Adsorption of H2S molecule on TiO2/Au nanocomposites: A density functional theory study

The adsorption of hydrogen sulfide molecule on undoped and N-doped TiO2/Au nanocomposites was investigated by density functional theory (DFT) calculations. The results showed that the adsorption energies of H2S on the nanocomposites follow the order of 2N doped (Ti site)>N-doped (Ti site)>Undoped (Ti site). The structural properties including bond lengths, angles and adsorption energies and electronic properties in view of the projected density of states (PDOSs) and molecular orbitals (MOs) were analyzed in detail. The results indicated that the interaction between H2S molecule and N-doped TiO2/Au nanocomposite is stronger than that between H2S and undoped nanocomposite, suggesting that N-doping helps to strengthen the interaction of H2S with TiO2/Au nanocomposite. Mulliken population analysis was conducted to analyze the charge transfer between the nanocomposite and H2S molecule. Although H2S molecule has no significant interaction with undoped nanocomposite, it tends to be strongly adsorbed on the N-doped nanocomposite. The results also suggest that the two doped nitrogen atoms in TiO2 greatly strengthen the adsorption process, being a helpful procedure to help in the design and development of improved sensor devices for H2S detection.