Insight into the Properties of Plasmonic Au/TiO(2) Activated by O(2)/Ar Plasma

The performance of CO oxidation over plasmonic Au/TiO(2) photocatalysts is largely determined by the electric discharge characteristics and physicochemical properties of discharge gas. To explore the activation mechanism of Au/TiO(2), an O(2) and Ar mixture gas as a discharge gas was employed to activate Au/TiO(2). The photocatalytic activity in CO oxidation over activated Au/TiO(2) was obtained, and the electric discharge characteristics, Au nanoparticle size, surface chemical state, optical property and CO chemisorption were thoroughly characterized. As the O(2) content increases from 10% to 50%, the amplitude of the current pulses increases, but the number of pulses and the discharge power decrease. The photocatalytic activity of Au/TiO(2) rises rapidly at first and then remains constant at 75% when the O(2) content is above 50%. Compared with the discharge gas of 10% and 30% O(2)/Ar, the sample activated by 50% O(2)/Ar plasma possesses less metallic Au and more surface oxygen species and carbonate species by X-ray photoelectron spectroscopy, which is consistent with UV-vis diffuse reflectance spectra and CO chemisorption. The CO chemisorption capacities of the activated samples are the same at a long exposure time due to the approximate Au nanoparticle size observed by transmission electron microscopy. An increase in carbonate species generated from the oxygen species on the surface of TiO(2) is discovered.