Photocatalytic removal of organic dyes mediated by p-NiO/p-CuO isotype heterojunctions under sunlight illumination

Abstract

Building heterojunctions between different semiconductors is one of the most typical approaches to separating photo-induced electrons and holes in order to enhance photocatalytic efficiency. In this study, NiO, CuO, and NiO–CuO nanocomposites thin films are obtained under the same deposition conditions by a simple spray pyrolysis technique. The structural, morphological, and optical properties of the deposited thin films were investigated using different techniques such as XRD, Raman, SEM, EDX, PL, and UV–visible spectroscopy. XRD and Raman analysis revealed that NiO, CuO, and NiO–CuO have crystalline cubic, monoclinic, and mixed phases, respectively. EDX analysis confirmed the chemical composition, and SEM images reveal different morphologies depending on the Ni:Cu molar ratio. The photodegradation of MB dye in the presence of the thin films was examined under sunlight. Compared with individual metal oxides, NiO–CuO nanocomposites are better as photocatalysts. Optical measurements were able to connect these enhanced photocatalytic activities to the synergistic effects of combining NiO and CuO, which promoted the creation of defects and highly reactive species on surfaces and an effective separation of photogenerated charges. The benefits of p-p isotype heterojunctions for dye photodegradation that this study has illustrated provide a novel perspective on metal oxydes-based nanocomposites for the development of efficient and novel photocatalysts.