Ishigaki Takamasa, Nakada Yusuke, Tarutani Naoki, Uchikoshi Tetsuo, Tsujimoto Yoshihiro, Isobe Masaaki, Ogata Hironori, Zhang Chenning, Hao Dong
Department of Chemical Science and Technology, Hosei University, 3-5-4 Kajino-cho, Koganei, Tokyo 184-8584, Japan.
Department of Applied Chemistry, Graduate School of Science and Engineering, Hosei University, 3-5-4 Kajino-cho, Koganei, Tokyo 184-8584, Japan.
R Soc Open Sci. 2020 Jan 15;7(1):191539. doi: 10.1098/rsos.191539. eCollection 2020 Jan.
Nano-size EVONIK AEROXIDE P25 titanium dioxide, TiO, powder was heat-treated at temperatures, 700-900°C, in air. An X-ray diffraction study showed that the P25 powder is composed of approximately 20 and approximately 80 mass% of rutile and anatase phases, respectively. It was also shown that the transformation from anatase to rutile induced by high-temperature heat treatment was almost completed at 750°C, whereas a small amount (less than 3 mass%) of anatase phase was still left even in the powder heat-treated at 900°C. The transformation behaviour was consistent with results obtained by Raman scattering spectroscopy. Raman experiments also indicated that high-temperature heating induced the formation of oxide ion vacancies. Powders were dispersed in methyl orange (MO) aqueous solution, and the bleach rate of MO was measured to evaluate photocatalytic activity under ultraviolet (UV)- and visible-light irradiation. After the heat treatment, the UV-light photocatalytic performance sharply deteriorated. Interestingly, visible-light photocatalytic activity was enhanced by high-temperature heating and reached the highest performance for an 800°C-heated sample, indicating that the P25 powder obtained high visible-light photocatalytic performance after heat treatment. Even after 900°C heat treatment, the photocatalytic performance was higher than that of as-received powder. Enhancement of photocatalytic activities was discussed in relation to visible light absorption and charge carrier transfer.
纳米级赢创德固赛AEROXIDE P25二氧化钛TiO粉末在空气中于700 - 900°C进行热处理。X射线衍射研究表明，P25粉末分别由约20质量%的金红石相和约80质量%的锐钛矿相组成。研究还表明，高温热处理诱导的从锐钛矿相向金红石相的转变在750°C时几乎完成，而即使在900°C热处理的粉末中仍残留少量（小于3质量%）的锐钛矿相。这种转变行为与拉曼散射光谱得到的结果一致。拉曼实验还表明，高温加热会诱导氧离子空位的形成。将粉末分散在甲基橙（MO）水溶液中，测量MO的漂白速率以评估紫外（UV）光和可见光照射下的光催化活性。热处理后，紫外光光催化性能急剧下降。有趣的是，可见光光催化活性通过高温加热得到增强，并且对于800°C加热的样品达到最高性能，这表明P25粉末在热处理后获得了高可见光光催化性能。即使经过900°C热处理，其光催化性能仍高于原样粉末。结合可见光吸收和电荷载流子转移对光催化活性的增强进行了讨论。
