Effect of synthesis methods on microstructural, optical, and photocatalytic activity of CuBi2O4

The synthesis method used to prepare CuBi₂O₄ significantly influences its microstructure, optical properties, and photocatalytic performance. In this study, CuBi₂O₄ was synthesized via four different methods—citrate-nitrate auto-combustion, hydrothermal, sol-gel, and co-precipitation to evaluate their impact on material characteristics and photocatalytic efficiency. Comprehensive structural analyses using X-ray diffraction confirmed that all synthesized samples crystallized in the tetragonal P4/ncc space group. Morphological analysis via field-emission scanning electron microscopy revealed that hydrothermally synthesized CuBi₂O₄ exhibited a highly porous nanostructure composed of cubic nanorods, leading to a higher surface area. Brunauer-Emmett-Teller analysis confirmed that this sample had the highest surface area (19.7 m²/g), which correlated with enhanced photocatalytic activity. Diffuse reflectance spectroscopy showed band gap variations between 1.6 and 2.1 eV, depending on synthesis conditions. The photocatalytic performance was assessed through methyl orange degradation under sunlight, where the hydrothermally synthesized sample demonstrated superior efficiency, achieving a 65% degradation rate within 195 min, which was significantly higher than other methods. The enhanced activity was attributed to the synergistic effects of increased porosity, smaller particle size, and optimized light absorption properties. These findings provide valuable insights into tailoring synthesis techniques for optimizing CuBi₂O₄-based photocatalysts for environmental remediation and solar energy applications.

Graphical Abstract