Solar Interfacial Evaporation and Desalination Performance of Carbon Spheres-Corn Stalk Double-Layer Evaporator
To obtain freshwater from saline water and seawater, a double-layer evaporator consisting of carbon spheres and corn stalks was fabricated (abbreviated as CC). Corn stalks served as the evaporator substrate, and a mixed hydrogel of carbon spheres and polyvinyl alcohol functioned as the photothermal conversion layer. The solar-driven interfacial evaporation and desalination performance of the CC evaporator was investigated. The glucose-derived carbon spheres exhibited a uniform morphology and achieved 95% light absorption across 200–2500 nm. Under 1 sun (1 kW·m−2) irradiation, the CC with 3 cm height (CC-3) reached an exceptional evaporation rate of 3.55 kg·m−2·h−1 with a remarkable energy efficiency of 97.53%. When different wind speeds (1.5, 2, and 2.5 m·s−1) were applied, the evaporation rates further increased to 7.17, 8.92, and 10.41 kg·m−2·h−1, respectively. The evaporation rate of CC-3 for 3.5% saline was 3.46 kg·m−2·h−1. A 5-day long-time experiment exhibited stable desalination and excellent salt tolerance. Under a wind speed of 2.5 m·s−1, the evaporation rate reached 9.56 kg·m−2·h−1. In an outdoor natural light within a closed system and 2.5 m·s−1 of wind speed, the maximum evaporation rate and cumulative evaporation amount for seawater were 9.59 kg·m−2·h−1 and 66.0 kg·m−2, with no salt crystallization observed on the CC surface. These results demonstrate the potential practical application of the CC evaporator in seawater desalination.