Environmentally safe and renewable solar vapor generation device based on Prussian blue nanoparticles immobilized on cellulose nanofibers

Abstract

Solar vapor generation is a sustainable solution to overcome the shortage of fresh water. Although several solar vapor generation devices showing significant evaporation rates have been developed over the past years, there are still remaining problems such as fabrication difficulties and potential environmental hazards. In this report, we demonstrate a solar evaporation device composed of agar hydrogel (AHG) and Prussian blue (PB) immobilized on cellulose nanofiber (CNF). The CNF-PB/AHG device shows a high evaporation rate of 2.22 kg m−2 h−1 under one sun illumination arising from the combined effects of the high water-transport performance of CNF/AHG and the good photothermal ability of PB. The device does not exhibit salt fouling or any decline in desalination performance under a long-term day and night simulation due to the salt-rejection ability of AHG. The average fresh water generation in the field test is 5.95 kg m−2 day−1. Furthermore, the used device can be resurrected without decline of the vapor generation performance through a simple re-fabrication process due to the remarkable stability of CNF-PB and reversible sol-gel transition of AHG. In conclusion, the CNF-PB/AHG device is an environmentally safe, low-cost, easily manufacturable, and renewable solar desalination system.