Nonaqueous synthesis of TiO2 nanorods using inductively coupled plasma

Titanium dioxide (TiO₂) nanorods are widely used in many fields such as self-cleaning surfaces, photocatalytic lithography and pollutant control, owing to their outstanding physical, chemical and optical properties. Traditional methods for synthesizing TiO₂ nanorods are mostly tedious with high cost and tremendous energy consumption. In this work, TiO₂ nanorods with excellent optical, electrochemical, and hydrophilic properties were rapidly synthesized on titanium alloy (TC4) by using inductively coupled plasma (ICP) with strong chemical reactivity and high temperature characteristic. XRD patterns and SEM images confirm the conversion of TC4 into rutile TiO₂ nanorods after irradiated by ICP at 800 W for only one pass, and the nanorods tend to grow longitudinally under prolonged ICP processing. Moreover, the well-developed single-crystalline feature of TiO₂ nanorod is affirmed by TEM test. To reveal the growth mechanism of TiO₂ nanorods, three types of substrates (polished TC4 by electrochemical polishing (ECP), polished TA2 by ECP and oxidized TC4 by anodizing) were used to grow TiO₂ nanorods. However, TiO₂ nanorods with good morphology were only formed on the first type of substrate due to the existence of β phase Ti, which could suppress thermal transmission between grains. In addition, the results of UV–Vis absorption spectrum, electrochemical test, and static water contact angle of the treated TC4 samples show that TiO₂ nanorods synthesized by ICP possess excellent optical, electrochemical, and hydrophilic properties.