Search

Carbon electrocatalysts consisting of metal complexes such as MN x or MS x are promising alternatives to high-cost Pt catalysts for the hydrogen evolution reaction (HER). However, the exact HER active sites remain elusive. Here, molecular metal dithiolene-diamine (MS2N2, M=Co and Ni), metal bis(dithiolene) (MS4), and metal bis(diamine) (MN4) complexes were selectively incorporated into carbon-rich 2D metal-organic frameworks (2D MOFs) as model carbon electrocatalysts. The 2D MOF single layers, powders, and composites with graphene were thus prepared and showed definite active sites for H2 generation. The electrocatalytic HER activity of the 2D MOF-based catalysts with different metal complexes follow the order of MS2N2>MN4>MS4. Moreover, the protonation preferentially occurred on the metal atoms, and the concomitant heterolytic elimination of H2 was favored on the M-N units in the MS2N2 active centers. The results provide an in-depth understanding of the catalytic active sites, thus making way for the future development of metal complexes in carbon-rich electrode materials for energy generation. [ABSTRACT FROM AUTHOR]

Viscoelastic vesicle gels were prepared by mixing a nonionic surfactant, tetraethylene glycol monododecyl ether (C12EO4), and an anionic dye, sodium 4-phenylazobenzoic acid (AzoNa). The gels, which were composed of multilamellar vesicles, were analyzed by cryogenic transmission electron microscopy (cryo-TEM), freeze-fracture transmission electron microscopy (FF-TEM), 2H NMR spectroscopy, and small-angle X-ray scattering (SAXS). The mechanism of vesicle-gel formation is explained by the influence of anionic molecules on the bilayer bending modulus. Interestingly, the vesicle gels were observed to be sensitive to temperature, pH, and light. The viscoelastic vesicle gels respond to heat; they thin at lower temperatures and become thicker at higher temperatures. The vesicle gels are only stable from pH 7 to 11, and the gels become thinner outside of this range. UV light can also trigger a structural phase transition from micelles to multilamellar vesicle gels. [ABSTRACT FROM AUTHOR]

Two ‐ dimensional metal – organic framework (MOF) sheets were synthesized by incorporation of the molecular metal dithiolene – diamine (MS2N2, M=Co and Ni), metal bis(dithiolene) (MS4), and metal bis(diamine) (MN4) complexes. 2D MOFs were applied as model carbon ‐ rich electrocatalysts for the hydrogen evolution reaction in water, and these studies provided an in ‐ depth understanding of the catalytic active sites, thus paving the way for the future development of metal complexes in carbon ‐ rich electrode materials for energy generation. More information can be found in the Communication by G. Seifert and X. Feng et al. on page 2255 ff. [ABSTRACT FROM AUTHOR]