Temperature-controlled growth and optical properties of ZnO nanorods with quadrangular and hexagonal cross sections

High-density ZnO nanorods with quadrangular and hexagonal cross sections were synthesized by chemical vapor deposition combining with a sol–gel method. It was found that the different morphologies could be obtained by changing the growth temperature. The growth mechanism was presented. The photoluminescence (PL) spectra demonstrated that both the quadrangular and hexagonal cross sections ZnO nanorods had a weak ultraviolet (UV) emission but a very strong and wide green emission. Interestingly, the quadrangular ZnO nanorods showed a stronger green emission than the hexagonal ones. Our X-ray photoelectron spectroscopy (XPS) results indicated that the quadrangular ZnO nanorods had a higher oxygen adsorption ability, and which should be the primary reason for its stronger green emission.