Interfacial evaporation and salt-blocking kinetics in Janus membrane for solar desalination

Janus membrane with superhydrophobic-superhydrophilic composite wettability have excellent vapor evaporation and salt-blocking performance in solar desalination. The influence of Janus membrane infiltration on the transport mechanism of water molecules and salt ions in nano-channels remains unclear. Herein, this study has pioneered a nanoscale interfacial evaporation model of Janus membrane using the molecular dynamics simulation method. This model intuitively reveals the whole process of water evaporation, salt ion movement, and blockage all over the Janus membrane under different ratios, salinity, temperatures, and channel geometrical parameters for the first time, based on which the mechanism of salt-blocking kinetics has also been revealed. Moreover, experimental studies were also conducted by preparing Janus graphene membranes with various wetting ratios and evaporation performance and salt resistance in NaCl solution were tested. And the simulated and actual findings agreed exactly, showing that the Janus structure with the maximum evaporation efficiency and the best salt stability had a hydrophobic ratio of 0.5. The article provides the first simulation investigation into the microscopic mechanisms of water-salt transport and salt-blocking failure in hydrophilic/hydrophobic Janus membrane, which is expected to predict the evaporation and salt resistance performance, guide experimental design, and promote the individualization process of solar-driven interfacial desalination.