Formic Acid Solution Research Articles

Comparative Analysis of Needleless and Needle-Based Electrospinning Methods for Polyamide 6: A Technical Note.

This study investigates the influence of needleless versus needle-based electrospinning methods on the fiber diameter of polyamide 6 (PA6) nanofibers under comparable conditions, with an emphasis on potential pharmaceutical applications. Additionally, it examines how varying solvent systems impact fiber diameter specifically in needleless electrospinning. In this study, it was found that fibers produced by the needleless method were thicker compared to those produced by the needle-based method, a trend attributable to the specific solution characteristics and parameter settings unique to this study. Notably, a 2 : 1 acetic acid : formic acid solvent mixture yielded the largest fiber diameters among the solvent systems assessed for needleless electrospinning. These results underscore the potential of PA6 nanofibers in pharmaceutical applications, suggesting that further optimization of electrospinning conditions could enhance their suitability. The study also discusses the implications of scale-up production using needleless technology, highlighting its viability for industrial applications over single-needle electrospinning.

Analysis of Major Chemical Constituents in Jiuwei Decoction Based On Capillary Electrophoresis Coupled With Quadrupole Time‐of‐Flight Mass Spectrometry

ABSTRACTAn analytical method for identifying the chemical constituents in the Chinese herbal combination Jiuwei decoction was established using capillary electrophoresis coupled with quadrupole time‐of‐flight mass spectrometry. Nine herbs were extracted with a 60:40 (v/v) ethanol/water solution to prepare the Jiuwei decoction. Electrophoretic separation was carried out using a 50 µm i.d., 125 cm bare fused silica capillary at a constant temperature of 25°C for sample injection. The chemical composition was analyzed and identified in both positive and negative ion modes. In the positive separation mode, a separation voltage of 30 kV was applied, with a 1% aqueous formic acid solution serving as the background electrolyte (BGE), along with a 50:50 (v/v) methanol/water solution containing 0.1% formic acid as the sheath liquid. In the negative separation mode, a separation voltage of −30 kV was employed, utilizing a 50 mM ammonium acetate solution (pH 9.0) as the BGE, combined with a 50:50 (v/v) methanol/water solution containing 5 mM ammonium acetate as the sheath liquid. The MassHunter Qualitative Analysis software (version 10.0) was utilized to identify 52 compounds based on accurate mass, isotope abundance, isotopic patterns, and fragmentation information. The data were compared with the Agilent Personal Compound Database and Library of traditional Chinese medicine (TCM), as well as multiple online databases (TCMSP, ChemSpider, PubChem, PubMed, and Web of Science) and relevant literature. The fragmentation pathways of representative compounds were also characterized. This study identified the chemical composition of Jiuwei decoction, providing a molecular basis for further exploration of its pharmacological effects and presenting a robust methodology for the compositional analysis of complex TCM mixtures.

Corrosion Behaviour of Boronized Ductile irons in Formic and Nitric Acid Solutions

Corrosion Behaviour of Boronized Ductile irons in Formic and Nitric Acid Solutions

Determination of the Content of Hairy Vetch Isoflavone Glucoside in Qianliekang Tablets

Objective: To determine the content of maohui isoflavone glycoside based on its composition in Qianliekang tablets. Methods: High-Performance Liquid Chromatography (HPLC) was employed for the determination, with a detection wavelength set at 260 nm; column temperature maintained at 25°C; and mobile phase consisting of acetonitrile-0.1% formic acid solution (14:86). The flow rate was standardized to 1.0 ml/minute. Results: A good linear relationship between sample content and peak area was observed within the range of 0.051 μg to 0.816 μg for maohui isoflavone glycoside, with a relative standard deviation (RSD) of repeatability reaching 1.47%. The average recovery rate was found to be 98.21%, with an RSD of 2.31%. Conclusion: This method demonstrates excellent stability, high accuracy, precision, and reproducibility, making it suitable for quality control of Qianliekang tablets.

