DFT study on the interaction of HCHO molecule with S-doped TiO_(2) (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 CeH bond of HCHO molecule is broken.The oxygen and carbon atoms of HCHO are bonded to the titanium and sulfur atoms of SeTiO_(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 CeH 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(H_(2))is bonded to the O atom(O_(2))of O_(2) molecule.The remaining CeO 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).