Development of MXene-decorated sodium alginate/SiO2@n-docosane hierarchical phase-change microcapsules for solar-driven sustainable seawater desalination

A novel type of MXene-decorated and sodium alginate (SA)-coated phase-change microcapsules (hereafter named "MXene/SA/SiO2-MEPCM") was designed as a bifunctional solar absorber for the interfacial evaporator to realize sustainable seawater desalination. The MXene/SA/SiO2-MEPCM was fabricated by encapsulating ndocosane as a phase change material (PCM) in the SiO2 shell, followed by depositing a SA layer and decorating MXene nanosheets. An innovative integration of SA and MXene nanosheets enables the microcapsules to achieve a high light absorption capability of over 97 % together with good wettability, promoting a high evaporation rate of 2.11 kg center dot m (-2)center dot h (-1) under one-sun illumination. The MXene/SA/SiO2-MEPCM exhibits a high latent heat capacity of over 150 J center dot g (-1) for consecutive and high-efficient evaporation under intermittent solar illumination. Compared to the evaporator without a PCM core, the MXene/SA/SiO2-MEPCM-based evaporator achieved an increase in evaporation mass by 1.4 kg center dot m (-2) through 5-cycle consecutive evaporation processes under solar illumination and natural cooling. Furthermore, its total water production was increased by 1.01 kg center dot m (-2) under natural solar illumination for 7.5 h on a semi-cloudy day. The MXene/SA/SiO2-MEPCM also exhibits good recyclability for