Impedance Analysis on Ant-Nest Corrosion of Copper- Effect of Phosphorus Content in Copper on Corrosion Morphology-

In recent years, leakage of refrigerant due to ant-nest corrosion has become a problem in copper piping used in heat exchangers of air-conditioning equipment.1) In our laboratory, we have succeeded in electrochemically reproducing ant-nest corrosion by galvanostatic polarization of phosphorus-deoxidized copper immersed in 600 ppm, formic acid solution of pH 5.5 at a current density of 0.3 mA/cm2..2) The pits of ants-nest corrosion have a fractal structure with a repetitive branching shape. Our laboratory reported that the number of branching in ant-nest corrosion can be determined by using a transmission line model (TLM) with blanched structure equivalent circuit from impedance spectra.3) Furthermore, the oxidation phosphorus dissolved from copper causes a decrease in pH at the bottom of the small pore, and the pH decrease accelerates the branching. In this experiment, galvanostatic polarization was applied to copper tubes with different phosphorus contents as working electrodes to reproduce ant-nest corrosion. Furthermore, the number of branching of ant-nest corrosion was determined by impedance analysis using TLM. Based on these results, the effect of phosphorus content on corrosion morphology was discussed.Experimental conditions:The electrolyte solution was a 600 ppm formic acid solution of pH 5.5. Copper tubes with various phosphorus contents (0.003, 0.004, 0.007, 0.015, 0.31 wt%) were used as working electrodes. The outside of the copper tube was used as the working electrode (test surface), and the rest of the test surface was covered with insulating tape to define the electrode area (electrode area: 7.85 cm2). In addition, the bottom hole of the copper tube was covered with a rubber stopper to prevent the solution from entering to inside of the copper tube. The test surface was polished with abrasive papers No. 800, 1200, and 2000, polished with diamond pastes of 6, 3, and 1 μm particles diameters, and then cleaned with methanol. Constant current polarization was performed for 72 h at a current density of 0.3 mA/cm2 using a platinum wire as a counter electrode, a saturated KCl silver/silver chloride electrode (SSE) as a reference electrode. References 1) S. Ito, T. Hosogi, M. Watanabe, H. Tsueoka, M. Itagaki, Zairyo-to-Kankyo，67, 37-40 (2018).2) M. Itagaki, A. Makita, H. Watanabe, I. Shitanda, T. Hosogi, S. Ito, Electrochim. Acta 479, 143873 (2024).3) M. Itagaki, Y. Hatada, I. Shitanda, K. Watanabe, Electrochim. Acta 55, 6255–6262 (2010).

A Validated Liquid Chromatography-Tandem Mass Spectrometry Method for the Determination of Methylophiopogonanone A in Rat Plasma and Its Application to Pharmacokinetic Study.

Methylophiopogonanone A (MOA) is one of the homoisoflavonoids isolated from Ophiopogon japonicus, which has been demonstrated to have extensive pharmacological activities. The aim of this study was to develop and validate a liquid chromatography-tandem mass spectrometry method for the measurement of MOA in rat plasma. Methylophiopogonanone B (MOB) was used as internal standard. After precipitation with acetonitrile, the samples were separated using a Waters ACQUITY HSS T3 column with 0.1% formic acid solution and acetonitrile as mobile phase. Mass detection was monitored using multiple reactions monitoring mode with precursor-to-product ion transition of m/z 343.2 > 135.1 for MOA and m/z 329.2 > 121.1 for internal standard. The assay showed good linearity over the concentration range of 1-1000 ng/mL, with correlation coefficient > 0.997. The lower limit of quantification (LLOQ) was 1 ng/mL. Acetonitrile-mediated precipitation showed high extraction efficiency (> 80%). The accuracy and precision were within the acceptable limits. MOA was demonstrated to be stable in rat plasma under the tested storage conditions. After validation, the proposed method was applied to the pharmacokinetic study of MOA in rat plasma, and the data revealed that MOA showed rapid absorption and elimination from rat plasma. The oral bioavailability of MOA in rat was 24.5%.

