The interaction between HCHO and TiO2 (1 0 1) surface without and with water and oxygen molecules

Abstract

The interactions between formaldehyde (HCHO) molecule and TiO2 (1 0 1) surface without and with water and oxygen were studied using density functional theory calculations. The adsorption energy of HCHO adsorption on TiO2 surface without water and oxygen is −360.96 kJ/mol, and HCHO molecule is not dissociated. The oxygen and carbon atoms of HCHO are bonded to the titanium and oxygen (O1) atoms of TiO2 surface, respectively, and form a dioxymethylene (CH2O2) structure. The adsorption energy of HCHO adsorption on TiO2 surface system with water and oxygen is −723.40 kJ/mol, and O2, H2O and HCHO molecules are all dissociated. HCHO molecule not only interacts with TiO2 surface, but also combines with O2 molecule. Two CH bonds of HCHO are broken, one hydrogen atom (H1) is bonded to the oxygen atom (O2) of O2, while another hydrogen atom (H2) is bonded to the O atom (O1) of TiO2 surface. The remaining CO bond that the dissociated and new formed HO bonds can be oxidized to form carbon dioxide and water in subsequent action by oxygen from the atmosphere. H2O and O2 molecules have a great effect on the degradation process of HCHO molecule on TiO2 (1 0 1) surface.