Laser-Induced Porous Graphene on a Polyimide Membrane with a Melamine Sponge Framework (PI@MS) for Long-Term Stable Steam Generation

Recently, solar-driven interfacial evaporation has demonstrated its huge potential in mitigating the freshwater shortage crisis. However, the pollution and salt formation on evaporation surfaces seriously hinder its practical application. Herein, we developed a porous graphene membrane originating from a polyimide membrane with a melamine sponge framework (PI@MS) through laser processing for stable and efficient interfacial evaporation. With the assistance of alternating wrapping of expanded polystyrene foam (thermal insulator) and air-laid paper (water pumping channels), which ensure plentiful water supply as well as heat localization, the porous graphene membrane achieved a high evaporation rate (∼1.31 kg m–2 h–1) and photothermal conversion efficiency (∼85.4%) under 1 sun light intensity. Moreover, the salt rejection experiment demonstrated that the evaporator developed in our work possessed remarkable stability and salt-rejecting ability as it could maintain its evaporation performance for a long time (>12 h) in a highly concentrated NaCl solution (10 wt %) without any salt crystals forming on the surface nor inside the pores of the membrane.