Br Anions Research Articles

Radiation‐Sensitive Layered Hybrid Double Perovskites Driven by a Dual‐Ion‐Woven Supramolecular Framework for X‐ray Tomography

A promising candidate for X‐ray detection is layered hybrid double perovskites (LHDPs) with excellent structural stability, but their sensitivity is generally limited by unsatisfactory interlayer charge transport. Herein, employing one ethylenediamine (EDA) chain as a structural inducer, we successfully obtain unusual Dion‐Jacobson (DJ) phase LHDPs, (EDABr)4AgBiBr8 and (EDABr)4CuBiBr8, featuring a Ruddlesden‐Popper‐like (RP‐like) interlayer. Thanks to the bridging of bromine anions, organic cations are linked via charge‐assisted hydrogen bonds, where two ionic spacers are orderly woven into a supramolecular framework. Consequently, the RP‐like interlayer space is regulated by the dual‐ion‐woven supramolecular framework with embedded charge‐assisted hydrogen bond networks, remarkably enriching interlayer interactions and boosting charge transport. Through theoretical calculations, structural roles of the supramolecular framework are elucidated by extra orbital contribution and large diffusion barrier of Br anions. As proof of concept, the sensitivity of RP‐like devices up to 5250 μC Gyair−1cm−2 is a record‐high of LHDP‐based X‐ray detectors for now, while a low detection limit (91 nGyair s−1) and outstanding radiation‐resistant capability (50 Gyair) are achieved. Moreover, an oriented membrane device is prepared to demonstrate high‐performance X‐ray tomography. These findings offer a brand‐new interlayer‐modulation strategy for the construction of sensitive and stable scintillation semiconductors.

Crystallization Control to Prepare Uniform CsPbI2Br Thin Films for High-Efficiency Perovskite Solar Cells.

All-inorganic perovskite solar cells (PSCs) face challenges related to film inhomogeneity, which arises from nonideal crystallization. This issue significantly impedes the advancement of all-inorganic PSCs. In this study, we observed that during the crystallization process of CsPbI2Br, the Br-rich intermediate phase is often preferentially deposited, leading to an uneven distribution in the out-of-plane direction of the perovskite film. To address this issue, crown ether molecules (dibenzo-18-crown-6) were introduced into the perovskite precursor solution. The complexation of crown ether with Cs cations and Br anions optimizes the crystallization sequence of the perovskite, ensuring that the intermediate phase closely conforms to the standard stoichiometric ratio. This adjustment significantly mitigates the problem of uneven halogen ion distribution along the out-of-plane direction. Furthermore, the crown ether thermally decomposes during the high-temperature annealing process, thereby not affecting the composition of the final perovskite film. Following crown ether treatment, the efficiency of the PSCs reached 14.08%, and the unpackaged devices maintained 80% of their initial efficiency after 1000 h of exposure to light in an atmospheric environment.

U(VI) sorption by CTAB/Bent–MOF-74 from various carbonate solutions

CTAB/Bent-MOF-74 was synthesized via hydrothermal method to investigate its U(VI) sorption in carbonate solutions. Generally, CTAB/Bent-MOF-74 (∼87.6 mg·g−1) showed better sorption capacity than CTAB/Bent-MOF-71 (∼64.2 mg·g−1) and CTAB/Bent-CS-35 (∼81.4 mg·g−1) in U(VI)-Cl coexist carbonate solutions when pH = 8.0, [NaHCO3] =2 mmol·L−1, [NaCl] =0.1 mol·L−1 and [U(VI)] =50 mg L−1. The competitive sorption between HCO3−/CO32−, OH−, halide ions and U(VI) complexes ions as well as the weakened electrostatic attraction decreased the composite's uranium sorption efficiency and capacity at high pHinitial, NaHCO3, phosphate, Ca/Mg and halide ions concentrations. The pseudo-second-order kinetics and Langmuir models indicated a monolayer homogeneous chemisorption process. Besides, 0.1mol·L−1 HCl shows the highest desorption efficiency among the selected desorbents, and the sorption rate is still high even after four times of desorption. In particular, the decreasing inhibitory capacity of the halide ions was on the order of I−, F−, Br−, Cl−. Characterization analyzes confirmed the good structural stability and Br anion exchange as well as the -OH/-COOH coordination and electrostatic attraction, which could be the predominant sorption mechanisms of U(VI) by CTAB/Bent-MOF-74. The results provided theoretical references for understanding the uranium sorption in natural uranium-containing water and designing potential uranium-extracting materials.

