Understanding Interfacial Properties for Enhanced Solar Evaporation Devices: From Geometrical to Physical Interfaces

Various materials and device configurations have been reported to enhance the evaporation efficiency of solar interfacial evaporation systems, but it has not yet been revealed how to quantitatively assess the optimal materials and devices to maximize evaporation performance. In this study, the evaporation interface (location and thickness) is identified to quantify the interplay of optical and transport processes for guiding the rational design of materials and devices. We theoretically and experimentally demonstrate that an absorption coefficient of 400 m^-1 pinning the interfacial location below the top surface leads to optimal efficiency with reduced radiation and convection losses. A multistage evaporation device based on the optimized interface properties in the transitional region was demonstrated showing an evaporation rate of 5.38 kg m^-2 h^-1, which is 12% higher than that in the interfacial region. In addition, the optimized device can operate stably with seawater for more than 10 h without salt crystallization.