Opto-structural properties and photocatalytic activities of CuO NPs synthesized by modified sol-gel and Co-precipitation methods: A comparative study

Abstract

The study presents a comprehensive investigation into the synthesis of CuO nanoparticles (NPs) through two distinct chemical processing methods, namely modified sol-gel and co-precipitation, and delves into the intricate details of the process optimization and explores the opto-structural properties of the synthesized NPs. The crystal structure of the NPs produced following both the routes was monoclinic with high crystallinity as revealed from their X-ray diffraction (XRD) pattern analysis. However, the co-precipitation route yields slightly larger crystallite sizes and higher crystallinity for lower annealing temperatures. Field emission scanning electron microscope (FE-SEM) revealed that the NPs obtained from sol-gel route have fused irregular-shaped cluster structure, whereas NPs produced via co-precipitation route exhibit a well-controlled spherical morphology. The study further characterizes the optical properties of the NPs through UV–Vis spectroscopy and demonstrates that both direct and indirect band gap values are higher for NPs produced through the sol-gel method. Moreover, NPs synthesized through co-precipitation exhibit superior photocatalytic activity compared to those produced through sol-gel, attributed to their unique morphological attributes. Photocatalytic properties were investigated from the degradation of rhodamine B under ultra-violet (UV) irradiation.