Latent heat-assisted cooling for high-efficiency solar-driven freshwater production.

Solar-driven interfacial evaporation has shown great potential in freshwater production due to its minimal carbon footprint and adaptability to diverse water sources. However, while significant progress has been made in enhancing vapor generation rates, limited heat dissipation during condensation continues to constrain overall water production efficiency. Here, we introduce a latent heat-assisted evaporative cooling (LHEC) strategy that effectively dissipates condensation heat by harnessing water's latent heat. Using delignified wood as the demonstrating LHEC substrate, we achieved a 2.5-fold increase in heat dissipating heat flux and accelerated vapor diffusion from the evaporation region toward the condensation interface. This approach improves solar water production efficiency to 0.76 (versus 0.49 in conventional systems) and demonstrates robust salt resistance for long-term operation. Notably, the plug-and-play design of the LHEC substrate enables seamless integration into a range of solar evaporation architectures, including single/multi-stage systems, all of which benefit from its enhanced condensation performance. This universality offers a fully passive, single solar-powered solution. This LHEC strategy represents a significant step forward in scalable, efficient and environmentally sustainable freshwater production.