Metastable β‐Bi₂O₃ Nanoparticles with Potential for Photocatalytic Water Purification Using Visible Light Irradiation

Abstract

Photocatalytic studies under visible light irradiation using nanosized β-Bi2O3 are reported. β-Bi2O3 nanoparticles are prepared starting from the well-defined bismuth oxido cluster [Bi38O45(OMc)24(DMSO)9]⋅2 DMSO⋅7 H2O (OMc=O2CC3H5) using a straightforward hydrolysis and annealing protocol. Powder X-ray diffraction studies, transmission electron microscopy, diffuse reflectance UV/Vis spectroscopy and nitrogen adsorption measurements (using the Brunauer–Emmett–Teller (BET) theory) are used for the characterization of the as-prepared β-Bi2O3. By time-dependent annealing, the crystallite size can be controlled between (17±2) nm and (45±5) nm with BET surface areas of 7 to 29 m2 g−1. The indirect band gap of the as-prepared β-Bi2O3 amounts to (2.15±0.05) eV. The decomposition rates for rhodamine B (RhB) solutions are in the range of 2.46×10−5 to 4.01×10−4 s−1 and depend on the crystallite size, amount of catalyst and concentration of RhB. Photocorrosion experiments have shown the formation of Bi2O2CO3 after several catalytic cycles. However, the catalyst can be recycled to phase-pure β-Bi2O3 nanoparticles by annealing for one hour under argon atmosphere at 380 °C. Furthermore, the photocatalytic activity of as-prepared β-Bi2O3 nanoparticles for the decomposition of phenol, 4-chlorophenol, 2,4-dichlorphenol, 4-nitrophenol, triclosan and ethinyl estradiol is demonstrated.

Nonaqueous Synthesis of a Bismuth Vanadate Photocatalyst By Using Microwave Heating: Photooxidation versus Photosensitized Decomposition in Visible‐Light‐Driven Photocatalysis

“…[44] This phenomenon was described previously forp hotocatalystss uch as Bi 2 O 3 and seems to be independentofthe investigated catalyst system. [4,5,45] Notably,a tt he beginning, BiVO 4 -4 shows ar ate constant of 1.74 10 À2 min À1 comparable with k 1 of BiVO 4 -3, but after 30 min the reaction is decelerated to ar ate constant of 6.71 10 À3 min…”

“…The conversion of photon energy into chemical energy has become of interest not only for photoinduced water splitting as an environmentally friendly methodt op roduce hydrogen but also forw ater and air purification by the oxidation of pollutants andr eduction of CO 2 . [2,3] In the last few years, diverse Bi-containing visible-light-driven photocatalysts, such as Bi 2 O 3 , [4,5] Bi 2 O 2 CO 3 , [6] BiFeO 3 , [7] Bi 2 WO 6 [8] ,a nd Bi 2 MoO 6 [9] and bismuth titanates Bi 4 Ti 3 O 12 ,B i 12 TiO 20 ,a nd (Bi 2Àx Ti 0.75x )Ti 2 O 7 , [10] have been investigated intensely. [11] BiVO 4 is among the most promising candidates and, in addition to high photocatalytic activity, it offers low toxicitya nd negligible photocorrosion.…”

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

“…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. However, for the practical use of the photocatalyst material, the β-Bi 2 O 3 powder needs to be dispersed in the wastewater for purification and then removed.…”

Green synthesis of the reduced graphene oxide–CuI quasi-shell–core nanocomposite: A highly efficient and stable solar-light-induced catalyst for organic dye degradation in water

“…Among the nanocomposites, CuI-RG2 exhibited the highest photocatalytic activity as it may induce 100% removal within 90 min. Moreover, we noticed no appreciable blue shift in the UV-visible spectra, which suggests that the degradation process of RhB at the surface of the CuI-RGO nanocomposites is faster than the desorption processes of de-ethylated RhB intermediates [42].…”