One-dimensional inorganic arrangement in the bismuth oxalate hydroxide Bi(C2O4)OH

Two new bismuth salts with succinic acid: synthesis, structural, spectroscopic and thermal characterization

Two novel bismuth succinate hydrates, namely, poly[[diaqua(μ3-butane-1,4-dicarboxylato)hemi(μ-butane-1,4-dicarboxylato)bismuth] monohydrate], {[Bi(C4H4O4)1.5(H2O)2]·H2O}n (1), and poly[[μ-aqua-aqua(μ3-butane-1,4-dicarboxylato)(μ-butane-1,4-dicarboxylato)-μ-oxido-dibismuth] monohydrate], {[Bi2(C4H4O4)2O(H2O)2]·H2O}n (2), have been synthesized. Their crystal structures were determined by single-crystal X-ray diffraction and the compounds were characterized by IR and Raman spectroscopy, powder X-ray diffraction and thermal analysis. The crystal structure analysis revealed that the compounds are coordination polymers, with 1 having a two-dimensional layered structure and 2 displaying a three-dimensional (3D) framework. Fully deprotonated succinate anions (C4H4O42-) in two different conformations (trans and gauche) are included in their composition. The Bi3+ cations are surrounded by O atoms from the carboxylate groups of succinate anions and aqua ligands. BiO9 coordination polyhedra in 1 are connected in pairs by edges. These pairs are bound together by bridging succinate ligands to form layers. Bismuth coordination polyhedra of two different types (BiO9 and BiO7) in 2 are connected by edges to form infinite ribbons. Ribbons of polyhedra with bridging succinate ligands form a 3D polymeric structure.

Novel pure α-, β-, and mixed-phase α/β-Bi2O3 photocatalysts for enhanced organic dye degradation under both visible light and solar irradiation

Combining the pure α- and β-phases of bismuth oxide enhances its photocatalytic activity under both visible and solar irradiation. α-Bi₂O₃, β-Bi₂O_3, and α/β-Bi₂O₃ were synthesized by a solvothermal calcination method. The structural, optical, and morphological properties of the as-synthesized catalysts were analyzed using XRD, UV-DRS, XPS, SEM, TEM, and PL. The bandgaps of α/β-Bi₂O₃, α-Bi₂O₃, and β-Bi₂O₃ were calculated to be 2.59, 2.73, and 2.34 eV, respectively. The photocatalytic activities of the catalysts under visible and solar irradiation were examined by the degradation of carcinogenic reactive blue 198 and reactive black 5 dyes. The kinetic plots of the degradation reactions followed pseudo-first-order kinetics. α/β-Bi₂O₃ exhibited higher photocatalytic activity (∼99%) than α-Bi₂O₃ and β-Bi₂O₃ under visible and solar irradiation. The TOC and COD results confirmed the maximum degradation ability of α/β-Bi₂O₃, and the decolorization percentage remained above 90%, even after five cycles under visible irradiation. The photocatalytic dye degradation mechanism employed by α/β-Bi₂O₃ was proposed based on active species trapping experiments.

Cs desorption behavior during hydrothermal treatment of illite with oxalic acid

The desorption of radioactive cesium (Cs) in soil is influenced by the clay mineral type, adsorption site, and concentration of Cs. In this study, experiments to detect desorption of non-radioactive and radioactive Cs from illite using oxalic acid were performed for 2 days at 70 °C in hydrothermal conditions. The results showed that the ¹³³Cs removal efficiency by oxalic acid and inorganic acid treatment was similar at high concentration (22.86 mmol/kg) of non-radioactive ¹³³Cs. In the radioactive ¹³⁷Cs experiment, the removal efficiency by oxalic acid was higher than that by inorganic acid at low concentration (0.79 × 10^-6 mmol/kg) of radioactive ¹³⁷Cs. Based on the illite hypothetical frayed edge site (FES) concentration of 0.612 mmol/kg, the results suggested that ¹³⁷Cs was preferentially adsorbed to FES on illite. The ¹³⁷Cs at low concentration was difficult to remove because it was irreversible adsorption to FES, while the non-radioactive Cs at high concentration was mainly adsorbed to planar sites, and so was easy to desorb by ion exchange. Based on the results of NMR, FTIR, and XPS analyses, we concluded that the higher efficiency of ¹³⁷Cs removal at low concentration by oxalic acid treatment than by treatment with inorganic acid was because of chelation effects associated with the complexation of oxalic acid (ligands) and metal ions in irreversible site (FES).

