Bismuth-based Compounds Research Articles

A review of bismuth-based photocatalysts for antibiotic degradation: Insight into the photocatalytic degradation performance, pathways and relevant mechanisms

The intensive production and utilization of antibiotics worldwide has inevitably led to releases of very large amounts of these medicines into the environment, and numerous strategies have recently been developed to eliminate antibiotic pollution. Therefore, bismuth-based photocatalysts have attracted much attention due to their high adsorption of visible light and low production cost. This review summarizes the performance, degradation pathways and relevant mechanisms of typical antibiotics during bismuth-based photocatalytic degradation. First, the band gap and redox ability of the bismuth-based catalysts and modified materials (such as morphology, structure mediation, heterojunction construction and element doping) were compared and evaluated. Second, the performance and potential mechanisms of bismuth oxides, bismuth sulfides, bismuth oxyhalides and bismuth-based metal oxides for antibiotic removal were investigated. Third, we analysed the effect of co-existing interfering substances in a real water matrix on the photocatalytic ability, as well as the coupling processes for degradation enhancement. In the last section, current difficulties and future perspectives on photocatalytic degradation for antibiotic elimination by bismuth-based catalysts are summarized. Generally, modified bismuth-based compounds showed better performance than single-component photocatalysts during photocatalytic degradation for most antibiotics, in which h+ played a predominant role among all the related reactive oxygen species. Moreover, the crystal structures and morphologies of bismuth-based catalysts seriously affected their practical efficiencies.

Medicinal chemistry and biomedical applications of bismuth-based compounds and nanoparticles.

Bismuth as a relatively non-toxic and inexpensive metal with exceptional properties has numerous biomedical applications. Bismuth-based compounds are used extensively as medicines for the treatment of gastrointestinal disorders including dyspepsia, gastric ulcers and H. pylori infections. Recently, its medicinal application was further extended to potential treatments of viral infection, multidrug resistant microbial infections, cancer and also imaging, drug delivery and biosensing. In this review we have highlighted the unique chemistry and biological chemistry of bismuth-209 as a prelude to sections covering the unique antibacterial activity of bismuth including a description of research undertaken to date to elucidate key molecular mechanisms of action against H. pylori, the development of novel compounds to treat infection from microbes beyond H. pylori and the significant role bismuth compounds can play as resistance breakers. Furthermore we have provided an account of the potential therapeutic application of bismuth-213 in targeted alpha therapy as well as a summary of the biomedical applications of bismuth-based nanoparticles and composites. Ultimately this review aims to provide the state of the art, highlight the untapped biomedical potential of bismuth and encourage original contributions to this exciting and important field.

Atomic Structure and Electronic Properties of Intermetallic CaBi2 Thin Films.

Intermetallic bismuth-based compounds have attracted great interest as promising candidates for novel topological superconductivity. Among them, CaBi2 is a newly discovered member for which the atomic structure and electronic properties have never been systematically explored. Using low-temperature scanning tunneling microscopy/spectroscopy (STM/S), we systematically characterized the atomic structure and electronic properties of CaBi2(010) thin films grown by molecular beam epitaxy (MBE) and found that their growth follows a Stranski-Krastanov mode. A nonreconstructed IBi layer and a (1 × 2) reconstructed IICa layer were found to be the most common surfaces. Nonreconstructed IIIBi and VCa layers were further exposed with reduced bismuth growth flux. All of these constituent layers exhibit unique features in the STS spectra, indicating that unique electronic properties exist in each specific constituent layer. Our findings provide for deeper understanding of the physical properties of this compound and suggest further studies of the two-dimensional (2D) layered materials family.

Boosting photocatalytic activity through in-situ phase transformation of bismuth-based compounds on carbon dots and quantification analysis of intrinsically reactive species in photocatalysis

As a photocatalyst, both BiOCOOH and (BiO)2CO3 are only active under UV light irradiation. In this contribution, a room-temperature approach is firstly demonstrated to develop in situ incorporation of green carbon dots (CDs) into BiOCOOH (CDs@BiOCOOH) by taking advantage of the residual HCOOH for preparing CDs. As-prepared CDs@BiOCOOH is endowed with broad visible light absorption. By the reaction with NaBH4, BiOCOOH is subsequently transformed into (BiO)2CO3 at room temperature, forming a new heterostructure of CDs@(BiO)2CO3. Not only does this heterostructure display exceptionally stronger visible light harvesting capability than CDs@BiOCOOH due to the introduction of more structural defects in the process of phase transformation, but it also possesses more superior degradation ability for the organic pollutants under visible light. Its photocatalytic activity is raised to over 7 times comparing to BiOCOOH. Accordingly, a facile and room-temperature synthesis strategy is presented for large-scale production of CDs@(BiO)2CO3 with highly efficient use of sunlight. To understand photocatalytic mechanism, we offer a unique technique for the quantification and the kinetics evaluation of the intrinsic reactive species produced in photocatalysis as well.

