DFT study on the interaction of HCHO molecule with S-doped TiO2 (001) surface without and with water and oxygen molecules

The interactions of formaldehyde (HCHO) molecule with S-doped anatase TiO 2 (001) surface without and with water and oxygen were studied by density functional theory (DFT). The adsorption energy of HCHO adsorption on S-doped TiO 2 surface with water and oxygen (−709.62 kJ/mol) is much larger than that without water and oxygen (−312.14 kJ/mol). For HCHO adsorption system without water and oxygen, one C H bond of HCHO molecule is broken. The oxygen and carbon atoms of HCHO are bonded to the titanium and sulfur atoms of S TiO 2 surface, respectively, and form a CH 2 OS structure. For the system with water and oxygen, H 2 O and HCHO molecules are both dissociated. HCHO molecule not only interacts with TiO 2 surface, but also combines with O 2 molecule. Two C H bonds of HCHO are broken, one hydrogen atom (H1) is bonded to the sulfur atom (S) of TiO 2 surface doping, while another hydrogen atom (H2) is bonded to the O atom (O2) of O 2 molecule. The remaining C O bond can be oxidized to form CO 2 in subsequent action by oxygen from the atmosphere. The surface doping of sulfur have significant impact on the degradation of HCHO molecule on anatase TiO 2 (001) surface with H 2 O and O 2 .