Omniphobic melamine sponge for interfacial solar desalination of saturated water with anti-fouling performance

Abstract

Interfacial solar desalination has shown great potential to address the global freshwater scarcity attributing to the advantages of high energy conversion efficiency, environmental friendly, cost effective and so on. However, accompanied by rapid vapor generation in the interfacial region, salt simultaneously crystallizes on the surface of photothermal materials, especially in highly concentrated brine, which would seriously affect the efficiency and long-term stability due to the blocking of vapor escaping channels as well as decreasing of solar absorption. In addition, organic substances in seawater may also pollute the absorbers during evaporation. Here, we demonstrate an omniphobic-hydrophilic melamine sponge based janus photothermal absorber by taking advantage of the 1H,1H,2H,2H-perfluorooctyltrichlorosilane modification, providing the upper layer both hydrophobic and oleophobic features, resulting in salt resistance and anti-fouling performance, respectively. Even with saturated NaCl solution as input, no salt accumulation was observed on the light absorbing surface during 8 h continuous evaporation. Moreover, the absorber exhibits excellent anti-fouling properties in oily water. Our strategy provides an avenue for the development of multifunctional solar absorbers aiming to sustainable treatment of highly concentrated brine and oil-bearing water.