Ionic Liquid BMIMBF4 Research Articles

Improving stability of perovskite solar cells using BMIMBF4/IPA as green mixed anti-solvent

Interfacial passivation of perovskite films is an effective way to further improve the power conversion efficiency (PCE) and long-term stability of perovskite solar cells (PSCs). In this work, the combination of ionic liquid (IL) BMIMBF4 and isopropanol (IPA) are used as green mixed anti-solvent. The existence of ionic liquids can delay the crystallization of perovskite and obtain dense perovskite films, because the non-volatile characteristics of BMIMBF4 is left on the surface of perovskite, which is used for interfacial passivation. The perovskite film, which is prepared by mixed anti-solvent, can effectively reduce surface defects and significantly inhibit non-radiative recombination. Comparing with IPA as single anti-solvent, the PCE increased from 14.49% to 16.25%. In addition, the perovskite film with mixed anti-solvent still retains 76.8% of the initial efficiency after the unpacked PSCs are soaked in 100 mW/cm2 light for 20 days, and it retains 72.6% of the initial efficiency after 20 days of aging in an air atmosphere with 50∼60% relative humidity. The significant improvement of stability shows that the mixed green anti-solvent which combining BMIMBF4 with IPA is an effective strategy for preparing stable PSCs by one-step method.

An ionic liquid-assisted strategy for enhanced anticorrosion of low-energy PEO coatings on magnesium–lithium alloy

A low-energy plasma electrolytic oxidation (LePEO) technique is developed to simultaneously improve energy efficiency and anti-corrosion. Ionic liquids (1‑butyl‑3-methylimidazole tetrafluoroborate (BmimBF4)) as sustainable corrosion inhibitors are chosen to investigate the corrosion inhibition behavior of ionic liquid (ILs) during the LePEO process for LA91 magnesium–lithium (Mg–Li) alloy. Results show that the ionic liquid BmimBF4 participates in the LePEO coating formation process, causing an increment in coating thickness and surface roughness. The low conductivity of the ionic liquid is responsible for the voltage and breakdown voltage increases during the LePEO with IL process (LePEO-IL). After adding BmimBF4, corrosion current density decreases from 1.159 × 10−4 A·cm−2 to 8.143 × 10−6 A·cm−2. The impedance modulus increases to 1.048 × 104 Ω·cm−2 and neutral salt spray remains intact for 24 h. The superior corrosion resistance of the LePEO coating assisted by ionic liquid could be mainly attributed to its compact and thick barrier layer and physical absorption of ionic liquid. The ionic liquid-assisted LePEO technique provides a promising approach to reducing energy consumption and improving film performance.

Effect of Electrode Morphology on Performance of Ionic Actuators Based on Vat Photopolymerized Membranes.

Bucky gel electrodes are composed of morphology-determining polyvinylidene difluoride (PVDF) filled with carbon nanotubes (CNT). The electrodes are commonly fabricated via the casting of a CNT dispersion containing PVDF and ionic liquid. In this study, several pore-forming additives such as polyethylene glycol (PEG), dibutyl phthalate (DBP), and the common ionic liquid BMIMBF4 were used to control the morphology of the bucky gel electrodes. The crystalline phase type and content of PVDF in the electrodes were determined by FT-IR and DSC, respectively. SEM revealed a sponge-like structure in the case of the use of BMIMBF4 and a spherulite structure if PEG and DBP were used as additives. A strong influence of morphology on the anisotropic increase in the volume of electrodes upon impregnation with electrolyte was observed. The PEG-based electrode elongated more than the others, while the BMIMBF4-based electrode thickened to a greater extent. Ionic actuators were fabricated to experimentally reveal the effect of electrode morphology on their electromechanical efficiency. A high-precision vat photopolymerization technique was used to fabricate identical ionic membranes and minimize their influence on the properties of the actuators. The electrodes were characterized by the same porosity and electrical capacitance, while the actuators differ significantly in performance. As a result, a simple method of using pore-forming additives made it possible to increase the maximum deformation of bucky gel ionic actuators by 1.5 times by changing the morphology of the electrodes.

