Fig. 3: Characterization of mechanochemically synthesized and exfoliated few-layer BP.

a Particle size analysis of RP, as-converted BP, and ball mill exfoliated BP showing progressively narrower and smaller size distributions as a result of conversion, comminution, and exfoliation. b Raman spectra confirming the amorphous nature of RP, as well as the crystalline nature of both converted and exfoliated BP. c Photoluminescence (PL) emission of exfoliated BP on SiO2 with a broad spectrum due to the bilayer to multilayer BP in the exfoliated material.