Influence of Cu-Doping Concentration on the Structural and Optical Properties of SnO2 Nanoparticles by Coprecipitation Route

Tin dioxide (SnO2) nanoparticles doped with varying concentrations of copper were synthesized and characterized using various techniques. The X-ray diffraction analysis revealed that all doped and undoped SnO2 samples had a rutile-type tetragonal structure. The average crystalline size of the doped samples estimated using Scherrer’s formula and the Williamson–Hall plot decreased as dopant concentration increased. Images from scanning electron microscopy revealed spherical grains in the samples. The transmission electron microscope was used to examine the particle nature, and nearly spherical particles were discovered. The energy-dispersive X-ray spectroscopy analyses confirmed that the synthesized nanoparticles were nearly stoichiometrically composed of the expected elements copper, oxygen, and tin. The bandgap energy of doped and undoped SnO2 nanoparticles was determined using UV–visible diffuse reflectance spectra, and it was found to decrease as Cu2+ ion concentration increased. The photoluminescence study at the excitation wavelength of 300 nm revealed defect-oriented emissions between 350 and 500 nm. All the obtained results showed that the physical properties of SnO2 can be easily engineered through Cu doping for various optoelectronic applications using a low-cost coprecipitation method.