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Self-floating nanostructured Ni–NiOₓ/Ni foam for solar thermal water evaporation

Wu, Dandan, Qu, Dan, Jiang, Wenshuai, Chen, Ge, An, Li, Zhuang, Chunqiang, Sun, Zaicheng
Journal of materials chemistry A 2019 v.7 no.14 pp. 8485-8490
absorbance, coatings, contact angle, energy conservation, evaporation rate, foams, freshwater, nanoparticles, nickel, semiconductors, solar heaters, temperature, thermal conductivity, thermal energy
Solar thermal water evaporation is a clean, sustainable, and energy-saving approach to fresh water generation compared with traditional methods. Electroplated coating, such as nickel black, have been commercialized in solar water heaters. Inspired by this, we developed a nanostructured Ni–NiOₓ/Ni foam (NF) composed of Ni metal nanoparticles and NiOₓ with defects. The Ni–NiOₓ/NF exhibited high solar absorbance due to the plasmonic effect of metal Ni nanoparticles and defects. Ni–NiOₓ/NF also showed a low thermal conductivity, which prevented the loss of thermal energy and thermal transfer, which will be beneficial to the generation of localized high temperatures. The as-prepared Ni–NiOₓ/NF can self-float on the water surface without any other materials owing to a high contact angle. The average water evaporation rate of the as-prepared Ni–NiOₓ/NF reached 1.41 kg m⁻² h⁻¹ and the average solar conversion efficiency was about 94%. The best sample exhibited a water evaporation rate of 1.45 kg m⁻² h⁻¹ and 96% solar conversion efficiency. This report highlights potential semiconductor materials as highly efficient solar water evaporation materials.