Yamazaki Yukari, Mori Kohsuke, Kuwahara Yasutaka, Kobayashi Hisayoshi, Yamashita Hiromi
Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Osaka 565-0871, Japan.
Unit of Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520, Japan.
ACS Appl Mater Interfaces. 2021 Oct 20;13(41):48669-48678. doi: 10.1021/acsami.1c13756. Epub 2021 Oct 6.
Defect engineering of metal oxides is a facile and promising strategy to improve their photocatalytic activity. In the present study, Pt/TiO was prepared by a reduction treatment assisted by hydrogen spillover to pure rutile, anatase, and brookite and was subsequently used for hydrogen production from an aqueous methanol solution. With increasing reduction temperature, the photocatalytic activity of the rutile Pt/TiO increased substantially, whereas the activity of anatase Pt/TiO decreased and that of brookite Pt/TiO was independent of the treatment temperature. Electron-spin resonance analysis revealed that rutile and brookite possess similar defect sites (Ti and concomitant oxygen vacancy) after the reduction at 600 °C, whereas different resonance signals were observed for anatase after the reduction at 600 °C. During the reduction process, electrons donated from spillover hydrogen migrate between the conduction band and the inherent midgap states. This research demonstrates that the depth of the inherent midgap states, depending on the crystal phases, influences the generation of defects, which play a key role in the photocatalytic performance of Pt/TiO.
金属氧化物的缺陷工程是一种简便且有前景的提高其光催化活性的策略。在本研究中，通过氢溢流辅助还原处理制备了Pt/TiO，用于纯金红石、锐钛矿和板钛矿，并随后用于从甲醇水溶液中制氢。随着还原温度的升高，金红石型Pt/TiO的光催化活性大幅提高，而锐钛矿型Pt/TiO的活性降低，板钛矿型Pt/TiO的活性与处理温度无关。电子自旋共振分析表明，在600℃还原后，金红石和板钛矿具有相似的缺陷位点（Ti和伴随的氧空位），而在600℃还原后，锐钛矿观察到不同的共振信号。在还原过程中，溢流氢提供的电子在导带和固有带隙中间态之间迁移。本研究表明，取决于晶体相的固有带隙中间态的深度影响缺陷的产生，而缺陷在Pt/TiO的光催化性能中起关键作用。
