Diffusion and Entropy of Supercooled Water in Nanoslit

•The diffusion is dominated by pair-wise excess entropy.•Water behaves into several layers clearly especially closed to the graphene sheet.•Layered water closed to the graphene sheets preferred triangle and square. Understanding the supercooled water behaviors in different circumstances is essential and provides the foundation to apply. The behaviors of supercooled water in nanoslit haven’t been studied yet, though these of supercooled bulk water were studied about wo decades ago. Here molecular dynamics simulations of water were conducted to investigate the diffusion and structures in nanoslit systematically. The diffusion coefficient of water close to the graphene sheets decreased with increasing pressure which was different from bulk water. The diffusion was strongly related to excess entropy. The existence of graphene sheets caused the layered water. Further, the water layer close to graphene sheets preferred ordered triangular and square to pentagonal and hexagonal structures.