Ag Intercalation in Layered Cs3Bi2Br9 Perovskite for Enhanced Light Emission with Bound Interlayer Excitons.

Cesium bismuth bromide (CBB) has garnered considerable attention as a vacancy-ordered layered perovskite with notable optoelectronic applications. However, its use as a light source has been limited due to its weak photoluminescence (PL). Here, we demonstrate metal intercalation as a novel approach to engineer the room-temperature PL of CBB using experimental and computational methods. Ag, when introduced into CBB, occupies vacant sites in the spacer region, forming octahedral coordination with surrounding Br anions. First-principles density functional theory calculations reveal that intercalated Ag represents the most energetically stable Ag species compared to other potential forms, such as Ag substituting Bi. The intercalated Ag forms a strong polaronic trap state close to the conduction band minimum and quickly captures photoexcited electrons with holes remaining in CBB layers, leading to the formation of a bound interlayer exciton, or BIE. The radiative recombination of this BIE exhibits bright room-temperature PL at 600 nm and a decay time of 38.6 ns, 35 times greater than that of free excitons, originating from the spatial separation of photocarriers by half a unit cell separation distance. The BIE as a new form of interlayer exciton is expected to inspire new research directions for vacancy-ordered perovskites.

An Eutectic Mixture in the Tetrabutylammonium Bromide-Octanol System: Macroscopic and Microscopic Points of View.

An eutectic mixture of tetrabutylammonium bromide and octanol in the molar ratio 1-10 exhibited a melting point of -17 °C. This system was investigated by means of infrared spectroscopy, in the liquid and in the solid state. Classical molecular dynamics was performed to study the fine details of the hydrogen bond interactions established in the mixture. Both octanol and the mixtures displayed an almost featureless far-infrared spectrum in the liquid state but it becomes highly structured in the solid phase. DFT calculations suggest that new vibrational modes appearing in the mixture at low temperatures may be related to the population of the higher energy conformers of the alcohol. Mid-infrared spectroscopy measurements evidenced no shift of the CH stretching bands in the mixture compared to the starting materials, while the OH stretching are blue shifted by a few cm-1. Consistently, molecular dynamics provides a picture of the mixture in which part of the hydrogen bonds (HB) of pure octanol is replaced by weaker HB formed with the Br anion. Due to these interactions the ionic couple becomes more separated. In agreement with this model, the lengths of all HB are much larger than those observed in mixtures containing acids reported in previous studies.

Full-color, time-valve controllable and Janus-type long-persistent luminescence from all-inorganic halide perovskites

Long persistent luminescence (LPL) has gained considerable attention for the applications in decoration, emergency signage, information encryption and biomedicine. However, recently developed LPL materials – encompassing inorganics, organics and inorganic-organic hybrids – often display monochromatic afterglow with limited functionality. Furthermore, triplet exciton-based phosphors are prone to thermal quenching, significantly restricting their high emission efficiency. Here, we show a straightforward wet-chemistry approach for fabricating multimode LPL materials by introducing both anion (Br−) and cation (Sn2+) doping into hexagonal CsCdCl3 all-inorganic perovskites. This process involves establishing new trapping centers from [CdCl6-nBrn]4− and/or [Sn2-nCdnCl9]5− linker units, disrupting the local symmetry in the host framework. These halide perovskites demonstrate afterglow duration time ( > 2,000 s), nearly full-color coverage, high photoluminescence quantum yield ( ~ 84.47%), and the anti-thermal quenching temperature up to 377 K. Particularly, CsCdCl3:x%Br display temperature-dependent LPL and time-valve controllable time-dependent luminescence, while CsCdCl3:x%Sn exhibit forward and reverse excitation-dependent Janus-type luminescence. Combining both experimental and computational studies, this finding not only introduces a local-symmetry breaking strategy for simultaneously enhancing afterglow lifetime and efficiency, but also provides new insights into the multimode LPL materials with dynamic tunability for applications in luminescence, photonics, high-security anti-counterfeiting and information storage.

Groundwater Contamination in Arid Coastal Areas: Qatar as a Case Study.

