Solution Plasma Process-Derived Defect-Induced Heterophase Anatase/Brookite TiO2 Nanocrystals for Enhanced Gaseous Photocatalytic Performance

We report a simple room-temperature synthesis route for increasing the reactivity of a TiO2 photocatalyst using a solution plasma process (SPP). Hydrogen radicals generated from the SPP chamber interact with the TiO2 photocatalyst feedstock, transforming its crystalline phase and introducing oxygen vacancy defects. In this work, we examined a pure anatase TiO2 as a model feedstock because of its photocatalytic attributes and well-characterized properties. After the SPP treatment, the pure anatase crystalline phase was transformed to an anatase/brookite heterocrystalline phase with oxygen vacancies. Furthermore, the SPP treatment promoted the absorption of both UV and visible light by TiO2. As a result, TiO2 treated by the SPP for 3 h showed a high gaseous photocatalytic performance (91.1%) for acetaldehyde degradation to CO2 compared with the activity of untreated TiO2 (51%). The SPP-treated TiO2 was also more active than nitrogen-doped TiO2 driven by visible light (66%). The overall photocatalytic performance was related to the SPP treatment time. The SPP technique could be used to enhance the activity of readily available feedstocks with a short processing time. These results demonstrate the potential of this method for modifying narrow-band gap metal oxides, metal sulfides, and polymer composite-based catalyst materials. The modifications of these materials are not limited to photocatalysts and could be used in a wide range of energy and environment-based applications.