1421276-06-3Relevant academic research and scientific papers
Hydrophilicity control of visible-light hydrogen evolution and dynamics of the charge-separated state in dye/TiO2/Pt hybrid systems
Han, Won-Sik,Wee, Kyung-Ryang,Kim, Hyun-Young,Pac, Chyongjin,Nabetani, Yu,Yamamoto, Daisuke,Shimada, Tetsuya,Inoue, Haruo,Choi, Heesung,Cho, Kyeongjae,Kang, Sang Ook
, p. 15368 - 15381 (2012)
Visible-light-driven H2 evolution based on Dye/TiO 2/Pt hybrid photocatalysts was investigated for a series of (E)-3-(5'-{4-[bis(4-R1-phenyl)amino]phenyl}-4,4'-(R2) 2-2,2'-bithiophen-5-yl)-2-cyanoacrylic acid dyes. Efficiencies of hydrogen evolution from aqueous suspensions in the presence of ethylenediaminetetraacetic acid as electron donor under illumination at λ>420 nm were found to considerably depend on the hydrophilic character of R1, varying in the order MOD (R1=CH 3OCH2, R2=H)≈MO4D (R1=R 2=CH3OCH2)>HD (R1=R 2=H)>PD (R1=C3H7, R 2=H). In the case of MOD/TiO2/Pt, the apparent quantum yield for photocatalyzed H2 generation at 436 nm was 0.27A±0.03. Transient absorption measurements for MOD- or PD-grafted transparent films of TiO2 nanoparticles dipped into water at pH 3 commonly revealed ultrafast formation (.+) followed by multicomponent decays, which involve minor fast decays (1 and major slower decays with significant differences between the two samples: 1) the early decay of the major components for MOD is about 2.5 times slower than that for PD and 2) a redshift of the spectrum occurred for MOD with a time constant of 17 ps, but not for PD. The substituent effects on H2 generation as well as on transient behavior have been discussed in terms substituent-dependent charge recombination (CR) of Dye.+ with electrons in bulk, inner-trap, and/or interstitial-trap states, arising from different solvent reorganization. Photosensitized H2 generation by a series of Dye/TiO2/Pt hybrids revealed clear dependence on the hydrophilic/hydrophobic character of the substituent R of Dye (see figure; I(H2)=apparent quantum yield for H2 generation.), which was shown by femtosecond transient spectroscopy to arise from the hydrophilic control of charge recombination (CR) between Dye.+ and the injected electron TiO2(e -). Copyright
