step is limited by reaction between I − and Ag + at the solid–liquid interface. The reaction is probably negligible for pH > 7 and in the absence of oxidising conditions.