Energy-force coupling in interfacial solar vapor generation: A pathway to sustainable salt management

Abstract

Interfacial solar vapor generation (ISVG) has emerged as a promising approach for sustainable desalination, yet effective salt management remains challenging, particularly in high-salinity conditions. Herein, this review will introduce an energy-force coupling framework to analyze how solar energy is transformed into mechanical forces—such as gravity, capillary action, Marangoni convection, and diffusion—that drive essential functions of salt management: salt resistance for continuous vapor generation, zero-liquid discharge (ZLD) for combined vapor generation and salt extraction, and selective high-value salt (e.g. Lithium) concentration. By investigating capillary action for surface energy conversion, Marangoni-driven convection for gradient-based transport, and diffusion for concentration-driven ion separation, we elucidate the mechanisms through which solar energy sustains clean evaporation surfaces. This process is achieved by the coordinated interplay of multiple forces, enabling precise control of salt crystallization and facilitating targeted recovery of high-value salts. By reframing salt management as a dynamic interplay of solar-driven forces, this perspective provides a foundational approach to designing next-generation desalination systems that extend beyond water recovery to resource extraction, as well as offering transformative insights to guide sustainable desalination technologies aimed at addressing both freshwater and mineral resource needs.