Photothermal converting polypyrrole/polyurethane composite foams for effective solar desalination

As a green and renewable energy source, solar energy is one of the best options to drive desalination and water purification processes. In this paper, a lightweight commercial polyurethane foam (PUF) was chosen as the support modified with a black polypyrrole (PPy) layer to obtain a simple and effective photothermal conversion “black foam” (PPy-PUF). Due to the excellent spectral absorption capacity of the polypyrrole layer as well as surficial PPy micro-wrinkles, the surface temperature of the black foam rapidly increased when irradiated with solar illumination. Combined with the porous structure, low thermal conductivity, and hydrophilicity of the polyurethane foam, it can be continuously used for desalination and water purification purposes. The evaporation rate of water can be as 3.789 kg·m−2·h−1 under 4-sun and the evaporation efficiencies as 86.9% under 1-sun. The internal microstructure and photothermal conversion performance of the PPy-PUF materials proved that they are highly suitable for practical applications such as desalination and water purification, which provide feasible solutions for water shortage, sustainable energy, and environmental improvement.