Carbon dioxide (CO₂) is one of the main factors leading to the greenhouse effect, so the capture of CO₂ gas is currently a hot spot of research. Hollow silica-based porous ionic liquids (HS-liquids) are porous liquids containing cavities that are not only fluid but also have a high specific surface area and were used for the capture of CO₂. However, the mechanism of CO₂ absorption by HS-liquids has not been studied. In this work, the mechanism of CO₂ absorption by HS-liquids was systematic studied by density functional theory (DFT). First, five possible models for absorbing CO₂ in HS-liquids were constructed and optimized. The interaction energies between HS-liquids and CO₂ at different sites were obtained. Moreover, the effects of HS-liquids with different degrees of polymerization of polyethylene glycol and different alkyl chain lengths on CO₂ absorption were also investigated. Results show that the strongest absorption site locates near the polyethylene glycol unit. Then, the electrostatic potential (ESP) and reduced density gradient (RDG) methods were employed to further understand the interaction nature between them. The results show that hydrogen bonding dominates the weak interaction between the HS-liquid and CO₂.

二氧化碳（CO ₂）是导致温室效应的主要因素之一，因此，CO ₂气体的捕获是当前研究的热点。中空的二氧化硅基多孔离子液体（HS-液体）是包含腔的多孔液体，所述腔不仅是流体，而且具有高的比表面积，并且用于捕获CO ₂。但是，尚未研究HS-液体吸收CO _2的机理。在这项工作中，通过密度泛函理论（DFT）系统研究了HS液体吸收CO ₂的机理。首先，构建并优化了5种可能的在HS液体中吸收CO _2的模型。HS-液体与CO之间的相互作用能₂在不同的地点获得。此外，还研究了聚乙二醇不同聚合度和烷基链长度不同的HS-液体对CO ₂吸收的影响。结果表明，最强的吸收位点位于聚乙二醇单元附近。然后，采用静电势（ESP）和降低密度梯度（RDG）方法进一步了解它们之间的相互作用性质。结果表明，氢键控制着HS-液体与CO ₂之间的弱相互作用。