Highly efficient and stable solar-powered desalination by tungsten carbide nanoarray film with sandwich wettability

Solar-powered desalination is a promising way to resolve the worldwide water crisis for its low consumption and simple facility. Considering the fragility and aggregations of traditional materials, which may decrease efficiency, we herein introduce a robust tungsten carbide (WC) nanoarray film as a stable and efficient photothermal material, whose absorption is over 97.5% throughout almost the whole solar spectrum range (220-2200 nm) due to nanoarray structure and thus enhanced localized surface plasmon resonance. Besides, for the first time, we modified the film with sandwich wettability. It accelerates evaporation by reducing water's reflection of light, enlarging hydrophobic-hydrophilic boundaries, and depressing heat dissipation. Combining high absorption with unique wettability, the WC nanoarray film offers high solar-to-vapor efficiency of 90.8% and produces drinking water at the rate of (1.06 ± 0.10) kg m^-2 h^-1 from man-made seawater and (0.98 ± 0.18) kg m^-2 h^-1 from heavy metal sewage under one sun (AM 1.5) while 98% performance remains after 1 h × 100 times' reutilization.