How cryogenic surface properties govern CO2 crystal nucleation: Molecular simulations of lattice constants and wettability effects

Understanding the nucleation of carbon dioxide (CO2) crystals on heat transfer surfaces is crucial for improving cryogenic carbon capture. Using molecular dynamics simulations, this study investigates how surface lattice constants and wettability affect CO2 crystal nucleation. Results demonstrate material-dependent variations in nucleation rates, preferential nucleation sites, and temperature thresholds of CO2 crystal nucleation. Notably, copper surfaces with a 3.61 Å lattice spacing promote highly ordered CO2 adsorption layers. This ordering shows exceptional geometric match (99.65%) with the structure of Pa3 crystals, leading to higher nucleation temperatures and faster nucleation rates. Furthermore, wettability studies reveal that a contact angle of 58° minimizes the deviation in interplanar spacing within the adsorption layer from the Pa3 crystal standard (to only 0.21%). Combining the optimal lattice constant (3.61 Å) and wettability (58°) synergistically raises the CO2 nucleation temperature threshold to 153 K. This significantly enhances the efficiency of converting gaseous CO2 into high-purity solid form. This work clarifies how surface properties jointly influence the kinetics of low-temperature CO2 solidification and provides a theoretical basis for designing efficient heat exchange surfaces in cryogenic carbon capture systems.