Bulk Self-Assembly of Hybrid GO-clay Nanosheets

Bulk self-assembly provides an efficient technique for large-scale production of materials which is often limited using the interfacial or deposition methods. One promising system in this context could be provided by functionalization of insulating nanosheets for the production of conductive/insulative heterostructures, for instance use in electronic devices. One such material is clay which completely delaminates in water to form insulating nanosheets, exhibiting one of the largest electron bandgaps known so far in 2D layers (1).<br/><br/>Here we present the self-assembly of graphene oxide (GO-) and synthetic fluorohectorite clay heterostructures in a bulk mixture of the two individual components in the presence of polyethyleneimine-ethyleneoxide (PEI-EO). The synthetic clay mineral used here is superior to other clays in terms of charge distribution, homogeneity, and crystalline perfection (2). This clay mineral delaminates in water to form nematic structures with cations present in the interlayer regions. Double layer clay nanosheets can be readily obtained via ordered stratification by partial interlayer cation exchange using ammonium cations (NH₄⁺), providing bilayers with a net negative charge, and which can be double side coated with the polymer (2, 3). The GO is incorporated onto the clay surface via the polymer adhesion layer to form the complex GO-clay heterostructures. These 2D nanosheets have been investigated using SPM and XRD to determine their composition, mechanical and adhesion properties.<br/><br/>The results indicate that the synthesized GO-clay nanosheets presents interesting properties for possible applications in electronics and semiconductive devices. We are currently extending this work and attempting the cleavage of the double layer GO-clay nanosheets into single GO-clay layers to produce micrometer sized GO-clay Janus platelets.<br/><br/>Reference:<br/>(1) Pacakova B.; Vullum P.E.; Kirch A.; Breu J.; Miranda C.R.; Fossum J.O. Large Bandgap Insulating Superior Clay Nanosheets. MRS Bulletin. 2022, 47.<br/>(2) Stoter M.; Godrich S.; Feicht P.; Rosenfeldt S.; Thurn H.; Neubauer J.W; Seuss M.; Linder P.; Kalo H.; Moller M.; Fery A.; Forster S.; Papastavrou G.; Breu J. Controlled Exfoliation of Layered Silicate Heterostructures into Bilayers and their Conversion into Giant Janus Platelets. Angew. Chem. Int. Ed. 2016, 55, 7398-7402.<br/>(3) Michels-Brito P.H.; Malfatti-Gasperini A.; Mayr L.; Puentes-Martinez X.; Tenorio R.P.; Wagner D.R.; Knudsen K.D.; Araki K.; Oliveira R.G.; Breu J.; Cavalcanti L.P.; Fossum J.O. Unmodified Clay Nanosheets at the Air-Water Interface. Langmuir. 2021, 37, 1, 160-170.