Enhanced solar-driven desalination by recycling of condensation latent heat in multistage solar steam gap distiller with low evaporation enthalpy

In this research work, a multi-stage solar steam gap distiller (MSSGD) was designed to enhance the efficiency of solar seawater desalination, addressing the challenges associated with traditional seawater desalination methods, such as difficulties in collecting fresh water, low evaporation efficiency, and the impact of condensation water droplets and water vapor on light absorption. The MSSGD employs three-dimensional disordered porous copper foam as the substrate for light absorber, which is transformed into super-hydrophilic copper oxide foam through thermal oxidation. Subsequently, Zn-Co metal–organic framework (MOF) is in situ grown on CuO foam by a hydrothermal method and carbonized at high temperature, resulting in excellent light absorption capability (97.8 %), self-absorption properties (2.23 cm/s), water activation capacity (873 J/g), and cycle stability. The thickness of air gap and the total number of stages is determined by theoretical calculation and simulation analysis, achieving a maximum evaporation rate of 4.64 kg/m 2 ·h under 1 sun, a water collection rate of 83 %, and a solar-steam efficiency of 201 %. Furthermore, the MSSGD demonstrates favorable evaporation performance and salt tolerance across various seawater salinities, with the produced fresh water meeting WHO standards. This indicates its potential for application in remote water treatment or seawater desalination and lays a foundation for the advancement of solar seawater desalination technology, providing new insights.