Showing papers on "Iodide published in 2019"
TL;DR: It is found that a combination of triphenylphosphine and sodium iodide under 456-nanometer irradiation by blue light–emitting diodes can catalyze the alkylation of silyl enol ethers by decarboxylative coupling with redox-active esters in the absence of transition metals.
Abstract: Most photoredox catalysts in current use are precious metal complexes or synthetically elaborate organic dyes, the cost of which can impede their application for large-scale industrial processes. We found that a combination of triphenylphosphine and sodium iodide under 456-nanometer irradiation by blue light–emitting diodes can catalyze the alkylation of silyl enol ethers by decarboxylative coupling with redox-active esters in the absence of transition metals. Deaminative alkylation using Katritzky’s N-alkylpyridinium salts and trifluoromethylation using Togni’s reagent are also demonstrated. Moreover, the phosphine/iodide-based photoredox system catalyzes Minisci-type alkylation of N-heterocycles and can operate in tandem with chiral phosphoric acids to achieve high enantioselectivity in this reaction.
435 citations
TL;DR: The homochirality in 2D lead iodide perovskite ferroelectrics facilitates crystallization in polar space groups, and indicates an effective way to design high-performance 2DLead iodide Perovskites with great application prospects.
Abstract: 2D organic-inorganic lead iodide perovskites have recently received tremendous attention as promising light absorbers for solar cells, due to their excellent optoelectronic properties, structural tunability, and environmental stability. However, although great efforts have been made, no 2D lead iodide perovskites have been discovered as ferroelectrics, in which the ferroelectricity may improve the photovoltaic performance. Here, by incorporating homochiral cations, 2D lead iodide perovskite ferroelectrics [R-1-(4-chlorophenyl)ethylammonium]2 PbI4 and [S-1-(4-chlorophenyl)ethylammonium]2 PbI4 are successfully obtained. The vibrational circular dichroism spectra and crystal structural analysis reveal their homochirality. They both crystalize in a polar space group P1 at room temperature, and undergo a 422F1 type ferroelectric phase transition with transition temperature as high as 483 and 473.2 K, respectively, showing a multiaxial ferroelectric nature. They also possess semiconductor characteristics with a direct bandgap of 2.34 eV. Nevertheless, their racemic analogue adopts a centrosymmetric space group P21 /c at room temperature, exhibiting no high-temperature phase transition. The homochirality in 2D lead iodide perovskites facilitates crystallization in polar space groups. This finding indicates an effective way to design high-performance 2D lead iodide perovskite ferroelectrics with great application prospects.
219 citations
TL;DR: CoS2/CoS heterojunction nanoparticles with uneven charge distribution can significantly boost electrocatalytic activities of I−/I3 − and S2/Sx 2− redox reactions by improving absorptivity of charged ions and promoting charge transfer.
Abstract: Aqueous polysulfide/iodide redox flow batteries are attractive for scalable energy storage due to their high energy density and low cost. However, their energy efficiency and power density are usually limited by poor electrochemical kinetics of the redox reactions of polysulfide/iodide ions on graphite electrodes, which has become the main obstacle for their practical applications. Here, CoS2/CoS heterojunction nanoparticles with uneven charge distribution, which are synthesized in situ on graphite felt by a one-step solvothermal process, can significantly boost electrocatalytic activities of I−/I3− and S2−/Sx2− redox reactions by improving absorptivity of charged ions and promoting charge transfer. The polysulfide/iodide flow battery with the graphene felt-CoS2/CoS heterojunction can deliver a high energy efficiency of 84.5% at a current density of 10 mA cm−2, a power density of 86.2 mW cm−2 and a stable energy efficiency retention of 96% after approximately 1000 h of continuous operation. Polysulfide/iodide redox flow batteries are promising due to low cost and high-solubility components, but are limited by energy efficiency and power density. Here the authors fabricate heterojunction electrocatalysts to achieve improved performance in a polysulfide/iodide redox flow battery.
188 citations
TL;DR: The SANi-I exhibits robust structural stability and exceptional electrocatalytic activity for the hydrogen evolution reaction, and in-situ Raman spectroscopy reveals that the hydrogen adatom is adsorbed by a single iodine atom, forming the I-Hads intermediate, which promotes the HER process.
