Zehui Zhao, Yulong Zhao, Yushan Zhang, Qiaozhi Wang, Huawei Chen, Xianxian Cui, Yong Xiang
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.