Synthesis Route to Supported Gold Nanoparticle Layered Double Hydroxides as Efficient Catalysts in the Electrooxidation of Methanol

This work describes a new one-step method for the preparation of AuNP/LDH nanocomposites via the polyol route. The novelty of this facile, simple synthesis is the absence of additional reactants such as reductive agents or stabilizer, which gives the possibility to obtain phase-pure systems free of undesiderable effect. The AuNP formation is confirmed by SEM, TEM, PXRD, and XAS; moreover, the electrochemical characterization is also reported. The electrocatalytic behavior of AuNP/LDH nanocomposites has been investigated with respect to the oxidation of methanol in basic media and compared with that of pristine NiAl-Ac. The 4-fold highest catalytic efficiency observed with AuNP/LDH nanocomposites suggests the presence of a synergic effect between Ni and AuNP sites. The combination of these experimental findings with the low-cost synthesis procedure paves the way for the exploitation of the presented nanocomposites materials as catalysts for methanol fuel cells

Novel Synthesis of Gold Nanoparticles Supported on Alkyne-Functionalized Nanosilica

A novel, convenient method for the preparation of gold nanoparticles supported on alkyne-functionalized nanosilica is presented. Silica nanoparticles functionalized with alkynyl carbamate moieties (<b>SiO</b>_<b>2</b><b>@Yne</b>) were synthesized by co-condensation of the difunctional organosilane [3-(2-propynylcarbamate)­propyl]­triethoxysilane (PPTEOS) with tetraethoxysilane (TEOS) in an alkaline medium. The alkynyl-carbamate functionalities present on silica are able to capture the gold precursor HAuCl₄, spontaneously reduce it, and stabilize the resulting supported Au_NPs, having an average size of ca. 11 nm. The prepared <b>Au</b>-<b>SiO</b>_<b>2</b><b>@Yne</b> was thoroughly analyzed by X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), atomic absorption spectroscopy (AAS), FT-IR, and UV–vis spectroscopy. The catalytic activity of <b>Au</b>-<b>SiO</b>_<b>2</b><b>@Yne</b> was investigated for the reduction of 4-nitrophenol to 4-aminophenol by NaBH₄, and kinetic constants <i>k</i> in the order of magnitude of about 10^–2 s^–1 were found