Preparation of Janus melamine sponge suitable for solar evaporation

Solar evaporation plays an indispensable role in natural circulation and industrial production. Recently, heating on the air–water surface has been a new trend to improve the efficiency of solar evaporation. Hence that we proposed a method to prepare Janus melamine sponge (MS) for solar evaporation. The Janus MS composed of C, O, N, and Si elements has great mechanical and optical absorption properties. The superhydrophilic part which could store water in the MS and inhibit the temperature balance caused by water flow, the superhydrophobic part on the other side ensured that the sponge gracefully floated in the water which could selectively heat the surface of water. Besides, this Janus MS had a certain salt-repellent ability, which could be used for seawater desalination. The evaporation rate of the Janus MS was about 1.3 kg m−2 h−1 and the evaporation efficiency of water was about 89.6% under the light source with an intensity of 1000 W/m2. The Janus MS can provide new ideas for solar evaporation and meet a wide range of requirements in related fields.