Centre for Clean Environment and Energy and Griffith School of Environment, Gold Coast Campus, Griffith University, Queensland 4222, Australia.
Chemistry. 2011 May 16;17(21):5949-57. doi: 10.1002/chem.201002433. Epub 2011 Apr 8.
Anatase TiO(2) microspheres with controlled surface morphologies and exposed crystal facets were directly synthesized on metal titanium foil substrates by means of a facile, one-pot hydrothermal method without use of any templating reagent. The obtained products were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelecron spectroscopy (XPS), and the focused ion beam (FIB) technique. The sizes of the resultant microspheres ranged from 1.1 to 2.1 μm. The transformation of anatase TiO(2) microspheres with exposed {001} facets surface to nanosheets surface with {101} facets was achieved by simply controlling the hydrothermal reaction time. The anatase TiO(2) microspheres with exposed square-shaped plane {001} facets were obtained by controlling the reaction time at 1 h. The prolonged reaction time transforms the anatase TiO(2) microspheres with exposed square-shaped plane {001} facets to eroded {001} facets then to a nanosheet surface with exposed {101} facets. With hydrothermal synthesis, the surface morphological structure and crystal facets formation are highly dependent on dissolution/deposition processes, which can be strongly influenced by attributes, such as pH of the reaction media, the total concentration of dissolved and suspended titanium species, and the concentration of fluoride in the reaction solution. The changes of these attributes during the hydrothermal process were therefore measured and used to illustrate the morphology and crystal-facet transformation processes of anatase TiO(2) microspheres. The surface morphologies and crystal-facet transformations during hydrothermal processes were found to be governed by the compositional changes of the reaction media, driven by dynamically shifted dissolution/deposition equilibria. The photocatalytic activities of the photoanodes made of anatase TiO(2) microspheres were evaluated. The experimental results demonstrated that the photocatalytic activity of anatase TiO(2) microspheres with exposed {001} facets was found to be 1.5 times higher than that of the anatase TiO(2) microspheres with exposed {101} facets.
锐钛矿 TiO(2) 微球具有可控的表面形态和暴露的晶面，通过简便的一锅水热法在金属钛箔基底上直接合成，无需使用任何模板试剂。使用 X 射线衍射 (XRD)、扫描电子显微镜 (SEM)、透射电子显微镜 (TEM)、X 射线光电子能谱 (XPS) 和聚焦离子束 (FIB) 技术对所得产物进行了表征。所得微球的尺寸为 1.1-2.1μm。通过简单地控制水热反应时间，将锐钛矿 TiO(2) 微球从暴露{001}面的锐钛矿 TiO(2)微球转变为具有{101}面的纳米片表面。通过控制水热反应时间为 1h，获得具有暴露的正方形平面{001}面的锐钛矿 TiO(2)微球。延长反应时间会将暴露的正方形平面{001}面的锐钛矿 TiO(2)微球转变为侵蚀的{001}面，然后转变为具有暴露的{101}面的纳米片表面。通过水热合成，表面形态结构和晶面形成高度依赖于溶解/沉淀过程，这可以受到反应介质的 pH 值、溶解和悬浮钛物种的总浓度以及反应溶液中氟化物浓度等属性的强烈影响。因此，测量了水热过程中这些属性的变化，并用于说明锐钛矿 TiO(2)微球的形态和晶面转化过程。发现水热过程中的表面形态和晶面转化受反应介质组成变化的控制，由动态变化的溶解/沉淀平衡驱动。评估了由锐钛矿 TiO(2)微球制成的光阳极的光催化活性。实验结果表明，暴露{001}面的锐钛矿 TiO(2)微球的光催化活性比暴露{101}面的锐钛矿 TiO(2)微球高 1.5 倍。
