Ultrasound-assisted regioselective ring opening of epoxides with nitrogen heterocycles using pyrrolidonium and imidazolium-based acidic ionic liquids

Imidazolium and N-methyl-2-pyrrolidonium ionic liquids under ultrasound irradiation were developed as a green and expeditious approach for C-alkylation and N-alkylation of the nitrogen heterocycles including indoles and imidazoles with aliphatic and aromatic epoxides. Ionic liquids were used with a dual role of catalyst and solvent. The highest yield (85 %) was obtained with N-methyl-2- pyrrolidonium dihydrogen phosphate [H-NMP]H2PO4 as a pyrrolidonium ionic liquid under ultrasound at 50 kHz, with a reaction time of 60 min and reaction temperature of 60 °C. The combination of ionic liquids and ultrasonic irradiation was found to be an effective, green and eco-friendly method for alkylation of indoles and imidazoles

High Active Material Loading in Organic Electrodes Enabled by an in‐situ Electropolymerized π‐Conjugated Tetrakis (4‐Aminophenyl) Porphyrin

Porphyrin complexes have been widely studied as promising electrode material in diverse energy storage systems and chemistries. However, like other organic electrodes, porphyrins often suffer from low conductivity and, consequently, require a significant amount (typically 40 %) of electrochemically inactive conductive carbon that occupies volume and mass without storing energy. In this study, we investigate [5,10,15,20 tetrakis(4-aminophenyl)-porphyrin] (TAPP) and its metal complexes as redox-active cathode materials to address the aforementioned issues. The lithium-ion cells prepared with a high content of CuTAPP active material (70 wt %) demonstrate a stable discharge capacity of ∼120 mAh/g when cycling with a constant current density of 1000 mA/g. The material also showed superior rate capability, e. g., ∼60 mAh/g at 8 A/g. The results of DFT calculations and experimental analysis indicate that the degree of planarity of the metalloporphyrins directly correlates to their cycling stability. Moreover, the contribution from the central metal redox during the cycling is found to be the reason for the significantly higher performance of the Cu-complex compared to the metal-free complex. The findings of this study show a general approach for facing common conductivity challenges of organic electrodes and open up a pathway for practical application of organics electrode materials in energy storage application

A comparison of CO2 adsorption behaviour of mono- and diamine-functionalised adsorbents

The paper presents a study for investigating i) the effect of amination of poly(GMA)-grafted polyethylene/polypropylene (PE/PP) substrates with trimethylamine (TMA) and ethylenediamine (EDA) and ii) their impact on carbon dioxide (CO2) adsorption capacity of the obtained adsorbents. The chemical, structural, and morphological changes of the aminated adsorbents were evaluated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. The amination yield with TMA was 40% higher than EDA. However, the obtained adsorbent showed two times lower CO2 adsorption capacity (at 30 bars) than the adsorbent with EDA and stood at 0.6 mmol g-1 compared to 1.2 mmol g-1

GO-modified membranes for vanadium redox flow battery

Graphene oxide (GO) has attracted tremendous attention in membrane-based separation field as it can filter ions and molecules. Recently, GO-based materials have emerged as excellent modifiers for vanadium redox flow battery (VRFB) application. Its high mechanical and chemical stability, nearly frictionless surface, high flexibility, and low cost make GO-based materials as proper materials for the membranes in VRFB. In VRFB, a membrane acts as the key component to determine the performance. Therefore, employing low vanadium ion permeability with excellent stability membrane in vanadium electrolytes is important to ensure high battery performance. Herein, recent progress of GO-modified membranes for VRFB is briefly reviewed. This review begins with current membranes used for VRFB, followed by the challenges faced by the membranes. In addition, the transport mechanism of vanadium ion and the stability properties of GO-modified membranes are also discussed to enlighten the role of GO in the modified membranes

Highly conductive anion exchange membranes based on polymer networks containing imidazolium functionalised side chains

Two novel types of anion exchange membranes (AEMs) having imidazolium-type functionalised nanofibrous substrates were prepared using the facile and potentially scalable method. The membranes’ precursors were prepared by graft copolymerization of vinylbenzyl chloride (VBC) onto syndiotactic polypropylene (syn-PP) and polyamide-66 (PA-66) nanofibrous networks followed by crosslinking with 1,8-octanediamine, thermal treatment and subsequent functionalisation of imidazolium groups. The obtained membranes displayed an ion exchange capacity (IEC) close to 1.9 mmol g–1 and ionic (OH-) conductivity as high as 130 mS cm–1 at 80 °C. This was coupled with a reasonable alkaline stability representing more than 70% of their original conductivity under accelerated degradation test in 1 M KOH at 80 °C for 360 h. The effect of ionomer binder on the performance of the membrane electrode assembly (MEA) in AEM fuel cell was evaluated with the optimum membrane. The MEA showed a power density of as high as 440 mW cm−2 at a current density is 910 mA cm−2 with diamine crosslinked quaternized polysulfone (DAPSF) binder at 80 °C with 90% humidified H2 and O2 gases. Such performance was 2.3 folds higher than the corresponding MEA performance with quaternary ammonium polysulfone (QAPS) binder at the same operating conditions. Overall, the newly developed membrane was found to possess not only an excellent combination of physico-chemical properties and a reasonable stability but also to have a facile preparation procedure and cheap ingredients making it a promising candidate for application in AEM fuel cell

Rapid Surface Modification of Ultrafiltration Membranes for Enhanced Antifouling Properties

