Fabrication of Monopile Polymer Foams via Rotating Gas Foaming: Hybrid Applications in Solar‐Powered Interfacial Evaporation and Water Remediation

Solar‐powered interfacial evaporation has emerged as an innovative and sustainable technology for clean water production and it has motivated the design and fabrication of monolithic 3D steam generators and related hybrid applications. However, the existing porous and hydrophilic 3D scaffolds fabricated via conventional processing techniques remain one of the main roadblocks toward scalable and mass applications. Herein, a series of closed‐cell 3D polymer foams is developed via a “rotating” gas‐foaming technique. Monopile supporting structures with reticulated and hydrophilic gas pockets are formed in the 3D foams, resulting in controlled shapes and heights, ultralight weight, efficient water diffusion, and optimized solar and environmental energy input. Gratifyingly, the 3D foam with a selected height of 12 cm attains an outstanding water evaporation rate of 5.8 kg m −2 h −1 under 1 sun. Furthermore, selected photothermal, adsorbent, and photocatalytic materials on the 3D foam introduce water remediation beyond clean water production, exhibiting organic pollutant removal efficiencies over 90% in indoor and outdoor experiments. An ease‐of‐mold approach to shape‐controlled fabrication of polymer foams is demonstrated and their intriguing properties for solar‐powered hybrid applications such as organic pollutant removal in wastewater are highlighted.