Author:
Bai Jaeil,Francisco Joseph S.,Zeng Xiao Cheng
Abstract
Both carbon dioxide (CO2) and water (H2O) are triatomic molecules that are ubiquitous in nature, and both are among the five most abundant gases in the Earth’s atmosphere. At low temperature and ambient pressure, both CO2 and H2O form molecular crystals––dry ice I and ice Ih. Because water possesses distinctive hydrogen bonds, it exhibits intricate and highly pressure-dependent phase behavior, including at least 17 crystalline ice phases and three amorphous ice phases. In contrast, due to its weak van der Waals intermolecular interactions, CO2 exhibits fewer crystalline phases except at extremely high pressures, where nonmolecular ordered structures arise. Herein, we show the molecular dynamics simulation results of numerous 2D polymorphs of CO2 molecules in slit nanopores. Unlike bulk polymorphs of CO2, 2D CO2 polymorphs exhibit myriad crystalline and amorphous structures, showing remarkable polymorphism and polyamorphism. We also show that depending on the thermodynamic path, 2D solid-to-solid phase transitions can give rise to previously unreported structures, e.g., wave-like amorphous CO2 structures. Our simulation also suggests intriguing structural connections between 2D and 3D dry ice phases (e.g., Cmca and PA-3) and offers insights into CO2 polyamorphic transitions through intermediate liquid or amorphous phases.
Funder
National Science Foundation
Publisher
Proceedings of the National Academy of Sciences
Cited by
6 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献