Dependence of Photocatalytic Activity on Aspect Ratio of Shape-Controlled Rutile Titanium(IV) Oxide Nanorods

Shape-controlled rutile titanium(IV) oxide (TiO2) nanorods with various aspect ratios were prepared by two-step synthesis in the presence of two kinds of inorganic anions. The first synthesis step from titanium(III) chloride solution induced the formation of aggregated needlelike rutile TiO2, the shape of which largely depended on the inorganic anion used. Moreover, shape-controlled rutile TiO2 rods with {110} side crystal faces and {111} and/or {001} edge crystal faces were obtained by hydrothermal treatment of the needlelike rutile TiO2. Their aspect ratios were largely influenced by the starting material used in the hydrothermal treatment. The photocatalytic activity for decomposition of acetaldehyde increased with decreasing aspect ratio because the surface area ratio of {111} and/or {001} to {110} exposed crystal faces, which are attributed to oxidation and reduction sites respectively, became more optimal.

在两种无机阴离子存在的情况下，通过两步合成法制备了具有不同长径比的形状可控的金红石型二氧化钛（TiO₂）纳米棒。从氯化钛（III）溶液开始的第一步合成促使了聚集的针状金红石型TiO₂的形成，其形状在很大程度上取决于所使用的无机阴离子。此外，通过对针状金红石型TiO₂进行水热处理，获得了具有{110}侧面晶面以及{111}和/或{001}端面晶面的形状可控的金红石型TiO₂棒。它们的长径比在很大程度上受到水热处理中所使用的起始原料的影响。由于分别归因于氧化位点和还原位点的{111}和/或{001}与{110}暴露晶面的表面积比变得更优，乙醛分解的光催化活性随着长径比的降低而提高。