Greatly enhanced H2S sensitivity using defect-rich titanium oxide films

Abstract

Defect-rich titanium oxide films were prepared using the laser ablation technique. The target pellet used for the ablation was rutile phase pure stoichiometric TiO₂. X-ray photoelectron and synchrotron soft X-ray absorption spectroscopy measurements have revealed the chemical composition of the films. Using 200 mJ of laser energy, the stoichiometric transfer of TiO₂ from the target to the substrate was achieved. The films prepared using 500 mJ of laser energy were observed to be highly defect-rich with a composition of Ti/TiO_x. The gas sensing characteristics of these films were tested. The unique defect-richness of the films favours the formation of excessive overlayers of chemisorbed oxygen on the surface of the films in large proportions as compared to the lattice oxygen, making the films rich in titanium forming Ti–Ti electronic bonds, producing a great enhancement in the sensitivity toward highly toxic H₂S gas.