Efficient conversion of chitin to 5-hydroxymethylfurfural in a formic acid/calcium chloride system

Chitin is a class of biomass second only to cellulose in abundance, and the preparation of platform compounds from chitin holds great promise. Herein, a pretreatment biphasic solvent system and a catalytic two-stage process are combined for the direct synthesis of 5-hydroxymethylfurfural (HMF) from chitin. The first step of the process, i.e., the pretreatment of chitin with a CH3OH/CaCl2 solution, alters the structure of chitin, allowing it to be depolymerized more easily. In the second step of the process, a green and recyclable biphasic catalytic solvent system comprising a formic acid solution and n-butanol is prepared using pretreated chitin (Ca-PC) as the starting reactant, realizing an HMF yield of 47.65 % in 32 min. This HMF yield surpasses that reported in the literature (19.3 %–30 %). The synergistic interaction of Ca2+, introduced via formic acid pretreatment, is the key to the catalytic system of chitin, which disrupts the internal hydrogen bonding of chitin and simultaneously improves HMF selectivity. In summary, we have promoted the depolymerization of chitin using a simple and effective pretreatment process, designed a catalytic system with a green recyclable reaction, and effectively improved the yield of HMF directly prepared from chitin.

AQbD-enhanced green RP-UPLC-PDA methodology for quantification and forced degradation studies for omeprazole, amoxicillin, and rifabutin

The ternary combination like omeprazole (OMP), amoxicillin (AMX), and rifabutin (RFB) was approved by the FDA in November 2019 for combating Helicobacter pylori infections and ulcers caused by this infection. This study aims to develop and authenticate a robust and eco-friendly RP-UPLC technique aimed at the concurrent analysis of OMP, AMX, and RFB, following ICH guidelines, Analytical Quality by Design (AQbD), and green analytical chemistry (GAC) principles. The analysis used the Thermo C18 column (100 mm × 2.1 mm, 1.7 µm), ethanol, and formic acid solution (43:57) as mobile phase with a flow rate of 0.2 ml/min at 272 nm. The method was developed based on the ICH Q14 and validated according to ICH Q2(R1) followed by Forced degradation studies under various conditions. The method showed good linearity for OMP, AMX, and RFB, with coefficient of determination (r2) of 0.9995, 0.9993, and 0.9997, respectively. Precision studies indicated low %RSD values, confirming high reproducibility. Forced degradation studies confirmed the stability of the drugs for 30 min in acid, base, and redox reactions, and they were also stable for 6 h at 105 °C in dry conditions. GAPI assessment depicted a green and yellow pictogram, AGREE scored 0.85, BAGI scored 80, and RGB12 Whiteness Assessment Tool scored 97.5%. The developed RP-UPLC-PDA technique is robust and reliable for the concurrent quantification of the triple combination. It aligns with sustainability goals, enhancing the efficiency and environmental sustainability of pharmaceutical analysis, and setting a benchmark for future analytical methods.

1H and 13C NMR and FTIR Spectroscopic Analysis of Formic Acid Dissociation Dynamics in Water.

The formation and transport of ionic charges in formic acid-water (HCOOH-H2O) mixtures with initial water mole fractions ranging from XH2Oi = 0 to 1 were investigated using 13C and 1H NMR, FTIR spectroscopy, viscosity, conductivity, and pH measurements. The maximum molar concentration of ions (H3O+ and HCOO-), along with the relative differences between theoretical and experimental densities, spin-lattice relaxation times (T1), activation energies (Ea), viscosity (η), and conductivity (σ), were identified within the range of XH2Oi ≈ 0.5-0.7. These results indicate that pure formic acid (FA) solutions predominantly consist of cyclic dimers at room temperature. As the water mole fraction increases up to 0.6, a structural shift occurs from cyclic dimers to a mixture of linear and cyclic dimers, driven by the formation of strong hydrogen bonds. Beyond a water mole fraction of 0.6, the structure transitions to linear dimers, with FA molecules behaving as free entities in the water. Furthermore, the acidity was found to increase approximately 2-fold with every 0.1 increment in water mole fraction. These findings are critical for understanding the kinetics of formic acid anions in body fluids, the structure of the hydrogen bonding network, and ionization energies.

