Spray deposited β-Bi2O3 nanostructured films with visible photocatalytic activity for solar water treatment

Abstract

Bismuth oxide thin films were obtained by the spray pyrolysis method using bismuth acetate as the precursor salt. The films were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), UV-vis diffuse reflectance, X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). The XRD patterns indicated that the pure β phase is obtained at 450 °C and was also confirmed by FTIR. This phase presents a nanoplate morphology which is adequate for the photocatalytic reactions. Moreover, the band gap value was 2.6 eV indicating a good capacity of visible light absorption. The photocatalytic degradation of the Methyl Orange (MO) dye was pH dependent, an acid solution being easier to degrade. However, the Bi2O3 films were easily converted into BiOCl when they were in contact with a solution containing HCl. In order to preserve the β-Bi2O3 phase, the Acid Blue 113 dye with its natural pH of 8 was used to evaluate the stability of the photocatalytic activity after five degradation cycles. The photoactivity was practically stable indicating a good performance of the material. This encouraged us to test the films in a continuous flow solar reactor prototype for the degradation of the dye solution using sunlight radiation exclusively. The good performance of the β-Bi2O3 films indicates that they can be used for sustainable water treatment applications.

Photochemical solution processing of films of metastable phases for flexible devices: the β-Bi2O3 polymorph

“…The film shows to be efficient for the degradation of the dye, which is totally degraded for short times of light exposure. Therefore, these results demonstrate the efficiency of these thin film materials for visible-light photocatalysis41518464748 that should be associated to the high purity of the β-Bi 2 O 3 polymorph achieved by this synthesis strategy.…”

“…The introduction of impurities is a common strategy to stabilize this phase, but it leads to a strong decrease in the photoactivity. Other strategies have been used for the synthesis of this phase with different degrees of success41415161718. Most of them have focused on the preparation of pure β-Bi 2 O 3 nanostructure materials (nanopowders, nanoflakes, nanowires or nanosheets), by different approaches such as induced aqueous synthesis19, formation of bismuth oxido clusters precursors1520, metal vapor transport, induced template4, hydrothermal methods2122 or microwave processes22.…”

Thin Coatings of α‐ and β‐Bi2O3 by Ultrasonic Spray Coating of a Molecular Bismuth Oxido Cluster and their Application for Photocatalytic Water Purification Under Visible Light

“…In addition, a high visible‐light‐harvesting potential and incident photon‐to‐electron conversion efficiency were shown for β‐Bi 2 O 3 nanoporous films obtained by radio frequency magnetron sputtering using Bi targets and sol‐gel spin coating of a solution of bismuth(III) nitrate pentahydrate in the presence of additives such as an ethanolic solution of triton X‐100 and citric acid . The water purification efficiency of single‐phase tetragonal β‐Bi 2 O 3 coatings synthesized by spray pyrolysis using bismuth(III) acetate as the precursor was evaluated for the degradation of organic dye solutions like methyl orange, acid blue 113, rhodamine B and indigo carmin under UV and visible light . Photochemical solution deposition using the photosensitive bismuth(III)‐ N ‐methyldiethanolamine complex is another suitable preparation method in order to immobilize tetragonal β‐Bi 2 O 3 .…”

Enhanced p-cresol photodegradation over BiOBr/Bi2O3 in the presence of rhodamine B

“…[27][28][29][30][31] However, its photoactivity is hampered by fast electron-hole pair recombination. To facilitate the separation of the photo-generated electrons and holes, Bi 2 39 To achieve a high degree of cohesion at the interfaces within the composite, solid Bi 2 O 3 was chemically converted to BiOBr by etching with varying amounts of HBr.…”