Crystal Structure and Thermal Behavior of SbC2O4OH and SbC2O4OD

The order of OH groups in the crystal structure of SbC2O4OH, a potential precursor in the synthesis of ternary oxides, was debated. Neutron diffraction on the deuteride SbC2O4OD revealed disordered OD groups with half occupation for deuterium atoms on either side of a mirror plane (SbC2O4OD at T = 298(1) K: Pnma, a = 582.07(3) pm, b = 1128.73(5) pm, c = 631.26(4) pm). O–H stretching frequencies are shifted by a factor of 1.35 from 3390 cm−1 in the hydride to 2513 cm−1 in the deuteride as seen in infrared spectra. SbC2O4OH suffers radiation damage in a synchrotron beam, which leaves a dark amorphous residue. Thermal decomposition at 564 K yields antimony oxide, carbon dioxide, carbon oxide, and water in an endothermic reaction. When using SbC2O4OH as a precursor in reactions, however, ternary oxides are only formed at much higher temperatures.

Multiparameter High-Throughput and in Situ X-ray Diffraction Study of Six New Bismuth Sulfonatocarboxylates: Discovery, Phase Transformation, and Reaction Trends

With the employment of high-throughput methods, the system Bi³⁺/4,8-disulfonyl-2,6-naphthalenedicarboxylic acid (H₄DSNDC)/H₂O/additive (HNO₃ or NaOH) was systematically investigated under hydrothermal reaction conditions. The influence of the molar ratio of the starting materials, pH, and reaction temperature and time was investigated in more than 500 reactions. The product formation is highly sensitive toward small changes of the synthesis parameters, but six new bismuth sulfonatocarboxylates were reproducibly obtained starting from clear solutions of the reactants. All compounds were structurally characterized from single-crystal X-ray diffraction data. Fully deprotonated linker ions are found in [Bi₆O₆(OH)₂(H₂O)₄(DSNDC)] (1), [Bi₂(OH)₂(DSNDC)] (2), [Bi₈O₇(OH)₂(H₂O)₂(DSNDC)₂] (3), and [Bi₇O₅(OH)₃(H₂O)₄(DSNDC)₂]·4H₂O (4), while the presence of larger amounts of acid or short reaction times leads to compounds with noncoordinating -COOH groups, [Bi₂(OH)₂(H₂O)₂(DSNDC)(H₂DSNDC)] (5) and [Bi₆O₄(OH)₄(H₂O)₁₂(H₂DSNDC)₃]· xH₂O (6), respectively. The inorganic building units (IBUs) in all six structures differ substantially from each other; the IBUs found in 2 ({Bi₂(OH)₂}), 5 (BiO₈ polyhedron), and 6 ({Bi₆O₄(OH)₄} cluster) have been reported in the literature, while new IBUs are observed for 1 (chains of composition {Bi₃O₃(OH)}_∞), 3 ({Bi₁₆O₁₄(OH)₄} cluster), and 4 ({Bi₇O₅(OH)₃} cluster). Systematic variation of the reaction temperature and time indicated their distinct influence on product formation. Hence, in situ powder X-ray diffraction measurements at Deutsches Elektronen-Synchrotron, Hamburg, Germany, employing synchrotron radiation were carried out. In all studied in situ reactions, compound 6 is first observed and subsequently transformed to 1, 2, 4, and 5, depending on the reaction time and temperature as well as concentration of the starting materials.

Preparation and Characterization of α-Zinc Molybdate Catalyst: Efficient Sorbent for Methylene Blue and Reduction of 3-Nitrophenol

Zinc molybdate (ZnMoO₄) was prepared by thermal decomposition of an oxalate complex under a controlled temperature of 500 °C. Analyses of the oxalate complex were carried out using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). On the other hand, analyses of the synthesized zinc molybdate were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller technique (BET). The efficiency of the synthesized catalyst was tested with the reduction reaction of 3-nitrophenol (3-NP), and was also applied as a sorbent for methylene blue dye (MB) in aqueous solutions. The catalytic test of zinc molybdate shows a very high activity. The concentration reduction progress and adsorption of the dye were followed by an ultraviolet-visible (UV-vis) spectrophotometer.

