MXene-doped kapok fiber aerogels with oleophobicity for efficient interfacial solar steam generation

Although the evaporation efficiency of photothermal materials (PMs) in pure water and brine solutions has been extensively studied, there few research on the performance in complex oily wastewater. Herein, a new monolithic solar steam generator derived from kapok fiber-based MXene composite aerogel (named as KFs-MXene) was fabricated by dipping the aerogels (KFs) which composed of kapok fiber and sodium alginate (SA) as substrates in the suspension of MXene. Benefitting from the outstanding light absorption (about 97%), better thermal insulation (thermal conductivity, 0.05039 W m^-1 K^-1), abundant porosity (95.60%) and rapid water transportation. KFs-MXene show good interfacial solar steam generation (ISSG) performance, resulting in a high water evaporation rate of 1.47 kg m^-2h^-1 with an outstanding evaporation efficiency of 90.4% under 1 kW m^-2 irradiation. To improve the antifouling performance of KFs-MXene, chemically hydrophilic and oleophobic modification was applied, making the KFs-MXene can also be widely used in oily wastewater. Under 1 kW m^-2 illumination, the evaporation rate and energy conversion efficiency of KFs-MXene with hydrophilic and oleophobic modification (O-KFs-MXene) in 1 wt% oily water can reach to 1.40 kg m^-2h^-1 and 82.87%, and the evaporation efficiency and rate of O-KFs-MXene remain stable in the continuous 6 h solar driven interface evaporation process.