IMX Seminar Series - Solutions of anionic 2D materials and phosphorene nanoribbons

I will focus on recent work [1, 2, 3] in which we demonstrate that a range of ion-intercalated layered materials can spontaneously dissolve in polar solvents to form ionic solutions of 2D materials. The thermodynamically-driven dissolution is benign, advantageously maintains the morphology of the starting materials and can achieve solutions containing exclusively individualised monolayers. The charge on the anionic nanosheet solutes is reversible, enables targeted deposition over large areas via electroplating and can initiate novel self-assembly upon drying [1].
Surprisingly, applying this method to crystals of black phosphorus results in nanoribbons rather than 2D nanosheets [2]. Despite the motivation of over 100 publications predicting that phosphorene nanoribbons (PNRs) would have extraordinary properties, until our work, no one had made PNRs, and there was no obvious way of applying established routes for forming graphene nanoribbons to phosphorene. The PNRs we produce have typical widths of 4-50 nm, predominantly single-layer thickness, lengths up to 75 μm. The PNRs are atomically-flat single crystals, aligned exclusively in the zigzag crystallographic orientation with remarkably uniform widths along their entire lengths, and are extremely flexible. Our work thus enables the search for predicted exotic states in PNRs including spin density waves, tunable magnetism and topological states, and testing in applications where PNRs are predicted to give transformative advantages, ranging from fast-charging batteries, to flexible thermoelectric devices and nanoelectronics.
 

1. P. Cullen, et al. Nat. Chem. 15, 555 (2017),
2. T.S. Miller et al. Nano Letts. 17, 5891 (2017)
3. M. Watts, et al. Nature 586, 216 (2019)