Phosphorene and Black Phosphorus: The 31P NMR View

This work aims at characterizing for the first time the P-31 spin interactions determining the nuclear magnetic resonance (NMR) properties of solid black phosphorus (bP) and of its few-layer exfoliated form (fl-bP). Indeed, the knowledge of these properties is still very poor, despite the great interest received by this layered phosphorus allotrope and its exfoliated 2D form, phosphorene. By combining density functional theory (DFT) calculations and solid-state NMR experiments on suspensions of fl-bP nanoflakes and on solid bP, it has been possible to characterize the P-31 homonuclear dipolar and chemical shift interactions, identifying the network of P-31 nuclei more strongly dipolarly coupled and highlighting two kinds of magnetically nonequivalent P-31 nuclei. These results add an important missing piece of information to the fundamental chemico-physical knowledge of bP and support future extensive applications of NMR spectroscopy to the characterization of phosphorene-based materials.