A 3D photothermal bar for efficient steam generation

Solar water evaporation is a potential technique for clean water production with zero energy input but is restricted by low evaporation rates that are usually below 5 kg m- 2 h-1. We developed a 3D hydrogel using low -price industrial carbon nanotubes and polyacrylamide (3D CAH). The hydrogel was applied as an evaporation layer. Moreover, the hydrogel covered a cotton bar that was used as a water supply layer. In addition, a downwards water supply mode was applied. It is demonstrated that an evaporation rate for a single 3D CAH was as high as 72.3 kg m- 2 h-1. When a number of 3D CAHs worked simultaneously, the 3D CAHs were densely arranged, which resulted in an evaporation rate of 12.2 kg m- 2 h-1. The two evaporation rates were higher than other reported evaporation rates, showing the importance of properly designing the structure of hydrogels. Furthermore, the 3D CAH showed a good performance in anti-salt accumulation. As a result, the 3D CAH is a good candidate for clean water production, considering its high evaporation rate and cost-effectiveness as well as facile fabrication.