Controlled Formation of α- and β-Bi₂O₃ with Tunable Morphologies for Visible-Light-Driven Photocatalysis

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Persistent organic contaminants in water pose significant environmental risks.
• Photocatalysis is a promising eco-friendly technology for water remediation.
• Understanding the structure-property relationships of bismuth oxide (Bi₂O₃) photocatalysts is crucial for optimizing their performance.

Purpose of the Study:

• To develop a straightforward synthesis method for phase-pure α- and β-Bi₂O₃ with tunable morphologies.
• To investigate the influence of structural and morphological features on the photocatalytic activity of Bi₂O₃.
• To evaluate the efficiency of Bi₂O₃ in degrading organic pollutants like Rhodamine B and Methyl Orange.

Main Methods:

• Hydrothermal synthesis followed by controlled calcination to produce α- and β-Bi₂O₃.
• X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET), and UV-Vis spectroscopy for material characterization.
• Photocatalytic degradation experiments using Rhodamine B and Methyl Orange as model pollutants.

Main Results:

• Phase-pure α- and β-Bi₂O₃ with flower-like, broccoli-like, and fused morphologies were successfully synthesized.
• Flower-like β-Bi₂O₃ exhibited the highest surface area and a lower bandgap, enhancing visible light response.
• Flower-like β-Bi₂O₃ achieved 81% degradation of Rhodamine B in 4 hours and 73% degradation of Methyl Orange in 3 hours (complete removal under acidic conditions).

Conclusions:

• The synthesis method allows for controlled production of Bi₂O₃ with tailored phases and morphologies.
• Both crystal phase and morphology significantly impact the photocatalytic efficiency of Bi₂O₃.
• Flower-like β-Bi₂O₃ demonstrates excellent potential as a reusable and stable photocatalyst for water remediation.