Electrospun gelatin/hyaluronic acid nanofibers as a platform for uric acid delivery to neural tissue.

Uric acid (UA) is an antioxidant that has been reported to be a neuroprotective compound for injuries and diseases, and specifically, diseases of the central nervous system. However, uric acid is highly insoluble in aqueous solutions, and high levels in the serum lead to gout, which limits its use in humans. Here, we develop a novel drug delivery platform that will release uric acid in a sustained manner for application to neural tissue. We demonstrate that one-step incorporation of UA into an electrospun gelatin/hyaluronic acid nanofiber mat results in controlled release of UA in culture medium. Taking a unique approach, we made solutions of 12% gelatin and 1% hyaluronic acid in a formic acid solvent and added UA for production of nanofiber mats. We then dehydrothermally crosslinked the mats and tested for release of UA into physiological cell culture medium. To test whether the mats have any detrimental effects on healthy nervous system tissue, we cultured spinal cord explants on the mats extended and assessed extensions from the explants. We observed that comparable numbers and lengths of dendrites are extended from the spinal cord tissue, regardless of the amount UA content in the mats. Our results suggest that electrospun gelatin/hyaluronic acid nanofibers can be used as a platform for sustained uric acid delivery to neural tissue without detrimental effects.

A novel, sensitive, and fast ultra-high-performance liquid chromatography tandem mass spectrometry method for TNG908 determination in dog plasma and pharmacokinetic study.

TNG908 is a potent and selective protein arginase methyltransferase 5 (PRMT5) inhibitor that is currently going through phase I/II clinical development for the treatment of non-small cell lung cancer. To facilitate pharmacokinetic and toxicokinetic studies of TNG908, here, we reported an ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the detection of TNG908 in dogs. The dog plasma samples were precipitated by acetonitrile and analyzed using a Waters ACQUITY BEH C18 column combined with a Thermo triple quadrupole mass spectrometer. The mobile phase consisted of 0.1% formic acid solution and acetonitrile, at a flow rate of 0.3mL/min. TNG908 and internal standard were monitored by selective reaction monitoring (SRM) with m/z 410.2 > 150.1 and m/z 394.2 > 278.1, respectively. The method demonstrated excellent linearity over the concentration range of 1-1000 ng/mL, with a correlation coefficient greater than 0.995. Acetonitrile-mediated protein precipitation showed high extraction efficiency and a recovery above 80%. The validated assay was further applied to measure TNG908 in dog plasma after oral and intravenous administration and achieved success. The obtained pharmacokinetic parameters indicated low clearance of TNG908 (3.7 ± 0.8mL/min/kg) and moderate oral bioavailability (>36.4%).

Study on the influence characteristics of multi-working condition parameters on membrane electrode type CO2 electrolyzer

The electrochemical conversion of carbon dioxide (CO2) into basic chemicals or carbon-based fuels is a promising new strategy for carbon resource utilization. Within this domain, solid-electrolyte CO2 electrolyzer demonstrate significant potential for the continuous production of pure formic acid solutions. This study, leveraging a 4 cm2 visualization electrolyzer, explores the impact of three working condition parameters on performance: working voltage, gas flow rate, and the intermediate chamber water flow rate. It compares the variations in current density, formic acid concentration, and the distribution of liquid water on the cathode side under different working conditions. The results indicate that the working voltage, current density, and formic acid yield are all positively correlated; overly low gas flow rates can lead to CO2 deficiency and diminished electrolyzer performance; concentration control of the formic acid solution is effectively achieved by adjusting the intermediate chamber water flow rate; and during the electrolyzer reaction process, almost all of the liquid water is positioned at the bends downstream of the cathode flow channel.

