Effects of Adsorbates on Thermal Transport in Metal-Organic Frameworks

Fast heat transfer during gas adsorption/separations in metal-organic frameworks (MOFs) plays a key role in improving their efficiency for gas storage/capture. Despite its importance, heat transfer in MOFs is not well understood, and whether it is helped or hindered by the presence of adsorbates is an open question. Our computational and experimental research indicate that depending on the nature of guest-framework interaction, adsorbates can increase or decrease thermal conductivity. The presence of physisorbed guests introduces new phonon scattering channels resulting from gas-framework collisions, which serve to reduce thermal conductivity. On the other hand, enhancement in thermal conductivity is observed for e-2–Zn₂(dobpdc) (e-2 = N-ethylethylenediamine; dobpdc⁴⁻ = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate) in the presence of chemisorbed CO₂.