报告摘要:

Mixed-anion materials that consist more than one anionic species in a single-phase have attracted attention for various applications.^[1] Oxynitrides containing d⁰- or d¹⁰-metal cations are typical example of visible-light-driven photocatalysts for water splitting and CO₂ conversion, since as compared to O-2p orbital, p orbitals of less electronegative anion can form a valence band that possesses more negative potential.^[2]

  Considering the key concept of mixed-anion photocatalysts (i.e., the utilization of high energy anion p orbitals for the valence band control), oxyfluorides are obviously unsuitable as visible-light photocatalysts because of the highest electronegativity of fluorine. However, we found that an oxyfluoride Pb₂Ti₂O_5.4F_1.2 possessed an unprecedented small band gap of ca. 2.4 eV, and functioned as a stable photocatalyst for visible-light water reduction/oxidation and CO₂ reduction when modified with suitable promoters.^[3] Density functional theory calculations showed that the unprecedented visible-light-response of Pb₂Ti₂O_5.4F_1.2 arises from strong interaction between Pb-6s and O-2p orbitals, which is caused by a short Pb–O bond in the pyrochlore lattice due to the fluorine substitution. Owing to the stable valence nature, photoelectrochemical water oxidation to O₂ was also achieved with a modified Pb₂Ti₂O_5.4F_1.2 electrode under simulated sunlight.^[4–6] A microwave-assisted hydrothermal approach enables to synthesize well-defined octahedral shaped Pb₂Ti₂O_5.4F_1.2 particles at mild conditions, which showed an improved activity for visible-light H₂ evolution.^[7]

  In this talk, recent progress on the “unconventional” mixed-anion photocatalysts for artificial photosynthetic reactions will be presented.

1. H. Kageyama et al., Nat. Commun. 9, 772 (2018).

2. A. Miyoshi, K. Maeda, Solar RRL 5, 2000521 (2021).

3. R. Kuriki et al., J. Am. Chem. Soc. 140, 6648 (2018).

4. N. Hirayama et al., J. Am. Chem. Soc. 141, 17158 (2019).

5. K. Maeda et al., Bull. Chem. Soc. Jpn. 94, 1869 (2021).

6. R. Mizuochi et al., J. Phys. Chem. C 127, 21544 (2023).

K. Aihara et al., ACS Materials Lett. 5, 2355 (2023). 

报告人简介：

Kazuhiko Maeda, 2007年博士毕业于东京大学，师从Kazunari Domen教授。2008-2009年在美国宾夕法尼亚州立大学从事博士后研究（合作导师：Thomas E. Mallouk教授），2009年加入东京大学任助理教授，2012年加入东京工业大学任副教授，2022年任东京工业大学任教授。主要的研究兴趣是光能到化学能转化的多相光催化研究，特别是光解水和二氧化碳固定。