Recent advances in solar thermal interfacial distillation

The growing global demand for freshwater has intensified research into energy-efficient desalination technologies. Among various desalination methods, distillation-based technologies can utilize renewable solar sources and low-grade waste heat but are typically energy intensive. In recent years, solar thermal interfacial evaporation has emerged as a promising approach to enhance energy efficiency in seawater distillation by delivering heat directly to the liquid-vapor interface and bypassing the bulk fluid. Significant efforts have been made in materials development to achieve high solar-to-vapor efficiency in single-stage evaporators. This perspective reviews recent advances in solar interfacial evaporation, with emphasis on salt-rejection strategies, condenser development, and system-level integration for multi-stage operation. We further highlight several opportunities for realizing scalable solar thermal distillation: mitigating salt accumulation in evaporators through passive or low-power active advection-driven removal mechanisms; advancing condensation strategies to reduce overall thermal resistance and enable compact multi-stage integration, such as through thin-film condensation; and innovating multi-stage designs by optimizing gap thickness, improving sensible and latent heat reutilization. In addition, integrating waste heat sources offers a promising route to reduce reliance on external energy inputs, while addressing biofouling and other real-world limitations is crucial to ensure long-term durability.