Abstract: Common-metal-based single-atom catalysts (SACs) are quite difficult to design due to the complex synthesis processes required. Herein, we report a single-atom nickel iodide (SANi-I) electrocatalyst with atomically dispersed non-metal iodine atoms. The SANi-I is prepared via a simple calcination step in a vacuum-sealed ampoule and subsequent cyclic voltammetry activation. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and synchrotron-based X-ray absorption spectroscopy are applied to confirm the atomic-level dispersion of iodine atoms and detailed structure of SANi-I. Single iodine atoms are found to be isolated by oxygen atoms. The SANi-I is structural stable and shows exceptional electrocatalytic activity for the hydrogen evolution reaction (HER). In situ Raman spectroscopy reveals that the hydrogen adatom (Hads ) is adsorbed by a single iodine atom, forming the I-Hads intermediate, which promotes the HER process.
153 citations
TL;DR: In this paper, the effect of partial guanidinium substitution into methylammonium lead iodide has been investigated for mixed-cation perovskite solar cells.
Abstract: Halide perovskite solar cells containing a mixture of A-site cations are attracting considerable interest due to their improved stability and high power conversion efficiencies. Ionic transport is known to be an important predictor of perovskite behaviour, but the impact of partial A-site substitution on iodide ion diffusion is poorly understood. Here, we combine ab initio modelling, impedance spectroscopy and muon spin relaxation to investigate the effect on iodide ion transport of incorporating a low concentration of each of seven different sized cations (from small rubidium to large guanidinium) into methylammonium lead iodide. Experimental and simulation results are in good agreement, indicating that these cation substitutions increase the activation energy for iodide ion diffusion. We show for the first time that partial guanidinium substitution into methylammonium lead iodide strongly suppresses iodide ion transport. The insights gained from this multi-technique study are important for the future design of mixed-cation perovskite solar cells with enhanced performance.
152 citations
TL;DR: With the MASnI3 as light harvester, mesoporous perovskite solar cells were prepared, and a maximum power conversion efficiency (PCE) of 7.13 % is delivered with good reproducibility.
Abstract: Tin-based halide perovskite materials have been successfully employed in lead-free perovskite solar cells, but the overall power conversion efficiencies (PCEs) have been limited by the high carrier concentration from the facile oxidation of Sn2+ to Sn4+ . Now a chemical route is developed for fabrication of high-quality methylammonium tin iodide perovskite (MASnI3 ) films: hydrazinium tin iodide (HASnI3 ) perovskite film is first solution-deposited using presursors hydrazinium iodide (HAI) and tin iodide (SnI2 ), and then transformed into MASnI3 via a cation displacement approach. With the two-step process, a dense and uniform MASnI3 film is obtained with large grain sizes and high crystallization. Detrimental oxidation is suppressed by the hydrazine released from the film during the transformation. With the MASnI3 as light harvester, mesoporous perovskite solar cells were prepared, and a maximum power conversion efficiency (PCE) of 7.13 % is delivered with good reproducibility.
140 citations
TL;DR: In this article, a solid-state method was used to synthesize single crystals of perovskite-phase cesium lead iodide (γ-CsPbI3) that are kinetically stable at room temperature.
Abstract: We use a solid-state method to synthesize single crystals of perovskite-phase cesium lead iodide (γ-CsPbI3) that are kinetically stable at room temperature. Single crystal X-ray diffraction charact...
137 citations
TL;DR: This represents the first example of highly enantioselective carboiodination of olefin-tethered aryl iodides, which provides a perfect atom economy method to construct a series of optically active 2,3-dihydrobenzofuran, indolines and chromane bearing an alkyl iodide group in moderate to good yields.
Abstract: A highly enantioselective palladium-catalyzed iodine atom transfer cycloisomerization of unactivated alkenes has been developed. This represents the first example of highly enantioselective carboiodination of olefin-tethered aryl iodides, which provides a perfect atom economy method to construct a series of optically active 2,3-dihydrobenzofuran, indolines and chromane bearing an alkyl iodide group in moderate to good yields. Moreover, the use of readily available starting materials, a broad substrate scope, high selectivity, mild reaction conditions, as well as versatile transformation of the product make this approach attractive. The mechanism of this Pd(0)-catalyzed asymmetric carboiodination of alkenes has been investigated with density functional theory.
104 citations
TL;DR: This one-pot protocol could well be expanded to access various 2-fluoroalkylbenzoselenazoles starting from (2-isocyanophenyl)(methyl)selane, perfluoroALKyl iodides or ICF2COOEt and TMEDA.
100 citations
TL;DR: Transient absorption spectroscopy revealed that the iodide expulsion process leaves a defect-rich perovskite lattice behind as charge carrier recombination in the re-formed lattice is greatly accelerated.
Abstract: Halide ion mobility in metal halide perovskites remains an intriguing phenomenon, influencing their optical and photovoltaic properties. Selective injection of holes through electrochemical anodic ...
