利用变温扫描隧道显微镜原位测量锐钛矿型TiO_(2)(001)重构表面

In-situ Measurements of Reconstructed Anatase TiO_(2)(001)Surface by Variable-Temperature STM

金属氧化物表面的催化性能主要取决于其表面原子结构,在不同的样品处理条件和催化反应过程中,表面原子结构通常会发生变化.因此,获得不同处理条件的表面原子形貌对于进一步理解复杂重构表面的催化机理具有重要意义.本文报道了氩离子刻蚀后的锐钛矿TiO_(2)(001)薄膜,在不同温度加热处理下的表面形貌演变,并使用变温扫描隧道显微镜进行了表征.实验结果表明,在不同的加热温度下,样品的表面形貌不同.热处理过程中,O原子从体相向TiO_(2)(001)表面迁移,对形成(1x4)重构过程中Ti^(2+)和Ti^(3+)态的再氧化起了重要作用.TiO_(2)(001)-(1x4)表面的原子级分辨图像显示出不对称的脊链特征,这很好地支持了TiO_(2)(001)-(1x4)重构表面的完全氧化结构模型.

The catalytic performance of metal oxide surface mainly depends on its atomic surface structure,which usually changes under various treatment conditions and during catalytic reactions.Therefore,it is quite important to acquire the atomic geometries of the surfaces under different treatments for further understanding the catalytic mechanisms in the surfaces with complicated reconstructions.Here,we report the investigation on the evolution of surface geometries of the Ar+-ion-sputtered anatase TiO_(2)(001)films followed by heating treatments at various temperatures,characterized using variable-temperature scanning tunneling microscopy.Our experimental results reveal the different surface morphologies at different heating temperatures.During the heating treatment,the migrations of O atoms from the bulk to the surface of TiO_(2)(001)play an important role in the reoxidation of the Ti^(2+)and Ti^(3+)states for the formation of(1×4)reconstruction.The atomic-resolution images of the ridges show asymmetric features,which well support the fully oxidized structural model of the reconstructed TiO_(2)(001)-(1×4)surface.