Growth of Chlorine-Doped ZnO Nanorod Arrays on Different Substrates

In this study, zinc nitrate (Zn(NO3)2), hexamethylenetetramine (C6H12N4), and sodium chloride (NaCl) were employed as precursor materials to synthesize ZnO nanorod arrays on two distinct types of substrates using the hydrothermal method. We investigated how different substrates and varying chlorine concentrations influence the synthesis properties of chlorine-doped ZnO nanorod arrays. Specifically, this study aimed to explore the structural, morphological, and optical properties of the synthesized ZnO nanorod arrays. The substrates investigated were an indium tin oxide (ITO) substrate with a ZnO seed layer and an ITO substrate with a self-assembled monolayer (SAM) of molecules. The formation of the SAM involved placing a clean ITO conductive glass substrate into a high-pressure reactor, along with a vial containing 0.2 mm of octadecyltrichlorosilane. Using this process, a uniform SAM was created on the ITO substrate. The molar ratio of Zn(NO3)2, C6H12N4, and NaCl was maintained at 1:1:x, where x varied as 0, 0.1, 0.2, 0.3, and 0.4. This corresponded to NaCl volumes of 0, 2.5, 5.0, 7.5, and 10.0 mM, respectively. The crystallinity and orientation of the nanorods were assessed with their surface morphology using scanning electron microscopy (SEM). By systematically varying the chlorine concentration and substrate type, the role of these parameters was understood in tailoring the characteristics of ZnO nanorod arrays for potential applications in optoelectronic devices, sensors, and photocatalysts.