The Arab region is located in an arid environment and suffers from water scarcity and poor water quality which are expected to become more severe in coming years due to global warming. In this study, the groundwater quality of 205 wells in Qatar was investigated. The physical parameters of pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, inorganic carbon (IC), and organic carbon (OC) were determined. The study characterized the concentrations of major anions of Cl, F, Br, NO3, PO4, and SO4, and major cations of Ca, K, Mg, and Na. Importantly, metals and metalloids including V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Pb, and U were determined. The results revealed that the groundwater of all wells is not drinkable due to high salinity (average TDS 4598 mg/L and salinity 0.4%, respectively). Additionally, average concentrations of major anions Cl, SO4, and F were 1472, 1064, and 1.9 mg/L, respectively, and all exceed the World Health Organization (WHO) guidelines for drinking water. However, NO3 concentration in 11 out of 205 wells was above the WHO guidelines of 50 mg/L due to intensive agriculture and fertilizer applications. Major cations of Ca, K, Mg, and Na were higher than WHO guidelines with average concentrations of 345, 63, 127, and 923 mg/L, respectively. All trace metals were much lower than the WHO guidelines for drinking water; however, the vanadium (V) average concentration in groundwater of all wells was 31 μg/L, which is five times higher than the Dutch guidelines (whereas the WHO has no guidelines for V). The groundwater of Qatar is dominated by Ca and Mg sulfates in Sabkha environments and dominated by NaCl in the coastal zones from evaporate environments consisting of coastal salt flats, salt pans, estuaries, and lagoons supersaturated by salts and the influence of sea water intrusion.

Halide Engineering in Mixed Halide Perovskite-Inspired Cu2AgBiI6 for Solar Cells with Enhanced Performance.

Cu2AgBiI6 (CABI) is a promising perovskite-inspired absorber for solar cells due to its direct band gap and high absorption coefficient. However, the nonradiative recombination caused by the high extrinsic trap density limits the performance of CABI-based solar cells. In this work, we employ halide engineering by doping bromide anions (Br-) in CABI thin films, in turn significantly improving the power conversion efficiency (PCE). By introducing Br- in the synthetic route of CABI thin films, we identify the optimum composition as CABI-10Br (with 10% Br at the halide site). The tailored composition appears to reduce the deep trap density as shown by time-resolved photoluminescence and transient absorption spectroscopy characterizations. This leads to a dramatic increase in the lifetime of charge carriers, which therefore improves both the external quantum efficiency and the integrated short-circuit current. The photovoltaic performance shows a significant boost since the PCE under standard 1 sun illumination increases from 1.32 to 1.69% (∼30% relative enhancement). Systematic theoretical and experimental characterizations were employed to investigate the effect of Br- incorporation on the optoelectronic properties of CABI. Our results highlight the importance of mitigating trap states in lead-free perovskite-inspired materials and that Br- incorporation at the halide site is an effective strategy for improving the device performance.

PIL@NENPs composite as a synergetic heterogeneous catalyst to enhance the efficiency of CO2 cycloaddition with epoxides

The conversion CO2 into highly value-added chemicals requires the development of efficient heterogenous catalysts in the cycloaddition reaction. Herein, the covalent integration strategy of amino-functionalized poly(ionic liquid)s (PIL-NH2HBr) with nitrogen-enriched nano-porous polytriazines (NENPs) was used to synthesize a novel hybrid catalyst, labelled as PIL@NENPs. Several characterization techniques were used to confirm the effective synthesis of PIL-NH2HBr, NENPs and PIL@NENPs composites. Through the PIL-NH2HBr surface integration, the CO2 adsorption capacity of NENPs was greatly improved in the PIL@NENPs composites. The catalytic activity studies shown that the PIL@NENPs exhibited better catalytic activity than PIL-NH2HBr and NENPs in CO2 cycloaddition reaction due to their synergetic effects. Moreover, the PIL@NENPs composite was found to be very easy to separate, had shown good stability and recyclability, and very effective for a variety of epoxides in the CO2 cycloaddition reaction. The Density Functional Theory (DFT) calculations further revealed that the epoxides were activated by hydrogen bond donor (HBD) groups and Br anions whereas the CO2 was activated by N sites. Finally, combining the DFT calculations and activities of different catalysts, a possible reaction mechanism for CO2 cycloaddition catalyzed by PIL@NENPs was proposed.

Counter-anion size engineering in polyfluorene-based cathode interlayers to enhance thickness independence

We synthesized a novel cathode interlayer material by replacing a Br anion with a TFSI anion. The increased anion size hindered the intermolecular interaction, allowing for the suppression of self-aggregation even on thick films.

