Biomimetic Janus photothermal membrane for efficient interfacial solar evaporation and simultaneous water decontamination

Solar-driven water evaporation has been regarded as a promising technology to generate clean water due to the abundance and environmental friendliness of solar energy resources. However, the limited clean water production and limitation in tailored solar-driven system (SDS) have impeded its practical application. Herein, inspired by Lemna minor, a biomimetic, hierarchically structured, photothermal membrane (b-HPM) comprising Ti3C2Tx MXene and oxidized carbon nanotubes cross-linkage is designed. The hydrophilic bottom layer of b-HPM with macropores helps promote water transportation whilst the hydrophobic mesoporous upper layer accelerates solar/contaminant absorption and inhibits heat loss. Such-acquired Janus membrane not only improves the water transfer rate to reach 1.66 kg m−2h−1 but also harvests excellent evaporation efficiency of 99.73% deriving from the direct solar light energy (92.58%) and ambient environment (7.15%) under one-sun illumination. Impressively, PPCP removal of > 99% in raw wastewater, and no pollutants were found in the distilled water. More encouragingly, b-HPM enables a high evaporation rate and contaminant removal efficiency in real waterbody with long-term utilization based upon experimental and theoretical calculation results. Our designed SDS synergizes the merits of facile preparation, high light utilization efficiency, high-rate clean water generation, stability and robust performance, holding great promise in solving freshwater shortage and remedying water pollution under natural sunlight.