Browsing by Subject "Nonionic surfactant"

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    Standing mesochannels: mesoporous PdCu films with vertically aligned mesochannels from nonionic micellar solutions
    (American Chemical Society, 2018) Iqbal, M.; Kim, J.; Yuliarto, B.; Jiang B.; Li C.; Dağ, Ömer; Malgras, V.; Yamauchi, Y.
    Mesoporous bimetallic palladium (Pd) alloy films with mesochannels perpendicularly aligned to the substrate are expected to show superior electrocatalytic activity and stability. The perpendicular mesochannels allow small molecules to efficiently access the active sites located not only at the surface but also within the film because of low diffusion resistance. When compared to pure Pd films, alloying with a secondary metal such as copper (Cu) is cost-effective and promotes resistance against adventitious poisoning through intermediate reactions known to impair the electrocatalytic performance. Here, we report the synthesis of mesoporous PdCu films by electrochemical deposition in nonionic micellar solutions. The mesoporous structures are vertically aligned on the substrate, and the final content of Pd and Cu can be adjusted by tuning the initial precursor molar ratio in the electrolyte solution.
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    The synthesis of mesostructured silica films and monoliths functionalised by noble metal nanoparticles
    (Royal Society of Chemistry, 2003) Dag, Ö.; Samarskaya, O.; Coombs, N.; Ozin, G. A.
    A lyotropic AgNO3, HAuCl4 and H2PtCl6-silica liquid crystalline (LC) phase is used as a supramolecular template for a one-pot synthesis of novel noble metal or complex ion containing nanocomposite materials in the form of a film and monolith. In these structures, Ag+, AuCl4- and PtCl62- ions interact with the head group of an oligo(ethylene oxide) type non-ionic surfactant (C12H25(CH2CH2O)10OH, denoted as C12EO10) assembly that are embedded within the channels of hexagonal mesostructured silica materials. A chemical and/or thermal reduction of the metal or complex ions produces nanoparticles of these metals in the mesoporous channels and the void spaces of the silica. The LC mesophase of H2O:X:HNO3:C12EO10, (where X is AgNO3, HAuCl4 and H2PtCl6), and nanocomposite silica materials of meso-SiO2-C12EO10-X and meso-SiO2-C12EO10-M (M is the Ag, Au and Pt nanoparticles) have been investigated using polarised optical microscopy (POM), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), Fourier transform (FT) Raman and UV-Vis absorption spectroscopy. Collectively the results indicate that the LC phase of a 50 w/w% H2O:C12EO10 is stable upon mixing with AgNO3, HAuCl4 and H2PtCl6 salts and/or acids. The metal ions or complex ions are distributed inside the channels of the mesoporous silica materials at low concentrations and may be converted into metal nanoparticles within the channels by a chemical and/or thermal reduction process. The metal nanoparticles have a broad size distribution where the platinum and silver particles are very small (typically 2-6 nm) and the gold particles are much larger (typically 5-30 nm).