MXene/MnO₂ nanocomposite coated superior salt-rejecting biodegradable luffa sponge for efficient solar steam generation

Solar steam generation is widely regarded as one of the potential green approaches for freshwater regeneration by utilizing solar energy. Herein, the MXene/MnO₂ nanocomposite-coated biodegradable luffa sponge (Ti₃C₂-MnO₂@LS) is proposed as an efficient solar evaporator for solar steam generation. The thin layer of Ti₃C₂-MnO₂ coated on the surface of the luffa sponge (LS) serves as the solar absorber and enhances the hydrophilicity of the LS, while the thermally insulating LS layer with microporous structure endows sufficient water transportation and localizes heat for interfacial water evaporation. Combining MXene with MnO₂ can increase the surface area as well as the stability. The Ti₃C₂-MnO₂@LS delivers a solar evaporation rate as high as 1.36 kg m⁻² h⁻¹, with a solar steam conversion efficiency of 85.28 % under one sun irradiation. Furthermore, this Ti₃C₂-MnO₂@LS exhibits superior salt-rejecting properties even under highly concentrated saltwater desalination and excellent wastewater purification performance. This work demonstrates the prospects of combining novel 2D materials with biomass-based materials for practical solar steam generation.