Thermal Tuning of Ag-Doped ZnO Materials for Photocatalytic Applications

This study investigates the synthesis and photocatalytic performance of Ag-doped ZnO (5%) nanoparticles fabricated via the spray pyrolysis method at varying calcination temperatures (400, 500, 600, and 700 °C). X-ray diffraction (XRD) analysis confirmed the formation of pure ZnO with a hexagonal wurtzite structure, while additional peaks indicated successful Ag incorporation. Surface morphology analysis using SEM revealed that lower calcination temperatures produced more homogeneous and compact particles, while higher temperatures led to increased aggregation and irregular structures. Crystallite size increased from 5.94 nm at 400 °C to 9.34 nm at 700 °C. FTIR showed the strongest O–H band at 400 °C, indicating more surface hydroxyl groups. The 400 °C sample also showed the highest photocatalytic activity, due to its smaller crystallite size and greater –OH content. As calcination temperature increased, photocatalytic activity declined due to reduced surface homogeneity and hydroxyl availability. These results emphasize the importance of thermal treatment in refining the structural and surface features of Ag-doped ZnO for improved photocatalytic efficiency.