Surface Modification of Au/TiO2 Catalysts by SiO2 via Atomic Layer Deposition

Atomic layer deposition (ALD) was utilized for the surface engineering of metallic nanoparticles to tame their sintering problems and catalytic activities. We chose the surface modification of gold nanocatalysts as an example to demonstrate the concept of this ALD-based approach. Herein, an active Au/TiO2 catalyst was modified by amorphous SiO2 via ALD, and the samples were characterized by inductively coupled plasma-optical emission spectrometry (ICP-OES), scanning (SEM-EDX) and transmission electron microscope−energy-dispersive X-ray spectrometry (TEM-EDX), X-ray diffraction (XRD), and thermogravimetry/differential thermogravimetry (TG/DTG), and the catalytic activities in CO oxidation and H2 oxidation were tested with respect to the pretreatment temperature and SiO2 content. A significant sintering resistance and changes in catalytic activities were observed. The difference between the SiO2/Au/TiO2 samples prepared by gas-phase ALD and solution-phase chemical grafting was discussed.