Key Structure–Property Relationships in CO₂ Capture by Supported Alkanolamines

Heterogeneous interfaces exhibit remarkable material properties resulting from their structural motifs, the judicious placement of functional chemical groups, etc. It has been a long-standing challenge to manipulate and design interface structures at the atomic level to achieve new functionalities. Here, we demonstrate that by modifying the length of the backbone in alkanolamines one can control the packing density of organic monolayers adsorbed on rutile TiO₂ and the interaction strength between their amine functional group and the substrate. As a result, we observed strikingly different activities in CO₂ capture by the amine functional group of different alkanolamines on TiO₂(110). Synchrotron photoelectron spectroscopy at near-ambient CO₂ pressures showed that adsorbed 2-amino-1-ethanol (monoethanolamine, MEA) is inactive, whereas the amine group in 3-amino-1-propanol (3AP)/TiO₂(110) readily reacts with and captures CO₂. Our results suggest that the geometry of the interface plays a decisive role in the reactivity of adsorbed functionalized organic molecules, such as solid-supported alkanolamines for CO₂ capture