Phenyltrimethylammonium‐Alloying Strategy for Efficient and Durable Formamidinium‐Based Perovskite Solar Cells

As for the commonly used formamidinium lead iodide (FAPbI3) perovskite, adding small amount of larger organic cations is a viable strategy to overcome its instability caused by formamidinium (FA) or iodide (I). Herein, FAPbI3 perovskite is modified by addition of quaternary cation phenyltrimethylammonium (PTMA), which forms 2D perovskite phase. With the presence of PTMA cations and small‐sized Br anions, the local strain of perovskite layer is mitigated. Also, X‐ray analyses reveal that PTMA cation directs FAPbI3 to have more vertically oriented structure, which aids the enhanced photocarrier generation and extraction. Defect analyses suggest that PTMA bromide alloying also greatly reduces the trap sites. Due to these combined effects, the PTMABr‐modified device results in the improved open‐circuit voltage plus stability under 60 °C or 1 sun illumination, maintaining 80% of its initial efficiency after 1800 and 1400 h, respectively.

Selenocyanate (SeCN−) acts as an efficient competitive substrate for myeloperoxidase and decreases biological damage induced by hypochlorous acid

The leukocyte-derived enzyme myeloperoxidase (MPO) is a key component of the innate immune response and mediates the killing of pathogens via the generation of the powerful oxidant hypochlorous acid (HOCl). Unintended or excessive formation of this species can however result in damage to host tissues, and this is linked with multiple pathologies associated with acute or chronic inflammation. The active (Compound I) form of MPO is promiscuous and can oxidize multiple alternative anions, in addition to the Cl− used to generate HOCl. These alternative substrates may therefore modulate MPO-mediated HOCl damage. In the current study we examined the hypothesis that selenocyanate (SeCN−), the selenium analogue of thiocyanate (SCN−, a well-established competitive MPO substrate) would inhibit HOCl-mediated damage to human plasma fibronectin (hpFN) or the extracellular matrix laid down by human coronary artery smooth muscle cells. SeCN− modulated HOCl and MPO-mediated damage, in a dose-dependent manner. These data are consistent with SeCN− acting as both a competitive substrate for Compound I of MPO (with IC50 ∼23 μM), and as a direct scavenger of HOCl. Inhibition of protein damage by SeCN− was also detected in the presence of the physiological anions Br−, I− and SCN− at the concentrations typically present in human plasma, consistent with a high affinity of SeCN− for MPO Compound I. In addition, the protective effects of SeCN− and SCN−, as competitive MPO substrates, were additive. Together these data indicate that modest concentrations of SeCN− can, like its sulfur analogue SCN−, act as an effective modulator of inflammation-induced damage.

DFT calculations of optoelectronic and thermoelectric properties of K2NaTlX6 (X = Cl, Br, I) halide double perovskites for energy harvesting applications

The DFT approach was employed to investigate the mechanical, optical and thermoelectric properties of double perovskites (DPs) compounds K2NaTlX6 (X = Cl, Br, I). PBEsol-GGA approximation along with birch-Murnaghan equation is used to calculate the lattice constant, other structural and ground state parameters. The structural, thermodynamic and mechanical stability of these compounds was demonstrated by computing tolerance factor, formation energy and Born criteria. Poisson and Pugh ratio are analyzed to describe the brittle or ductile nature of these studied double perovskites compounds. The anion Cl, Br and I-based double perovskites exhibited direct bandgap as determined from band structure calculations. The study further examined the optical absorption and dielectric constant of the compounds across the energy range 0–10 eV confirming their ability to absorb light in the infrared to visible spectrum. Furthermore, the suitability of the studied double perovskites for thermoelectric applications was assessed using BoltzTraP coding. The Seebeck coefficient, electric conductivity and figure of merit were analyzed, suggesting that these compounds hold promise as viable candidates for thermoelectric applications.

Tetrabutylammonium bromide/triethanolamine deep eutectic solvents with double hydrogen bond as efficient catalysts for fixation of CO2 in cyclic carbonates under mild conditions