87 citations
TL;DR: This work reports the formation enthalpies of two CsPbI3 poly-morphs, α and δ, using a combination of room temperature solution calorimetry in dimethylsulfoxide (DMSO) and differential scanning calorIMetry and shows that both polymorphs are stable with respect to their binary halides.
Abstract: Cesium lead iodide (CsPbI3) perovskite has shown great potential as a light absorbing material for solar cell applications. Despite intense research leading to increasing power conversion efficienc...
TL;DR: In this paper, the stability of formamidinium lead iodide (FAPbI3) perovskites is improved by incorporating cesium (Cs) into the crystal structure.
Abstract: The stability of formamidinium lead iodide (FAPbI3) perovskites is generally improved by incorporating cesium (Cs) into the crystal structure. However, the effectiveness of this approach is limited...
TL;DR: IL-induced formation of dynamic complex iodide anions in IL@MOF composites facilitates record iodine adsorption capacities for both iodine vapor and solution.
Abstract: Highly efficient capture of radioactive iodine from vapor or solvent remains a serious task for nuclear waste disposal and environmental protection, for which the development of excellent adsorbents is of great importance. Herein, a new strategy named IL-induced formation of dynamic complex iodide anions in IL@MOF composites was developed to prepare efficient iodine capture adsorbents. The IL@PCN-333(Al) composite shows record iodine adsorption capacities of 7.35 g g−1 and 3.4 g g−1 for iodine vapor and solution, respectively. The mechanism study reveals that complex iodide anions can be dynamically formed by the reaction of bromide ions in the IL and iodine molecules, which have strong electrostatic interactions with the imidazolium cations of the IL. Owing to the reversibility of the polyiodide formation, the IL@PCN-333(Al) also shows excellent recyclable performance. This work provides a general methodology for intensification of the interactions of neutral molecules and host materials that may find applications in various adsorption-based separation processes.
TL;DR: Tunable femtosecond stimulated Raman spectroscopy coupled with density functional theory calculations elucidate a series of [ZnI x (OH 2 ) 4-x ] 2-x superhalide ions serving as iodide vehicles in the electrolyte, which eliminates most free iodide ions, thus preventing the consequent dissolution of the cathode-plated iodine as triiodides.
Abstract: Plating battery electrodes typically deliver higher specific capacity values than insertion or conversion electrodes because the ion charge carriers represent the sole electrode active mass, and a host electrode is unnecessary. However, reversible plating electrodes are rare for electronically insulating nonmetals. Now, a highly reversible iodine plating cathode is presented that operates on the redox couples of I2 /[ZnIx (OH2 )4-x ]2-x in a water-in-salt electrolyte. The iodine plating cathode with the theoretical capacity of 211 mAh g-1 plates on carbon fiber paper as the current collector, delivering a large areal capacity of 4 mAh cm-2 . Tunable femtosecond stimulated Raman spectroscopy coupled with DFT calculations elucidate a series of [ZnIx (OH2 )4-x ]2-x superhalide ions serving as iodide vehicles in the electrolyte, which eliminates most free iodide ions, thus preventing the consequent dissolution of the cathode-plated iodine as triiodides.
TL;DR: In this paper, an aqueous organic redox flow battery (AORFB) using anthraquinone-2,7-disulfonic acid disodium salt and potassium iodide (KI) as the negative and positive active species is suggested.
TL;DR: In this article, methylammonium lead(II) iodide perovskite has been doped with imidazolium iodide in high concentrations to boost solar cell performance, by passivating defects.
TL;DR: In this paper, the existence of a large miscibility gap between 0.29 ≤ x ≤ 0.92 (± 0.02) for the MAPb(I1−xBrx)3 solid solution has been proven.
Abstract: By using synchrotron X-ray powder diffraction, the temperature dependent phase diagram of the hybrid perovskite tri-halide compounds, methyl ammonium lead iodide (MAPbI3, MA+ = CH3NH3+) and methyl ammonium lead bromide (MAPbBr3), as well as of their solid solutions, has been established. The existence of a large miscibility gap between 0.29 ≤ x ≤ 0.92 (±0.02) for the MAPb(I1−xBrx)3 solid solution has been proven. A systematic study of the lattice parameters for the solid solution series at room temperature revealed distinct deviations from Vegard's law. Furthermore, temperature dependent measurements showed that a strong temperature dependency of lattice parameters from the composition is present for iodine rich compositions. In contrast, the bromine rich compositions show an unusually low dependency of the phase transition temperature from the degree of substitution.
