title: Long-time charge separation in porphyrin/KTa(Zr)O3 as water splitting photocatalyst.
abstract: Artificial photosynthesis is one of the chemists' dreams and the separation of charges with long lives is fundamental for achieving artificial photosynthesis. In actual photosynthesis, Z-scheme excitation separates electronic charge with high efficiency using solar light. Here we report that photo-excitation in Cr-tetraphenylporphyrin chroride (Cr-TPPCl)/Zr doped KTaO(3) (KTa(Zr)O(3)) is analogous to the Z-scheme in photosynthesis, and that we achieve complete charge separation at room temperature. Photovoltaic decay and transient fluorescence spectra measurements showed that the photo-excited charge in KTa(Zr)O(3) transferred to the HOMO of Cr-TPPCl within a few hundred pico-seconds on charge transfer. In contrast, the reduced state of the Cr-TPPCl species that was formed by the electronic injection from KTa(Zr)O(3) was observed for more than 0.5 s at room temperature in the transient decay of the absorption spectra change after the initial excitation of KTa(Zr)O(3). The formed reduced state of Cr-TPPCl was highly stable and was detected by static ESR measurements.
authors.affiliation: Department of Applied Chemistry, Kyushu University, 744 Motooka, Fukuoka 8190395, Japan. h.hagiwara@cstf.kyushu-u.ac.jp
authors.forename: Hidehisa
authors.initials: H
authors.lastname: Hagiwara
authors.forename: Takanori
authors.initials: T
authors.lastname: Inoue
authors.forename: Shintaro
authors.initials: S
authors.lastname: Ida
authors.forename: Tatsumi
authors.initials: T
authors.lastname: Ishihara
mesh_terms: D002384:Catalysis; D002857:Chromium / Q000737:chemistry; D004579:Electron Transport; D010087:Oxides / Q000737:chemistry*; D010788:Photosynthesis; D011166:Porphyrins / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry*; D013635:Tantalum / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry
chemical_list: D010087:Oxides; D011166:Porphyrins; C409084:tetraphenylporphyrin; D014867:Water; D002857:Chromium; D013635:Tantalum; D015040:Zirconium; D011188:Potassium