Analysis of the conversion of cadmium carbonate to cadmium oxide in thin films with photocatalytic application

This study reports the green synthesis of cadmium carbonate (CdCO₃) thin films via chemical bath deposition, followed by controlled thermal conversion to cadmium oxide (CdO) at temperatures ranging from 30 to 500°C. The detailed mechanism of the CdCO₃-to-CdO phase transformation was investigated, revealing a stepwise chemical reaction involving coordination complex formation. Scanning electron microscopy analysis revealed a pyramidal morphology in all CdCO₃ samples. FTIR spectroscopy confirmed the presence of carbonate, carboxylate, and hydroxyl groups, while X-ray diffraction analysis confirmed the successful phase transition to CdO. Optical characterization yielded band gaps between 1.87 and 2.37 eV. Despite the successful synthesis and phase transformation, the resulting nanostructured CdO films exhibited modest photocatalytic efficiency (8–14%) in 90 min, suggesting the need for further optimization.