High Catalytic Efficiency of Nanostructured β-CoMoO₄ in the Reduction of the Ortho-, Meta- and Para-Nitrophenol Isomers

Nanostructured β-CoMoO₄ catalysts have been prepared via the thermal decomposition of an oxalate precursor. The catalyst was characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The efficiency of these nanoparticles in the reduction of ortho- and meta-nitrophenol isomers (2-NP, 3-NP, and 4-NP) to their corresponding aminophenols was tested using UV-visible spectroscopy measurements. It was found that, with a β-CoMoO₄ catalyst, NaBH₄ reduces 3-NP instantaneously, whilst the reduction of 2-NP and 4-NP is slower at 8 min. This difference is thought to arise from the lower acidity of 3-NP, where the negative charge of the phenolate could not be delocalized onto the oxygen atoms of the meta-nitro group.

Preparation, Characterization and Catalytic Activity of Nickel Molybdate (NiMoO₄) Nanoparticles

Nickel molybdate (NiMoO₄) nanoparticles were synthesized via calcination of an oxalate complex in static air at 500 °C. The oxalate complex was analyzed by thermal gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The as-synthesized nickel molybdate was characterized by Brunauer–Emmett–Teller technique (BET), X-ray diffraction (XRD), and transmission electron microscopy (TEM) and its catalytic efficiency was tested in the reduction reaction of the three-nitrophenol isomers. The nickel molybdate displays a very high activity in the catalytic reduction of the nitro functional group to an amino. The reduction progress was controlled using Ultraviolet-Visible (UV-Vis) absorption.

Bi2(C2O4)3·7H2O and Bi(C2O4)OH Oxalates Thermal Decomposition Revisited. Formation of Nanoparticles with a Lower Melting Point than Bulk Bismuth

Two bismuth oxalates, namely, Bi₂(C₂O₄)₃·7H₂O and Bi(C₂O₄)OH, were studied in terms of synthesis, structural characterization, particle morphology, and thermal behavior under several atmospheres. The oxalate powders were produced by chemical precipitation from bismuth nitrate and oxalic acid solutions under controlled pH, then characterized by X-ray diffraction (XRD), temperature-dependent XRD, IR spectroscopy, scanning electron microscopy, and thermogravimetric differential thermal analyses. New results on the thermal decomposition of bismuth oxalates under inert or reducing atmospheres are provided. On heating in nitrogen, both studied compounds decompose into small bismuth particles. Thermal properties of the metallic products were investigated. The Bi(C₂O₄)OH decomposition leads to a Bi-Bi₂O₃ metal-oxide composite product in which bismuth is confined in a nanometric size, due to surface oxidation. The melting point of such bismuth particles is strongly related to their crystallite size. The nanometric bismuth melting has thus been evidenced ∼40 °C lower than for bulk bismuth. These results should contribute to the development of the oxalate precursor route for low-temperature soldering applications.

Investigation on the effect of an anion layer on photocatalytic activity: carbonate vs. oxalate

The separate [Bi₂O₂]²⁺ and CO₃²⁻ layers can greatly improve the charge separation efficiency.

Morphology-dependent photoelectrochemical properties of multi-scale layered Bi(C2O4)OH

In this work, different morphologies have been synthesized, which can be controlled by simply tuning oxalate source, EG/W volumetric ratio, H₂C₂O₄/Bi(NO₃)₃ molar ratio, hydrothermal temperature and duration.

Nanostring-cluster hierarchical structured Bi2O3: synthesis, evolution and application in biosensing

A new Bi₂O₃ with a nanostring-cluster hierarchical structure was employed for glucose enzyme immobilization and was designed for biosensors.

Simple soluble Bi(iii) salts as efficient catalysts for the oxidation of alkanes with H2O2

Simple soluble Bi(iii) salts exhibit pronounced catalytic activity in the oxidation of inert alkanes with H₂O₂via a radical mechanism with participation of the HO˙ radicals.

Topochemical synthesis of Bi2O3 microribbons derived from a bismuth oxalate precursor as high-performance lithium-ion batteries

A one-dimensional inorganic arrangement in the bismuth oxalate hydroxide Bi(C₂O₄)OH was directly transformed into bismuth oxide Bi₂O₃via a simple thermal decomposition without a morphology change.