Self-Assembling of Alkyl-Polytannin-Al (III) Janus Nanosheets for Environmental Applications: From Nanoplastics Capture to Interfacial Functionality

Janus nanosheets have garnered significant attention in nanoscience due to their distinctive asymmetric structures and versatile applications. Traditional synthesis methods are often time-consuming and complex, emphasizing the urgent need for a simplified and environmentally sustainable synthesis method. Herein, a reactive template method was employed to fabricate amphiphilic alkyl-polytannin-Al3+ (alkyl-PTA-Al (III)) Janus nanosheets. This was achieved using self-assembling octadecylamine (ODA) bilayers as reactive templates. Due to the flexibility and multiple reactive groups of polytannins (PTA), alkyl-PTA-Al (III) Janus nanosheets were utilized as trapping agents for capturing polystyrene (PS) nanoplastics first in water, achieving a removal efficiency of 89.07%. By exploiting the singular anisotropic wettability of alkyl-PTA-Al (III) Janus nanosheets, they can self-assemble at oil–water interfaces, reducing interfacial tension and acting as promising solid surface emulsifiers capable of stabilizing emulsions for up to 180 days. Additionally, the surface functionalization of alkyl-PTA-Al (III) Janus nanosheets with Ag nanoparticles through in situ reduction effect of tannins enabled the catalytic reduction of p-nitrophenol at the emulsion interface, achieving a 99.30% conversion within only 8 min. This work presents a straightforward self-assembly method for creating amphiphilic alkyl-polyphenol Janus nanosheets, highlighting their potential environmental applications in nanoplastics capture, interfacial emulsification and catalysis.