Enhanced efficiency and stability of Dion–Jacobson quasi-two-dimensional perovskite solar cells by additive

Dion–Jacobson (DJ) quasi-two-dimensional (quasi-2D) perovskite solar cells (PSCs) have attracted increasing attention owing to their potential stability compared with the Ruddlesden-Popper (RP) phase. It is known that the low efficiency and poor thermal stability retard the application of quasi-2D PSCs. Here, DJ quasi-2D perovskite films based on propane-1.3-diammonium (PDA) spacer cations were prepared by a hot casting technique. Ionic liquid additive of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) was introduced into the quasi-2D perovskite precursor solution to improve the crystal quality and morphology of the films. The quasi-2D PSCs with BMIMBF4 achieved an optimal power conversion efficiency (PCE) of 14.07%, which is higher than the 12.45% of the control devices. The impressive 1.17 V high open-circuit voltage and 14.07% efficiency are the highest values for the reported PDA-based n–i–p type devices. Moreover, the thermal stability of the solar cells was significantly enhanced by the addition of BMIMBF4. The PCE of the devices with BMIMBF4 maintains 72% of the initial value after annealing at 85 °C for 120 h, while the PCE of control devices drops to 19% of the initial value. These results prove that the introduction of ionic liquid BMIMBF4 is a pragmatic method to elevate the efficiency and thermal stability of quasi-2D PSCs.

Synthesis of Benzothiophene-3-carboxylic Esters by Palladium Iodide-Catalyzed Oxidative Cyclization-Deprotection-Alkoxycarbonylation Sequence under Aerobic Conditions.

A palladium-catalyzed carbonylative approach to benzothiophene-3-carboxylic esters, starting from simple and readily available building blocks [2-(methylthio)phenylacetylenes, CO, an alcohol, and O2 (from air)], is reported. The process is catalyzed by the simple PdI2/KI catalytic system to give the desired products in fair to high yields (57-83%). Interestingly, the reaction also works nicely in the ionic liquid BmimBF4 as the solvent, with the possibility to recycle the catalytic system several times without appreciable loss of activity.

Design & Characterization of Pb Electrode for Sensing Trichloroethylene in Ionic Liquid/Acetonitrile Co-Solvents

Design & Characterization of Pb Electrode for Sensing Trichloroethylene in Ionic Liquid/Acetonitrile Co-Solvents

Enlarging crystal grains with ionic liquid to enhance the performance of perovskite solar cells

The grain boundaries of perovskite polycrystalline are defect region that not only provides carrier recombination sites but also introduces device degradation pathways. Efforts to enlarging the grain size of perovskite film and reducing its grain boundary are crucial for highly efficient and stable PSCs. Here, we applied an ionic liquid molecule BMIMBF4 to passivate the surface of the perovskite film. We find that the ionic liquid BMIMBF4 helps to reduce the activation energy for grain boundary migration and facilitate the grain growth, leading to significantly enlarged grain in the perovskite film. The reduction of grain boundary regions suppresses the non-radiative recombination from the boundary defects, causing for longer carrier lifetime in the perovskite film. The improved quality of the perovskite film results in an enhancement of the PCE to 20.4%. Under continuous illumination for 500 h, the PSCs remains 84% of its initial efficiency.

Electrochemical synthesis and amidation of benzoin: benzamides from benzaldehydes

Abstract The benzoin condensation starting from benzaldehyde and the subsequent benzoin amidation to benzamide can be efficiently carried out under very mild conditions in an electrolysis cell. Among the advantages of using electrochemistry to generate our active reagents, the use of the easily dosed and non pollutant electron, instead of stoichiometric amounts of redox reagents or bases, usually renders the electrochemical methodology “greener” than classical organic reactions. Benzoin is obtained in good yield (85 %) carrying out the reaction in the room temperature ionic liquid BMIm-BF4. In this electrochemical reaction this liquid salt assumes the double role of solvent-supporting electrolyte system and precatalyst, yielding the corresponding N-heterocyclic carbene. The subsequent benzoin amidation is carried out by electrochemically generated superoxide anion, in the presence of an aliphatic primary or secondary amine. In this case the system superoxide/molecular oxygen acts as base and oxidant, yielding very good yields of benzamides (up to 89 %).

