Highly Sensitive Detection of H2S Molecules Using a TiO2- Supported Au Overlayer Based Nanosensors: A Van Der Waals Corrected DFT Study

The adsorption of the H2S molecule on the undoped and N-doped TiO2 anatase supported Au nanoparticles were studied using density functional theory calculations. The adsorption of H2S on both Au and TiO2 sides of the nanoparticle was examined. On the TiO2 side, the fivefold coordinated titanium site was found to be the most favorable binding site, giving rise to the strong interaction of H2S with TiO2 supported Au overlayer. It was found that the central sulfur atom of the H2S molecule preferentially binds to the fivefold coordinated titanium sites via formation of strong chemical bonds. By substituting nitrogen atom into the oxygen vacancy of TiO2, significant changes in the bond lengths, bond angles and adsorption energies of the complex systems occur. The adsorption of H2S on the N-doped TiO2-supported Au nanoparticle is more favorable in energy than the adsorption on the pristine one, indicating the strong interaction of H2S with N-doped TiO2-supported Au. Thus, the N-doped nanoparticle can be utilized as potentially efficient H2S gas detection device. The substantial overlaps between the projected density of states of the titanium and sulfur atoms indicate, the formation of a chemical bond between the nanoparticle and H2S molecule. This work not only proposes a theoretical basis for gas sensing behaviors of TiO2- supported Au overlayers, but also provides an effective strategy for the development of innovative sensor devices for H2S recognition in the environment.