Paper HC+SS-TuM3
Imaging the Ordering of Weakly Adsorbed CO₂ Molecules on Rutile Titania using Ambient Pressure Microscopy and Spectroscopy

Tuesday, October 23, 2018, 8:40 am, Room 201A

Recently, great effort has been devoted to the capture, activation and conversion of carbon dioxide (CO₂), a ubiquitous greenhouse gas and by-product of many chemical processes. The high stability and non-polar nature of CO₂ leads to weak bonding with well-defined surfaces of metals and oxides. The interactions of CO₂ involve intermolecular forces with noncovalent bonding (van der Waals), and often a surface needs to be functionalized to create polar sites that can “capture” or bind CO₂. Images from ambient pressure scanning tunneling microscopy show that a substantial amount of CO₂ can reside on a TiO₂(110) surface at room temperature as a consequence of weak bonding interactions with the substrate. Furthermore, the adsorbates exhibit a disorder-order transition on this surface, despite the lack of a strong interaction that may serve to impose its substrate periodicity on the adsorbed film. This phenomena is of interest to many areas of the surface science and chemistry community wherein condensation of van der Waals gases such as CH₄, N₂, or CO₂.

We have employed microscopic imaging under in situ conditions, soft X-ray spectroscopy and theory to decipher the unique ordering behavior seen for CO₂ on TiO₂(110).