Precision-engineered, polymer-lean, digital light processing 3D-printed hydrogels for enhancing solar steam generation and sustainable water treatment

Interfacial solar steam generation (ISSG) using hydrogels offers a sustainable approach to desalination, addressing global water scarcity challenges. However, conventional hydrogel fabrication methods, such as moulding or direct ink writing 3D printing, lack the precision to control micro- and/or macrostructures effectively. Digital light processing (DLP) 3D printing has emerged as a powerful alternative, enabling the reproducible and high-fidelity fabrication of hydrogels with precisely engineered structures. In this study, we developed a novel DLP printing "ink" that maintains excellent printability while minimizing precursor concentrations. Using this ink, we successfully printed hydrogels with tunable engineered structures, allowing for precise control over water transport and heat management. These hydrogels demonstrated a high evaporation rate of 3.56 kg m^-2 h^-1 and an impressive daily water production rate exceeding 10 L m^-2. This research thus advance the practical application of ISSG technology, providing a cost-effective and sustainable solution for freshwater production.