First-principles Study of Formaldehyde Adsorption on TiO_2 Surfaces

Using DFT method,HCHO adsorption on TiO2rutile(110),and anatase(101)surfaces was investigated.The results show that both physisorption and chemisorption of HCHO can be formed stably on these surfaces.In physisorptions,the influence on the structures of HCHO was negligible.However,the distortion caused by adsorption of molecular structures was significant in chemisorptions.The molecule formed into a dioxymethylene species(CH2O2)through bonding with a surface 2fold coordinated O atom(O2C).The elongation of carbonyl in the chemically adsorbed HCHO by 14%-17%indicated that intramolecular interaction of HCHO has been weakened and it was easy to be decomposed.Additionally,due to the higher capability of adsorption of HCHO,rutile(110)showed a higher activity than anatase(101)surface.