Omnidirectional Light-Absorbing Biomimetic Tree Canopy Evaporator for Stable Daytime Freshwater Production

Solar-driven water evaporation is a highly promising low-carbon technology owing to its clean operation and off-grid applicability. However, diurnal variations in solar position cause significant fluctuations in freshwater production, hindering its practical deployment. Inspired by the omnidirectional light-harvesting capability of natural tree canopies, we design and fabricate a biomimetic canopy evaporator via projection micro-stereolithography (PµSL) based 3D printing technique. The optimized configuration enables spontaneous capillary-driven liquid transport, achieving a rising height up to 27.8 mm. Through rational 3D assembly, these unit cells form a continuous curved canopy-like evaporation surface, which maintains an average solar-weighted absorptance of 92.13% over a wide incidence angle range (0°–90°). Combined with a capillary-driven microstructure that ensures stable water supply, the system delivers an average evaporation rate of 3.57 kg m⁻² h⁻¹ under 1 sun illumination, with an evaporation rate fluctuation of only 2.77%. This work presents a novel design strategy that integrates biomimicry with modular fabrication, offering new insights into the development of high-performance solar evaporators.