Functional oil-repellent photothermal materials based on nickel foam for efficient solar steam generation

Abstract

The production of fresh water by means of solar steam generation has emerged as one of frontier technologies for addressing the global water shortage issue. Here, we report the preparation of new photothermal materials by chemical modification of nickel foam with sulfur via a simple hydrothermal method for solar steam generation. The generation of nano nickel wire on the surface of skeleton of nickel foam by sulfur treatment could construct a much more dense network with hierarchical porous structure and hydrophilicity, which significantly enhance their light absorption (average 40–50% for untreated nickel foam while 91% for sulfur treated nickel foam (named as S–Ni foam) as well as water transportation. In the way, the as-prepared S–Ni foam possesses a high energy conversion efficiency of 83.6% under 1 kW m−2 irradiation. In view of most of reported photothermal materials which suffer the drawback of lose effectiveness in oily water, the S–Ni foam was further chemically modified with an anionic coordination between sodium perfluorooctanoate (PFO) and poly diallyl dimethyl ammonium (PDDA) chloride to achieve a strong hydrophilic-oleophobic wettability (named as OR-S-Ni foam). Such unique wettability endows the as-resulted OR-S-Ni foam excellent oil-repellent performance, making it possible solar vaporization even in water containing oils or organics contaminates, which should be of significantly technological significance for practical solar steam generation by largely extends its applications range.