A Comprehensive Review: The Synthesis, Characterization, and Applications of CuO and CuS Nanomaterials

Semiconductor nanomaterials, including transition metal oxides and sulfides, present a variety of applications such as chemical transformations, energy conversion and storage, chemical and bio-sensing, as well as antimicrobial properties, owing to their adjustable physicochemical characteristics. Copper oxide (CuO) and copper sulfide (CuS) are often highlighted in these applications, either separately or together, due to their properties that are influenced by composition and the ability of both materials to engage in oxidation and reduction reactions. Effective catalysis necessitates a precise equilibrium among various electronic states, energy levels, defect doping, phase, and even the morphology of the catalyst, as all these factors directly affect charge transfer kinetics and separation kinetics. The methods of synthesis play a vital role in regulating these elements, which in turn dictate catalytic efficiency and performance. A multitude of chemical, physical, and biological methods have been documented in the literature for the synthesis of CuO and CuS nanoparticles, focusing on the ease of adaptation, reproducibility of the process, and scalability suitability. Various characterization techniques have been employed to analyze the reaction products: X-ray diffraction; scanning electron microscopy (SEM) and transmission electron microscopy (TEM); X-ray photoelectron spectroscopy (XPS); Fourier transform infrared spectroscopy (FTIR); energy dispersive X-ray spectroscopy (EDX); ultraviolet–visible spectroscopy; and Raman spectroscopy. The fundamental properties of CuO and CuS nanoparticles, such as phase control, stoichiometry control, defects, doping, size, shape, and quantum effects, will be examined alongside their performance in catalysis, sensing, biomedical applications, photocatalytic activity, and pharmaceutical applications, as well as long-term stability and environmental health safety.