Facile One-Step Route for the Development of in Situ Cocatalyst-Modified Ti 3+ Self-Doped TiO 2 for Improved Visible-Light Photocatalytic Activity.

Development of visible-light-driven photocatalysts by employing a relatively simple, efficient, and cost-effective one-step process is essential for commercial applications. Herein, we report for the first time the synthesis of in situ Cu-ion modified Ti self-doped rutile TiO by such a facile one-step solution precursor plasma spray (SPPS) process using a water-soluble titanium precursor. In the SPPS process, Ti self-doping on Ti of rutile TiO is found to take place because of electron transfer from the created oxygen vacancies to Ti-ions. In situ Cu modification of the above Ti self-doped rutile TiO by additionally introducing a Cu solution into plasma plume is also demonstrated. While the Ti self-doping induces broad absorption in the visible-light region, the addition of Cu ion leads to even broader absorption in the visible region owing to resulting synergistic properties. The above materials were evaluated for various self-cleaning photocatalytic applications under visible-light illumination. Cu-ion modified Ti self-doped rutile TiO is noted to exhibit a remarkably enhanced visible-light activity in comparison with Ti self-doped rutile TiO, with the latter itself outperforming commercial TiO photocatalysts, thereby suggesting the suitability of the material for indoor applications. The broad visible-light absorption by Ti self-doping, the holes with strong oxidation power generated in the valence band, and electrons in Ti isolated states that are effectively separated into the high reductive sites of Cu ions upon visible-light irradiation, accounts for improved photocatalytic activity. Moreover, the synthesis process (SPPS) provides a valuable alternative to orthodox multistep processes for the preparation of such visible-light-driven photocatalysts.