In this work, several ultrafiltration (UF) membranes with enhanced antifouling properties were fabricated using a rapid and green surface modification method that was based on the plasma-enhanced chemical vapor deposition (PECVD). Two types of hydrophilic monomers-acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) were, respectively, deposited on the surface of a commercial UF membrane and the effects of plasma deposition time (i.e., 15 s, 30 s, 60 s, and 90 s) on the surface properties of the membrane were investigated. The modified membranes were then subjected to filtration using 2000 mg/L pepsin and bovine serum albumin (BSA) solutions as feed. Microscopic and spectroscopic analyses confirmed the successful deposition of AA and HEMA on the membrane surface and the decrease in water contact angle with increasing plasma deposition time strongly indicated the increase in surface hydrophilicity due to the considerable enrichment of the hydrophilic segment of AA and HEMA on the membrane surface. However, a prolonged plasma deposition time (>15 s) should be avoided as it led to the formation of a thicker coating layer that significantly reduced the membrane pure water flux with no significant change in the solute rejection rate. Upon 15-s plasma deposition, the AA-modified membrane recorded the pepsin and BSA rejections of 83.9% and 97.5%, respectively, while the HEMA-modified membrane rejected at least 98.5% for both pepsin and BSA. Compared to the control membrane, the AA-modified and HEMA-modified membranes also showed a lower degree of flux decline and better flux recovery rate (>90%), suggesting that the membrane antifouling properties were improved and most of the fouling was reversible and could be removed via simple water cleaning process. We demonstrated in this work that the PECVD technique is a promising surface modification method that could be employed to rapidly improve membrane surface hydrophilicity (15 s) for the enhanced protein purification process without using any organic solvent during the plasma modification process

Molecular Engineering of Metalloporphyrins for High‐Performance Energy Storage: Central Metal Matters

Porphyrin derivatives represent an emerging class of redox-active materials for sustainable electrochemical energy storage. However, their structure–performance relationship is poorly understood, which confines their rational design and thus limits access to their full potential. To gain such understanding, we here focus on the role of the metal ion within porphyrin molecules. The A$_2$B$_2$-type porphyrin 5,15-bis(ethynyl)-10,20-diphenylporphyrin and its first-row transition metal complexes from Co to Zn are used as models to investigate the relationships between structure and electrochemical performance. It turned out that the choice of central metal atom has a profound influence on the practical voltage window and discharge capacity. The results of DFT calculations suggest that the choice of central metal atom triggers the degree of planarity of the porphyrin. Single crystal diffraction studies illustrate the consequences on the intramolecular rearrangement and packing of metalloporphyrins. Besides the direct effect of the metal choice on the undesired solubility, efficient packing and crystallinity are found to dictate the rate capability and the ion diffusion along with the porosity. Such findings open up a vast space of compositions and morphologies to accelerate the practical application of resource-friendly cathode materials to satisfy the rapidly increasing need for efficient electrical energy storage

Rapid Surface Modification of Ultrafiltration Membranes for Enhanced Antifouling Properties

In this work, several ultrafiltration (UF) membranes with enhanced antifouling properties were fabricated using a rapid and green surface modification method that was based on the plasma-enhanced chemical vapor deposition (PECVD). Two types of hydrophilic monomers-acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) were, respectively, deposited on the surface of a commercial UF membrane and the effects of plasma deposition time (i.e., 15 s, 30 s, 60 s, and 90 s) on the surface properties of the membrane were investigated. The modified membranes were then subjected to filtration using 2000 mg/L pepsin and bovine serum albumin (BSA) solutions as feed. Microscopic and spectroscopic analyses confirmed the successful deposition of AA and HEMA on the membrane surface and the decrease in water contact angle with increasing plasma deposition time strongly indicated the increase in surface hydrophilicity due to the considerable enrichment of the hydrophilic segment of AA and HEMA on the membrane surface. However, a prolonged plasma deposition time (>15 s) should be avoided as it led to the formation of a thicker coating layer that significantly reduced the membrane pure water flux with no significant change in the solute rejection rate. Upon 15-s plasma deposition, the AA-modified membrane recorded the pepsin and BSA rejections of 83.9% and 97.5%, respectively, while the HEMA-modified membrane rejected at least 98.5% for both pepsin and BSA. Compared to the control membrane, the AA-modified and HEMA-modified membranes also showed a lower degree of flux decline and better flux recovery rate (>90%), suggesting that the membrane antifouling properties were improved and most of the fouling was reversible and could be removed via simple water cleaning process. We demonstrated in this work that the PECVD technique is a promising surface modification method that could be employed to rapidly improve membrane surface hydrophilicity (15 s) for the enhanced protein purification process without using any organic solvent during the plasma modification process

A Self-Conditioned Metalloporphyrin as a Highly Stable Cathode for Fast Rechargeable Magnesium Batteries

Development of practical rechargeable Mg batteries (RMBs) is impeded by their limited cycle life and rate performance of cathodes. As demonstrated herein, a copper‐porphyrin with meso‐functionalized ethynyl groups is capable of reversible two‐ and four‐electron storage at an extremely fast rate (tested up to 53 C). The reversible four‐electron redox process with cationic‐anionic contributions resulted in a specific discharge capacity of 155 mAh g$^{-1}$ at the high current density of 1000 mA g$^{-1}$. Even at 4000 mA g$^{-1}$, it still delivered >70 mAh g$^{-1}$ after 500 cycles, corresponding to an energy density of >92 Wh kg$^{-1}$ at a high power of >5100 W kg$^{-1}$. The ability to provide such high‐rate performance and long‐life opens the way to the development of practical cathodes for multivalent metal batteries