Reactivity Screening of Anatase TiO_2 Nanotubes Array and Anatase Thin Films: A Surface Chemistry Point of View

摘要

As a reactivity screening we collected thermal desorption spectroscopy (TDS) data of iso-butane, O_2, CO_2, and CO adsorbed on an ordered TiO_2 nanotubes (TiNTs) array. As a reference system iso-butane adsorption on an anatase TiO_2 thin film has been considered as well. The as-grown TiNTs are vertically aligned and amorphous. Polycrystalline (poly.) anatase or poly. anatase/rutile mixed nanotubes are formed by annealing confirmed by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The anatase thin film was grown on SrTiO_3(001) and characterized by XRD and atomic force microscopy (AFM). Surprisingly, oxygen distinctly interacts with the TiNTs whereas this process is not observed on fully oxidized single crystal rutile TiO_2(l10). Desorption temperatures of 110-150 K and 100-120 K were observed for CO_2 and CO, respectively, on the TiNTs. Variations in the binding energies of the alkanes on TiNTs and anatase thin films also were present, i.e., a kinetic structure-activity relationship (SAR) is evident.