A 3D-printed hierarchical chimney for high-yield solar evaporation

Abstract

Solar water evaporation can produce water at low carbon footprint using abundant solar energy, but efficiency and stability are hindered by low evaporation rates and salt accumulating issues. We report a hierarchical solar evaporator made of cellulose acetate and graphene oxide via 3D printing. It features hierarchical structures at three levels: millimeter-scale chimney-shaped evaporator resembling chimney effect for directional steam flow, and micro-cells, micro-cavities, and nano-channels that enhance water supply and solar absorption. An evaporation rate up to 10.2 kg m-2 h-1 with simulated natural sunlight is achieved. The hierarchical structures suppress salt crystal formation, ensuring long-term stability. In the outdoor experiment under natural sunlight, the fresh water yield of the evaporators from real seawater reaches 95.1 kg m-2 day-1. The 3D-printed evaporator also demonstrates excellent long-term performance and reusability when treating realistic pharmaceutical wastewater. This study synergizing 3D printing and hierarchical solar evaporators demonstrates effective solution to energy-water nexus challenge.