Synthesis of TiO2 nanocoral structures in ever-changing aqueous reaction systems.
Synthesis of TiO2 nanocoral structures in ever-changing aqueous reaction systems.
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DOI：
10.1021/la203943j
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发表时间：
2012-01
期刊：
影响因子：
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通讯作者：
Tetsuro Soejima;R. Jin;Y. Terayama;A. Takahara;Takamasa Shiraishi;S. Ito;N. Kimizuka
中科院分区：
文献类型：
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作者：
Tetsuro Soejima;R. Jin;Y. Terayama;A. Takahara;Takamasa Shiraishi;S. Ito;N. Kimizuka
开发了一种远非平衡策略来在各种表面上合成珊瑚状 TiO(2) 纳米结构。 TiO(2)纳米珊瑚结构由锐钛矿基膜和金红石纳米线层组成，它们连续形成在浸有TiOSO(4)-H(2)O(2)水溶液的基底上。 TiO(2) 的连续沉积始于水相中钛过氧络合物的水解和缩合反应，导致非晶态薄膜的沉积。该薄膜充当粘合界面，金红石纳米线在其上连续生长。这种初始沉积反应伴随着反应介质pH值的变化，这是金红石纳米晶体生长的有利条件。在金红石纳米珊瑚层的生长过程中，无定形基膜转变为锐钛矿相。这些连续沉积反应发生在低至 80 °C 的温度下，温和的合成条件允许使用多种基材，例如 ITO（氧化铟锡）、玻璃，甚至有机聚合物薄膜。通过重复金红石纳米珊瑚的生长反应可以控制纳米珊瑚层的厚度。 TiO(2) 纳米珊瑚表现出光催化活性，Ag(I) 离子的位点特异性还原反应优先在金红石纳米线层上进行。金红石纳米线层还表现出乙醛的光催化分解，随着纳米线层厚度的增加，乙醛的分解得到促进。使用时间转变反应介质可以形成双相TiO(2)纳米珊瑚结构，并且非平衡合成方法的概念将广泛适用于开发结构梯度无机纳米界面。
A far-from-equilibrium strategy is developed to synthesize coral-like nanostructures of TiO(2) on a variety of surfaces. TiO(2) nanocoral structures consist of anatase base film and rutile nanowire layers, and they are continuously formed on substrates immersed in aqueous TiOSO(4)-H(2)O(2). The sequential deposition of TiO(2) starts with hydrolysis and condensation reactions of titanium peroxocomplexes in the aqueous phase, resulting in deposition of amorphous film. The film serves as adhesive interface on which succeeding growth of rutile nanowires to occur. This initial deposition reaction is accompanied by shift in pH of the reaction media, which is favorable condition for the growth of rutile nanocrystals. During the growth of rutile nanocoral layers, the amorphous base films are transformed to anatase phase. These sequential deposition reactions occur at temperatures as low as 80 °C, and the mild synthetic condition allows the use of a wide range of substrates such as ITO (indium tin oxide), glass, and even organic polymer films. The thickness of nanocoral layer is controllable by repeating the growth reaction of rutile nanocorals. TiO(2) nanocorals show photocatalytic activity as demonstrated by site-specific reduction of Ag(I) ions, which proceeds preferentially on the rutile nanowire layer. The rutile nanowire layer also shows photocatalytic decomposition of acetaldehyde, which is promoted upon increase of the thickness of the nanowire layer. The use of temporally transforming reaction media allows the formation of biphasic TiO(2) nanocoral structures, and the concept of nonequilibrium synthetic approach would be widely applicable to developing structurally graded inorganic nanointerfaces.