The molecular catalyst sensitized system (MCSS), where an excited molecular catalyst adsorbed on a semiconductor such as TiO₂ injects electrons to the conduction band of the semiconductor leading to hydrogen evolution/CO₂ reduction coupled with an oxidation of water on the molecular catalyst, has been one of the most probable candidates in the approach to artificial photosynthesis. For a full utilization of visible light, however, a serious light scattering of the aqueous suspension of TiO₂ in the visible region, which is generally experienced, should be avoided. Here, we report a preparation of optically transparent colloidal dispersion of TiO₂ by the sol/gel reaction of TiCl₄ through progressive hydrolysis/condensation under the basic condition without any calcination processes. The TiO₂ nanoparticles (TiO₂(NPs)) obtained were characterized as an amorphous particle (∼10–15 nm) having a microcrystal domain of anatase within several nm by XRD, Raman spectroscopies, XRF, XAFS, TG/DTA, and HRTEM, respectively. The energy-resolved distribution of carrier electron traps in TiO₂(NPs) as a fingerprint of TiO₂ was characterized through reversed double-beam photo-acoustic spectroscopy to have a close similarity to that of TiO₂(ST-01) as well as the observation of carrier traps by transient absorption spectroscopy. Though the powder TiO₂(NP) itself was not dispersed well in aqueous solution, the wet TiO₂(NPs) as prepared before being dried up provided a completely transparent aqueous dispersion under the acidic condition (1 M HCl). Addition of methanol enabled the colloidal dispersion (TiO₂(NPs, MeOH/H₂O, 0.1 M HCl)) to keep the optical transparency for longer than 1 year (550 days), which is the first example of TiO₂ dispersion storable for such a long period. TiO₂(NPs, MeOH/H₂O) exhibited a moderate photocatalytic reactivity of H₂ evolution with a quantum yield of ∼2.6% upon 365 nm light irradiation. An optically transparent thin film of TiO₂(NPs, MeOH/H₂O) was also successfully prepared on a glass plate to exhibit an enhanced hydrophilicity upon UV light irradiation.

中文翻译：

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溶胶/凝胶逐步水解/缩合制备的TiO2纳米颗粒的光学透明胶体分散体，可保存一年以上。

分子催化剂敏化系统（MCSS），其中吸附在诸如TiO _2之类的半导体上的激发分子催化剂将电子注入半导体的导带，从而导致氢释放/ CO ₂还原以及分子催化剂上的水氧化，一直是人工光合作用方法中最有可能的候选人之一。然而，为了充分利用可见光，应该避免通常经历的在可见光区域中TiO ₂的水悬浮液的严重光散射。在这里，我们报告通过TiCl ₄的溶胶/凝胶反应制备TiO ₂的光学透明胶体分散体通过在碱性条件下进行逐步水解/缩合而无需任何煅烧过程。通过XRD，拉曼光谱，XRF，XAFS，TG / DTA和HRTEM将获得的TiO ₂纳米颗粒（TiO ₂（NPs））表征为具有几纳米范围内锐钛矿微晶结构域的非晶颗粒（〜10-15 nm）。 ， 分别。通过反向双光束光声光谱法表征了作为TiO ₂指纹的TiO ₂（NPs）中载流子电子陷阱的能量分辨分布，与TiO ₂（ST-01）以及与TiO ₂（ST-01）的相似性瞬态吸收光谱法观察载流子陷阱。虽然粉末TiO ₂（NP）本身不能很好地分散在水溶液中，在酸性条件下（1 M HCl）干燥之前制备的湿TiO ₂（NPs）提供了完全透明的水分散体。添加甲醇可使胶体分散体（TiO ₂（NPs，MeOH / H ₂ O，0.1 M HCl））保持光学透明性超过1年（550天），这是TiO ₂分散体可存储的第一个实例。这么长的时间。TiO ₂（NPs，MeOH / H ₂ O）在365 nm的光照射下具有中等的H ₂放出光催化活性，量子产率约为2.6％。光学透明的TiO ₂薄膜（NPs，MeOH / H还成功地在玻璃板上制备了₂ O），以在紫外线照射下表现出增强的亲水性。