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Long-time charge separation in porphyrin/KTa(Zr)O3 as water splitting photocatalyst

2011; Royal Society of Chemistry; Volume: 13; Issue: 40 Linguagem: Inglês

10.1039/c1cp22425e

1463-9084

Hidehisa Hagiwara, Takanori Inoue, Shintaro Ida, Tatsumi Ishihara,

TiO2 Photocatalysis and Solar Cells

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 KTaO3 (KTa(Zr)O3) 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)O3 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)O3 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)O3. The formed reduced state of Cr-TPPCl was highly stable and was detected by static ESR measurements.