From Structural Design to Molecular Mechanisms: The Evolution of Solar Evaporators

Abstract

To address global water scarcity, solar-driven interfacial evaporation has emerged as a promising solution that minimizes energy consumption and environmental impact by harvesting solar energy directly at the air–water interface. Recent advances show that performance breakthroughs depend on the synergistic interplay between macroscopic structural designs and molecular-level mechanisms. This review traces the evolution of solar evaporators, from buoyancy-driven floating architectures and enhanced water transport enabled by capillary and osmotic pressure differences, to state-of-the-art regulation of water association states through hydrophobic interaction, hydrogen-bonding, and electrostatic interaction. These strategies accelerate mass transport, optimize solar energy utilization, lower evaporation enthalpy, and enhance long-term stability, achieving water transport rates up to 0.091 g min^–1, evaporation rates up to 6.92 kg m^–2 h^–1 under 1 kW m^–2 illumination, and salt rejection efficiencies above 99.99%. Despite these advances, challenges remain in achieving a precise mechanistic understanding of interfacial evaporation, scaling up fabrication, and standardized performance evaluation. This review highlights these issues and outlines future research directions to accelerate the practical deployment of solar-driven interfacial evaporation technologies for sustainable desalination and water purification.