Potentially scalable fabrication of salt-rejection evaporator based on electrogenerated polypyrrole-coated nickel foam for efficient solar steam generation

Solar steam generation (SSG) is a green and sustainable way for desalination . Herein, we report for the first time the electrodeposition fabrication of bilayer photothermal material (named PPy-NF-PUS) for efficient desalination, which was prepared by electrodeposited polypyrrole on nickel foam (PPy-NF) as the upper layer for solar absorption and polyurethane sponge (PUS) as the lower layer for water pumping and thermally insulating. Taking advantages of superhydrophilic wettability , strong light absorption and the porous network structure of PPy-NF, in well combination with the low thermal conductivity and super-absorbent capacity of PUS , the PPy-NF-PUS shows excellent energy conversion efficiency of 82.18% under 1 sun irradiation. Moreover, the PPy-NF-PUS shows excellent salt-resistant performance, e.g., when salt was placed on the surface of the solar evaporator of PPy-NF-PUS, it could dissolve quickly. In addition, the PPy-NF-PUS was modified by composite coating to achieve a strong hydrophilic-oleophobic wettability. Such unique wettability endows the modified PPy-NF-PUS shows excellent oil-repellent performance. Besides, an outdoor water evaporation and collection device was designed, and the average evaporation rate of PPy-NF-PUS was 1.2562 kg m −2  h −1 under about 0.755 sun irradiation, thus showing great potential for practical application in SSG, by combination with its simple, potentially scalable fabrication process.