Pompon dahlia-inspired 3D architecture for omnidirectional light harvest and high-efficiency solar steam generation

Abstract

3D solar-driven interfacial evaporators have emerged as a promising technology to address freshwater scarcity, offering a sustainable means of providing affordable drinking water for off-grid areas. However, integrating key characteristics such as effective light absorption and photothermal conversion, optimized thermal management, efficient water transport structures, and resistance to salt scaling and omnidirectional light-harvesting into a single device remains challenging. Here, we present a novel bio-inspired solar evaporator design derived from the unique hierarchical structures of the Pompon Dahlia (PPD). The resulting evaporator after graphitization features conical cavities and star-like topological structures that enhance light absorption as well as heat and mass transfer, enabling efficient and stable solar evaporation across a broad salinity range, and the interesting 3D spherical geometry ensures minimal performance variation despite changes in solar elevation angles. The evaporator demonstrates high steam generation performance with an evaporation rate of 2.25 kg m² h⁻¹ and an efficiency of 97.2 % under 1-sun irradiance. Within 10-h operation, no salt deposition occurs at a salinity of 5 wt%, and only 11.1 % salt coverage appears on the evaporator in high-salinity brine (10 wt%), with an acceptable performance degradation of 8.8 %. Notably, even at an extremely solar elevation angle of 0°, a maximum performance decrease is limited at 15 %. This bio-inspired design, inheriting the natural hierarchical structure of PPD, paves the way for the development of efficient and reliable solar evaporators capable of operating across a wide range of salinities throughout all daylight hours