Magnetically Driven Tunable 3D Structured Fe3O4 Vertical Array for High‐Performance Solar Steam Generation

Structural design of the solar-absorbing layer has been considered as one of the most direct and effective approaches for improving the solar steam generation performance by maximizing the absorption of sunlight, but great challenges in manipulation simplification and structure controllability still remain. Herein, a polyester (PET) fabric covered with a vertically aligned 3D tower-like ferrosoferric oxide (Fe3 O4 ) array via a convenient magnetically driven spray-coating method is reported, and both the spatial density and height of the Fe3 O4 array are tunable upon spraying time. It shows an extremely high solar absorbance (98.6%) in the entire solar spectrum, which is superior to the corresponding 2D Fe3 O4 structure (91.1%). Combining the obtained 3D Fe3 O4 /PET with a yolk-shell hydrophobic/superhydrophilic modified melamine-formaldehyde (mMF) sponge, the carefully designed and fabricated 3D Fe3 O4 /PET-mMF evaporator can realize a high water evaporation rate of 1.59 kg m-2 h-1 under 1 kW m-2 solar illumination, outperforming most related solar steam generation systems. With the advantages of cost-effectiveness, high evaporation rate, reliable endurance, and structural controllability, this 3D structural design provides an avenue to build up high-performance solar energy-driven water steam generation systems.