From a Cerium-Doped Polynuclear Bismuth Oxido Cluster to β-Bi₂O₃:Ce

Abstract

The simultaneous hydrolysis of Bi(NO 3 ) 3 •5H 2 O and Ce(NO 3 ) 3 •6H 2 O results in the formation of novel heterometallic bismuth oxido clusters with the general formula [Bi 38 O 45 (NO 3 ) 24 (DMSO) 28+δ ]:Ce (DMSO = dimethyl sulfoxide; cerium content <1.50%), which is demonstrated by single-crystal X-ray diffraction analysis. The incorporation of cerium into the cluster core is a result of the interplay of hydrolysis and condensation of the metal nitrates in the presence of oxygen. Diffuse-reflectance UV−vis and X-ray photoelectron spectroscopy reveal the presence of Ce IV in the final bismuth oxido clusters as a result of oxidation of the cerium source. The cerium atoms are statistically distributed mainly on the bismuth atom positions of the central [Bi 6 O 9 ] motif of the [Bi 38 O 45 ] cluster core. Hydrolysis and subsequent annealing of the bismuth oxido clusters in the temperature range of 300−400 °C provides β-Bi 2 O 3 :Ce samples with slightly lowered band gaps of approximately 2.3 eV compared to the undoped β-Bi 2 O 3 (approximately 2.4 eV). The sintering behavior of β-Bi 2 O 3 is significantly affected by the cerium dopant. Finally, differences in the efficiency of the asprepared β-Bi 2 O 3 :Ce and undoped β-Bi 2 O 3 samples in the photocatalytic decomposition of the biocide triclosan in an aqueous solution under visible-light irradiation are demonstrated.

Plasmonic Bismuth Nanoparticles: Thiolate Pyrolysis Synthesis, Size-Dependent LSPR Property, and Their Oxidation Behavior

“…The so-formed β-Bi 2 O 3 exhibits a P 4̅ b 2 space group with lattice parameters of a = 10.9384 Å and c = 5.6234 Å, consistent with literature data ( a = 10.93 Å, c = 5.63 Å; PDF #29-0236) . Another space group, P 4̅2 1 c , was also described frequently for tetragonal β-Bi 2 O 3 . ,, β-Bi 2 O 3 is a metastable phase, ,,,− and when stabilized at RT it exhibits semiconducting characteristics with great potential for photocatalysis. , The UV–vis–NIR absorption spectrum (Figure S9) indicates that the as-obtained yellow-color β-Bi 2 O 3 NP powders have a band gap ( E g ) energy ∼2.15 eV, slightly smaller than the literature values (2.4–2.5 eV). ,, The RT stabilization of the metastable β phase can be attributed to its reduced surface energy and crystal defects (e.g., O vacancy or impurities/dopants). ,, Conventionally, β-Bi 2 O 3 was produced from the cooling of high-temperature δ-Bi 2 O 3 polymorph (fluorite structure). ,,, However, as revealed by Raman spectroscopy or XRD, β-Bi 2 O 3 could be also formed by thermal oxidation or laser-induced oxidation of elemental Bi, ,,,, although monoclinic α-Bi 2 O 3 variant was also suggested. , Obviously, the oxidation-driven chemical transformation from Bi to Bi 2 O 3 in our work presents a reliable method capable of synthesizing RT-stabilized β-Bi 2 O 3 NPs.…”

Well‐Defined, Molecular Bismuth Compounds: Catalysts in Photochemically Induced Radical Dehydrocoupling Reactions

“…Indeed, a range of inorganic bismuth compounds such as (nanostructured) oxides (Bi 2 O 3 ), [8] titanates (Bi 4 Ti 3 O 12 ), [9] vanadates (BiVO 4 ), [10] halide perovskites (Cs 3 Bi 2 Br 9 ), [11] and an oxybromide (Bi 24 O 31 Br 10 (OH) δ ) [12] have been exploited in photocatalytic transformations. Catalysed types of reactions include the degradation of organic dyes such as methyl orange, [9] antibiotics such as tetracycline, [10] and biocides such as triclosan, [8b] as well as CH activation of aliphatic and aromatic hydrocarbons, [11] transfer (de)hydrogenation of alcohols/ketones, [12] and olefin polymerisation [8a] . These applications of bismuth compounds in heterogeneous catalysis suggest that photochemical strategies might also be applicable for well‐defined, molecular bismuth compounds under homogeneous conditions.…”

Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

“…In recent years, body-centered-cubic (BCC) γ-Bi 2 O 3 nanostructures have received enormous attention because of their enhanced photocatalytic performance for water purification and water splitting [1][2][3][4][5][6][7][8][9][10]. The high-temperature metastable γ-Bi 2 O 3 is one out of nine polymorphs of Bi 2 O 3 (α-, β-, γ-, δ-, ω-, ε-, η-, ζand R-phases) [11]. Schumb et al [12] was the first to report on the preparation of γ-Bi 2 O 3 by heating β-Bi 2 O 3 at 750-800 • C followed by cooling in the air at 639 • C [13].…”