Dual-bioinspired janus nanofiber membranes with tunable ZnO nanowire architecture for high-efficiency emulsion purification and antibacterial defense

Janus membrane has been attracting more and more attention in field of oil-water separation, owing to its asymmetric wettability on opposite surfaces. Inspired by the special structure of lotus leaves and Setaria viridis, we successfully fabricated dual-bioinspired Janus nanofiber membranes via sequential electrospinning and low-temperature hydrothermal synthesis. The structure and performance were modulated by adjusting Zn(NO 3 ) 2 ·6H 2 O concentration and Zn(Ac) 2 ·2H 2 O addition amount. Specifically, with the Zn(NO 3 ) 2 ·6H 2 O concentration increasing from 0 g·L −1 to 22.2 g·L −1 , the diameter of ZnO NWs increased and the hydrophilic nanofiber layer became denser. When Zn(NO 3 ) 2 ·6H 2 O concentration was 14.8 g·L −1 , the hydrophilic nanofiber layer of obtained Janus nanofiber membrane exhibited excellent separation performance for oil-in-water emulsions with remarkable separation flux of 1957.68 L·m −2 ·h −1 and high separation efficiency of 98.53%. Moreover, the hydrophobic nanofiber layer showed relatively excellent separation performance for water-in-oil emulsions with remarkable separation flux of 1336.77 L·m −2 ·h −1 and high separation efficiency of 98.98%. Additionally, with Zn(Ac) 2 ·2H 2 O addition amount increasing from 0 wt% to 2.0 wt%, the growth density of ZnO NWs increased, while the diameter decreased slightly. Correspondingly, the separation flux and separation efficiency of hydrophilic nanofiber layer for oil-in-water emulsions increased with increase of Zn(Ac) 2 ·2H 2 O addition amount. Besides, the incorporation of ZnO NWs endowed the Janus nanofiber membranes with intrinsic antibacterial properties against both E. coli and S. aureus . Our study not only emphasized the tunability of Janus nanofiber membranes but also highlighted their dual functionality as effective option for effective oil-water separation and antibacterial barriers.