Ammonium Iodide Research Articles

Oxidative decarboxylative ammonium hypoiodite-catalysed dihydrobenzofuran synthesis.

The catalytic use of quaternary ammonium iodides under oxidative conditions allows for the direct conversion of readily available β-ketolactones into dihydrobenzofurans via a decarboxylative oxidative cycloetherification sequence facilitated by an in situ formed ammonium hypoiodite species.

THE SYNTHESIS OF METHYLAMMONIUM LEAD IODIDE ON MESOPORE TiO2 THIN FILM APPLYING OSTWALD RIPENING PROCESS UNDER AMBIENT CONDITION

Organometallic halide-based perovskite solar cells have played a significant role in the development of photovoltaic technology. The synthesis of the perovskite usually needs specific atmospheres, especially controlled humidity. Here, we demonstrate the synthesis of compact methylammonium lead iodide perovskite (MAPbI3) on TiO2 under ambient conditions through one and two-step spin-coating deposition methods, which both resulted in an unconverted PbI2 on the films. The two-step method provided a higher amount of PbI2 regarding the reaction of methyl ammonium iodide (MAI) with an outer layer of the first bonded PbI2 hindered the inner layer to interact with MAI. The Ostwald ripening (OR) process that was applied to the thin film resulted through one-step deposition synthesis has successfully converted the unformed PbI2 to MAPbI3 with a more uniform, lower void, and higher crystal size as confirmed by XRD and SEM analysis results. The application of MAPbI3 prepared using OR treatment in the solar cell resulted in higher efficiency (7.64%) than the one synthesized without OR (4.91%).

Surface interface structural studies of CH3NH3PbI3 thin films using synchrotron source X-ray diffraction for solar cell application

Presently, Organic-inorganic hybrid-based Perovskite material research is gaining attraction in the solar energy field, with efficiencies reaching upwards of 25.7 percent. Even though various efforts have been made to increase the shelf life and to reduce the degradation of perovskite material, still several complicated processes are required to achieve better structural properties and chemical stability. In this paper, Perovskite material is prepared with an optimized molar ratio (PbI2/MAI) = 1.0/1.0, this combination of PbI2 (Lead Iodide) and MAI (Methyl Ammonium Iodide) provides the best inter-diffusion (as noticed) and structural ordering. The above-stated ratio of PbI2 (Lead Iodide) and MAI (Methyl Ammonium Iodide) is suggested to be one of the best molar ratios in the literature. Except of this, there is still a lack of studies found in literature like the optimized structure properties for better device performance, as well as the thickness dependence structural properties variation and the role of inter-diffusion of MAI and PbI2. The present studies focused on the Synchrotron source-based X-ray Diffraction measurements to understand the structural properties of such films at the three different angles of incidence supported by SEM and AFM data. Finally, the present study of this perovskite material paves a way to understand the diffusion of MAI into the PbI2 along with the film thickness of 350 ± 50 nm of the Perovskite layer for one molar ratio in detail. Last but not the least, together with the Synchrotron source-based GIXRD measurements SEM, AFM, and UV–Vis spectroscopy helped to understand the distribution of PbI2 after MAI gets diffused into it and a little amount of un-used PbI2 leftover along with the entire film after the PbI2 and MAI Interaction.

Ambient environment induced synergetic improvement in morphology and iodine vacancy passivation by MAI surface engineering in mixed-cation lead mixed-halide (FA0.85MA0.15PbI0.55Br0.45) perovskite solar cells

