A self-floating, salt-resistant 3D Janus radish-based evaporator for highly efficient solar desalination

Abstract Solar desalination is currently considered as one of the most hopeful approaches to produce freshwater in a green and sustainable way. Herein, a mass-produced, low-thermal conductive, self-floating, and porous radish was selected as the substrate to construct a 3D-Janus evaporator for long-term solar desalination. The 3D-Janus radish-based evaporator revealed strong light absorption characteristics (absorbing >90% of the light ranging from 250 to 2500 nm) due to the addition of multi-walled carbon nanotubes (MWCNTs, an excellent light absorber). Meanwhile, the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) endowed the hydrophilic radish (water contact angle (WCA) of 33°) with a hydrophobic surface (WCA of 126°) to achieve Janus characteristic. During the evaporation test, a 3D-MWCNTs@PVDF-HFP/Radish revealed an evaporation rate of 2.35 kg m−2 h−1 with a light-to-heat conversion of ~121.6% under a simulated solar irradiation. Also, the 3D-MWCNTs@PVDF-HFP/Radish presented an excellent salt-resistance even in evaporating 20 wt% NaCl solution for 10 consecutive days, without surface salt accumulation. Meanwhile, the salt removal capacity was over 99%, suggesting such excellent evaporator can supply pure water with low ion concentration from the actual high salinity seawater. This self-floating, salt-resistant 3D Janus radish evaporator offer a potential choice for future practical applications of biomass solar desalination.