Thermal Conductivity of Amine-Appended Metal-Organic Frameworks for Carbon Capture using Neural Network Interatomic Potentials

Diamine-appended Mg2(dobpdc) (dobpdc 4-=4,4’-dioxidobiphenyl-3,3’-dicarboxylate) metal-organic frameworks (MOFs) capture CO2 via cooperative adsorption mechanisms, enabling a small temperature or pressure swing to reach full working capacity. As the adsorption/desorption process is temperature driven, understanding thermal transport in these materials is vital to their use in carbon capture applications. Previous molecular dynamics simulations of Zn2(dobpdc) MOFs suggest they are in the ultra-low thermal conductivity regime[1]. In this work, we combine neural network potentials[2] with a recently-introduced general framework[3] to predict the thermal conductivity of amine-appended Mg2(dobpdc). We explain its origin and identify the responsible phonon modes, comparing the case of the diamine-appended MOF with the unfunctionalized MOF with and without CO2. Implications for thermal management of these materials in carbon capture applications are discussed.

[1] Babaei et al. ACS Appl. Mater. Interfaces 12, 44617 (2020)

[2] Shaidu et al, in preparation (2022)

[3] Simoncelli et al. Nat. Phys. 15, 809 (2019)