Water Transport Properties of Plasma-Modified Commercial Anion-Exchange Membrane for Solid Alkaline Fuel Cells

In the field of low-temperature fuel cells, solid alkaline membrane fuel cells (SAMFCs) appear to be a very promising new fuel cell technology. Nevertheless, commercial hydroxyl-exchange membranes suitable for SAMFCs suffer from some limitations, especially low retention to water at the cathode (where water is required to be reactive in the electrochemical reaction), which weakens fuel cell performances. In this study, the commercial Morgan ADP membrane by Solvay has been modified on the surface by plasma processes using argon or argon/triallylamine as gaseous phases. Plasma-treated and untreated membranes have been characterized in terms of water sorption and diffusion properties performing water vapor sorption measurements. Analysis of sorption isotherms and related modeling from Park model has shown that plasma treatments induce a decrease in water sorption and diffusion abilities without qualitatively affecting the water transport properties. Plasma modification from triallylamine leading to the deposition of a highly cross-linked film on the membrane surface is more influent than argon plasma treatment, causing surface physical cross-linking coupled to hydrophilization effect

Direct Observation of Polylysine Side-Chain Interaction with Smectites Interlayer Surfaces through ¹H−²⁷Al Heteronuclear Correlation NMR Spectroscopy

Direct Observation of Polylysine Side-Chain Interaction with Smectites Interlayer Surfaces through 1H−27Al Heteronuclear Correlation NMR Spectroscop

Synthesis and Characterization of Crystalline Structures Based on Phenylboronate Ligands Bound to Alkaline Earth Cations

We describe the preparation of the first crystalline compounds based on arylboronate ligands PhB(OH)3– coordinated to metal cations: [Ca(PhB(OH)3)2], [Sr(PhB(OH)3)2]·H2O, and [Ba(PhB(OH)3)2]. The calcium and strontium structures were solved using powder and single-crystal X-ray diffraction, respectively. In both cases, the structures are composed of chains of cations connected through phenylboronate ligands, which interact one with each other to form a 2D lamellar structure. The temperature and pH conditions necessary for the formation of phase-pure compounds were investigated: changes in temperature were found to mainly affect the morphology of the crystallites, whereas strong variations in pH were found to affect the formation of pure phases. All three compounds were characterized using a wide range of analytical techniques (TGA, IR, Raman, XRD, and high resolution 1H, 11B, and 13C solid-state NMR), and the different coordination modes of phenylboronate ligands were analyzed. Two different kinds of hydroxyl groups were identified in the structures: those involved in hydrogen bonds, and those that are effectively “free” and not involved in hydrogen bonds of any significant strength. To position precisely the OH protons within the structures, an NMR-crystallography approach was used: the comparison of experimental and calculated NMR parameters (determined using the Gauge Including Projector Augmented Wave method, GIPAW) allowed the most accurate positions to be identified. In the case of the calcium compound, it was found that it is the 43Ca NMR data that are critical to help identify the best model of the structure

Synthesis and Characterization of Crystalline Structures Based on Phenylboronate Ligands Bound to Alkaline Earth Cations

We describe the preparation of the first crystalline compounds based on arylboronate ligands PhB(OH)3– coordinated to metal cations: [Ca(PhB(OH)3)2], [Sr(PhB(OH)3)2]·H2O, and [Ba(PhB(OH)3)2]. The calcium and strontium structures were solved using powder and single-crystal X-ray diffraction, respectively. In both cases, the structures are composed of chains of cations connected through phenylboronate ligands, which interact one with each other to form a 2D lamellar structure. The temperature and pH conditions necessary for the formation of phase-pure compounds were investigated: changes in temperature were found to mainly affect the morphology of the crystallites, whereas strong variations in pH were found to affect the formation of pure phases. All three compounds were characterized using a wide range of analytical techniques (TGA, IR, Raman, XRD, and high resolution 1H, 11B, and 13C solid-state NMR), and the different coordination modes of phenylboronate ligands were analyzed. Two different kinds of hydroxyl groups were identified in the structures: those involved in hydrogen bonds, and those that are effectively “free” and not involved in hydrogen bonds of any significant strength. To position precisely the OH protons within the structures, an NMR-crystallography approach was used: the comparison of experimental and calculated NMR parameters (determined using the Gauge Including Projector Augmented Wave method, GIPAW) allowed the most accurate positions to be identified. In the case of the calcium compound, it was found that it is the 43Ca NMR data that are critical to help identify the best model of the structure

Synthesis and Characterization of Crystalline Structures Based on Phenylboronate Ligands Bound to Alkaline Earth Cations

We describe the preparation of the first crystalline compounds based on arylboronate ligands PhB(OH)3– coordinated to metal cations: [Ca(PhB(OH)3)2], [Sr(PhB(OH)3)2]·H2O, and [Ba(PhB(OH)3)2]. The calcium and strontium structures were solved using powder and single-crystal X-ray diffraction, respectively. In both cases, the structures are composed of chains of cations connected through phenylboronate ligands, which interact one with each other to form a 2D lamellar structure. The temperature and pH conditions necessary for the formation of phase-pure compounds were investigated: changes in temperature were found to mainly affect the morphology of the crystallites, whereas strong variations in pH were found to affect the formation of pure phases. All three compounds were characterized using a wide range of analytical techniques (TGA, IR, Raman, XRD, and high resolution 1H, 11B, and 13C solid-state NMR), and the different coordination modes of phenylboronate ligands were analyzed. Two different kinds of hydroxyl groups were identified in the structures: those involved in hydrogen bonds, and those that are effectively “free” and not involved in hydrogen bonds of any significant strength. To position precisely the OH protons within the structures, an NMR-crystallography approach was used: the comparison of experimental and calculated NMR parameters (determined using the Gauge Including Projector Augmented Wave method, GIPAW) allowed the most accurate positions to be identified. In the case of the calcium compound, it was found that it is the 43Ca NMR data that are critical to help identify the best model of the structure