Fig. 7
SEM images of a H@TNAs-2, c H@TNAs-3 and e H@TNAs-4. b, d, f The cross-sections of H@TNAs-2, H@TNAs-3 and H@TNAs-4, respectively. The as-prepared H@TNAs have a diameter of 85 ± 10 nm and a tube length of 8.5 ± 0.3 μm
Fig. 7 | Nanoscale Research Letters