Integrating a Self-Floating Janus TPC@CB Sponge for Efficient Solar-Driven Interfacial Water Evaporation

Solar-driven photothermal interfacial evaporation is considered as one of the most promising strategies in seawater desalination and wastewater treatment. In desalination, evaporation efficiency and salt resistance are regarded as two inter-constraint measures. Thus, it is still challenging to fabricate solar evaporators with both high evaporation efficiency and excellent salt resistance. In the present work, a self-floating Janus sponge composed of hydrophobic carbon black (CB) coating and hydrophilic porous thermoplastic polyurethane-carbon nanotube (TPC) nanofibrous substrate (TPC@CB) is fabricated via a simple electrospinning and gas templating expansion method. Attributing to the unique trilaminar functional architecture: the upper superhydrophobic solar-absorption coating, the intermediate ultrathin heat localization layer, and the lower cellular thermal insulation layer, the Janus TPC@CB sponge exhibits high evaporation efficiency (1.80 kg m^-2 h^-1 with an energy efficiency of 97.2% under 1.0 solar irradiation) and outstanding salt resistance ability. Moreover, zero liquid discharge in salt-containing wastewater treatment is realized using the Janus TPC@CB sponge as a solar-driven photothermal medium. This work provides a promising approach to seawater desalination and wastewater treatment.