Photocatalytic Bi2O3/TiO2:N Thin Films with Enhanced Surface Area and Visible Light Activity

Highly reusable Bi2O3/electron-Cu-shuttle in-situ immobilized polyacrylonitrile fibrous mat for efficient photocatalytic degradation of methylene blue and rhodamine B dyes

Organic semiconductor-based photocatalysts have been alluring due to their edge over inorganic photocatalysts. In this study, a reusable copper-bismuth oxide/polyacrylonitrile (Cu-Bi2O3/PAN) fibrous mat was prepared by fast-process flame spray pyrolysis and electrospinning for photocatalytic degradation of methylene blue (MB) and rhodamine B (RhB) dyes. The results confirmed a well-defined morphology of Cu-Bi2O3/PAN fibers and good coordination of flame-made Cu-Bi2O3 particles with the functional groups of PAN. The Cu-Bi2O3/PAN fibrous mat exhibits remarkable photocatalytic performance of 96.2% MB and 98.6% RhB degradation, with a reaction rate as high as about 4.5- and 10.2-times than that of flame-made Cu-Bi2O3 particles and PAN under neutral condition, even after 10 cycles. The Cu-Bi2O3/PAN exhibits complete degradation of MB and RhB in 90 and 150 min under alkaline and slightly acidic conditions, respectively. The synergistic effect of Cu-Bi2O3 and coordination bond between particles and functional groups of PAN promoted carrier migration, suppressed recombination of carriers and provided abundant radicals on the surface of the mat. Superoxide and hydroxyl radicals were the major active species involved in the degradation of RhB and MB, respectively. This work provides an insight into designing the Cu-metal-shuttle based photocatalysts to optimize fibrous mat application in water remediation.

Study of Prepared Lead-Free Polymer Nanocomposites for X- and Gamma-ray Shielding in Healthcare Applications

Polymer composites were synthesized via melt mixing for radiation shielding in the healthcare sector. A polymethyl-methacrylate (PMMA) matrix was filled with Bi₂O₃ nanoparticles at 10%, 20%, 30%, and 40% weight percentages. The characterization of nanocomposites included their morphological, structural, and thermal properties, achieved using SEM, XRD, and TGA, respectively. The shielding properties for all synthesized samples including pristine PMMA were measured with gamma spectrometry using a NaI (Tl) scintillator detector spanning a wide range of energies and using different radioisotopes, namely Am-241 (59.6 keV), Co-57 (122.2 keV), Ra-226 (242.0), Ba-133 (80.99 and 356.02 keV), Cs-137 (661.6 keV), and Co-60 (1173.2 and 1332.5 keV). A substantial increase in the mass attenuation coefficients was obtained at low and medium energies as the filler weight percentage increased, with minor variations at higher gamma energies (1173 and 1332 keV). The mass attenuation coefficient decreased with increasing energy except under 122 keV gamma rays due to the K-absorption edge of bismuth (90.5 keV). At 40% loading of Bi₂O_3, the mass attenuation coefficient for the cesium ¹³⁷Cs gamma line at 662 keV reached the corresponding value for the toxic heavy element lead. The synthesized PMMA-Bi₂O₃ nanocomposites proved to be highly effective, lead-free, safe, and lightweight shielding materials for X- and gamma rays within a wide energy range (<59 keV to 1332 keV), making them of interest for healthcare applications.

Electrodeposition of Bi from Choline Chloride-Malonic Acid Deep Eutectic Solvent

Deep eutectic solvent (DES) has been widely used in the field of metal electrodeposition as an economical and environmentally friendly green solvent. Metallic bismuth films were prepared by electrodeposition from choline chloride-malonic acid (ChCl-MA) deep eutectic solvent (DES) containing BiCl₃. Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy were used to study the structure of ChCl-MA-BiCl₃, and the results showed that Bi(III) was in the form of [BiCl₆]^3- ions. The viscosity of ChCl-MA-BiCl₃ ranges from 200 to 1200 mPa·s at temperatures from 363 K to 323 K. The conductivity of 0.01 M Bi(III) in ChCl-MA is 3.24 ms·cm^-1 at 363 K. The electrochemical behavior and electrodeposition of Bi(III) in DES were investigated by cyclic voltammetry (CV) and chronoamperometry. The results showed that the electrodeposition reaction was a quasi-reversible reaction controlled by the diffusion and the nucleation of bismuth was a three-dimensional instantaneous nucleation. The diffusion coefficient of Bi(III) in ChCl-MA was 1.84 × 10^-9 cm²·s^-1. The electrodeposition product was observed by scanning electron microscopy (SEM), and the results showed that the deposition potential has a significant influence on the morphology of the bismuth film. X-ray photoelectron spectroscopy (XPS) shows that bismuth and bismuth oxides are present in the deposited film obtained by electrodeposition.

Driving up the Electrocatalytic Performance for Carbon Dioxide Conversion through Interface Tuning in Graphene Oxide-Bismuth Oxide Nanocomposites

The integration of graphene oxide (GO) into nanostructured Bi₂O₃ electrocatalysts for CO₂ reduction (CO₂RR) brings up remarkable improvements in terms of performance toward formic acid (HCOOH) production. The GO scaffold is able to facilitate electron transfers toward the active Bi₂O₃ phase, amending for the high metal oxide (MO) intrinsic electric resistance, resulting in activation of the CO₂ with smaller overpotential. Herein, the structure of the GO-MO nanocomposite is tailored according to two synthetic protocols, giving rise to two different nanostructures, one featuring reduced GO (rGO) supporting Bi@Bi₂O₃ core-shell nanoparticles (NP) and the other GO supporting fully oxidized Bi₂O₃ NP. The two structures differentiate in terms of electrocatalytic behavior, suggesting the importance of constructing a suitable interface between the nanocarbon and the MO, as well as between MO and metal.

Synthesis of modified beta bismuth oxide by titanium oxide and highly efficient solar photocatalytic properties on hydroxychloroquine degradation and pathways

With the outbreak of coronavirus pandemic the use of Hydroxychloroquine increased. These compounds have harmful effects on the environment, such as generation of antibiotic-resistant bacteria; therefore, their degradation has been considered as one of the environmental challenges. The purpose of this research is to synthesize heterogeneous structure of TiO₂/β-Bi₂O₃ by hydrothermal method for solar degradation of Hydroxychloroquine. Then, the accurate characteristics of the synthesized samples were investigated by XRD, FESEM, TEM, XPS, UV–vis (DRS), and BET surface analyzer. Photocatalytic degradation of Hydroxychloroquine was studied under sunlight, and it was found that the visible light absorption of TiO₂ photocatalyst by mixing β-Bi₂O₃ nanoparticles was greatly increased and 91.89% of the degradation was obtained in 120 min of photocatalytic reaction. This improvement can be attributed to the increased specific surface area, efficient charge transfer, and reduced electron-hole recombination with the β-Bi₂O₃ compound. Kinetic studies also reacted to follow pseudo-first-order kinetics. Also, demonstrated high stability and recyclability for nanoparticles, so that after 6 cycles of using the catalyst in take, 70.59% degradation was performed. According to the results, the excellent photocatalytic degradation activity demonstrated by the TiO₂/β-Bi₂O₃, therefore, it is a potential candidate for the process of removing other organic contaminants from aqueous solutions.