Formation and Stabilization Mechanisms of Enols on Pt through Multiple Hydrogen Bonding

Abstract

Lateral interactions between coadsorbed molecules on surfaces might trigger specific reaction pathways and stabilize otherwise energetically unstable reaction intermediates. These phenomena can crucially affect the overall activity and selectivity of catalytic processes and can be employed for purposeful functionalization of surfaces to improve their catalytic efficiency. In this report, we present a study on the atomistic-level details of intermolecular interactions between acetophenone adsorbates on Pt. We show that these interactions trigger an important reaction of keto–enol tautomerization producing an enol reaction intermediate, which is envisaged to enable low-barrier hydrogenation of simple carbonyl compounds. By combining scanning tunneling microscopy and infrared reflection–absorption spectroscopy, we found that several types of hydrogen-bonded oligomer species can be formed, including ketone–enol dimers and ketone–enol–enol trimers. Their evolution exhibits a strong temperature dependence, sugg...