Carbon-doped TiO₂ via Solution Plasma

Carbon-doped TiO₂ is one of the photocatalysts showing the potential to improve photocatalytic activity and initiate visible light activity. An electrical discharge in liquid phase, so-called solution plasma (SP), was successfully applied to synthesize carbon-doped TiO₂. The formation of carbon-doped TiO₂ was simply conducted by the discharge under a mixture of tetrabutyl orthotitanate and alcohols, as sources of TiO₂ and carbon, respectively, without the addition of a reducing agent. The different synthesis conditions, e.g., different electrode configurations (e.g., pin-to-pin, pin-to-coil, and crisscross), and discharge time (i.e., 5, 10, and 30 min), were investigated. The obtained carbon-doped TiO₂ was found to have a carbon content of more than 10% and a particle size ranging from 10 nm to 2 μm, depending on the synthesis conditions. The different electrode configurations were found to lead to different plasma modes. They provided the different amounts of energy to proceed the reaction in the plasma field, which exhibited the relationship to dopant concentration in TiO₂ as well as their photocatalytic activity and visible light activity. Consequently, it could imply that SP allows for the simple and tunable synthesis of carbon-doped photocatalysts for the photodegradation of a wide range of environmental pollutants.