Low-cost, scalable fabrication of antibacterial asymmetric hydrogels inspired by mangrove systems for superior oil-water separation and salt-tolerant evaporation.

Offshore oil spill incidents not only pollute marine ecosystems but also exacerbate freshwater shortages in coastal regions where seawater is abundant but drinkable water is scarce. Addressing these dual challenges requires materials that can efficiently separate oil from water while simultaneously enabling seawater desalination. Here, inspired by the asymmetric architecture of mangrove systems, we developed a scalable strategy for constructing composite hydrogels with hierarchical pore structures. The fabricated hydrogel integrates oil-water separation and salt-tolerant solar evaporation into a single platform, offering a unified solution for treating oil-contaminated seawater. It achieves a separation efficiency of 99.1% even after 20 cycles, while sustaining a stable evaporation rate of 2.91 kg·m-²·h-¹ for 10 days in 3.5 wt.% NaCl solution. Under illumination, the hydrogel further exhibits antibacterial activity with an inhibition rate of 89.72%, ensuring water quality. This work demonstrates a practical and low-cost approach to the integrated purification of oil-polluted saline water, highlighting its potential for large-scale environmental applications.