Understanding how CO2 behaves and interacts with surfaces is paramount for the development of sensors and materials to attempt CO2 mitigation and catalysis. Combining CO-functionalized AFM and STM with first-principles simulations, we resolved how CO2 molecules are confined by one-dimensional metal-organic chains of 1,4-phenylene diisocyanide bridged by gold adatoms. We resolved how CO2 molecules physisorb and self-assemble with sub-molecular resolution, and found the formation of chiral, windmill-like arrangements of CO2 molecules that enclose standing individual CO2 molecules and other foreigner species, which together explain the previously unassigned kagome tiling of this surface system — a result relevant to CO2 capture, and on-surface synthesis strategies. Our results show the complementarity of AFM and STM using functionalized probes and their potential to explore greenhouse gas molecules at surface-supported model systems.
O. Custance, et al., “Structure and Defect Identification at Self-Assembled Islands of CO2 Using Scanning Probe Microscopy”, ACS Nano, 2024, vol. 18, p. 26759

Using AFM with oxygen-terminated probes at cryogenic temperature, we imaged individual water molecules on partially reduced CeO2−x(111) surfaces as sharp, asymmetric "boomerang-like" features, radically different from the symmetric triangular motifs reported previously. We show that these boomerang-like features localize near subsurface oxygen vacancies, where Ce3+ sites adjacent to the vacancy breaks the local symmetry and governs the water's orientation. Force spectroscopy further distinguishes these elusive Ce3+ centers by their distinct interaction signatures — a result directly relevant to the water-gas-shift reaction for the production of hydrogen and to future studies of single-atom catalysts. By resolving how subsurface defects control water adsorption at the atomic scale, this work demonstrates the power of chemically selective AFM for probing site-specific reactivity in oxide catalysts, laying the groundwork for direct investigations of complex systems such as single-atom catalysts, metal-support interfaces, and defect-engineered oxides.
O. Custance, et al., “Near-surface defects break symmetry in water adsorption on CeO2−x(111)”, Communications Materials, 2026, vol. 7, p. 39. (a Nature Portfolio journal)