100 MeV O7+ ion irradiation induced electrochemical enhancement in NiBTC metal-organic framework based composite polymer electrolytes incorporated with ionic liquid

Nickel 1,3,5-benzenetricarboxylate (NiBTC) metal-organic framework (MOF), has been synthesized by solvothermal method and dispersed in Poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) polymer. The composite polymer electrolyte membranes were irradiated with 100 MeV O7+ swift heavy ion (SHI) at different fluences and ionic liquid (IL) BMIMBF4 has been incorporated after irradiation. Increasing % uptake of IL has been observed upon IL incorporation as SHI irradiation can enlarge the micropore volumes of NiBTC-MOF by inducing missing linker defects. FTIR spectra depict shifting of carboxylate vibrational modes with increasing fluence suggesting elongation of metal-linker molecular bonds in NiBTC-MOF due to interaction of BF4- anion of IL with unsaturated Ni metal nodes with increasing uptake of IL. Non-Debye relaxation ion dynamics has been revealed from dielectric modulus spectra and optimum ionic conductivity of 9.9 × 10−3 Scm−1 is achieved for the nanocomposite membrane at the fluence of 3.3 × 1012 ions cm−2 at 380 K. The frequency dependent AC conductivity increases with increasing fluence due to higher IL uptake as well as chain scission of the polymer segments. The electrochemical stability of the nanocomposite membrane increases with increasing fluence and attains a maximum value of 6.1 V at 3.3 × 1012 ions cm−2.

Electrochemical Reduction of CO2 at Copper Nanoparticles Cathode in Ionic Liquid BMIMBF4:Synthesis of Dimethyl Carbonate

Electrochemical Reduction of CO2 at Copper Nanoparticles Cathode in Ionic Liquid BMIMBF4:Synthesis of Dimethyl Carbonate

Fluorescent probe dependence of the solvation dynamics in ionic liquid BmimBF4 and propylene carbonate mixtures: a time-resolved fluorescence and quantum chemistry study

In this work, steady-state and time-resolved fluorescence experiments on solvation of C153, C102, 4-ANMP and PRODAN fluorescent probes in BmimBF4 and BmimBF4/PC mixtures with a molar fraction of ionic liquid equal to 0.65 and 0.85 are reported. Quantum Chemistry calculations were performed to complete the experimental data interpretation. All the four studied probes exhibit similar solvation dynamics, with their average solvation times following the trend 4-ANMP < C153 ≅ C102 < PRODAN. A specific interactions hypothesis was put forward to explain the slight divergence of 4-ANMP and PRODAN spectra shift. The C153 molecule, showing a big change in dipole moment (8.7 D) upon the photoexcitation, little geometry relaxation upon the excitation due to its rigid structure, small change in dipole moment orientation and relatively small hydrogen bonding ability is thus proved to be the most adequate for use in the study of the solvation dynamics in various environments, including ionic liquids and ionic liquid/molecular solvent mixtures.

Motion Simulation of Ionic Liquid Gel Soft Actuators Based on CPG Control.

The ionic liquid gel (ILG), a new type of soft actuator material, is a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), hydroxyethyl methacrylate (HEMA), diethoxyacetophenone (DEAP), and ZrO2 polymerized into a gel state under ultraviolet (UV) light irradiation. The soft actuator structure consists of a layer of ionic liquid polymer gel sandwiched between two layers of activated carbon capped with gold foil. The volume of the cationic BMIM+ in the ionic liquid BMIMBF4 is much larger than that of the anionic BF4 −. When voltages are applied to both sides of the actuator, the anions and cations move toward the anode and cathode of the electrode, respectively, under the electric field. The volume of the ILG cathode side therefore expands, and the volume of the ILG anode side shrinks, hence bending the entire actuator toward the anode side. The Ogden model was selected as the hyperelastic constitutive model to study the mechanical properties of the ILG by nonlinear analysis. As the ILG is an ideal material for the preparation of a supercapacitor, the equivalent circuit of the ILG can be modeled by the supercapacitor theory to identify the transfer function of the soft actuator. The central pattern generator (CPG) control is widely used in the area of biology, and CPGs based on bioinspired control methods have attracted great attention from researchers worldwide. After the continuum soft actuator is discretized, the CPG-based bioinspired method can be used to control the soft robot drivers. According to the simulation analysis results, the soft actuator can be smooth enough to reach the specified location.