Perovskite solar cells (PSCs), have made tremendous progress but are still far away from theoretically estimated power conversion efficiencies (PCEs) and commercialization. Defects present in the perovskite materials and at various interfaces (between ETL/HTL and perovskite) in devices are inhibiting the performance to get closer to the theoretical limits, whereas the controlled atmosphere fabrication is creating a bottleneck in large scale production. Therefore, meticulous attention is required to overcome these problems. In this work, we report a very simple, facile and efficient post-synthesis surface treatment with methyl ammonium iodide (MAI) for surface and grain boundary defect passivation in the PSCs processed in fully ambient atmosphere. Ambient atmosphere, MAI surface treatment showed synergetic improvement, firstly it healed the defects (iodine trap states) existing on the surface/interface and grain boundaries and secondly increased the grain size, thereby reducing the defect sites. The improved crystallinity, morphology and decreased defects, reduced the trap density and non-radiative recombination losses leading to fast charge extraction. As a result, planar (n-i-p) PSCs, passivated with optimum MAI concentration, showed significantly higher boost (14%) in the power conversion efficiency (PCE) compared to previous MAI surface treatments, where no morphological changes were observed.

Interface Engineering in Perovskite Solar Cells by Low Concentration of Phenylethyl Ammonium Iodide Solution in the Antisolvent Step

In spite of the outstanding properties of metal halide perovskites, its polycrystalline nature induces a wide range of structural defects that results in charge losses that affect the final device performance and stability. Herein, a surface treatment is used to passivate interfacial vacancies and improve moisture tolerance. A functional organic molecule, phenylethyl ammonium iodide (PEAI) salt, is dissolved with the antisolvent step. The additive used at low concentration does not induce formation of low‐dimensional perovskites species. Instead, the organic halide species passivate the surface of the perovskite and grain boundaries, which results in an effective passivation. For sake of generality, this facile solution‐processed synthesis was studied for halide perovskite with different compositions, the standard perovskite MAPbI3, and double cation perovskites, MA0.9Cs0.1PbI3 and MA0.5FA0.5PbI3, increasing the average photoconversion efficiency compared to the reference cell by 18%, 32%, and 4% respectively, observed for regular, n‐i‐p, and inverted, p‐i‐n, solar cell configurations. This analysis highlights the generality of this approach for halide perovskite materials in order to reduce nonradiative recombination as observed by impedance spectroscopy.

Transition Metal‐Free Sulfenylation of C−H Bonds for C−S Bond Formation in Recent Years: Mechanistic Approach and Promising Future

AbstractTransition metal‐free sulfenylation of C−H bonds for C−S bond formation has recently emerged as sustainable protocols for the functionalisation of various molecules. Researchers have extensively developed such protocols for the construction of biologically relevant sulfur scaffolds. There has been a gradual shift from metal‐catalyzed to metal‐free C−S bond formation methodologies, because the latter offer environmentally benign and inherently safe access to novel synthetic routes in organic chemistry. The present review offers a dynamic discussion on recent advances in transition metal‐free C−S bond formation via C−H bond functionalization using different surrogate sulfenylating reagents. The review has comprehensively been devoted to radical and ionic mechanistic approaches. Some simple and eco‐friendly reagents for sulfenylation viz. tertbutyl hydrogen peroxide (TBHP), hydrogen peroxide (H2O2), iodine/potassium persulphate (I2/K2S2O8), inorganic bases, strong organic acids, iodine, I2/triphenyl phosphine (PPh3), N‐chlorosuccinamide (NCS), N‐bromosuccinamide (NBS), potassium iodate (KIO3), I2/bovine serum albumin (BSA), tetrabutyl ammonium iodide (TBAI)/HBr and graphene oxide along with their mechanistic approach has been detailed in this review. Moreover, modern methods for the C−S bond formation i. e., biocatalyst, electrochemical and visible light induced sulfenylation, and traditional sulfenylation methodologies have also been incorporated.

Open-Air Dual-Diamination of Aromatic Aldehydes: Direct Synthesis of Azolo-Fused 1,3,5-Triazines Facilitated by Ammonium Iodide.

A new and practical protocol for the synthesis of medicinally privileged azolo[1,3,5]triazines by simply heating under air has been presented. The in situ generated N-azolo amidines from commercially available aromatic aldehydes and 3-aminoazoles with ammonium iodide undergo the second diamination to accomplish the [3 + 1 + 1 + 1] heteroannulation reaction. This convenient process is appreciated by high efficiency, broad substrate scope, gram-scale synthesis, and operational simplicity under reagent-free conditions.

