Encapsulation of MXene in 3D Hydrogel Networks With High Salt Resistance Characteristics for Seawater Desalination

Solar seawater desalination technology can help alleviate the shortage of freshwater resources, with the advantages of being clean and pollution‐free. In this work, we used MXene as a photothermal material, polyvinyl alcohol (PVA) as a substrate, and glutaraldehyde as the crosslinking agent to prepare PVA/MXene double‐layer photothermal hydrogel (PMH) by the synergic effect of physical crosslinking and chemical crosslinking. Scanning electron microscopy, infrared spectrum, and x‐ray diffraction results show that the three‐dimensional porous PMH with submicron pores was successfully prepared through the physical combination of PVA and MXene. The optical absorption and photothermal conversion performances of PMH were studied. The water absorption rate of the evaporator is 86%, the light absorbance is 95%, the decomposition temperature is over 300°C. The contributing factors, the differences in thermogravimetry curves and thermal response curves of PMH, were analyzed according to the ice crystal growth theory, preparation conditions, and thermal diffusion equation, while finite element multiphysics simulation further elucidated the coupled heat‐mass‐flow transport mechanisms. During the simulated seawater evaporation process, the evaporation rate of PMH is 1.829 kg m −2 h −1 , and the evaporation efficiency is 91.1%.