Floating MMT/MXene janus membrane for solar steam generation and mechanism of improving water transportation by DFT calculation.

• A novel janus binary membrane was designed for efficient solar desalination. • Hydrophilic MMT membrane was prepared for quick water supply. • High photothermal conversion efficiency was achieved with 84.86%. • Mechanism of increasing water transportation for MMT was calculated by DFT. This paper declared a janus membrane using MXene and montmorillonite (MMT) through simple vacuum filtration. This janus membrane not only can float under surface of water, but also has hydrophilic surface. The hydrophilic surface of membrane promotes the water transportation from bottom to the top of membrane, thus to increase photothermal conversion efficiency. The floatable janus membrane ensure energy limited under interface between water and air, which is important for improving the photothermal conversion efficiency. In addition, the janus membrane can generate steam with 1.22 kg m-2 h−1 under one sun illumination. Furthermore, under different illumination, the janus membrane still has a high conversion efficiency. The janus membrane also can produce fresh water from organic wastewater and heavy metal wastewater. It can be concluded that the janus membrane has a huge potential for practical application due to the simple preparation method, floatability, high photothermal conversion efficiency and excellent stability. The Density functional theory (DFT) calculation explained the mechanism of chitosan (CS) improving water transportation of MMT. [ABSTRACT FROM AUTHOR]