Pt-modified TiO2 nanorod array films on FTO with enhanced CO sensitivity: A combined experimental and first-principle study

In this work, highly regular TiO2 array films consisting of nanorods with a diameter of ∼119 nm were grown on FTO via a facile hydrothermal method. Then Pt nanoparticles with a size of ∼5 nm were modified on the surface of TiO2 nanorods via an in-situ reduction process. The gas-sensing performances of pristine TiO2 and Pt-modified TiO2 samples were systematically tested. The introduction of Pt nanoparticles could enhance the response and stability toward CO gas and decrease the optimal operating temperature from 400 ℃ to 360 ℃. And the Pt/TiO2-based sensor with a Pt content of 1.5 wt% exhibits the maximum CO sensitivity. Furthermore, the adsorption energies of Pt-modified or Pt-doped TiO2 for CO molecules were calculated using first-principles calculations. The chemical sensitivity of Pt to CO molecules may be responsible for the improved CO sensitivity. Additionally, the unique nanorod array structure of Pt/TiO2 and the nano-Schottky junction generated between them are helpful in enhancing the gas-sensing property.