Water wicking in phosphorene-based nanochannels: Effect of surface texture

The imbibition dynamics of water in a nanochannel made of two-dimensional phosphorene are explored using Molecular Dynamics. The partial wetting behavior of water nanodroplets on phosphorene sheets is examined first. The initial spreading of the wetted area (A) and internal energy (ΔE) are found to follow the power law, A ∼ t1/2 and ΔE-t1/2. Additionally, the Laplace pressure and equilibrium contact angle, determined from water plugs confined within nanoslits, verify the applicability of the Young-Laplace equation at the nanoscale. For water wicking in channels with a width of N layers of phosphorene sheets, the rate of change of both the penetration length and internal energy is proportional to t1/2. However, the imbibition rate in narrow nanoslits (N = 2 ∼ 5) depends on the orientation (armchair and zigzag) of the walls. This effect gradually diminishes as N increases. It was observed that, except for N = 1, the imbibition rate decreases with increasing channel width, which contradicts the prediction of Lucas-Washburn equation. Compared to smooth graphene-based channels, the imbibition rate is lower in phosphorene-based channels. Nonetheless, this difference decreases as the channel width increases, suggesting that the impact of surface roughness becomes less pronounced with larger channel widths.