Duckweed-inspired evaporator featuring multimode water pathways for thermal concentration and flow regulation to achieve efficient water-electricity cogeneration

Solar-driven water-electricity cogeneration has been considered as a promising technology to alleviate the freshwater-energy scarcity crisis. However, energy confinement on the evaporator surface remains challenging owing to unavoidable thermal losses to the bulk water, which leads to diminished water evaporation efficiency and reduced power output. Herein, a duckweed-inspired water-electricity cogeneration evaporator (d-WECE) with multimode water pathways is developed. Consisting of the arterial and multibranched channels, d-WECE exhibits low thermal conductivity and regulated water flow for high-efficiency desalination and electricity output. Experiments and numerical simulations reveal that the integrated water channels have a synergistic effect on thermal concentration and flow regulation, ensuring continuous water supply while minimizing heat losses, thereby delivering more energy to the evaporating surface. Consequently, an excellent evaporation rate of 2.42 kg m −2  h −1 and a high energy efficiency of 96.7%, under one-sun irradiation in seawater without salt deposition, have been achieved, accompanied by outstanding voltage (520 mV) and current (45 μA) output. More importantly, d-WECE can also maintain efficient and sustainable evaporation for the clean production of freshwater-electricity in outdoor operation. This work is expected to provide a viable route to design high performance solar-driven evaporators for the cogeneration of water and electricity.