LC-MS-Based Simultaneous Determination of Biomarkers in Dried Urine Spots for the Detection of Cofactor-Dependent Metabolic Disorders in Neonates.

Deficiency of cofactors for various enzymes can lead to inborn errors of metabolism. These conditions frequently occur as seizures, which lead to permanent brain damage. Newborn screening for biomarkers associated with these disorders can help in early detection and treatment. Our objective was to establish a liquid chromatography mass spectrometry technique for quantifying biomarkers in dried urine spots to detect specific vitamin-responsive inborn errors metabolism. Biomarkers were extracted from dried urine spots using a methanol:0.1% v/v formic acid solution (75:25) containing an internal standard mixture. Separation was achieved using a Luna PFP column (150mm×4.6mm, 3µm) under gradient elution conditions. The LC-MS technique was validated as per ICH M10 guidelines. Urine samples from healthy newborns in Udupi district, South India, were analyzed to establish reference values for these biomarkers. The method demonstrated excellent linearity (R2>0.99) with low limits of quantification: 0.1µg/mL for leucine, isoleucine, valine, proline, hydroxyproline, methylmalonic acid, and 3-hydroxyisovaleric acid; 0.01µg/mL for pipecolic acid and α-aminoadipic semialdehyde; and 0.03µg/mL for piperideine-6-carboxylate. Interconvertibility between urine and dried urine spot assays was observed from the results of the regression and Bland-Altman analyses. Reference intervals for these biomarkers in the Udupi neonatal population were established using the validated dried urine spot method.

Optimization of the demineralization process of black soldier fly (Hemertia illucens) pupa shell maggot chitosan and the physicochemical characteristics

Chitosan is a derivative compound of chitin that has undergone deacetylation. Chitosan has three stages of the manufacturing process, including demineralization, deproteinization, and deacetylation. Chitin is also found in the black soldier fly maggot pupae, but maggot pupae contain high minerals content that can affect the purity of the resulting chitosan. Therefore, demineralization treatment is necessary to remove minerals from maggot pupae shells. This study aims to optimize the demineralization process by finding the best type of acid solvent, the best incubation time, and combination treatments. The black soldier fly (BSF) maggot pupa shell was soaked using various formic acid, hydrochloric acid, and nitric acid solutions with incubation times of 60, 120, and 180 minutes. Chitosan characterization was carried out following SNI 7949:2022, including water content, ash content, nitrogen content, pH, deacetylation degree, characterization of functional groups with FT-IR, and as an antimicrobial comparison is formalin. The best demineralization treatment was obtained at 0.5 M nitric acid treatment with an incubation time of 120 minutes. The characterization of chitosan produced 7.81% water content, 0.56% ash content, 4.73% nitrogen content, pH 7.39, and 75.14% deacetylation degree. Characterization of groups on chitosan with FT-IR resulted in the absorption of O-H and N-H groups 3484 cm-1 and 3152 cm-1; C-H 2877 cm-1; and C=O 1653 cm-1. The inhibitory power against E. coli of the BSF maggot pupa shells chitosan is better compared to chitosan standard but not better than formalin.

