Figure 13.

a Schematic presentation of the self-supported topotactic transformation process for formation of needle-like Co3O4 nanotubes; b low-magnification SEM image of Co3O4 nanotubes; c high-magnification SEM image of Co3O4 nanotubes, the inset shows a cross-sectional view of nanotubes; d TEM image of a single nanotube [51]. Copyright Wiley–VCH Verlag Gmbh & Co. KGaA. Reproduced with permission

Liu and Xue Nanoscale Research Letters 2010 5:1525-1534   doi:10.1007/s11671-010-9728-5