ZnO structures comprising crystalline ZnO micro or nanorods and methods for making and using these ZnO structures are provided. The side surface of the central portion of each rod may comprise planes of the form {1 0 −1 0}, {0 1 −1 0}, {−1 1 0 0}, {−1 0 1 0}, {0 −1 1 0} or {1 −1 0 0}, with central edge regions including a crystallographic plane of the form {2 −1 −1 0} or {−2 1 1 0}. The tip of the rod may comprise planes of the form {1 0 −1 1} {0 1 −1 1}, {−1 1 0 1}, {−1 0 1 1}, {0 −1 1 1} or {1 −1 0 1} with tip edge regions including a crystallographic plane of the form {2 −1 −1 2} or {−2 1 1 2}. The rods may be joined at or near their bases to form a “flower-like” morphology. In an embodiment, a synthesis mixture is prepared by dissolving a zinc salt in an alcohol solvent, followed by addition of at least two additives. The zinc salt may be zinc nitrate hexahydrate, the first additive may be benzyl alcohol and the second additive may be urea.