Catalytic activity of Au/TiO2 and Pt/TiO2 nanocatalysts synthesized by arc plasma deposition under CO oxidation

Abstract

The fabrication of oxide-supported metal catalysts via wet chemical routes has been well known in heterogeneous catalysis. However, uniform deposition of metal nanoparticles, with controlled size and shape, on the support with high reproducibility is still a challenge in catalyst preparation. Among various synthesis methods, arc plasma deposition (APD) of metal nanoparticles or thin films on oxide supports has received great interest recently, due to its high reproducibility and large-scale production, and is being used in catalytic applications. In this work, Au and Pt nanoparticles, 2-4 nm in size, have been deposited on TiO2 powder by APD. The size of the metal nanoparticles was controlled by the arc voltage, metal deposition, and APD conditions. These catalytic materials were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP-AES), N2-physisorption, CO-chemisorption, and transmission electron microscopy (TEM). Catalytic activity of the materials was measured by CO oxidation using oxygen, as a model reaction, in a micro-flow reactor at atmospheric pressure. We found that Au/TiO2 is reactive, showing 100 % conversion at 80oC, while Pt/TiO2 shows 100 % conversion at 170oC. We discuss the effects of structure and metal-oxide interactions of the catalysts on catalytic activity.