1,721,067 research outputs found
Crosslinked sulfonated poly(phenylene sulfide sulfone) membranes for vanadium redox flow batteries
No full textIn this work, crosslinked hydrocarbon-based cation exchange membranes have been developed for vanadium redox flow battery applications. By Friedel-Crafts alkylation of sulfonated poly(phenylene sulfide sulfone) (sPSS), membranes with various degrees of crosslinking have been prepared in one step. Among those, the membrane containing 9% of crosslinker (sPSScl9) represents the best solution. Owing to a much higher selectivity, battery self-discharge and capacity fading (tested over 100 charge/discharge cycles at 120 mA cm−2) of sPSScl9 outperform benchmark Nafion of comparable thickness (N212). Furthermore, the crosslinking strategy permits to obtain stable membranes even in highly oxidizing environments, due to a combination of crosslinking, that holds together the polymer chains, and oxidation of sulfides to sulfones that increases the rigidity of the backbone. As a result, sPSScl9 incubated in the presence of V(V) shows unchanged ion exchange capacity and proton conductivity, and a 10× reduction of vanadium permeability with respect to untreated membranes
Effect of an ormosil-based filler on the physico-chemical and electrochemical properties of Nafion membranes
No full textElectrocatalytic CO2reduction on nanostructured metal-based materials: challenges and constraints for a sustainable pathway to decarbonization
No full textThe increasing release of carbon dioxide into atmosphere has caused serious environmental consequences and closing the carbon loop is therefore essential for promoting the transition towards a sustainable development. Electrochemical reduction of carbon dioxide (E CO2RR) represents a powerful strategy for reducing CO2 levels in atmosphere and obtaining value-added chemicals and fuels using renewable energy sources. Despite the important achievements obtained so far, major issues associated with activity and selectivity of electrocatalysts toward the production of multi-carbon (C2+) products hinder large-scale applications. Hence, a thorough understanding of catalytic mechanisms is needed for advancing the design of efficient electrocatalysts to drive the reaction pathway to the desired products. This review summarizes the latest advances in the design of nanostructured metal-based catalysts for E CO2RR, with a special emphasis on the synthesis procedures and electrochemical performance of metal-nitrogen-carbon catalysts. An overview on the catalytic mechanisms is included along with a discussion of the experimental and computational techniques for mechanistic studies and catalyst development. Finally, we outline a perspective on the relationship between structure, morphology and electrochemical activity highlighting challenges and outlook on developing metal-nitrogen-carbon electrocatalysts for E CO2RR to multi-carbon products
Effect of the phospholipid head group in antibiotic-phospholipid association at water-air interface
No full textWe studied the interactions of tetracycline antibiotics, TCs, with phospholipid monolayers with the two-fold aim of elucidating the mechanism of action of TCs and to provide a first step for the realization of bio-mimetic sensor for such drugs by means of the Langmuir-Blodgett technique. Preliminary surface tension studies demonstrated that surface activity of tetracycline is moderate and dependent on the pH of the subphase. We selected three phospholipids having hydrophobic chains of the same length but differing in the polar head structures, i.e. dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylethanolamine, and dipalmitoylphosphatidic acid. Surface pressure- and surface potential- area isotherms were employed to investigate the behavior of the phospholipid monolayers at the water-air interface when tetracycline was added to the aqueous subphase. Analysis of the results indicated that the electrostatic interaction is the driving force for migration of tetracycline towards the interface where localized adsorption to the head groups occurs. Nevertheless, such interactions appear to be insufficient to promote penetration of tetracycline through the hydrophobic layer
Air-breathing cathodes for microbial fuel cells based on iron-nitrogen-carbon electrocatalysts
No full textThis work reports the development of an iron-nitrogen-carbon electrocatalyst (Fe-N-C) synthesized by functionalization of carbon support using low-cost Fe- and N-based precursors in a wet impregnation procedure followed by a pyrolysis treatment under an inert atmosphere. Structure and surface chemistry were investigated by Raman and X-ray photoelectron spectroscopy (XPS), which indicated an efficient interaction of precursors with the carbon support during the wet-impregnations step, which allows obtaining a carbonized material with a high content of active sites based on Fe-Nx moieties. This led to Fe-N-C materials with high catalytic activity towards oxygen reduction at neutral pH, as demonstrated by cyclic voltammetry (CV) and hydrodynamic linear sweep voltammetry with rotating ring disk electrode (LSV-RRDE). The Fe-N-C electrocatalyst was incorporated in air-breathing cathodes and performance was optimized in terms of oxygen reduction activity and stability. Such cathodes were assembled in single-chamber microbial fuel cell prototypes, and electrical power and voltage generation were evaluated over time
