Abstract:
Carbon monoxide (CO), as a prototypical low-Z system, can polymerize under high pressure to form polymeric carbon monoxide (p-CO). The polymerization mechanism and structure are of fundamental importance to understand pressure-induced bonding and explore novel functional materials. However, progress in this field has been hindered by two major challenges: the high polymerization pressure required for CO and the metastable property of p-CO at ambient pressure. Recent studies have shown that hydrogen (H₂) doping can facilitate the polymerization of CO, but the reaction mechanisms and polymerization structures are still poorly understood. In this work, molecular dynamics simulations were performed to investigate the influence of H₂ on the polymerization mechanism of CO. The results demonstrate that a doping ratio of 10% can optimally reduce the polymerization pressure of CO. At 3~4 GPa, H₂ physically promotes the dimerization reaction of CO. At 5 GPa, the chemical inertness of H₂ inhibits further polymerization of CO. When the pressure reaches 10 GPa, H₂ participates in the polymerization reaction, forming C-H and O-H bonds. Finally, the polymerization progress produces a disordered three-dimensional network structure (p-CO/H) dominated by C-C and C=O bonds.
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