Eco-Friendly Synthesis of CdO Photocatalyst: Tuning Structural, Morphological, and Optical Characteristics via...

The resistance of azo dyes to degradation in wastewater, together with the limitations of conventional treatment technologies and the limited availability of green-synthesized cadmium oxide nanoparticles (CdO NPs) with tunable properties, represents a major environmental concern. To address these issues, CdO NPs were synthesized at various calcination temperatures (300°C-500°C) through a simple and cost-effective method using Ficus carica leaf extract as a reducing, capping, and stabilizing agent. Structural analyses revealed a calcination-induced phase transition from cadmium hydroxide (Cd(OH)₂) to crystalline CdO accompanied by a reduction in surface -OH groups, which can influence the surface properties and photocatalytic activity of the nanoparticles. The photocatalytic activity of CdO NPs, assessed via methyl orange degradation. The sample calcined at 500°C exhibited the highest efficiency, achieving 41% degradation in the absence of H₂O₂, which markedly increased to 95% upon H₂O₂ addition. Furthermore, the reusability test over 5 cycles showed only a minimal decrease in photocatalytic activity, demonstrating the stability of the CdO NPs.