A Novel Heterostructure of Co₃O₄/ZnO Nanowire Array Fabricated by Photochemical Coating Method

Abstract

We developed a facile solution-based synthetic route for the fabrication of two different types of novel Co3O4/ZnO nanowire heterostructures: tip-coated array type and fully coated horizontal (or colloidal) type. Two-step solution-based methods were used for the fabrication of the Co3O4/ZnO nanowire heterostructures. First, ZnO nanowires were grown by ammonia solution hydrothermal method. Afterward, Co3O4 was coated on the ZnO nanowires using a photochemical reaction. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed for the observation of the heterostructure morphology. Also, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to confirm the crystallinity and composition of the heterostructures. We found that the morphology of the heterostructures strongly depends on the photochemical reaction parameters such as the concentration of the cobalt ion solution, UV irradiation time, and geometrical alignment of the ZnO nanowires. The possible mechanism for the heterostructure formation was discussed.