802318.fig.004a
(a)
802318.fig.004b
(b)
Figure 4: (a) Cross-sectional views of water droplets on Ti, electropolished Ti, 100 nm TiO2 nanotubes, and N-doped 100 nm TiO2 nanotubes. (b) Graph showing water droplet contact angles at the surface of the nanotubes.