Adsorption and dissociation of H2S on the anatase TiO2(100) surface: DFT plus U study

This paper discusses the adsorption and dissociation of the hydrogen sulfide (H2S) molecule on the titanium dioxide surface. They were studied by density function theory (DFT). The GGA + U approach was used to analyze the adsorption behavior of the H2S molecule on the TiO2 anatase (100) surface. The results presented include adsorption energies, structural and electronic properties, charge transfer and work function. Different adsorption configurations are considered with coordination of H2S at the surface (Ti-5c, (Ti-5c)(2), O-2c and O-3c sites). The calculated adsorption energies are -0.31, -0.28, -1.14 and -5.66 eV. The most favorable adsorption sites lead to the dissociation of H2S into HS and H, where the S atom of HS binds to Ti-5c or O-2c atoms, leaving a dissociated H atom bonded to another O-2c site. Analysis of Bader's charges reveals a significant charge transfer between the molecule and the surface of the TiO2 anatase. The adsorption process reduces the work function and bandgap of the system, which improves the photocatalytic properties of TiO2.