Evaporating water using sunlight is an environmentally friendly approach to energy generation, water desalination, and wastewater treatment. Darkly colored materials can improve the efficiency of this process by converting light to heat. The materials used for this are usually inorganic, which makes it difficult to mold them into large sheets.

Yen Wei, Yan Ji, Tsinghua University, Beijing, China, and colleagues have developed a polymer that can easily be turned into a foam that can float on water and facilitate evaporation. The team crosslinked an amine-functionalized oligoaniline using paraformaldehyde, and cured the mixture on a template made from NaCl powder. The template was removed using deionized water.

The resulting black foam is mechanically durable, thermally stable, and can withstand organic solvents. Its performance is suitable for water desalination and the evaporation efficiency is high even in low-sunlight conditions.

• A durable monolithic polymer foam for efficient solar steam generation,
  Qiaomei Chen, Zhiqiang Pei, Yanshuang Xu, Zhen Li, Yang Yang, Yen Wei, Yan Ji,
  Chem. Sci. 2018.
  DOI: 10.1039/c7sc02967e