High Pressure Plasma Treatment for Controlling the Surface Activity and Optical Properties of TiO₂ Nanoparticles

The effect of high pressure radio frequency (RF) plasma treatment on TiO₂ surface and photocatalytic property has been investigated. X-ray photoelectron spectroscopy (XPS) measurements have shown the two different oxidation states of oxygen in the untreated TiO₂ powder. Its relative proportion changes with the different dose of plasma treatments. The proportion of Ti³⁺ surface states also changes after plasma treatment and strongly depends on combination of plasma power and treatment time. The photocatalytic activity of plasma-untreated and -treated samples was measured by observing the relative degradation of methylene blue. The result showed about 50% increase in photoactivity at the sample treated with 10 W RF power plasma. Low power plasma treatment is a more efficient process for achieving a photoactive surface. The effect of total dose (power and treatment time) and power has been also studied to modify the surface activity of TiO₂ nanoparticles.