Carbon monoxide sensing mechanism of highly oriented TiO2 from first principles

The structural, adsorptive and electronic properties of CO adsorption on TiO2 are investigated by the first principles calculations with special focus on three experimentally confirmed facets, namely (0 0 1), (1 0 0) and (1 0 1) surfaces, respectively. Calculation results predict that CO adsorbed on Ti site is the most energetically favorable mode among three low index TiO2 surfaces. It is found that the (1 0 0) surface hold more benefit for CO adsorption than that of other surfaces, which is mainly attributed to significant change of the electronic property of adsorbed surface and large electrons transfer between CO molecule and the surface. Calculation results theoretically verify the experimental fact that highly oriented TiO2 enable exhibit distinct sensing performance. These findings render a careful synthesis of TiO2 films so as to form a high orientation of (1 0 0) facet, which will be primarily important for further enhance CO sensing performance of TiO2-based sensor.