Imaging Water Dissociation onTiO2(110)

Scanning tunneling microscopy has been used to identify the adsorption site of ${\mathrm{H}}_2\mathrm{O}$ on ${\mathrm{TiO}}_2\left(110\right)-(1\times 1)$ at 150 K, and to monitor the site of the dissociation products at 290 K. Water adsorbs onto the rows of fivefold coordinated Ti atoms at 150 K, dissociating by 290 K to form bridging but not terminal hydroxyls. This points to the involvement of bridging O vacancies in the dissociation pathway.