Our study on charge-transfer dynamics in dye-sensitized photocatalysis using long-wavelength visible-light-absorbing metal-complex dyes has been published in ACS Catalysis.

In collaboration with the Maeda group at Institute of Science Tokyo, we have clarified the relationship between charge-transfer processes and hydrogen-evolution activity in a dye-sensitized photocatalytic system employing an Os(II) polypyridyl complex as the photosensitizer. This work has been published in ACS Catalysis.

In this study, we leveraged the strong long-wavelength visible-light absorption of the Os(II) complex arising from a triplet metal-to-ligand charge-transfer (³MLCT) transition, which enables efficient light harvesting up to around 800 nm. The Os(II) dye was integrated into a Pt-loaded semiconductor photocatalyst platform to evaluate its charge-transfer behavior and photocatalytic performance.

As a result, under visible-light irradiation, the Os(II)-sensitized system exhibited higher hydrogen-evolution activity than the corresponding Ru(II)-based system. In contrast, in Z-scheme overall water splitting, electron transfer between the photosensitizer and the redox mediator was identified as the rate-limiting step.

“Charge Transfer Dynamics in Dye-Sensitized Photocatalysts Using Metal Complex Sensitizers with Long-Wavelength Visible Light Absorption Based on Singlet–Triplet Excitation”
Haruka Yamamoto, Toshiya Tanaka, Masahito Oura, Kelly M. Kopera, Megumi Okazaki, Ken Onda, Thomas E. Mallouk, Kazuhiko Maeda
ACS Catal., 15, 20889-20898 (2025).