In situ TEM study of edge reconstruction and evolution in monolayer black phosphorus

Monolayer black phosphorus edges were in situ constructed inside a microscope, and spontaneous edge reconstruction occurred in all types of as-prepared edges that include ZZ_{[1, 0]}, ZZ_{[1, 0]}(K), DG_{[1, 1]}, and DG_{[1, 1]}(K) edges.