Chemical vapor infiltration method for deposition of gold nanoparticles on porous alumina supports

摘要

Knudsen's effusion method with mass spectral analysis of the composition of the gas phase was used to measure the temperature dependence of the saturated vapor of several (CH3)(2)AuL chelate complexes and to determine the thermodynamic parameters of their sublimation. Based on the results of this study, conditions for chemical vapor deposition of gold using dimethylgold(III) chelates were chosen. Gold nanoparticles were synthesized by chemical vapor deposition (infiltration) of (CH3)(2)Au(acac) on porous granules of gamma-Al2O3 with subsequent calcination in air at 325 degrees C. Particle size and the chemical state of gold in Au/gamma-Al2O3 systems were evaluated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). A vapor infiltration procedure is suggested to prepare metallic gold particles <= 5 nm in diameter from Au/gamma-Al2O3. It is shown that Au/gamma-Al2O3 systems obtained by chemical vapor infiltration and containing small gold crystallites possess high catalytic activity in CO oxidation reactions at 40 degrees C.