Fabrication of Bioinspired Superhydrophobic Paper by Polyphenol/Fe₂O₃/Myristic Acid Coating for Self-Cleaning Property and Oil/Water Emulsion Separation

A fluorine-free strategy was employed to fabricate multifunctional, self-cleaning cellulose paper by constructing a micronanostructured hierarchical surface through tannic acid-assisted Fe2O3 deposition followed by myristic acid modification. Owing to the rough structure's impact on surface wettability, the material exhibits exceptional superhydrophobicity (161°) and outstanding self-cleaning capabilities. The paper is resistant to extreme conditions such as acids, alkalis, abrasion, and high temperatures. Notably, the TA coating, which is based on polyphenol chemistry, contributes to improved separation performance. This is demonstrated by the excellent separation efficiency (>98%) and the high flux values ranging from 460 to 850 L/m2·h for various organic solvents under gravity-driven separation. Even after 15 cycles, the membrane maintains a flux >580 L/m2·h and a separation efficiency of ∼95%, confirming its robustness and reusability. Additionally, for emulsion systems, the separation efficiency was maintained in the range of ∼90%, confirming its applicability for complex oil–water emulsions. Further, the developed superhydrophobic paper also demonstrates efficient separation of emulsions. The technology, which avoids the use of fluorinated chemicals, employs a micronanostructured hierarchical surface and polyphenol chemistry to enhance oil/water separation efficiency and reusability, offering potential for practical applications.