AbstractBACKGROUNDCarbon dioxide is not only a major greenhouse gas but also an important carbon resource, which is abundant, renewable, low cost and non‐toxic. The coupling reaction of CO2 with epoxides has shown great potential in the field of chemical carbon fixation due to its 100% atomic utilization efficiency. Deep eutectic solvents (DESs) based on tetrabutylammonium bromide (TBAB) were evaluated for cycloaddition reaction of CO2 with propylene oxide (PO) to propylene carbonate (PC). Density functional theory (DFT) was used to calculate the catalytic performance of DES in CO2 cycloaddition reaction.RESULTSThe utilization of DES containing triethanolamine (TEA) as hydrogen bond donor significantly shortened the reaction time. Under optimal reaction conditions (30 mmol PO, 5 mol% TBAB/TEA (1:1) DES, 1.0 MPa CO2, 90 °C, 2 h), high PC yield (98%) was obtained. DFT calculations revealed that TBAB/TEA (1:1) DES was used as the catalyst for the coupling reaction between PO and CO2, with the ring‐opening process serving as the rate‐determining step and energy barrier of 17.9 kcal mol−1. TBAB/TEA (1:1) DES exhibited excellent recyclability and could be reused more than five times.CONCLUSIONTBAB/TEA (1:1) DES is a highly efficient homogeneous catalyst for the synthesis of cyclic carbonates through the cycloaddition reaction of CO2 and epoxides. The synergistic catalytic effect of the double hydrogen bonds between DES and Br anions is the reason for its high efficiency. © 2023 Society of Chemical Industry.

Interpenetration Phenomena via Anion Template Effects in Fe(II) and Co(II) Coordination Networks with a Bis-(1,2,4-triazole) Ligand.

Seven new coordination networks, [Fe(tbbt)3](BF4)2 (1), [Co(tbbt)3](BF4)2 (2), [Fe(tbbt)3](ClO4)2 (3), [Co(tbbt)3](ClO4)2 (4), [Fe(NCS)2(tbbt)2] (5), [Co(NCS)2(tbbt)2] (6), and [Fe(H2O)2(tbbt)2]Br2·2H2O (7), were synthesized with the linker 1,1'-(trans-2-butene-1,4-diyl)bis-1,2,4-triazole (tbbt) and structurally investigated. The structure of complexes 1-4 is composed of three interpenetrating, symmetry-related 3D networks. Each individual 3D network forms a primitive, nearly cubic lattice (pcu) with BF4- or ClO4- anions present in the interstitial spaces. The structure of compounds 5 and 6 is composed of two-dimensional sql layers, which are parallel to each other in the AB stacking type. These layers are interpenetrated by one-dimensional chains, both having the same formula unit, [M(NCS)2(tbbt)2] (M = Fe, Co). The structure of compound 7 consists of parallel, two-dimensional sql layers in the ABCD stacking type. The interpenetration in 1-6 is not controlled by π-π-interactions between the triazole rings or C=C bonds, as could have been expected, but by (triazole)C-H⋯F4B, C-H⋯O4Cl, and C-H⋯SCN anion hydrogen bonds, which suggests a template effect of the respective non-coordinated or coordinated anion for the interpenetration. In 7, the (triazole)C-H⋯Br anion interactions are supplemented by O-H⋯O and O-H⋯Br hydrogen bonds involving the aqua ligand and crystal water molecules. It is evident that the coordinated and non-coordinated anions play an essential role in the formation of the networks and guide the interpenetration. All iron(II) coordination networks are colorless, off-white to yellow-orange, and have the metal ions in the high-spin state down to 77 K. Compound 5 stays in the high spin state even at temperatures down to 10 K.

First-principles calculations to investigate mechanical, thermoelectric and optical performance of inorganic double perovskites Rb2AgAlZ6 (Z = Br, I) for energy harvesting

The clean and green energy is a merging technology of advanced era to achieve the demands of energy requirements. For this purpose, the double perovskites Rb2AgAlZ6 (Z = Br, I) are explored comprehensively in terms of optical, mechanical, thermoelectric, and thermodynamic characteristics. The stability of structures, elastic and thermodynamic have been ensured through tolerance factor, Born Criteria, and formation energy. The elastic constants of cubic symmetry are analyzed to distinguish ductile/brittle nature, anisotropy, Harness, minimum lattice thermal, conductivity, melting and Debye temperatures. The anions (Br, I) modified the band gaps (2.60, 1.08) eV which turned the absorption of light energy from ultraviolet to visible portion of spectrum. The absorption band of Rb2AgAsI6 in the energy range 1.7eV–3.4 eV is particularly significant for solar cells. The large Seebeck coefficient, and electrical conductivity while particularly low lattice thermal conductivity has been increased the figure of merit. The large figure of at low temperature open the new finding roots for realization of these DPs for thermoelectric and other energy applications.

A Novel POP-Ni Catalyst Derived from PBTP for Ambient Fixation of CO2 into Cyclic Carbonates.

