Figure 5.

TEM characterizations of single-crystalline nanoporous Nb₂O₅ nanotubes: (a) low-magnification TEM image of nanoporous Nb₂O₅ nanotubes; (b, c) high-magnification TEM images of nanoporous Nb₂O₅ nanotubes showing that these nanotubes have a nanoporous shell. The inset of Figure 5b shows the SAED pattern taken from an individual nanotube indicating that these nanotubes are single-crystalline; (d) HRTEM image of the porous shell of a single nanotube revealing (001) lattice planes. The red circles indicate that the shell of these nanotubes densely distributes nanopores.