Multifunctional Superhydrophobic Sponge In Situ Anchoring of Ag-MnO₂ via Polydopamine Activation for Efficient Oil–Water Separation, Photothermal Conversion and Antibacterial Applications

Frequent oil spills and the discharge of oily wastewater pose serious threats to the environment, ecosystems, and humans. Herein, a multifunctional superhydrophobic sponge was successfully prepared through the in situ growth of Ag-MnO₂ nanoparticles assisted by polydopamine rapid deposition and subsequent hydrophobic silicon modification. Owing to the synergistic effects of the hierarchical micro/nanostructure and methyl-terminated surface modification, the obtained superhydrophobic sponge has a water contact angle (WCA) of 156.5°, demonstrating excellent chemical stability and structural durability under harsh environmental media and mechanical damage. For oil-water separation, the adsorption capacity of modified sponge for various oils ranges from 58.2 to 132.6 times its own weight and great separation efficiency up to 98.38%. Through the photothermal conversion effect of Ag-MnO₂ nanocomposite, the surface temperature of the material can reach 64.1 °C under simulated radiation, achieving rapid adsorption and recovery of high-viscosity oil. Additionally, the immobilization of silver nanoparticles within the sponge skeleton effectively inhibits the growth of <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>, exhibiting antibacterial properties that facilitate the elimination of bacteria in organically contaminated water sources. Therefore, the multifunctional superhydrophobic sponge in this study provides high potential and efficient application for efficient oil-water separation, rapid crude oil recovery, and antibacterial pollution of water.