Silica-supported Au nanoparticles decorated by TiO2:: Formation, morphology, and CO oxidation activity

Au-TiO2 interface on silica support was aimed to be produced in a controlled way by use of Au hydrosol. In method A, the Au colloids were modified by hydrolysis of the water-soluble Ti(IV) bis(ammoniumlactato)-dihydroxide (TALH) precursor and then adsorbed on Aerosil SiO2 surface. In method B, Au sol was first deposited onto the SiO2 surface and then TALH was adsorbed on it. Regular and high-resolution transmission electron microscopy (TEM and HRTEM) and energy dispersive spectrometry (EDS) analysis allowed us to conclude that, in method A, gold particles were able to retain the precursor of TiO2 at 1.5 wt % TiO2 loading, but at 4 wt % TiO2 content the promoter oxide appeared over the silica surface as well. With method B, titania was detected on silica at each TiO2 concentration. In Au-TiO2/SiO2 samples, the stability of Au particles against sintering was much higher than in Au/TiO2. The formation of an active Au-TiO2 perimeter was proven by the greatly increased CO oxidation activity compared to that of the reference Au/SiO2.