Metallic bismuth (R-Bi) (Figure 1a) has a pseudolayered
structure very similar to that of rhombohedral graphite and black
phosphorus.8 In each layer, one Bi atom is connected with three
other Bi atoms according to the 8-N rule and thus forms a trigonal
pyramid. These pyramids further form a folded bismuth layer by
vertex-sharing. The distances between one Bi atom and its three
neighbors in the same layer and the neighboring layer are 3.072
and 3.529 Å, respectively, and the Bi-Bi-Bi bonding angle is
95.5°. The analogy between the layered structures of R-Bi (Figure
1a) and graphite/phosphorus suggests that the Bi nanotubes
(Figure 1b) may also exist. In fact, theoretical simulation indeed