Ambient Stabilization of Few Layer Phosphorene via Noncovalent Functionalization with Surfactants: Systematic 2D NMR Characterization in Aqueous Dispersion

Abstract

Phosphorene suffers from instability under ambient condition, despite its potential to bridge the gap between graphene and two-dimensional (2D) metal chalcogenides. We report effective exfoliation and stabilization of few layer phosphorene (FLP) in the presence of strongly interacting surfactants. Surfactants containing long hydrophobic chain and nonbulky charged headgroups (CTAB) effectively exfoliate and stabilize FLP in water, which is consistent with our density functional theory prediction. Nuclear magnetic resonance measurements are systematically employed to probe the interaction between surfactants and FLP. Retarded diffusion rate measured by 2D DOSY spectroscopy revealed the presence of noncovalently bonded CTAB over phosphorene. 2D NOESY spectroscopy further suggests the interdigitated arrangement of surfactants. Such a tight interaction impedes the ambient degradation rate of phosphorene by 70-80%. This work proposes a new insight into the control over ambient degradation of phosphorene without altering its intrinsic properties.