A solar-powered interfacial evaporation system based on MoS2-decorated magnetic phase-change microcapsules for sustainable seawater desalination

A novel solar-powered interfacial evaporator based on MoS2-decorated magnetic phase change microcapsules (hereafter named MoS2-MEPCM) has been developed for sustainable seawater desalination. MoS2-MEPCM was synthesized through encapsulating n-docosane as a phase change material core in an Fe3O4/SiO2 composite shell, followed by coating a poly(3,4-ethylenedioxythiophene) (PEDOT) functional layer and then decorating MoS2 nanosheets. The resultant microcapsules not only exhibit a high latent heat capacity of over 150 J g(-1), but also present a superior ability of broadband solar absorption and photothermal conversion thanks to a combination of the PEDOT functional layer and MoS2 nanosheets as solar absorbents. This can drive the highly efficient and continuous interfacial evaporation of seawater or wastewater both under solar illumination and in a dark environment. The MoS2-MEPCM-based evaporator developed in this study exhibits a high evaporation rate of 2.06 kg m(-2) h(-1) under an illumination intensity of 1.0 kW m(-2). Compared to the evaporator without an n-docosane core, the developed evaporator shows an increase in the water evaporation mass by 0.33 kg m(-2) under an illumination intensity of 1.0 kW m(-2) for 110 min and then holding in a dark environment for 110 min, and its total water production increases by 1.23 kg m(-2) under natural solar illumination for 10 h on a semi-cloudy day with unstable solar intensity. Moreover, the introduction of Fe3O4 nanoparticles into the capsule shell endows MoS2-MEPCM with magnetic effectiveness. This simplifies its separability from acuminated salt crystals and facilitates its recyclability for long-term use in solar-driven seawater desalination and wastewater purification. This study offers a new approach for the design and development of a highly efficient solar-powered evaporation system for seawater desalination and wastewater purification under intermittent solar illumination.

Automated summary

A novel solar-powered interfacial evaporator based on MoS2-decorated magnetic phase change microcapsules has been developed for sustainable seawater desalination. The microcapsules exhibit high latent heat capacity, broadband solar absorption, and photothermal conversion, driving efficient and continuous evaporation of seawater and wastewater. The evaporator shows high evaporation rate and increased water production, and the magnetic effectiveness of the microcapsules simplifies the separation and facilitates long-term recyclability.