Utilize Natural Forces in Water Treatment Through 3D‐Printed Structures: From Purification to Clean Energy

The utilization of natural forces for water purification has long been a pursuit of scientific and technological interest, offering the potential to reduce both energy consumption and secondary pollution associated with conventional processes. Structural materials play a pivotal role in water treatment by harnessing natural forces, such as gravity, capillarity, and solar energy, to purify water or even to generate clean energy from water, enabling structure-determined properties beyond material functionality. With their advantages in design freedom and structural customization, 3D printing techniques offer significant potential for materializing these designs into functional devices. This review investigates recent advances in 3D-printed materials and devices that utilize natural forces for water purification, including gravity-driven oil/water separation, solar-powered photodegradation, solar evaporation desalination, and photovoltaic water splitting for clean energy, with a particular focus on the benefits conferred by structural design. Harnessing the holistic design freedom and modular manufacturing capabilities afforded by 3D printing, the approach proposes an integrated water treatment system where an oil/water separator and a photodegradation module are assembled with solar evaporators to generate purified water for photovoltaic water splitting. This design aims to establish a conceptual framework that enables rapid iteration, collaborative innovation, and digital model-based standardization across the field.