Free-Standing Janus Nanosheets: Ultrafast Self-Assembly and Versatile Biphase-Application

The development of stable Janus architectures suitable for biphasic applications holds significant importance. A novel approach is introduced for interfacial supramolecular self-assembly, resulting in 2D Janus nanosheets (OA-TA/Fe) exhibiting an amphiphilic nature. These nanosheets consist of hydrophilic coordination complexes of ferric ions (Fe³⁺) and tannic acid (TA) on one side of both surfaces and hydrophobic alkyl chains on the other side of both surfaces. The synthesis of these 2D Janus nanosheets involves a simple, ultrafast, and environmentally benign process, eliminating the need for time-consuming multistep procedures and harsh synthetic conditions typically associated with Janus architecture formation. By exploiting the inherent singular anisotropic wettability inherent in OA-TA/Fe-2, the efficacy of these innovative Janus nanosheets in the efficient separation of various organic liquid-in-water and water-in-organic liquid emulsions is elucidated. Subsequent post-modification of OA-TA/Fe has facilitated the highly efficient remediation of contaminated oily wastewater, serving as a model biphasic catalysis reaction, wherein the Janus nanosheets function simultaneously as emulsifiers and catalysts within biphasic mixtures. The methodology establishes a rapid self-assembly approach for the creation of amphiphilic free-standing Janus nanosheets, offering compelling prospects for their application in diverse fields, as exemplified by, but not limited to, the case studies presented herein.