Figure 3

Arrays of ZnO-nanotapers with the same height and different sharpness degrees.
(a), Arrays of ZnO-nanotapers with the apical angle of ~10°, achieved from initial 0.1 M Zn(NH3)42+ solution without injection of DI water. (b–d), Arrays of ZnO-nanotapers with apical angles of (b) 15°, (c) 25° and (d) 35° respectively, achieved from initial 0.2 M Zn(NH3)42+ solution by injecting the DI water with flow speed of 0.05, 0.1 and 0.2 mL/min, respectively. The insets are the TEM images.