Bioinspired and 3D-printed solar evaporators for highly efficient freshwater-electricity co-generation

Interfacial solar steam generation, governed by dynamic mass and heat transfer processes, holds significant potential for alleviating the water-energy crisis. Various advanced water-electricity co-generation (WEG) systems have been developed in recent years. However, their complex preparation process and lack of harmonious integration hinder further advancement. To address these challenges, we design and fabricate a novel WEG system inspired by tree transpiration, based on the principle of charge separation induced by water passing through a negatively charged channel to achieve freshwater-electricity co-production. This system consists of melanin-like polydopamine nanoparticles (PDA NPs)-coated film for solar absorption and a support layer doped with PDA NPs for water transportation, thermal insulation, and power generation. The high degree of design freedom and flexibility afforded by the 3D printing technique allows for effectively regulating the water flow content and height, ensuring sufficient ion migration and brine circulation. This WEG system achieves a harmonious integration of water evaporation and electricity generation, which demonstrates an efficient, self-operating, and sustainable output of 0.48 V, 18.36 μA, and a water evaporation rate of 2.13 kg m^-2 h^-1 under one sun irradiation. This work provides new inspiration for the structural design of robust WEG systems for highly efficient freshwater-electricity co-generation.