Online restricted access molecularly imprinted solid phase extraction coupled with electrospray ionization-tandem mass spectrometry for determination of mebendazole and albendazole in milk samples

Multifunctional materials, such as restricted access molecularly imprinted polymers covered with bovine serum albumin (RAMIP-BSA), are effective alternatives for sample preparation techniques. This material selectively adsorbs analytes while excluding macromolecules, enhancing the analysis's efficiency. Among analytical techniques, ESI-MS/MS (Electrospray Ionization-Tandem Mass Spectrometry) has successfully identified and quantified various molecules, including trace-level drugs. Therefore, we proposed, for the first time, an integrated online extraction/analysis system that combines the benefits of RAMIP-BSA and ESI-MS/MS for analyzing mebendazole (MBZ) and albendazole (ABZ) in milk samples without the need for chromatographic separation. Initially, a RAMIP selective for MBZ was synthesized using the bulk method with methacrylic acid and glycidyl methacrylate. Then, the polymer was covered with bovine serum albumin. Subsequently, this adsorbent was packed in a small column and coupled with an ESI-MS/MS instrument in an online configuration. Milli-Q water was used as the loading and reconditioning mobile phases, and a solution of formic acid in methanol (1:100 v/v) was employed as the elution phase. The system enabled simultaneous extraction and determination of MBZ and ABZ in milk samples. The method exhibited linearity between 15.0 and 125.0 μg L−1 for MBZ and 10.0 and 125.0 μg L−1 for ABZ (with a correlation coefficient exceeding 0.99). The limits of quantification were 15.0 and 10.0 μg L−1 for MBZ and ABZ, respectively. Good precision and accuracy were achieved. The developed method was used to analyze MBZ and ABZ in real milk samples and proved to be a viable alternative to conventional sample preparation and chromatographic techniques.

Liquid chromatography-mass spectrometric method for the simultaneous analysis of branched-chain amino acids and their ketoacids from dried blood spot as secondary analytes for the detection of maple syrup urine disease

BackgroundMaple syrup urine disease (MSUD) is an aminoacidopathy caused by a defective branched-chain alpha-ketoacid dehydrogenase complex, leading to the accumulation of branched-chain amino acids (BCAAs) and their respective keto acids (BCKAs). A comprehensive test was developed to measure BCAAs and BCKAs using LC-MS from dried blood spot (DBS) samples for the diagnosis and prevention of MSUD in newborns and infants. MethodsAnalytes were extracted from DBS using a methanol:0.1 % v/v formic acid solution (75:25) containing internal standards and analyzed on a Luna PFP column (150 mm × 4.6 mm, 3 µm) at a flow rate of 0.3 mL/min. The method was validated for linearity, accuracy, precision, recovery, carry-over, matrix effect, hematocrit, blood volume, and punch position effects. Biomarker stability in the matrix and stock solution was assessed. Correlation with the plasma method was determined using Pearson’s correlation coefficient and Bland-Altman analysis. The method established reference ranges for the Udupi district population in South India. ResultsThe method demonstrated linearity (r2 > 0.99), with a lower limit of detection at 2 µM (BCAA) and 1 µM (BCKA), and acceptable recovery of QC samples. Hematocrit, blood volume, punch position, and storage condition effects were within acceptable limits. Correlation and Bland-Altman analysis showed strong interconvertibility between plasma and DBS assays. Reference ranges for leucine, isoleucine, valine, KIC, KIV, and KMV were established. ConclusionThe developed DBS method, requiring no derivatization and involving simple sample preparation with short run times, is a cost-effective and reliable approach for the confirmatory diagnosis of MSUD.

The morphology and thermo-regulating properties of electrospun PVA/PEG/Ag nanofibers of water and formic acid solvents