Comparison of ionic liquid and salt effects on the thermodynamics of amphiphile micellization in water

Ionic liquids are low-melting salts that have novel properties and are very useful as solvents or additives on the basis of the intermolecular interactions operating between the ionic liquid ions and various solute or solvent molecules. In this work, we compare the effects of ionic liquids and salt on the micellization of a representative amphiphilic block copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), Pluronic P123 (EO20PO70EO20). Ethylammonium nitrate (EAN) is used as a representative protic ionic liquid, to compare with its corresponding classic salt, ammonium nitrate (NH4NO3), and with 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4) as a representative aprotic ionic liquid. The protic ionic liquid EAN is similar with the classic salt NH4NO3 in promoting PEO-PPO-PEO micellization; they both increase the micellization entropy and lower the micellization enthalpy at higher concentration. The hydrogen bonding between EAN and PEO, and the ethyl group on the EAN cation, both assist the solvation of PEO-PPO-PEO molecules, which partially offsets their dehydration caused by the ionic liquid ions. These lead to a less significant change of the micellization thermodynamics parameters by EAN compared to NH4NO3. The aprotic ionic liquid BmimBF4 exhibits effects that are opposite to those of the protic ionic liquid EAN. The micellization enthalpy of PEO-PPO-PEO significantly increases in the presence of BmimBF4. The hydrogen bonds formed between BmimBF4 and PEO-PPO-PEO, along with nonpolar butyl clusters formed by Bmim cations assist the solvation of Pluronic P123, which in turn hinders micellization. This work compares for the first time the effects of a protic ionic liquid with a classic salt and with an aprotic ionic liquid on amphiphile micellization in aqueous solution in terms of thermodynamics.

Identifying critical factors for catalyst performance in methanol oxidation by Box–Behnken design

Methanol oxidation is one of the most important processes in a direct methanol fuel cell (DMFC). Proper anodic catalysis ensures high energy conversion and operation cost of the fuel cell. Although a proton exchange membrane is a successful electrolyte of DMFC, its drawbacks or limitations can be avoided by replacing the solid membrane with a liquid electrolyte that is not subject to evaporation, especially at elevated temperatures. A promising candidate for such electrolyte is an ionic liquid. The performance of the anode catalyst will be affected when the electrolyte has been changed. In our paper, we report a fast Box–Behnken design to identify the most critical factors that would determine the performance of a specific catalyst—platinum-coated gold nanoporous film (PGNF). Our research revealed that the catalytic kinetics is the critical factor for PGNF in aqueous solution electrolyte; while catalyst poisoning was the most critical when the ionic liquid BMImBF4 was the electrolyte. This example of how statistic tools could be used in the development of fuel cells could be expanded to the studies of other systems.

Approaches to electrodeposit molybdenum from ionic liquid

Molybdenum is a kind of refractory metal and can hardly be deposited in aqueous solution since it is more likely to form molybdenum oxide rather than elementary Mo, but molten salts and ionic liquid become alternative to obtain Mo layer. This paper shows an available process to obtain metallic state molybdenum deposit from ionic liquid. Mo layer was electrodeposited under constant current in ionic liquid 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4). Micromorphology of the electrodeposited Mo layer was observed by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Results show that elementary Mo layer was electrodeposited under constant current in ionic liquid BMIMBF4. Properties of the Mo layer are affected significantly by additive ethylene glycol (EG), deposition temperature and current density. By parallel tests taking into consideration of different technical factors, optimized process parameters are obtained as volume ratio of 2:1 in BMIMBF4 + EG system, deposition temperature of 150 °C and current density of 0.75 mA·cm−2.

Hierarchical Porous Carbons Derived from Renewable Poplar Anthers for High‐Performance Supercapacitors

AbstractHierarchical porous carbons with granular shape were prepared from waste biomass poplar anthers (PA) by pre‐carbonization and following KOH activation. The pore structure and surface chemistry of PA‐derived carbon can be controlled by adjusting the activation temperature. The material activated at 800 °C possesses a high surface area of 3639 m2 g−1, abundant mesopores, and appropriate amounts of oxygen‐ and nitrogen‐containing species. As a result, it exhibits excellent electrochemical performances as a supercapacitor electrode. The specific capacitance reaches 361.5 F g−1 at a current density of 0.5 A g−1 in 6 M KOH aqueous solution. In addition, it shows an impressive energy density of 60.8 Wh kg−1 at a power density of 10416.7 W kg−1 in the ionic liquid BMIMBF4. Particularly, a high electrochemical stability and an excellent reversibility were observed in both aqueous and non‐aqueous electrolytes.