TL;DR: In this paper, the synthesis of two-dimensional (2D) lead iodide with single-octahedra slabs separated by the smalar lattice was reported.
Abstract: Layered lead halides offer potential for light-emitting and photovoltaic devices. Here, we report the synthesis of two-dimensional (2D) lead iodide with single-octahedra slabs separated by the smal...
TL;DR: The results showed that Ag2O-Ag2O3 nanoparticles doped and uniformly dispersed on the surface of ZIF-8 matrix, and a mechanism explaining the excellent properties for adsorbents could be epitomized into three aspects, namely, the uptake performance of Ag2 O for I-, the strong oxidization of Ag1O3 for I-, and the adsorption of AgI for I2.
TL;DR: In this paper, single crystals of lead halide hybrid perovskites (e.g., CH3NH3PbI3 and CsPbBr3) have been developed as promising candidates for X-ray detection, owing to their excellent attributes including low...
Abstract: Single crystals of lead halide hybrid perovskites (e. g., CH3NH3PbI3 and CsPbBr3) have been developed as promising candidates for X-ray detection, owing to their excellent attributes including low ...
TL;DR: Silver-functionalized silica aerogel (AgAero) represents a strong candidate for safe sequestration of radioiodine from various nuclear waste streams and subsurface environments and demonstrated ability to remove IO3- through reduction to I-.
TL;DR: In this article, mesoporous Fe-based MOFs (Bi@MIL) were prepared by mixing Bi(III) and MIL-101(Fe) in Teflon-lined autoclave using solvothermal synthetic method.
TL;DR: A palladium-catalyzed enantioselective intramolecular σ-bond cross-exchange between C-I and C-C bonds is realized, providing chiral indanones bearing an alkyl iodide group and an all-carbon quaternary stereocenter.
Abstract: A palladium-catalyzed enantioselective intramolecular σ-bond cross-exchange between C-I and C-C bonds is realized, providing chiral indanones bearing an alkyl iodide group and an all-carbon quaternary stereocenter. Pd/TADDOL-derived phosphoramidite is found to be an efficient catalytic system for both C-C bond cleavage and alkyl iodide reductive elimination. In addition to aryl iodides, aryl bromides can also be used for this transformation in the presence of KI. Density-functional theory (DFT) calculation studies support the ring-opening of cyclobutanones occuring through an oxidative addition/reductive elimination process involving PdIV species.
TL;DR: Cross-linked chitosan microspheres by emulsion polymerization were investigated and proposed as the green and efficient adsorbents to treat iodine wastes via I- and -NH2 attraction, promising according to adsorbent dosage, pH, co-existing anions and recyclability analyzations.
TL;DR: State-of-the-art quantum dynamics simulations provide evidence for tunnelling in hydrogen-bond rearrangements in the iodide–dihydrate complex and show that it can be controlled through isotopic substitutions.
Abstract: A microscopic picture of hydrogen-bond structure and dynamics in ion hydration shells remains elusive. Small ion-dihydrate molecular complexes are ideal systems with which to investigate the interplay and competition between ion-water and water-water interactions. Here, state-of-the-art quantum dynamics simulations provide evidence for tunnelling in hydrogen-bond rearrangements in the iodide-dihydrate complex and show that it can be controlled through isotopic substitutions. We find that the iodide ion weakens the neighbouring water-water hydrogen bond, leading to faster water reorientation than in the analogous water trimer. These faster dynamics, which are apparently at odds with the slowdown observed in the first hydration shell of iodide in solution, can be traced back to the presence of a free OH bond in the iodide-dihydrate complex, which effectively triggers the overall structural rearrangements within it. Besides providing indirect support for cooperative hydrogen-bond dynamics in iodide solutions, the analysis presented here suggests that iodide ions may accelerate hydrogen-bond rearrangements at aqueous interfaces, where neighbouring water molecules can be undercoordinated.
TL;DR: Triethylsulfonium iodide is introduced as a redox mediator as well as an enabler of a protective layer on Li anode, leading to notable electrochemical performance.
Abstract: As soluble catalysts, redox mediators can reduce the high charging overpotential of lithium-oxygen batteries by providing sufficient liquid-solid interface for lithium peroxide decomposition. However, the redox mediators usually introduce undesirable reactions. In particular, the so-called "shuttle effect" leads to the loss of both the redox mediators and electrical energy efficiency. In this study, an organic compound, triethylsulfonium iodide, is found to act bifunctionally as both a redox mediator and a solid electrolyte interphase-forming agent for lithium-oxygen batteries. During charging, the organic iodide exhibits comparable lithium peroxide-oxidizing capability with inorganic iodides. Meanwhile, it in situ generates an interfacial layer on lithium anode via reductive ethyl detaching and the subsequent oxidation. This layer prevents the lithium anode from reacting with the redox mediators and allows efficient lithium-ion transfer leading to dendrite-free lithium anode. Significantly improved cycling performance has been achieved by the bifunctional organic iodide redox mediator.
