Synthesis of β-Bi2O3 towards the application of photocatalytic degradation of methyl orange and its instability

• Synthesis of Bi2O2CO3 and its conversion to phase pure β-Bi2O3.
• Pure β-Bi2O3 degrades larger amount of methyl orange compared to Bi2O2CO3.
• Pseudo first order kinetics fits well with higher correlation coefficient.
• Conversion of Bi2O3 to Bi2O2CO3 after photocatalytic degradation proves instability.

Bismuth oxide carbonate was synthesized from bismuth nitrate and potassium carbonate and then converted to phase pure β-Bi2O3 form by means of thermal decomposition. X-ray diffraction, HR-SEM, diffuse reflectance UV–vis and photocatalytic degradation studies were carried out on both the samples. Bi2O2CO3 exhibited a wide band gap of 3.406(5) eV while β-Bi2O3 had a lesser band gap of 2.589(3) eV. β-Bi2O3 degrades a higher amount of methyl orange because of its lesser band gap and its optimum loading was 0.1 g in 50 ml of 10 ppm solution. After photocatalytic degradation Bi2O2CO3 remains in the stable form whereas β-Bi2O3 changes to Bi2O2CO3.