Structural evidence of the oxidation of iodide ion into hyper-reactive hypoiodite ion by mammalian heme lactoperoxidase.

Lactoperoxidase (1.11.1.7, LPO) is a mammalian heme peroxidase found in the extracellular fluids of mammals including plasma, saliva, airway epithelial lining fluids, nasal lining fluid, milk, tears, gastric juices, and intestinal mucosa. To perform its innate immune action against invading microbes, LPO utilizes hydrogen peroxide (H2 O2 ) to convert thiocyanate (SCN- ) and iodide (I- ) ions into the oxidizing compounds hypothiocyanite (OSCN- ) and hypoiodite (IO- ). Previously determined structures of the complexes of LPO with SCN- , OSCN- , and I- show that SCN- and I- occupy appropriate positions in the distal heme cavity as substrates while OSCN- binds in the distal heme cavity as a product inhibitor. We report here the structure of the complex of LPO with IO- as the first structural evidence of the conversion of iodide into hypoiodite by LPO. To obtain this complex, a solution of LPO was first incubated with H2 O2 , then mixed with ammonium iodide solution and the complex crystallized by the addition of PEG-3350, 20% (wt/vol). These crystals were used for X-ray intensity data collection and structure analysis. The structure determination revealed the presence of four hypoiodite ions in the substrate binding channel of LPO. In addition to these, six other hypoiodite ions were observed at different exterior sites. We surmise that the presence of hypoiodite ions in the distal heme cavity blocks the substrate binding site and inhibits catalysis. This was confirmed by activity experiments with the colorimetric substrate, ABTS (2,2'-azino-bis(3-ethylbenzthiazoline-sulfonic acid)), in the presence of hypoiodite and iodide ions.

Exploring the Effect of Ammonium Iodide Salts Employed in Multication Perovskite Solar Cells with a Carbon Electrode.

Perovskite solar cells that use carbon (C) as a replacement of the typical metal electrodes, which are most commonly employed, have received growing interest over the past years, owing to their low cost, ease of fabrication and high stability under ambient conditions. Even though Power Conversion Efficiencies (PCEs) have increased over the years, there is still room for improvement, in order to compete with metal-based devices, which exceed 25% efficiency. With the scope of increasing the PCE of Carbon based Perovskite Solar Cells (C-PSCs), in this work we have employed a series of ammonium iodides (ammonium iodide, ethylammonium iodide, tetrabutyl ammonium iodide, phenethylammonium iodide and 5-ammonium valeric acid iodide) as additives in the multiple cation-mixed halide perovskite precursor solution. This has led to a significant increase in the PCE of the corresponding devices, by having a positive impact on the photocurrent values obtained, which exhibited an increase exceeding 20%, from 19.8 mA/cm2, for the reference perovskite, to 24 mA/cm2, for the additive-based perovskite. At the same time, the ammonium iodide salts were used in a post-treatment method. By passivating the defects, which provide charge recombination centers, an improved performance of the C-PSCs has been achieved, with enhanced FF values reaching 59%, which is a promising result for C-PSCs, and Voc values up to 850 mV. By combining the results of these parallel investigations, C-PSCs of the triple mesoscopic structure with a PCE exceeding 10% have been achieved, while the in-depth investigation of the effects of ammonium iodides in this PSC structure provide a fruitful insight towards the optimum exploitation of interface and bulk engineering, for high efficiency and stable C-PSCs, with a structure that is favorable for large area applications.

