Mangrove root-inspired evaporator enables high-rate salt-resistant solar desalination

Salt deposition is one of the most significant obstacles to emerging solar interfacial desalination. Several strategies have recently been developed to combat salt deposition. However, the poor performance of most reported salt-resistant evaporators (<1.5 kg m-2h−1) severely restricts the practical applications of this technology. Inspired by seawater-grown mangroves, we propose a bionic hydrogel-aerogel composite (HAC) evaporator with a respiratory root structure in this work. This bionic evaporator consists of a high-osmotic-pressure polyacrylamide (PAM) ionic hydrogel and a hydrophobic aerogel with vapor transport channels. The vapor escape surface is spatially separated from the salt deposition interface by constructing numerous vapor escape channels within the bionic evaporator, resulting in highly efficient salt-resistant evaporation. The HAC evaporator can run salt-free for 50 h in seawater with an evaporation rate of 2.7 kg m-2h−1, which is twice that of most salt-resistant evaporators. In addition, the evaporator can achieve evaporation rates of 2.4 kg m-2h−1 in 20% brine. This design significantly improves the evaporation rate when resistant to salt accumulation, providing a novel strategy for developing highly efficient, long-term stable solar interfacial evaporators.