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 Fe3O4-polyvinyl alcohol sponge photo-absorber (Fe-PAS) was made by employing sodium alginate and CaCl2 in a simple chemical crosslinking process. Because the porous structure of the polyvinyl alcohol sponge (which traps sunlight) and the narrow bandgap of the Fe3O4 (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.