Effect of the potassium iodide in tetrapropyl ammonium iodide-polyvinyl alcohol based gel polymer electrolyte for dye-sensitized solar cells

Low ionic conductivity in gel polymer electrolytes with large cations is undoubtedly a critical issue. This research’s main objective was to explore potassium iodide influences on the conductivity in gel polymer electrolytes. PVA-based gel polymer electrolytes (GPEs), including tetrapropyl ammonium iodide and potassium iodide have been prepared. The GPEs have been characterized by X-ray diffraction (XRD) and electrical impedance spectroscopy (EIS). The GPEs prepared haves been recognized as an amorphous region through the X-ray diffraction analysis. The GPE sample’s conductivity (100 wt% of tetrapropyl ammonium iodide) of 6.24 × 10−3 S cm−1 was the lowest. The existence of potassium iodide in the GPE system improves the conductivity. The conductivity of 9.72 × 10−3 S cm−1 of GPE containing 30 wt% of tetrapropyl ammonium iodide and 70 wt% of potassium iodide was the highest derived from the EIS analysis. All prepared GPEs have the potential to be used for dye-sensitized solar cell applications. The dye-sensitized solar cell efficiency has been improved by ~30% if potassium iodide exists in the GPE system.

The Effect of Halide Counter Ions and Methanol on the Foaming Behavior of Cationic Surfactants and a Mechanism Study

Abstract In this work, four quaternary ammonium cationic surfactants including cetyltrimethyl ammonium fluoride (CTAF), cetyltrimethyl ammonium chloride (CTAC), cetyltrimethyl ammonium bromide (CTAB) and cetyltrimethyl ammonium iodide (CTAI) were investigated to study the effect of halide anions on the surface activity and foaming performance. The result showed that CTAF had superior surface activity, which could reduce the surface tension of water to 33.15 mN/m at a low CMC (critical micelle formation concentration) of 1.65 mmol/L. Based on the calculation of Amin (the minimum occupied area per surfactant molecule), we assumed that this higher surface activity was related to the small ionic radius of the fluorine ion (F–). The foamability and foam stability of CTAF has great advantages over other surfactants studied. On this basis, the factors affecting the formation and stabilization of the CTAF foam were investigated. The results showed that foam formation benefited from high temperatures and low methanol concentration, while high salinity was beneficial for foam stability. When CTAF at a concentration of 0.2% was used as a foaming agent, foaming was excellent at a methanol concentration of 10%, a salinity of 22 ⨯ 104 mg/L, and a temperature of 90°C. With this study, uncertainties that existed in the literature regarding the effect of anion on surface activity and foam performance were explained and the effect of temperature, methanol and salinity on foam generation and stabilization was understood.

Preparation and characterization of some new complex salts of Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) ions with tetra propyl ammonium iodide

New series of trivalent and divalent metal complex salts with general formula [R]n[M Cl nIn], where R=Tetra propylammonium iodide, M=Cr3+, Fe3+, Mn2+, Co2+, Ni2+, Cu2+ and Zn2+, n=2 or 3 were prepared and characterized by elemental analysis molar conductance, IR, UV/Visible spectra studies and magnetic measurements. These studies, were revealed on octahedral geometry around Cr3+ and Fe3+ metal ions and tetrahedral geometry around divalent metal ions.

Manipulated Crystallization and Passivated Defects for Efficient Perovskite Solar Cells via Addition of Ammonium Iodide

Organic-inorganic metal halide perovskite materials have been widely studied as the light absorber for efficient photovoltaics. However, perovskite layers with defective nature are typically prepared with an uncontrollable crystallization process, intrinsically limiting further advance in device performance, and thus require delicate manipulation of crystallization processes and defect density. Here, we demonstrate an ammonium-assisted crystallization of perovskite absorbers during a two-step deposition to fabricate efficient solar cells. Addition of ammonium iodide (NH4I) is devised to manipulate the nucleation and crystal growth of perovskite, wherein the formation and transition of intermediate x[NH4+]•[PbI3]x- enables high-quality perovskite layers with an enlarged grain and reduced defect density. As a result, the perovskite solar cells (PSCs) achieve an average efficiency of 21.36% with a champion efficiency of 22.15% and improved environmental stability over 30 days in ambient conditions with varied relative humidity. These results with addition of NH4I provide an available and ingenious way to construct high-quality perovskite layers for efficient solar cells and will advance the commercial application of perovskite-based photovoltaics.

