A Systematic Study on the Crystal Facets-Dependent Gas Sensing Properties of Anatase TiO2 with Designed {010}, {101} and {001} Facets

Design and control of crystal facets is a promising way to optimize the gas sensing activity of metal oxides semiconductors. To study the crystal facets effects on the gas sensing properties, a series of anatase TiO2 with designed crystal facets were synthesized by hydrothermal routes. The gas sensing properties of the three most important low-index crystal facets ({010}, {001} and {101} facets) of anatase TiO2 were systematically studied and compared for the first time. It was found that {010} facets exhibited a surprisingly higher sensing activity in comparison with that of {101} facets and {001} facets, and the gas sensing activity order were determined to be {010} facets > {001} facets > {101} facets. The crystal facets-dependent gas sensing mechanism was investigated based on theory calculations from the atomic and electronic scale. It was found that the excellent gas adsorption properties and electron transfer properties both facilitated the gas response of {010} facets. The present results not only provide a new way to improve the gas response of TiO2 by exposing of {010} facets, but also deepen the understanding of crystal facets-dependent gas sensing properties of TiO2, which will be useful for the design of metal oxides gas sensing materials.