Hydrophilic polymer-stabilized porous composite membrane for water evaporation and solar desalination

Abstract

Solar steam generation is considered an effective and sustainable method for addressing freshwater shortages. However, several challenges to developing photothermal materials and improving evaporation performance currently exist. Herein, we designed a hydrophilic evaporator with double-layer structure by combining a hydrophilic polymer with three-dimensional porous carbon nanotube beads on a glass microfiber membrane. Poly(methacrylic acid) acted as a binder to stabilize the carbon-based photothermal layer along with continuously pumped water. The assembled carbon nanotube beads with porous structures not only harvested and converted light to heat but also provided available channels for fast vapor diffusion. An artificial tree evaporation configuration can effectively localize heat on the photothermal layer, which endowed the evaporator with a high evaporation rate of 1.62 kg m⁻² h⁻¹ with a solar-to-vapor energy conversion efficiency of 87% under 1 sun illumination. Meanwhile, excellent desalination performance and stable recycling test made the evaporator have great potential in practical applications.