The immobilization of homogeneous catalysts has always been a hot issue in the field of catalysis. In this paper, in an attempt to immobilize the homogeneous [Ni(Me6Tren)X]X (X = I, Br, Cl)-type catalyst with porous organic polymer (POP), the heterogeneous catalyst PBTP-Me6Tren(Ni) (POP-Ni) was designed and constructed by quaternization of the porous bromomethyl benzene polymer (PBTP) with tri[2-(dimethylamino)ethyl]amine (Me6Tren) followed by coordination of the Ni(II) Lewis acidic center. Evaluation of the performance of the POP-Ni catalyst found it was able to catalyze the CO2 cycloaddition with epichlorohydrin in N,N-dimethylformamide (DMF), affording 97.5% yield with 99% selectivity of chloropropylene carbonate under ambient conditions (80 °C, CO2 balloon). The excellent catalytic performance of POP-Ni could be attributed to its porous properties, the intramolecular synergy between Lewis acid Ni(II) and nucleophilic Br anion, and the efficient adsorption of CO2 by the multiamines Me6Tren. In addition, POP-Ni can be conveniently recovered through simple centrifugation, and up to 91.8% yield can be obtained on the sixth run. This research provided a facile approach to multifunctional POP-supported Ni(II) catalysts and may find promising application for sustainable and green synthesis of cyclic carbonates.

Experimental and theoretical study on ionic liquid [Bmim]Br-catalyzed decomposition of cumene hydroperoxide into dimethylbenzyl alcohol

The Ionic Liquid 1-butyl-3methyl-imidazolium bromide ([Bmim]Br) was found to be a good catalyst for the decomposition of Cumene Hydroperoxide(CHP) to ɑ,ɑ-Dimethylbenzyl alcohol(CA). The mechanism of [Bmim]Br-catalyzed conversion of CHP to CA has been studied using density functional theory(DFT) calculations. The DFT results showed that the Br anion of [Bmim]Br played a crucial role in the decomposition of CHP to CA. The energy barrier of [Bmim]Br-catalyzed decomposition of CHP is 21.4 kcal/mol. This research provides the feasibility of ionic liquid as catalysts for CHP decomposition to CA.

N-doped porous polymer with protonated ionic liquid sites for efficient conversion of CO2 to cyclic carbonates

A N-doped porous polymer with protonated ionic liquid sites was fabricated by a solvent-free self-assembly synthesis of resorcinol/formaldehyde resin, followed by modification with hydrobromic acid (HBr) to introduce ionic sites. Compared with the parent polymer PIP-HP, polymer PIP-HP-HBr maintains a high specific surface area after ion site construction, and the elevated activity was also acquired under metal/solvent/cocatalyst-free conditions with up to 99% yield of cyclic carbonates. Furthermore, the PIP-HP-HBr as a heterogeneous catalyst can be readily recovered and demonstrate excellent cycling stability. In addition, a plausible catalytic mechanism had been proposed that the high catalytic activity originates from the synergistic effect of hydrogen bond donor –OH and nucleophilic anion Br−.

Plasticizing effect of 1‐butyl‐3‐methylimidazolium bromide content on poly(vinyl alcohol)

AbstractPVA/IL composites were successfully prepared with an ionic liquid (IL), 1‐butyl‐3‐methylimidazolium bromide and poly(vinyl alcohol) (PVA). The plasticizing effect of IL on PVA was investigated using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), X‐ray diffraction (XRD), thermogravimetric analysis (TGA) and melt flow index (MI) measurements. FTIR analysis indicated that the anion (Br−) of IL could form hydrogen bonds with the hydroxyl groups of PVA. With an increase of IL, –OH absorption peaks of PVA/IL composites shifted to higher wavenumbers. DSC analysis showed that both melt and crystallization temperatures of the PVA/IL composites decreased as IL content increased. XRD analysis showed that the degree of crystallinity of the PVA/IL composites had a decreasing trend with an increase of IL. TGA showed that IL could effectively improve the thermal stability of PVA. The thermal stability of the PVA/IL composites decreased gradually with increasing IL content, but was higher than that of PVA. Thermal processing window (ΔT) analysis indicated that the addition of IL could significantly broaden ΔT of the PVA/IL composites, and their ΔT values first remained basically unchanged and then increased slightly with an increase of IL. In addition, MI analysis presented that the melt processability of the PVA/IL composites was not improved with the addition of IL and it was gradually improved with increasing IL content. In this work, PVA/IL composites with wide ΔT and high melt flow properties were prepared, which will lay a solid foundation for the preparation of high‐performance PVA fibers by melt spinning. © 2022 Society of Industrial Chemistry.