Phase-controlled synthesis of bismuth oxide polymorphs for photocatalytic applicationsElectronic supplementary information (ESI) available: Fig. S1-S8: EDS spectra of Bi2O2CO3 nanoflakes and β-Bi2O3 nanoparticles, zeta potential, time-resolved fluorescence spectrum, photocurrent response results of Bi2O3 polymorphs, and photodegradation profiles for organic dyes solutions. Tables T1 and T2: Unit cell parameters, and calculated EVB and ECB from Eg values. See DOI: 10.1039/c8qm00221e

• Main Authors: Selvamani, Thangavel, Anandan, Sambandam, Granone, Luis, Bahnemann, Detlef W, Ashokkumar, Muthupandian
• Format: Journal Article
• Language: English
• Published: 23.08.2018
• ISSN: 2052-1537
• DOI: 10.1039/c8qm00221e

In this study, bismuth oxide polymorphs (α and β phases) were synthesized using a post-calcination method using Bi 2 O 2 CO 3 nanoflakes as an intermediate. These samples were characterized by various spectroscopic techniques such as powder X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, UV-visible absorption, photoluminescence studies and microscopic analysis (scanning and transmission electron microscopy). The mechanism of the formation of β-Bi 2 O 3 nanoparticles and the α-Bi 2 O 3 coral-like morphology has been proposed. Furthermore, the photocatalytic performance of the bismuth oxide polymorphs was investigated via the degradation of organic dyes (rhodamine B, methylene blue, acid orange 7 and methyl orange) under simulated solar illumination. The results show that the β-Bi 2 O 3 nanoparticles possess superior photocatalytic activity compared to the α-Bi 2 O 3 coral-like morphology for the degradation of these dyes due to a higher photon adsorption (band gap of 2.2 eV for β-Bi 2 O 3 and 2.56 eV for α-Bi 2 O 3 ). However, the photocatalytic activity of these bismuth oxide polymorphs for the degradation of organic dyes followed the order of Rh B > AO 7 > MB > MO under identical experimental conditions. A plausible mechanism has been proposed for the photocatalytic activity. Bismuth oxide polymorphs (β-Bi 2 O 3 nanoparticles and α-Bi 2 O 3 coral-like morphology) were synthesized and they show an enhanced efficacy for the degradation of rhodamine B and acid orange 7 as compared to that of methylene blue and methyl orange under simulated solar illumination.