Janus MXene-based photothermal membrane for efficient and durable water evaporation

The interfacial solar steam generation for seawater desalination has attracted attentions of many researchers because of its excellent photothermal performance and efficiency. However, relatively high cost, complex equipment, and poor salt resistance limit its further practicability. Therefore, a solar evaporator with low cost, easily prepared and certain salt resistance is desideration. For this purpose, MXene was chosen as a light absorber, and filterable deposited on filter paper easily to obtain MXene-based flexible Janus membranes. Due to the introduction of ethyl cellulose, the membrane has Janus characteristics of hydrophobic upper layer, hydrophilic lower layer. Besides, the elasticity, multiple folding skill means it can be used for a long time, efficient desalination of seawater. Under one solar intensity of light, the light absorption rate of the MXene flexible Janus membrane can reach 90.81 %, the average evaporation rate is 1.34 kg m−2 h−1 in nearly 120 h of evaporation experiments, the average evaporation efficiency ≈ 81.5 %, and the main ion concentration of fresh water obtained after the experiments was also far below the World Health Organization standard. In summary, it was demonstrated that the device is suitable for long-term and efficient solar seawater desalination. •A MXene-based Janus membrane was prepared by simple filtration drying.•The Janus photothermal membrane shows excellent photothermal efficiency.•The membrane can durably purify simulated wastewater.