Thermal transport enhancement of hybrid nanocomposites; impact of confined water inside nanoporous silicon.

The thermal transport properties of porous silicon and nano-hybrid "porous silicon/water" systems are presented here. The thermal conductivity was evaluated using the equilibrium molecular dynamics technique for porous systems made of spherical voids or water-filled cavities. We revealed large thermal conductivity enhancement in the nano-hybrid systems as compared to their dry porous counterparts, which cannot be captured by effective media theory. This rise of thermal conductivity is related to the increase in the specific surface area of the liquid/solid interface. We demonstrated that the significant difference, more than two folds, in thermal conductivity of pristine porous silicon and "porous silicon liquid–composite" is due to the liquid density fluctuation close to the "solid–liquid interface" (layering effect). This effect is getting more importance for the large specific surface of the interfacial area. Specifically, the enhancement of the effective thermal conductivity is 50% for a specific surface area of 0.3 (1/nm), and it increases further upon the increase in the surface to volume ratio. Our study provides valuable insights into the thermal properties of hybrid liquid/solid nanocomposites and into the importance of confined liquids within nanoporous materials. [ABSTRACT FROM AUTHOR]