2-Propanol Interacting with Co3O4(001):A combined AIMD and vSFS study

The interaction of 2-propanol with Co3O4(001) was studied by vibrational sum fre-quency spectroscopy (vSFS) and by ab initio molecular dynamics (AIMD) simulations of 2-propanol dissolved in a water film to gain insight at the molecular level into the pathways of catalytic oxidation. The experimental study has been performed under near ambient condition, where the presence of water vapor is unavoidable, resulting in a water film on the sample and thereby allowing us to mimic the solution-water interface. Both experiment and theory conclude that 2-propanol adsorbs molecularly. The lack of dissociation is attributed to the adsorption geometry of 2-propanol in which the O-H bond does not point towards the surface. Furthermore, the copresent water not only competitively adsorbs on the surface but also inhibits 2-propanol deprotonation. The calculations reveal that the presence of water deactivates the lattice oxygen, thereby reducing the surface activity. This finding sheds light on the multifaceted role of water at the interface for the electrochemical oxidation of 2-propanol in aqueous solution as recently reported. At higher temperatures 2-propanol remains molecularly adsorbedon Co3O4(001) until it desorbs with increasing surface temperature.