▎ 摘　　要

Boron could be the next element after carbon capable of forming 2D-materials similar to graphene. Theoretical calculations predict that the most stable planar all-boron structure is the so-called alpha-sheet. The mysterious structure of the alpha-sheet with peculiar distribution of filled and empty hexagons is rationalized in terms of chemical bonding. We show that the hexagon holes serve as scavengers of extra electrons from the filled hexagons. This work could advance rational design of all-boron nanomaterials.