The solvent utilized in the electrospinning solution significantly impacts the morphology and thermal properties of PVA/PEG/Ag nanofibers. To prevent leakage of PEG, solid-liquid phase change, a suitable encapsulation method involves utilizing a combined single-phase electrospinning that incorporates PEG and supporting polymer of PVA. This study aims to investigate the production of thermal-regulating nanofibers from a solution containing PEG 6000, PVA, and AgNO3 precursor using electrospinning method. The influence of water and formic acid as a solvent on the morphology of the nanofibers was examined using SEM. The selected nanofiber characteristics and thermal performance were evaluated through FE-SEM, FT-IR, XRD, DSC, PCM leakage, and DTG tests. SEM images revealed that the formic acid-based nanofibers, consisting of two polymers and two polymer/Ag NPs, exhibited a nanoporous membrane, possibly due to enhanced cross-linking compared to water-based nanofibers. The results of the DSC indicated that fusion and solidification enthalpies of the selected water-based nanofibers were measured as 70.09 and −85.43 J/g, respectively. Unexpectedly, the DSC results indicated higher enthalpies compared to unheated samples. SEM image after thermal cycles, leakage results, and DTG of water-based nanofibers demonstrated their production with thermal stability, reliability, and the potential for creating shape-stable, thermally regulating fabricated nanofibers for various applications.

Advanced reduction processes initiated by oxidative radicals for trichloroacetic acid degradation: Performance, radical generation, and mechanism

The degradation of haloacetic acids (HAAs) in aqueous environments poses a challenge due to their oxidative resistance. Given that HAAs are highly carcinogenic disinfection byproducts, it is imperative to develop effective degradation methods to reduce their potential health risk. In this study, we found that only 27.2% of 200 μM trichloroacetic acid (TCA) was removed in the UV-activated persulfate (PS) system after 2 h, while complete removal was achieved with the addition of 15 mM formic acid (FA). The main products of TCA degradation were dichloroacetic acid and monochloroacetic acid. Results from free radical quenching experiments and electron paramagnetic resonance spectroscopy analyses indicated that reductive carbon dioxide radical (CO2•−) was the main active species responsible for TCA reduction. Oxidative radicals (i.e., SO4•− and •OH) generated from PS activation reacted with FA to form CO2•−, efficiently degrading TCA. The effects of PS and FA concentrations, solution pH, anions (e.g., Cl−, SO42−, and HCO3−), and small organic molecules (e.g., methanol, ethanol, and acetic acid) on degradation efficiency were examined. Overall, this study proposes a simple and efficient method to improve the degradation efficiency of HAAs in the UV/PS system and provides new insights into the advanced reduction processes used for water treatments.

Chromatographic Separation of Hydrophilic Organophosphates on a Porous Graphitized Carbon Sorbent Hypercarb Using an Aqueous Solution of Formic Acid As a Mobile Phase

Chromatographic Separation of Hydrophilic Organophosphates on a Porous Graphitized Carbon Sorbent Hypercarb Using an Aqueous Solution of Formic Acid As a Mobile Phase

Molecular Engineering of Poly(Ionic Liquid) for Direct and Continuous Production of Pure Formic Acid from Flue Gas.

Electrochemical CO2 reduction reaction (CO2RR) offers a promising approach to close the carbon cycle and reduce reliance on fossil fuels. However, traditional decoupled CO2RR processes involve energy-intensive CO2 capture, conversion, and product separation, which increases operational costs. Here, we report the development of a bismuth-poly(ionic liquid) (Bi-PIL) hybrid catalyst that exhibits exceptional electrocatalytic performance for CO2 conversion to formate. The Bi-PIL catalyst achieves over 90% Faradaic efficiency for formate over a wide potential range, even at low 15% v/v CO2 concentrations typical of industrial flue gas. The biphenyl in PIL backbone affords hydrophobicity while maintaining high ionic conductivity, effectively mitigating the flooding issues. The PIL layer plays a crucial role as a CO2 concentrator and co-catalyst that accelerates the CO2RR kinetics. Furthermore, we demonstrate the potential of Bi-PIL catalysts in a solid-state electrolyte (SSE) electrolyzer for the continuous and direct production of pure formic acid solutions from flue gas. Techno-economic analysis suggests that this integrated process can produce formic acid at a significantly reduced cost compared to the traditional decoupled approaches. This work presents a promising strategy to overcome the challenges associated with low-concentration CO2 utilization and streamline the production of valuable liquid fuels and chemicals from CO2.