Effects of Oxygen Vacancy on the Adsorption of Formaldehyde on Rutile TiO2(110) Surface

Oxygen vacancy (O-v) has significant influence on physical and chemical properties of TiO2 systems, especially on surface catalytic processes. In this work, we investigate the effects of O-v on the adsorption of formaldehyde (HCHO) on TiO2(110) surfaces through first principles calculations. With the existence of Ov, we find the spatial distribution of surface excess charge can change the relative stability of various adsorption configurations. In this case, the bidentate adsorption at five-coordinated Ti (Ti-5c) can be less stable than the monodentate adsorption. And HCHO adsorbed in O-v becomes the most stable structure. These results are in good agreement with experimental observations, which reconcile the long-standing deviation between the theoretical prediction and experimental results. This work brings insights into how the excess charge affects the molecule adsorption on metal oxide surface.