Time: 8th May, 2019, 3:00 pm
Venure: Energy Fundamentals Building, 1st floor conference room
Lecuter: Kazuhiko Maeda, Tokyo Institute of Technology
Mixed anion compounds that contain more than two anionic species in a single phase are good candidates as visible-light-responsive photocatalysts. The key concept in the mixed anion photocatalysts is the use of p orbitals of less electronegative anion than oxygen, which form a more negative valence band, without significantly affecting the conduction band minimum. As the result, a narrow-gap mixed anion material is obtained. For example, many oxynitrides that consist of early transition metal ions or typical metal ions have been reported as photocatalysts for visible-light water splitting and CO2 reduction. In this talk, recent progress on the development of new mixed anion photocatalysts made by our group will be given.
For example, we found that an anion-ordered pyrochlore oxyfluoride Pb2Ti2O5.4F1.2 works as a stable photocatalyst for visible-light-driven water reduction/oxidation and CO2 reduction. In terms of the electronegativity of anion, oxyfluorides had been believed to be unsuitable as visible-light photocatalysts, because of the highest electronegativity of fluorine. Nevertheless, Pb2Ti2O5.4F1.2 has a small band gap of ca. 2.4 eV and indeed works as a photocatalyst. Density functional theory calculations indicated that the unprecedented visible-light-response of Pb2Ti2O5.4F1.2 originates from strong interaction between Pb-6s and O-2p orbitals, which is enabled by a short Pb-O bond in the pyrochlore lattice due to the fluorine substitution.
Dr. Kazuhiko Maeda received his PhD from The University of Tokyo (2007) under the supervision of Professor Kazunari Domen. During 2008-2009, he was a postdoctoral fellow at The Pennsylvania State University, where he worked with Professor Thomas E. Mallouk. He then joined The University of Tokyo as an Assistant Professor in 2009. Moving to Tokyo Institute of Technology in 2012, he was promoted to an Associate Professor. He was also appointed as a PRESTO/JST researcher during 2010-2014. His major research interest is heterogeneous photocatalysis for light to chemical energy conversion, with a focus on water splitting and CO2 fixation. He published more than 160 peer-reviewed papers on international journals with more than 28,000 citations and h-index of 71.
Contact: SHEN Liyan, DNL16T2