Deformation-induced gas adsorption and self-desorption dynamics of a carbon nano-network: Molecular dynamics modeling focusing on CO₂ capture

Gas adsorption and separation/desorption are two pivotal stages in gas capture, demanding additional energy for liberating gas molecules from the adsorbent. Hence, it's essential to engineer an adsorbent with minimal energy consumption yet effective gas adsorption–desorption characteristics. Accordingly, this research introduces a carbon nano-network (CNN) material capable of inhaling and exhaling gases via self-deformation. Molecular dynamics simulations demonstrate that the gas adsorption–desorption capabilities of CNN can be efficiently regulated by its deformation. While the size of CNN minimally affects the gas sorption rate, a larger CNN necessitates a prolonged duration to achieve saturation under identical gas conditions. Incorporating elongated appendages in CNN enhances both its stability during contraction and its efficiencies in gas adsorption and desorption. We discerned that attaining a critical gas density within a confined space is imperative to initiate self-desorption of CNN. Specifically, if the gas density dips below this critical threshold–set at 5.2 times that of CO₂ at room temperature (300 K) and atmospheric pressure (1 Bar)–CNN exhibits no self-desorption capability. Nevertheless, even a marginal elevation in gas density triggers and maintains self-desorption with a consistently surpassing desorption ratio of 98 %. This discovery offers valuable insights for designing automatic self-desorption materials or apparatuses.