Synthesis and characterization of sulfonated poly(ether ether ketone) for proton exchange membranes Xing, P.; Robertson, Gilles; Guiver, Michael; Mikhailenko, S.; Wang, K.; Kaliaguine, S. AbstractSeries of sulfonated poly(ether ether ketone)s (SPEEKs) were prepared by sulfonation of commercial Victrex ® and Gatone ® PEEK for a comparative study of proton exchange membranes (PEM) intended for fuel cell applications. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d 6 ) solution of the purified polymers using 1 H NMR methods. The second method using a solvent suppression technique, in which DS results were obtained directly from 1 H NMR spectra of SPEEK dissolved in sulfuric acid (non-deuterated) reaction medium was evaluated. The variation between the two methods was determined. The room temperature sulfonation of PEEK, monitored directly by second 1 H NMR method, proceeded rapidly initially, reaching DS ∼ 0.8 within 1 week, but progressed slowly thereafter. A maximum DS of 1.0 was determined after 1 month at ambient temperature (∼22• C). The thermal properties of SPEEK were characterized by means of DSC and TGA. The mass averaged molecular weights M w of both Victrex ® and Gatone ® PEEK were estimated from intrinsic viscosities measured in sulfuric acid solutions. It was verified that higher temperature (55• C) did not induce any apparent chain degradation of Victrex ® (or Gatone ® ) PEEK by M w tests. The water uptake and swelling properties of prepared films were studied and the proton conductivities at different temperatures were measured. The conductivities of the SPEEKs were found to increase with increasing DS and temperatures. The effect of film casting solvents on the conductivities is also discussed.

No abstract

A new method for the preparation of proton exchange membranes (PEMs), based on cross-linked sulfonated poly(ether ether ketones) is reported. The cross-linking involves thermally activated bridging of the polymer chains with polyatomic alcohols, which makes the polymer mechanically stronger and reduces its swelling by water. Although the cross-linking occurs through the sulfonic acid group, a major portion of acid functions is not involved in cross-linking and remains available for proton transfer. Owing to this, membrane conductivities are only somewhat reduced, leaving some with values above 2 × 10 −2 S/cm at room temperature.

Efficient bimetallic nanocatalysts based on non-noble metals are highly desired for the development of new energy storage materials. In this work, we report a simple method for the synthesis of highly dispersed CuNi catalysts supported on mesoporous carbon or silica nanospheres using low cost metal nitrate precursors. The mesoporous carbonsupported Cu 0.5 Ni 0.5 nanocatalysts exhibit excellent catalytic performance for the hydrolysis of ammonia borane and decomposition of hydrous hydrazine with 100% hydrogen selectivity in aqueous alkaline solution at 60 o C. The chemical composition and size of the metal particles, which have a significant influence on the catalytic properties of the bimetallic CuNi supported materials, can readily be controlled by adjusting the metal loading and ratio of metal precursors. An exceedingly high turnover frequency of 3288 (mol H2 mol metal -1 h -1 ) and complete reaction within 1 min in dehydrogenation of ammonia-borane were achieved over a tailored-made catalyst obtained through precise monitoring of metal particle size, composition and support properties.

Mo–W carbide was synthesized via temperature-programmed reduction to generate a β-Mo2C phase with bulk morphology.

Plasmonic photocatalysis is among the most efficient processes for the photoreduction of CO2 into valuable fuels. The formation of localized surface plasmon resonance (LSPR), energy transfer, and surface reaction are the significant steps in this process. LSPR plays an essential role in the performance of plasmonic photocatalysts as it promotes an excellent, light absorption over a broad wavelength range while simultaneously facilitating an efficient energy transfer to semiconductors. The LSPR transfers energy to a semiconductor through various mechanisms, which have both advantages and disadvantages. This work points out four critical features for plasmonic photocatalyst design, that is, plasmonic materials, size, shape of plasmonic nanoparticles (PNPs), and the contact between PNPs and semiconductor. Various developed plasmonic photocatalysts, as well as their photocatalytic performance in CO2 photoreduction, are reviewed and discussed. Finally, perspectives of advanced architectures and structural engineering for plasmonic photocatalyst design are put forward with high expectations to achieve an efficient CO2 photoreduction shortly.

UV-vis spectroscopy is an inexpensive, simple, flexible, non-destructive, analytical method appropriate for a wide class of organic compounds and some inorganic species. UV-vis spectrophotometers measure the absorbance or transmittance of light passing through a medium as a function of the wavelength. Chemical engineers apply it for quantitative analysis, to derive liquid phase reaction kinetics, and to identify the mechanism at the molecular scale. High performance liquid chromatography and ultra-high performance liquid chromatography integrate UV-vis detectors to identify and quantify the concentration of compounds in liquid streams. Combining these techniques with mass spectrometry facilitates identifying all species. UV-vis diffuse reflectance spectroscopy is a variant with enhanced scattering properties that measures the properties of solids and powders. A bibliometric analysis of the 10 000 most cited papers referring to UV-vis (2016 and 2017) groups research in four major clusters: nanoparticles and nanostucutres; photocatalysis and water treatment; crystals, complexes, and derivatives; and Ag and Au nanoparticles biological interaction.

No abstract