Impact of Alkoxy Chain Length on Carbazole-based, Visible Light-driven, Dye Sensitized Photocatalytic Hydrogen Production
Impact of Alkoxy Chain Length on Carbazole-based, Visible Light-driven, Dye Sensitized Photocatalytic Hydrogen Production
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烷氧基链长对咔唑基、可见光驱动、染料敏化光催化制氢的影响
DOI：
10.1039/c5ta04991a
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发表时间：
2015
影响因子：
11.9
通讯作者：
Tatsumi Ishihara
中科院分区：
文献类型：
--
作者：
Motonori Watanabe;Hidehisa Hagiwara;Yudai Ogata;Aleksandar Staykov;Sean R. Bishop;Nicola H. Perry;Yuan Jay Chang;Shintaro Ida;Keiji Tanaka;Tatsumi Ishihara
合成了烷氧基苯基取代的咔唑基无金属有机染料，并将其有效地用于染料敏化、可见光驱动、光催化制氢。以三乙醇胺为牺牲剂，研究了TiO 2/染料/Pt结构光催化制氢反应。当烷氧基链的长度足够长以充分改善染料负载的TiO 2和水介质之间的界面处的疏水性时，染料负载的TiO 2光催化剂表现出高产率的氢气产生。在烷氧基苯基取代的咔唑染料中，具有最长烷氧基链（C22）的染料表现出最好的产氢性能，但其产率仅略好于具有第二长链长（C16）的染料的产率。染料C22在可见光照射（>420 nm）24小时后显示出3094的转换数（TON）。然而，不具有疏水取代基的化合物（C1）表现出最低的产氢性能，TON为1497。因此，当存在疏水取代基时，观察到产氢产率增加207%。时间分辨吸收光谱、阻抗谱和入射光子转换效率谱的分析表明，烷氧基链在染料负载TiO 2与水的界面处具有疏水作用。具体而言，染料的疏水性提高了电子从染料注入到水中的TiO 2表面用于制氢的电荷重组寿命。
Alkoxyphenyl-substituted carbazole-based metal-free organic dyes were synthesized and effectively used for dye-sensitized, visible-light-driven, photocatalytic hydrogen production. Photocatalytic hydrogen production was investigated using a TiO2/dye/Pt structure with triethanolamine as the sacrificial reagent. The dye-loaded TiO2 photocatalyst exhibited a high yield of hydrogen production when the length of the alkoxy chain was long enough to sufficiently improve the hydrophobicity at the interface between the dye-loaded TiO2 and the water medium. In the alkoxyphenyl-substituted carbazole dyes, the dye with the longest alkoxy chain (C22) exhibited the best hydrogen production performance, but it had a yield only slightly better than that of the dye with the second longest chain length (C16). The dye C22 displayed a turnover number (TON) of 3094 after 24 h of visible light irradiation (>420 nm). However, the compound with no hydrophobic substituent (C1), exhibited the lowest hydrogen production performance with a TON of 1497. Thus, a 207% increase in the hydrogen production yield was observed when hydrophobic substituents were present. Analysis of time-resolved absorption spectra, impedance spectra and incident photon conversion efficiency spectra revealed that the alkoxy chain has a hydrophobic effect at the interface between the dye-loaded TiO2 and the water. Specifically, the hydrophobicity of the dye improved the charge-recombination lifetime for electron injection from the dye into the TiO2 surface in the water for hydrogen production.