High-performance and scalable contactless solar evaporation with 3D structure.

Solar evaporation is a sustainable pathway for diverse water treatment technologies. The contactless evaporation stands out for its superior anti-contamination property. However, the evaporation performance is significantly limited by the non-contact heat transport, which is more pronounced in scalable applications with suppressed vapor escaping and tilted solar irradiation. Here, we propose a high-performance contactless solar evaporation design with three-dimensional (3D) solar-heating and vapor-escaping structure. Our theoretical analysis reveals that mass transport is the true bottleneck of contactless solar evaporation in scalable application, and can be significantly improved by our 3D design. A laboratory solar evaporation rate of 1.03 kg m h was demonstrated with our 3D design, which was 110% higher than the conventional design. Owing to the enhanced solar harvesting and transport, an average evaporation rate of 1.21 kg m h was demonstrated in outdoor field test with dilute solar flux of 589.98 W m. The scalability of 3D design was proved by the minimal difference (3%) in natural seawater evaporation performance between the small and large 3D devices. This work provides a robust, high-performance, and scalable solution for solar evaporation, especially for those scenarios with limited tolerance for contamination.