Magnetically-driven aerogel with pore-gradient structure for effective solar desalination of high-salinity

Delivering adequate water to the top surface of evaporator and simultaneously suppressing downward heat conduction is a significant challenge for high-performance solar-driven desalination. Here, through the magnetically-driven assembly strategy, an anisotropy pore-gradient aerogel (SMX-APG), which the pore size increases gradually from top to the bottom is prepared. This innovative design provides an efficient strategy to overcomes the challenging problem of balancing water transport and heat conduction loss for high-rate and stable solar desalination of high-salinity. A series of experiments and analysis reveal that the unique anisotropic pore-gradient structure of aerogel makes it be capable of effectively capturing heat from sunlight and localizing it at the water/air interface, while simultaneously guaranteeing an adequate water supply for vapor generation. When exposing the fabricated SMX-APG aerogel to the sunlight (1 kW m −2 ) to promote evaporation of 20 wt% saline, the recorded evaporation rate can reach up to approximately 3.88 kg m −2 h −1 . Even under continuous testing for a long time (8 h), there is no obvious performance degradation was observed. This work presents a novel preparation method for creating an anisotropic microstructure and represents a significant step towards designing and implementing highly efficient salt-resistant solar evaporators.