Effect of porous structural characteristics on the thermal conductivity of mesoporous silica by combined molecular dynamics and lattice dynamics methods

• Thermal conductivity of mesoporous silica shows clear dependence on pore structure . • Heat conduction is insensitive to hydroxyl passivation on amorphous silica surface. • Nanoporous structure can suppress the mean free path of propagons and diffusons. • Thermal conductivity is reduced through localization and scattering of heat carriers. Tuning the thermal performance of mesoporous silica is an essential developmental route for its engineering applications. The effect of porous structure on thermal behavior was investigated based on the combination of the advantages of molecular dynamics in simulating microstructural morphology and lattice dynamics in revealing physical insights in this study. The heat conduction mechanism within mesoporous silica was further revealed from the perspective of vibrational mode properties by analyzing the participation ratio, eigenmode spatial distribution and mean free path of heat carriers. The results show that the thermal conductivity of mesoporous silica can be precisely tailored by the simultaneous engineering of porosity, mesopore size, neck diameter and pore distribution. The effect of hydroxyl group passivation on heat transfer within mesoporous silica can be negligible at room temperature. The heat carriers in mesoporous silica undergo stronger localization process and more scattering effects with increasing pore size.