(c,d) Pure nanorod array with etched hole on top of each nanorod at 40 min. Fewer and multilayers of microflowers on nanorod array at (e,f) 1.5 h and (g,h) 3 h, respectively. (i) Nanorod array with microflowers etched away and (j) nanorods with shortened length at 5 h. BMN 673 supplier The phase of as-prepared nanostructures was characterized by XRD pattern, as shown in Figure 2. All diffraction peaks can be indexed to the hexagonal wurtzite phase of ZnO (JCPDS Card No. 36–1451) with not

any impurities. The strong relative intensity of the (0002) diffraction peak reveals a texture effect of the arrays consistent with c-axis-oriented nanorods, which will be further confirmed by TEM images (Figure 3). Figure 3a shows a typical TEM image of ZnO nanorod scratched from the ZnO nanorod array

on a FTO substrate. Corresponding HRTEM image and SAED pattern (Figure 3b), taken from the red circled area in Figure 3a, exhibit that ZnO nanorod is a single crystal with the preferential [0001] growth direction. Figure 3d illustrates the HRTEM image and SAED pattern of ZnO nanorod, a random branch of microflower as shown in Figure 3c, revealing that the growth direction of single crystal is also along [0001]. Figure 2 XRD pattern of as-prepared ZnO pure nanorod arrays and fewer and multilayers of microflowers on nanorod arrays. Figure 3 TEM (a,c) and HRTEM images (b,d) of ZnO nanorods and microflowers, respectively. Trametinib ic50 Based on the above growth phenomena, we propose a local dissolution-driven growth mechanism for present ZnO nanostructures. As we know, an alkaline solution is essential for the formation of ZnO nanostructures AMP deaminase because normally divalent

metal ions do not hydrolyze in acidic environments. In our experiments, both HMTA and NH3 · H2O provided the NH3 (NH4+) and OH−, and the NH3 served as the complex agent to form zinc amino complex [Zn(NH3)4]2+ with Zn2+, according to [21–24]. (1) (2) (3) In the initial reaction stage, the Zn2+ supplied from the decomposition of [Zn(NH3)4]2+ reacted with OH− and Zn(OH)2 colloids formed in the solution (reaction 4), and part of Zn(OH)2 colloids dissolved into Zn2+ and OH− because the precipitates of Zn(OH)2 are more soluble as compared to the ZnO precipitates (reaction 5). When the concentration of Zn2+ and OH− reached the supersaturation degree of ZnO, ZnO nuclei formed (reaction 6) and acted as building blocks for the formation of final products. The growth units of [Zn(OH)4]2− formed according to reaction 7 [25–27]. (4) (5) (6) (7) Wurtzite structured ZnO, which is confirmed by the XRD pattern (Figure 2), grown along the c-axis has high-energy polar surfaces such as ± (0001) surfaces with alternating Zn2+ terminated and O2− terminated surfaces [28]. Therefore, when a ZnO nucleus was newly formed, the incoming precursor molecules tended to favorably adsorb on the polar surfaces, leading to a fast growth along the [0001] direction (Figure 3a,b) and thus 1D nanorod structure formed.