Nanostructured ZnO has gained a lot of interest as a suitable material for various applications, especially sensing, energy conversion, and storage. ZnO nanostructures can be synthesized in several ways. It is one of the materials that can be prepared in a variety of morphologies including hierarchical nanostructures. This review article presents a review of current research activities on the growth of ZnO Nanorods. The article covers various water-based routes of synthesis and is further characterized by the type of substrate used for the growth. The growth factors involved in the hydrothermal and chemical bath deposition methods are discussed. These factors include the variety of precursors, time, temperature, and the seeding method employed. At the end, applications such as gas sensing and improvement in Opto-electric properties are discussed.

The growth of vertically aligned ZnO Nanorods arrays using Zinc Nitrate hexahydrate and Hexamethylene Tetramine (HMTA), by Chemical Bath Deposition on Silicon Wafer was investigated. The growth is conducted under influence of Ethane-1,2-diamine, the amine based enhancer was evaluated based on three different ratios (1:0.5, 1:1, 1:1.5) of enhancer to the precursor (Zinc Nitrate and HMTA). The effect different ratios of enhancers on morphology aspect ratio and crystallinity of the as grown Nanorods were studied under Scanning electron microscope (SEM) and X-ray powder diffraction (XRD). Electrical Properties such as current–voltage characteristics were investigated, its correlation to the morphology and aspect ratio of the Nanorods in the presence of 100μL-500μL of Aromatic Compound Cyclohexane and at different applied voltages.