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

ABSTRACT

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 (P µ SL) 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.