Fig. 1
From: Few layer 2D pnictogens catalyze the alkylation of soft nucleophiles with esters
Characterization of exfoliated black phosphorus. a Top view of the orthorhombic structure (Cmce space group) of BP. Upper plane P atoms marked in blue, lower plane in yellow. b Representative AFM topography image (inset, scale bar 5 µm) of the exfoliated sample spin-coated onto SiO2/Si substrates. c The corresponding Raman A1g (λexc = 532 nm) mapping of the same BP flakes (>14,000 single point spectra over a surface area of 40µm2 using a step size of 0.5 µm). The numbers denote the areas in which the Raman spectra shown in (f) were recorded. d Plot of the nanosheet length as a function of the flake height (obtained from AFM) considering a total amount of 252 replicates as well as the data corresponding to the IL blank (sample size = 116) Supporting Information S8 and 9). e Histogram of the apparent thickness of the exfoliated FL-BP obtained from AFM (sample size = 252). The inset shows an AFM image of a nanosheet along with its corresponding height profile of ca. 6 nm (inset, scale bar 400 nm). f Raman spectra of the nanosheets indicated in b and c (the numbers labeling the spectra in f correspond to the nanosheets marked by numbers in b and c). g Atomic resolution HAADF image acquired down the [110] axis, from the edge of a free-standing portion of a flake. The inset exhibits the raw image and a Fourier filtered (FFT) version, in false color. The scale bar represents 2 nm. h Compositional maps derived from electron energy-loss spectroscopy (EELS) measurements acquired on the free-standing portion of the BP flake. The P L2,3, C K, N K, and O K maps for this area are shown, the scale bar represents 20 nm. Data acquired at 80 kV. i XPS P 2p region of the neat bmim-BF4 IL (I), the highly concentrated FL-BP suspension (II) showing only P in oxidation state zero at P 2p3/2 = 130.2 eV (region for oxidized P species is indicated), and after removal of most of the IL by heating in UHV (III); spectra are offset and rescaled for sake of clarity. Source data are provided as a Source Data file