Polyphenylglyoxamide-Based Amphiphilic Small Molecular Peptidomimetics as Antibacterial Agents with Anti-Biofilm Activity.

The rapid emergence of drug-resistant bacteria is a major global health concern. Antimicrobial peptides (AMPs) and peptidomimetics have arisen as a new class of antibacterial agents in recent years in an attempt to overcome antibiotic resistance. A library of phenylglyoxamide-based small molecular peptidomimetics was synthesised by incorporating an N-alkylsulfonyl hydrophobic group with varying alkyl chain lengths and a hydrophilic cationic group into a glyoxamide core appended to phenyl ring systems. The quaternary ammonium iodide salts 16d and 17c showed excellent minimum inhibitory concentration (MIC) of 4 and 8 μM (2.9 and 5.6 μg/mL) against Staphylococcus aureus, respectively, while the guanidinium hydrochloride salt 34a showed an MIC of 16 μM (8.5 μg/mL) against Escherichia coli. Additionally, the quaternary ammonium iodide salt 17c inhibited 70% S. aureus biofilm formation at 16 μM. It also disrupted 44% of pre-established S. aureus biofilms at 32 μM and 28% of pre-established E. coli biofilms 64 μM, respectively. A cytoplasmic membrane permeability study indicated that the synthesised peptidomimetics acted via disruption and depolarisation of membranes. Moreover, the quaternary ammonium iodide salts 16d and 17c were non-toxic against human cells at their therapeutic dosages against S. aureus.

Surface Reconstruction Engineering with Synergistic Effect of Mixed‐Salt Passivation Treatment toward Efficient and Stable Perovskite Solar Cells

AbstractSurface passivation treatment is a widely used strategy to resolve trap‐mediated nonradiative recombination toward high‐efficiency metal‐halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in‐depth understanding of its passivation mechanism. Here, a systematic study on a mixed‐salt passivation strategy of formamidinium bromide (FABr) coupled with different F‐substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F‐substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed‐salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI2. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high‐quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed‐salt treatment. In addition, the introduction of the moisture resisted F‐substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long‐term stability under a high humid atmosphere as well as operational conditions.

Halogen-bond-driven supramolecular assemblies of quaternary-ammonium-iodide-containing polymers in three phases

Halogen bonding (XB) opens avenues to supramolecular assemblies. Here, we report XB-driven supramolecular assemblies of quaternary ammonium iodide (QAI)-containing polymers in three (solution, surface, and solid) phases. In the solution, QAI-containing block copolymers form unique self-assembly structures such as micrometer-sized giant vesicles (up to 5-μm diameter) and a 1-dimensional (1D) structure with multiple inter-vesicular linkages via XB. Exploiting the temperature dependence of XB strength, external molecules are successfully loaded and unloaded. On the surface, reversible XB crosslinking and decrosslinking of QAI-containing polymer brushes are achieved. The wettability of the polymer brush is finely tuned by the XB crosslinking density. In solid phase, QAI-containing monomers are co-crystalized (assembled) via XB. A polymer sheet is obtained via the solid-phase polymerization of the monomer co-crystal; the sheet enables capture and release of halogen-containing (XB-coordinating) guest molecules and thereby serves as an innovative host material. Giant vesicles and 1-dimensional assembly structure obtained via halogen bonding Temperature-responsive polymeric delivery carrier for loading external molecules Fine-tuning of polymer brush wettability by reversible halogen-bond crosslinking Polymeric host material of halogen-containing guests Le and Goto report halogen-bond-driven supramolecular self-assemblies of quaternary-ammonium-iodide-bearing polymers in three (solution, surface, and solid) phases, offering micrometer-sized vesicles and 1D structure, reversibly crosslinked polymer brushes on surfaces, and host material of halogen-containing guest molecules with tailored properties via halogen bonding.

