Figure 4.

Carbon nanobelt maps (a–c) show key steps in the sequence of structures formed after sequential dehydrogenation. Route (a) begins with removal of exterior hydrogen atoms, route (b) with interior hydrogen atoms, and route (c) interior hydrogen atoms coupled to C-C bond rotations, as described in the text. The 1H-loss structures for (a–c) are shown in more detail in Figure 2. Grey and white spheres represent carbon and hydrogen atom, respectively. Each single arrow represents the removal of one hydrogen atom. Carbon squares are shaded in blue. The enthalpy value under each molecular model indicates the relative stability between the three isomers grouped vertically by grey dashed lines, i.e., between structures with the same number of hydrogen atoms (+0.00eV is the most stable structure each time). Importantly, the 4H-loss structure formed along the route (c) can also be formed from the 1H- and 2H-loss structures formed along (b) by the bond rotation. (d) shows the calculated enthalpy for removal of a single hydrogen atom from the previous structure for the three routes (a–c). A complete map showing every step is included in  Supplementary Materials Figure S3.