Highly open 3D carbon structures enhance solar steam generation

3D bio-based carbon structures, characterized by high specific surface area and open macroporosity, were used to improve solar steam generation. These 3D structures were printed by laser stereolithography using an acrylate-tannin resin. After pyrolysis and eventual physical activation, the resulting 3D carbon structures were used as solar evaporators. Activation with CO 2 and water vapour resulted in 3D carbon structures with high specific surface areas and enhanced oxygen content, which in turn increased water sorption. Solar evaporation performances were as high as 2.45 kg m 2 h −1 under 1 sun illumination and low convection flow, 0.3 m s −1 , and increased to 7.32 kg m 2 h −1 when using forced convection flow, 4.5 m s −1 . These results show that 3D-printed carbons are promising materials for solar evaporation, especially in a complete water distillation system with forced air flow. • 3D-printed carbons boost solar steam generation efficiency after CO₂ activation • CO₂ activation increases surface area to 943 m 2 g −1 , improving water sorption • Radial grid design optimizes solar absorption and evaporation under convection • Radially rotated grid design evenly distributes solar radiation • Peak evaporation of 7.32 kg m −2 h −1 was achieved with forced airflow at 4.5 m s −1