The study of the morphology and structural, optical, and J-V characterizations of (CH3NH3PbI3) perovskite photovoltaic cells in ambient atmosphere

In this paper, the synthesis processes of perovskite active films of CH3NH3PbI3 (MAPbI3) have been studied for perovskite hybrid solar cells by spin and dip coating in ambient atmosphere, and without glove box to reduce production cost for technological applications. The morphology and structural, electrical and optical properties of perovskite films have been investigated by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopes (FE-SEM), Atomic Force Microscopes (AFM) and Ultraviolet–visible spectroscopy (UV-Vis). A precursor solution of lead Iodide (PbI2) with Dimethylformamide (DMF) solvent by spin coating at two stages (a) R=4500 rpm and (b) R=6000 rpm, and methyl ammonium iodide (CH3NH3I) with isopropanol solvent by dip coating, have been prepared for active perovskite layer (CH3NH3PbI3).

Rapid assessment of photovoltaic activity of perovskite solar cells by photoluminescence spectroscopy

Herein, we report a surprising yet noteworthy aspect that despite the perovskite absorbers being processed under similar conditions, the perovskite solar cells (PSC) exhibited radically different photovoltaic performance. Analysis of these absorbers unveil similar morphology, crystallinity and absorption properties. When steady-state photoluminescence (PL) is performed, a set of absorbers possesses an unexpected peak at 738 nm alongside the conventional peak around 770 nm. The absorbers exhibiting this unexpected peak have demonstrated significantly reduced photovoltaic activity compared to those without the peak. The origin of this phenomenon can be traced to the aged methyl ammonium iodide precursor. The study puts forward an important insight that PL analysis may provide additional information which enables rapid assessment of photoactivity of PSC – even before fabricating and testing the complete solar cell.

Cleaving Ergot Alkaloids by Hydrazinolysis-A Promising Approach for a Sum Parameter Screening Method.

Ergot alkaloids are mycotoxins formed by fungi of the Claviceps genus, which are some of the most common contaminants of food and feed worldwide. These toxins are a structurally heterogeneous group of compounds, sharing an ergoline backbone. Six structures and their corresponding stereoisomers are typically quantified by either HPLC-FLD or HPLC-MS/MS and the values subsequently summed up to determine the total ergot alkaloid content. For the development of a screening method targeting all ergot alkaloids simultaneously, the alkaloids need to be transferred to one homogeneous structure: a lysergic acid derivative. In this study, two promising cleaving methods—acidic esterification and hydrazinolysis—are compared, using dihydroergocristine as a model compound. While the acidic esterification proved to be unsuitable, due to long reaction times and oxidation sensitivity, hydrazinolysis reached a quantitative yield in 40‒60 min. Parallel workup of several samples is possible. An increasing effect on the reaction rate by the addition of ammonium iodide was demonstrated. Application of hydrazinolysis to a major ergot alkaloid mix solution showed that all ergopeptines were cleaved, but ergometrine/-inine was barely affected. Still, hydrazinolysis is a suitable tool for the development of a sum parameter screening method for ergot alkaloids in food and feed.

Preparation of Low Grain Boundary Perovskite Crystals with Excellent Performance: The Inhibition of Ammonium Iodide.

For the study, we prepared a low grain boundary three-dimensional CH3NH3PbI3 crystal (3D-MAPbI3) on TiO2 nanoarrays by inhibition of ammonium iodide and discussed the formation mechanism of the crystal. Based on the 3D-MAPbI3 crystal, solar cells showed modified performance with a power conversion efficiency (PCE) of up to 19.3%, which increases by 36.8% in contrast to the counterparts. We studied the internal photocurrent conversion process. The highest external quantum efficiency is up to 92%, and the electron injection efficiency is remarkably facilitated where the injection time decreases by 37.8% compared to the control group. In addition, based on 3D-MAPbI3, solar cells showed excellent air stability, which possesses 78.3% of the initial PCE, even though they were exposed to air for 30 days. Our results demonstrate a promising approach for the fabrication of perovskite solar cells with high efficiency and stability.