Biomimetic hierarchical fibrous-spherical membranes with robust superhydrophobicity for high-efficiency oil-water separation

We develop a novel cyclic alternating deposition strategy to fabricate a breathable and robust superhydrophobic membrane. • The membrane exhibits a water contact angle of 156.4 ± 1.7°, excellent self-cleaning and anti-icing properties. • The membrane demonstrates ultrahigh separation efficiency (98.4%) and outstanding absorption capacity (53.5 g/g). • The membrane maintains a contact angle above 153° after 50 friction cycles. Artificial superhydrophobic membranes show great promise for oily wastewater treatment and oil spill remediation, yet they often face a fundamental trade-off between liquid repellency and vapor permeability, with dense structures sacrificing breathability and ultimately leading to performance degradation under prolonged use. Therefore, integrating persistent superhydrophobicity with high breathability and mechanical durability remains challenging. Inspired by the hierarchical microarchitecture of Hygroryza aristata , this study develops a novel cyclic alternating deposition strategy that combines electrospinning and electrospraying to fabricate a breathable, flexible, and robust superhydrophobic membrane with a hierarchical fiber-sphere alternating structure (HFBA). It exhibits a water contact angle of 156.4 ± 1.7°, excellent self-cleaning and anti-icing properties, and satisfactory mechanical performance. It also demonstrates favorable breathability, with a steady-state water vapor transmission rate of 184.38 g·m −2 ·d −1 and a gas permeability of 2725.18 cc·m −2 ·d −1 , effectively reconciling the liquid-repellency/breathability trade-off. Moreover, it demonstrates ultrahigh separation efficiency (98.4%) and outstanding absorption capacity (53.5 g/g) for various oil–water mixtures. The membrane maintains a contact angle above 153° after 50 friction cycles and shows negligible efficiency loss (<1%) over 10 separation cycles, highlighting exceptional durability. This work provides a robust biomimetic material with significant potential for practical oil-polluted water treatment and marine environmental protection. Download: Download high-res image (219KB) Download: Download full-size image