A janus solar evaporator with 2D water path for highly efficient salt-resisting solar steam generation

Abstract

A Janus solar evaporator with 2D water path has been built by covering the hydrophobic soot-coated cloth/hydrophilic cloth bilayer on hydrophobic polyethylene (PE)-wrapped cellulose aerogel. Such a unique structure not only minimizes the heat conduction loss compared to the typical flat Janus structure in the direct contact mode, but also has a much better salt-resisting ability than common hydrophilic solar evaporator with 2D water channel. By using candle soot (CS) as light harvester, the obtained solar evaporator (SE-CS) was demonstrated to strongly resist salt deposition and efficiently generate steam from 3.5 to 20 wt% NaCl solution under 1.0 sun illumination. Furthermore, SE-CS could be used to produce steam from methyl orange (MO) solution (0.01 M) and heavy metal solution (Ni2+, Cu2+, Zn2+, and Pb2+ with concentration of 1000 mg L−1). In addition to CS, kerosene soot (KS) could also promote the efficient steam generation from 3.5 wt% NaCl solution over the obtained solar evaporator (SE-KS) under 1.0 sun irradiation. This work paves the way for practical application of solar-driven evaporation in seawater desalination and wastewater purification.