Photothermal Responsive Copper Foam with Superhydrophobic/Superhydrophilic Properties for On-Demand Oil/Water Separation and Crude Oil Recovery

With the increasing frequency of oil spill incidents and the discharge of oily wastewater, oil pollution has become a global environmental challenge. While numerous materials with superhydrophobic or underwater superoleophobic properties have been reported for treating oil contamination, few can achieve on-demand separation of heavy oil/light oil or efficiently absorb crude oil. Herein, we propose a simple, efficient, and economical method to prepare superwetting copper foam with switchable superhydrophilicity and superhydrophobicity. The nanoarray-structured superhydrophilic foam exhibits superhydrophilic/underwater superoleophobic properties, allowing water to permeate while blocking light oil. After modification, the superhydrophobic copper foam demonstrates superhydrophobicity and superoleophilicity, enabling effective filtration of heavy oil from oil-water mixtures. Moreover, the as-prepared foam can separate various types of oil-water mixtures with high separation efficiency. Benefiting from the light-absorbing properties of the nanostructure, the nanoarray copper foam also exhibits excellent photothermal performance, facilitating crude oil recovery. We anticipate that this filtration material with controllable wettability will provide a promising strategy for on-demand oil-water separation and crude oil retrieval, offering new insights into addressing oil pollution.