A Tunable Island‐Structured Bioinspired Interfacial Evaporator for Efficient Seawater Desalination and Energy Harvesting

ABSTRACT Interfacial solar evaporation is promising for seawater desalination and complex water treatment. Achieving high efficiency, long‐term stability under high salinity and efficient utilization of evaporation induced waste heat remains challenging. Based on ordered island arrays and stomatal transport networks of cacti, a biomimetic MXene/polypyrrole@polydopamine‐melamine foam (MXene/PPy@PDA‐MF) interfacial evaporator with adjustable island structures and photothermal units is proposed for control of solar energy capture, heat localization and coupled water/salt transport. Under 1 kW m − 2 irradiation, this evaporator achieved an evaporation rate of 4.025 kg m 2 h − 1 . It continued to evaporate for 7 days under a 20 wt.% NaCl condition without experiencing salt clogging, and it also yielded approximately 2.64 g of salt collected and recovered. The excellent salt tolerance originates from low‐resistance salt reflux pathways formed by hierarchical island arrays, combined with concentration‐gradient diffusion and coupled solutal/thermal Marangoni convection. Based on this, the thermal module was integrated to harvest evaporation induced waste heat with a maximum output power density of 1.083 W m − 2 . During the outdoor experiment, the freshwater production is 15.92 kg m − 2 d − 1 , with power density of 0.7 W m − 2 . This research provides new theoretical insights into integrated solar energy systems that couple interfacial evaporation and waste‐heat recovery.