Molecular thermodynamic understanding of transport behavior of CO₂ at the ionic liquids-electrode interface

The transport behavior of CO₂ at the ionic liquids (ILs)-electrode interface was revealed from the thermodynamic view via molecular dynamics simulations. The hopping and self-diffusive mechanisms were identified in the interfacial and bulk region, and thereafter a hopping-diffusion model was developed to evaluate the transport resistance of CO₂ from bulk to the interface. Meanwhile, the vibrational spectrum and entropy change of CO₂ at the interface were calculated using the thermodynamic analysis method. For ILs with the same cation ([Emim]⁺), both transport resistance and entropy decrease follow the order: [BF₄]⁻ < [AC]⁻ < [NO₃]⁻, indicating [BF₄]⁻ possesses the faster CO₂ transport efficiency across the electrical double layer. Furthermore, the methyl substitution effect on transport and thermodynamic properties was clarified, indicating the coupling relation between the transport process and thermodynamic advantage. These findings can lay the ground for the molecule design of ILs-electrode interface in the applications in the chemical engineering field.