Amorphous versus crystalline Al₂O₃ nanoparticles: a comparative study in photocatalytic dye degradation

This study focuses on the synthesis of aluminum oxide (Al₂O₃) nanoparticles and compares their amorphous and crystalline phases, emphasizing their suitability for photocatalytic dye degradation. The as-prepared Al₂O₃, synthesized using the sol–gel technique, is found to have an amorphous nature, which is later annealed at 1200°C to obtain its α phase of crystalline nature. Despite the widespread applications of aluminum oxide in various fields, the differences between its amorphous and crystalline phases are not well understood. This work bridges this gap by evaluating the amorphous and crystalline phases of Al₂O₃, particularly for dye degradation. As technologies advance to enhance aluminum-containing photocatalytic materials by doping, composites, and hybrids, understanding the impact of material phase on photocatalytic capabilities becomes crucial. The research comprehensively assesses structural, functional, morphological, optical, and dye degradation characteristics. Remarkably, amorphous Al₂O₃ demonstrates superior dye degradation efficacy compared with its crystalline counterpart, achieving an enhanced degradation efficiency of 87.2% for rhodamine B, a commonly used azo dye in the printing and textile industries.