Fe3O4-polyvinyl alcohol sponge as photo-absorber in interfacial solar steam generation

Interfacial solar steam generation (ISSG) is a potential technology to relieve the freshwater shortage. However, developing a cost-effective method to design photo-absorbers with steady desalination performance remains a significant challenge. A Fe 3 O 4 -polyvinyl alcohol sponge photo-absorber (Fe-PAS) was made by employing sodium alginate and CaCl 2 in a simple chemical crosslinking process. Because the porous structure of the polyvinyl alcohol sponge (which traps sunlight) and the narrow bandgap of the Fe 3 O 4 (which captures sunlight) work together, the light absorption of wet Fe-PAS can reach 96.54 %, making water evaporate at a rate of 1.44 kg m −2  h −1 . With the help of a sufficient water supply from the polyester fiber pillar (PFP), the Fe-PAS photo-absorber shows a steady evaporation rate of about 1.40 kg m −2  h −1 under 1-solar intensity during desalination. The 240 h (30 days, with 8 h of operation per day) of indoor desalination experiments prove that Fe-PAS is durable and has a steady evaporation performance. Outdoor desalination experiments demonstrate that Fe-PAS can extract freshwater from salt water. The Fe-PAS photo-absorber offers a substantial possibility in mitigating freshwater shortages.