Ion-engineered solar desalination: Enhancing salt resistance and activated water yield

Solar desalination, which relies on localized heating for interfacial water evaporation, is regarded as a promising and sustainable approach for freshwater production. Significant progress has been achieved in developing high-performance solar-driven interfacial vapor generators (SIVGs), however, their performance in high-concentration brine remains unsatisfactory. Herein, a novel SIVG is proposed as a candidate with advanced ionization engineering design for solar desalination, which exhibits enhanced desalination performance. The design of ionization engineering can promote salt-blocking effects through electrostatic attraction between salt ions in seawater and polymer chains of hydrogel-based evaporator, and high-continuity porous structures, which also contributes to a high evaporation performance by increasing the production of activated water molecules. Furthermore, the introduction of CuO nanoparticles with excellent localized surface plasmon resonance effect enables the light-absorbing copper-based hydrogel (LACH) to achieve an impressive sunlight absorptance rate of 95 %. The evaporation rate and energy efficiency of LACH reach a remarkable 3.93 kg·m−2·h−1 and 93.5 % in simulated brine (3.5 wt% NaCl solution) under one-sun illumination. The salt-resistant LACH-related SIVG is one of ideal candidates for sustainable freshwater harvesting over extended periods. This study is expected to offer valuable insights for advancing the research and development of next-generation solar desalination devices.