Tough, durable and saline-tolerant CNT@Gel-nacre nanocomposite for interfacial solar steam generation

Solar-driven interfacial evaporation materials based on nanocomposite hydrogels have emerged for seawater desalination. Nevertheless, the issue of mechanical degradation derived from the swelling behavior of hydrogel is often seriously underestimated, which strongly hinders the practical application for long-term solar vapor generation, especially in high-salinity brine. Herein, a novel CNT@Gel-nacre with enhanced capillary pumping design has been proposed and fabricated for tough and durable solar-driven evaporator through uniformly doping carbon nanotubes (CNTs) into the tough gel-nacre. Particularly, the salting out process gives rise to volume shrinkage and phase separation of polymer chains, endowing the nanocomposite hydrogel with significantly enhanced mechanical properties while simultaneously rendering more compact microchannels for water transportation, boosting the capillary pumping. Based on this unique design, the gel-nacre nanocomposite exhibits outstanding mechanical performances (13.41 MPa strength, 55.60 MJ m^-3 toughness), especially mechanical durability in high salinity brine for long-term service. Furthermore, excellent water evaporation rate of 1.31 kg m^-2h^-1 and conversion efficiency of 93.5% in 3.5 wt% sodium chloride solution, as well as stable cycling without salt accumulation can be achieved. This work demonstrates an effective strategy for achieving solar-driven evaporator with superior mechanical properties and durability even in brine environment, showing huge potentials in long-term seawater desalination.