Effect of wall interaction on the structure and thermal conductivity of confined monolayer water

The structure and thermal conductivity of monolayer water in a subnanometer channel considerably differ from that of bulk water because of wall interaction. In this paper, molecular dynamics simulation using the Green-Kubo formula is used to study the effect of wall interaction on the water structure and thermal conductivity of confined monolayer water. Results reveal that the trend of thermal conductivity of monolayer water with increasing area density in the channels of different wall interactions is similar, i.e., a slow increase at first, then a rapid rise, and finally a gradual decline. However, the peak thermal conductivity and corresponding area density considerably vary. This is attributed to the poor spatial constraint ability of the channels with weak wall interactions, which promotes the formation of wrinkle structures in high -density monolayer water, weakening the phonons dispersed in the horizontal direction and leading to low thermal conductivity. In contrast, channels with strong wall interactions have a strong constraint on water molecules and make the high -density monolayer water form a flat structure, which is beneficial for phonon dispersal, resulting in high thermal conductivity. However, the effect of wall interaction on the structure and thermal conductivity of low -density monolayer water remains weak. In summary, this study investigates the effect of wall interaction on the structure and thermal conductivity of monolayer water and reveals the corresponding physical mechanism, which is essential for enriching the thermal transport theory of nanoconfined fluids.