Manipulating calcination temperature on crystal structure and optical properties tuning of CuO nanostructures

• The TG analysis identified distinct thermal behavior and the activation energy during the calcination process. • XRD confirmed the formation of monoclinic CuO at 200°C, with comprehensive calculations of texture coefficient, crystallite size, and lattice constants. • The 400CuO sample exhibited the highest skin depth, correlating with the lowest Eg of 2.27 eV. • The 400CuO sample demonstrated the strongest PL emission signals at 437 and 470 nm. The research investigated the influence of calcination temperature on the properties of CuO nanostructures synthesized through a chemical precipitation method. Calcination at different temperatures (200, 400, and 600°C) significantly affected the crystal structure, morphology, and optical characteristics of the CuO nanostructures. Various characterization techniques were employed, including thermogravimetric analysis (TG), X–ray diffractometers (XRD), Fourier transform infrared spectrometers (FT–IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). TG analysis revealed thermal behavior and phase transitions, while XRD results confirmed a monoclinic structure of CuO at 200°C with the calculation of the texture coefficient, crystallite size, lattice constants, strain, and other physical properties. SEM images showed a transition from nanorods to plate structures with increasing calcination temperature. TEM images demonstrated the highly crystalline characteristics of CuO samples. The BET analysis depicted surface area reduction, and CuO nanostructures exhibited energy band gaps ranging from 2.23 to 2.78 eV. Calculating optical terms as a function of photon energy also examined optical behaviors. Photoluminescence spectra revealed oxygen and copper vacancy defects, which sublevels affected energy bandgap change. The 400CuO sample exhibited the strongest PL emission signal, indicating the highest crystallinity and the lowest degree of defects. The findings underscored the significant impact of calcination temperature on the morphology and optical properties of CuO nanostructures, providing insights into their structural characteristics and emerging defects. The study supports opto-electronic applications and contributes to the global goal of pollution control and clean water.