TL;DR: The study suggests the potential application of Bi on graphene-based materials for selective removal of both iodide and iodate from radioactive wastewater.
Abstract: Bismuth-functionalized graphene oxide (Bi-GO) was successfully synthesized and showed both high iodide and iodate removal efficiencies from radioactive wastewater. Batch experiments for kinetic and selectivity tests were performed, respectively. Additional SEM, XRD, FT-IR, and XPS analyses were performed for characterization of a sorbent and bismuth on the GO surface and this confirmed that bismuth on the GO surface reacted with iodine species by surface complexation (or precipitation). Dominant surface species are BiOI and Bi(IO3)3 for iodide and iodate removal, respectively. After the selectivity test using a KCl background solution with varying concentrations, Bi-GO still showed higher removal efficiencies (≥95%) for both iodide and iodate than the commercial silver-exchanged zeolite (≥95% for iodide and ≤25% for iodate). Our study suggests the potential application of Bi on graphene-based materials for selective removal of both iodide and iodate from radioactive wastewater.
TL;DR: Its synthetic application was illustrated through the derivatization of organoboron products and preparation of monofluorinated ibuprofen.
Abstract: A copper-catalyzed borylfluoromethylation of alkenes with fluoromethyl iodide and diboron reagents was disclosed. This protocol afforded the previously unknown and synthetically useful borylfluorom...
TL;DR: In this paper, high nucleation-mode iodine concentrations measured by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) confirmed that intense new particle formation (NPF) events were induced by iodine species.
Abstract: . Intense new particle formation (NPF) events were observed in the coastal atmosphere
during algae growth and farming season at Xiangshan gulf of the east China coast. High
nucleation-mode iodine concentrations measured by ultra-performance liquid chromatography
coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) confirmed that
the NPF events were induced by iodine species. Our study provides important information
on iodine speciation, size distributions, and its role in NPF in the context of heavy air
pollution in China's coastal areas. For the first time, we identified 5 inorganic iodine
species, 45 organic iodine compounds (35 molecular formulas), and a group of
iodide–organic adducts in aerosols. The concentrations and size distributions of iodine
species down to 10 nm were measured during the iodine-induced NPF, continental NPF, and
non-NPF days at the coastal site and compared to those at an inland site. The iodine in
the above four aerosol sample types were characterized by iodate, aromatic iodine
compounds, iodoacetic acid or iodopropenoic acid, and iodide–organic adducts,
respectively. Iodide and organic iodine compounds were found in the nucleation-mode
particles; however, it is still not clear whether they contributed to nucleation or just
new particle growth. Wild algae, as well as farmed algae, could be an important NPF
source in China's coastal areas.
TL;DR: In this article, the ionic conductivity of the gel polymer electrolytes (GPEs) was measured by electrochemical impedance spectrometer (EIS) and the GPEs increased with the presence of ionic liquids (ILs).
Abstract: Host polymer electrolytes are prepared using poly(ethylene oxide) (PEO) as a polymer, ethylene carbonate (EC) and propylene carbonate (PC) as solvents, sodium iodide (NaI) as salt, and iodine (I2) and with either one of the ionic liquids (ILs) which are 1-methyl-3-propylimidazolium iodide (MPII), 1-butyl-3-methylimidozium (BMII), and 1-hexyl-3-methylimidozium iodide (HMII) in each gel polymer electrolyte. The ionic conductivity of the gel polymer electrolytes (GPEs) was measured by electrochemical impedance spectrometer (EIS). The ionic conductivity of GPEs increased with the presence of ionic liquids (ILs). At room temperature, the dielectric behaviors of the GPEs were studied. The highest ionic conductivity of 9.41 mS cm−1 is achieved after addition of MPII ionic liquid. Meanwhile, Fourier-transform infrared and X-ray diffraction studies confirm complexation between PEO polymer, NaI salt, and ionic liquids (MPII, BMII, and HMII). Dye-sensitized solar cells (DSSCs) were fabricated using polymer electrolytes and studied under Sun simulator. The DSSC using MPII ionic liquid shows the highest efficiency of 9.35%.