Tuning structural and optical properties of copper oxide nanomaterials by thermal heating and its effect on photocatalytic degradation of Congo Red dye

In this study, Copper oxide (CuO) nanoparticles (NPs) were prepared using the chemical co-precipitation method and treated at different calcination temperatures. The synthesized CuO NPs have been calcinated at 300 °C, 500 °C, and 700 °C. The X-ray Diffraction (XRD) results exhibited a decrease in the width of the principle diffraction peak with the temperature rise. Crystallite size was determined by Scherrer’s formula, whereas, Williamson-Hall method presented drastic variation in size indicating the creation of lattice strain with the rise in calcination temperature. Scanning Electron Microscopy (SEM) images showed an increase in grain size and vary from 170 nm – 430 nm. X-ray Energy Dispersive Spectroscopy (EDS) results indicate the formation of CuO NPs and relative Cu contents increased (52.9 to 72.5 Atomic percentage) with temperature. Optical properties are also affected by the calcination temperature and a reduction in bandgap is observed with the increase in temperature. Fourier Transform Infra-red spectroscopy (FTIR) spectra of different samples showed identical bonding behavior and no apparent change in bonding was observed. Photo-degradation of Congo Red dye was performed with CuO NPs treated at different temperatures and NPs treated at 500 °C, have shown maximum degradation efficiency in 75 min under visible light.