Fig. 2: Electron microscopy shows particle size reduction through BP synthesis and exfoliation while retaining polycrystallinity.

a Scanning electron microscopy (SEM) images presenting faceted morphology of large particle sizes for RP, smaller particle sizes for BP, and narrow particle size for exfoliated BP flakes that consist of crystalline domains embedded in a lager bulk amorphous particle with plate-like morphology (SEM scale bars from left to right are 100 μm, 10 μm, and 2 μm, respectively). b Transmission electron microscopy (TEM) images and a selected area electron diffraction (SAED) pattern of polycrystalline BP manifesting large lattice domains and converted BP crystallinity. TEM scale bars from left to right are 50 nm, 10 nm, and 2 nm−1 respectively.