Advances in organic electroactive species for enhancing the performance of all-aqueous redox flow batteries in electrochemical energy storage
Full text linkAqueous organic redox flow batteries (AORFBs) are emerging as promising energy storage systems due to their scalability, safety, and environmentally friendly nature. This review provides a comprehensive analysis of the recent advances in organic electroactive species for AORFBs, highlighting critical strategies for improving battery performance. After an introduction that outlines the relevance of AORFBs in modern energy challenges, the paper deepens into the working principles and essential components of these systems. Recent developments in organic anolytes and catholytes are discussed, focusing on innovations that enhance redox reversibility, optimize redox potential, and increase solubility and stability under aqueous conditions. A comparative analysis is provided, evaluating these organic species regarding energy density, power density, and cycling stability, demonstrating the improved performance achieved in AORFB systems. The review concludes by identifying future research directions for designing and engineering next-generation organic electrolytes, emphasizing maximizing electrochemical stability and energy storage efficiency to advance the practicality and competitiveness of AORFBs
Modulation of tetracycline-phospholipid interactions by tuning of pH at the water-air interface
No full textThis paper is part of a systematic study of the interactions of tetracycline antibiotics with phospholipid monolayers at the water-air interface. Tetracyclines are widespread antibiotics that undergo a series of protonation equilibria in solution, depending on the pH. The surface activity of tetracyclines was determined by means of surface tension measurements for three different systems, i.e. water, TRIS and McIlvaine-EDTA buffer. Surface pressure-molecular area and surface potential-molecular area isotherms were acquired for dipalmitoylphosphatidic acid monolayers on TRIS buffer (pH=7.0) and McIlvaine-EDTA buffer (pH=4.0) solution as a function of tetracycline concentration in the subphase. Comparative analysis of surface potential data, with the molecular dipole moment of tetracycline obtained from semiempirical calculations, provided information on the orientation of tetracycline at the interface. Surface pressure measurements as a function of monolayer compression were described, applying either a continuous partition model or Langmuir adsorption isotherms. The results obtained in the case of buffer solutions were compared to those obtained for tetracycline in water subphases. The analysis of the results indicated that electrostatic interactions dictate the migration of tetracycline to the monolayer interface. Penetration of the molecule to the lipophilic portion of the monolayer was unlikely, especially at high surface pressures. The results showed that stronger interactions are established between the zwitterionic tetracycline and the deprotonated phosphatidic group in TRIS buffer solution; in this case, tetracycline binds at the monolayer interface following a Langmuir type adsorption. In the case of water, where the monodeprotonated acid and the tetracycline zwitterions are the only species involved, the data can be described by continuous partition of tetracycline between interfacial and bulk phases. The same holds for McIlvaine-EDTA buffer subphases, although the high concentrations of citrate ions in this buffer competitively interfere with tetracycline association at the monolayer interface
Communication—sulfonated poly (ether ether ketone) as cation exchange membrane for alkaline redox flow batteries
No full textA sulfonated poly (ether ether ketone) (sPEEK) was tested as the separator in a full alkaline flow battery with 2,6-dihydroxyanthraquinone-ferro/ferricyanide, DHAQ-FeCy, redox couples. Cell performance was compared to that of an identical cell utilizing a perfluorosulfonic acid (PFSA) membrane. Replacement of the PFSA membrane with sPEEK resulted in a 10% power density increase, a 40% decrease in capacity loss per day and an 85-fold decrease in ferricyanide permeation. Though long-term stability of sPEEK in alkaline media requires improvement, these results highlight the potential to produce non-fluorinated membranes with better performance in organic redox flow batteries than the commercially available PFSAs. © The Author(s) 2018
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