Fig. 3a shows the XRD pattern of cobalt-doped ZnO nanorods
recorded in the 2 u range of 20–70. All diffraction peaks can be
attributed to crystalline ZnO with the hexagonal wurtzite structure
[space group: P63mc(186); a) 0.3249 nm, c) 0.5206 nm] and are in
agreement with a reference standard for zinc cobalt oxide (JCPDS
072-8025). No additional peaks were detected that would indicate
formation of cobalt oxide or presence of starting precursor
materials. Sharp XRD peaks imply a high degree of crystallization