Unidirectional freezing robust PPy@GO-SA aerogel for stable and efficient solar desalination

Solar interfacial evaporation technology is an effective and sustainable method for seawater desalination. It is crucial to achieve high photothermal conversion efficiency, rapid evaporation rate, and long-term stability. In this study, a vertically aligned porous aerogel evaporator is prepared using sodium alginate as the substrate material and graphene oxide (GO) and polypyrrole (PPy) as the photothermal materials through a directional freezing technology. The polypyrrole@graphene oxide-sodium alginate evaporator exhibits a high solar photothermal conversion efficiency as high as 98.6 % and an evaporation rate of up to 4.66 kg·m⁻²·h⁻¹ under 1 sun. During the 144-hour desalination, the evaporator transports brine for evaporation in the daytime and removes salt residue from the evaporator surface at night. It has demonstrated a self-cleaning behavior and restored its desalination stability. Thus, this aerogel evaporator with a high evaporation rate and stable salt resistance shows great potential for practical applications in solar thermal conversion and seawater desalination.