Comprehensive synthesis route of crystalline copper oxide nanoparticles: A crystallographic analysis with functional application

Abstract

The synthesis pathway plays a crucial role in determining the crystallographic and functional properties of copper oxide nanoparticles (CuO NPs). Here, present a comparative study of biological, chemical and physical synthesis routes, emphasizing their influence on structure–property relationships. Environmentally benign biological methods, utilizing plant extracts and microorganisms, yielded NPs with distinctive surface chemistries. In contrast, chemical techniques, such as precipitation and sol–gel, provided precise control over particle size and distribution. Physical methods, including thermal decomposition and laser ablation, produced highly pure nanostructures with well-defined crystallographic symmetry. Advanced characterization, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy and transmission electron microscopy revealed route-dependent variations in morphology, size and phase composition. XRD identified the (111) reflection as the most intense diffraction, though its dominance varied with growth conditions, confirming a monoclinic crystal structure and atomic packing factor of ∼0.65. XPS verified the CuO oxidation state and Fourier-transform infrared spectroscopy detected Cu–O stretching bands between 500 and 700 cm⁻¹. The crystallographic attributes were directly linked to performance in antimicrobial activity, catalysis, gas sensing and energy storage. These findings establish a clear correlation between synthesis, structure and function, providing a framework for the targeted design of CuO NPs for advanced technological applications.