Rice Husk Derived Micro-Mesoporous Carbon Materials as Active Components of Supercapacitor Electrodes

Activated carbon materials (CM) were prepared from rice husk carbonized in the fluidized catalysts bed reactor. Textural characteristics of CM were studied by the adsorption of nitrogen at 77 K. Variation of synthesis conditions (conditions of carbonization and following activation) allowed to obtain materials with specific BET surface area from 440 to 2290 m2/g. Utilization of sodium or potassium carbonates results in the BET surface area up to 1200 m2/g. Activation by hydroxides of sodium or potassium yields the samples with the more developed surface up to 2290 m2/g. Electrochemical properties and capacitive characteristics were examined by cyclic voltammetry and chronopotentiometry in galvanostatic mode in aqueous electrolyte 1 M H2SO4 and ionic liquid BMIMBF4. It was shown, that at low charge/discharge rate (0.2 А/g) gravimetric capacitance depends linearly on specific surface of CM and does not depend on electrolyte nature. Insignificant (in the case of 1 М H2SO4) and significant (in the case of ionic liquid) decrease of specific capacitance is observed at high rates of charge/discharge (2 А/g), which is explained by influence of porous structure.

Pluronic L121, BMIM BF4 and PEG-400 comparison to identify the best solvent for CO2 sorption

The triblock copolymer L121 [poly(ethylene glycol)5-block-poly(propylene glycol)68-block-poly(ethylene glycol)5], the room temperature ionic liquid BMIM BF4 (1-butyl-3-methylimidazolium tetrafluoroborate) and the polymer PEG-400 (polyethylene glycol-400) have been compared in their liquid state to test their sorption capability of CO2 by exposure to high-pressure gas for 3h in a controlled system. The presence of the gas in the studied systems has been determined at atmospheric pressure in the temperature range 288.15–313.15K by using near-infrared (NIR) spectroscopy. The CO2 sorption in BMIM BF4 and PEG-400 was very small and detectable up to 293.15K, only L121 showed the CO2 typical bands in the NIR region of the spectra up to 313.15K, thus a linear correlation can be obtained by plotting the CO2 absorbance of those bands as a function of temperature. The effect induced by temperature on the swelling degree of L121 copolymer has also been investigated.

The influence of ionothermal synthesis using BmimBF4 as a solvent on nanophosphor BaFBr:Eu2+ photoluminescence.

Ionothermal synthesis is a strongly growing research area due to the outstanding physical and chemical properties of ionic liquids (ILs) in the design of new materials, however, the interaction of these IL molecules with optical materials and their effect on the luminescence properties of the materials are poorly known. In this work, it is shown that the imidazolium based BmimBF4 ionic liquid, used as a solvent during the synthesis, tethers at the surface of the nanoparticles and influences the photoluminescence of the nanophosphor BaFBr:Eu2+ materials. In time resolved spectra, two different emissions are observed for the material synthesized by the ionothermal approach, one corresponding to Eu(ii) 5d-4f transitions in the BaFBr host with a decay time of 843 ns and the other with a much faster decay time compared to the ionic liquid BmimBF4.

CO2 reduction in wet ionic liquid solution in microscale-based electrochemical reactor

A microscale-based electrochemical reactor was introduced for the reduction of CO2 into CH4, CH3OH, H2, HCOOH and HCHO with the presence of ionic liquid BMIM-BF4 (1-butyl-3-methylimidazolium tetrafluoroborate). Reduction of CO2 was studied under various experimental conditions controlled by factors such as solvent concentration, microreactor height, and mean residence time of fluids in the microreactor. A mathematical model reflecting geometry and flow conditions inside the microreactor was developed to simulate the chemical reaction process. The parameters of the mathematical model were determined using an optimization process in which the best fit between the experimental data and the model prediction was achieved. The model describes the reactions containing substrate reactants (CO2 and H2O) and final products (CH4, CH3OH, H2, HCOOH, and HCHO), which were measured throughout CO2 reduction process experiments.