2020 Roadmap on two-dimensional nanomaterials for environmental catalysis

Environmental catalysis has drawn a great deal of attention due to its clean ways to produce useful chemicals or carry out some chemical processes. Photocatalysis and electrocatalysis play important roles in these fields. They can decompose and remove organic pollutants from the aqueous environment, and prepare some fine chemicals. Moreover, they also can carry out some important reactions, such as O2 reduction reaction (ORR), O2 evolution reaction (OER), H2 evolution reaction (HER), CO2 reduction reaction (CO2RR), and N2 fixation (NRR). For catalytic reactions, it is the key to develop high-performance catalysts to meet the demand for targeted reactions. In recent years, two-dimensional (2D) materials have attracted great interest in environmental catalysis due to their unique layered structures, which offer us to make use of their electronic and structural characteristics. Great progress has been made so far, including graphene, black phosphorus, oxides, layered double hydroxides (LDHs), chalcogenides, bismuth-based layered compounds, MXenes, metal organic frameworks (MOFs), covalent organic frameworks (COFs), and others. This content drives us to invite many famous groups in these fields to write the roadmap on two-dimensional nanomaterials for environmental catalysis. We hope that this roadmap can give the useful guidance to researchers in future researches, and provide the research directions.

Alkali metal-substituted bismuth-based perovskite compounds: A DFT study

Abstract In this study, we have performed density functional theory based calculations to investigate the effect of alkali substituents M on the structure and electronic properties of (Bi0.5M0.5)TiO3 compounds with M = Li, Na and K. When the ionic radius of the substituting M cation increases, the corresponding direct band gap of (Bi0.5M0.5)TiO3 also increases. The same trend is found for the O-deficient Bi0.5M0.5TiO3-δ compounds, which were investigated by removing one Oxygen atom from the super cell creating an O-vacancy in it. The presence of the O-vacancy breaks the local symmetry of the crystal structures and generates excess electrons in the O-deficient compounds. This results in the appearance of an indirect bandgap in Bi0.5Na0.5TiO3-δ and Bi0.5K0.5TiO3-δ, except for Bi0.5Li0.5TiO3-δ that still exhibits a direct bandgap. Excess electrons induce the defect states within the original bandgap of the stoichiometric compounds and decrease the bandgap of the O-deficient compounds. In line with the electronic calculations, effective mass calculations have provided a preliminary insight into the photocatalytic performance of (Bi0.5M0.5)TiO3 and reveal a positive impact of K cations on the photocatalytic activity.

Recent Research Trends on Bismuth Compounds in Cancer Chemoand Radiotherapy.

Application of coordination chemistry in nanotechnology is a rapidly developing research field in medicine. Bismuth complexes have been widely used in biomedicine with satisfactory therapeutic effects, mostly in Helicobacter pylori eradication, but also as potential antimicrobial and anti-leishmanial agents. Additionally, in recent years, application of bismuth-based compounds as potent anticancer drugs has been studied extensively. Search for data connected with recent trends on bismuth compounds in cancer chemo- and radiotherapy was carried out using web-based literature searching tools such as ScienceDirect, Springer, Royal Society of Chemistry, American Chemical Society and Wiley. Pertinent literature is covered up to 2016. In this review, based on 213 papers, we highlighted a number of current problems connected with: (i) characterization of bismuth complexes with selected thiosemicarbazone, hydrazone, and dithiocarbamate classes of ligands as potential chemotherapeutics. Literature results derived from 50 papers show that almost all bismuth compounds inhibit growth and proliferation of breast, colon, ovarian, lung, and other tumours; (ii) pioneering research on application of bismuth-based nanoparticles and nanodots for radiosensitization. Results show great promise for improvement in therapeutic efficacy of ionizing radiation in advanced radiotherapy (described in 36 papers); and (iii) research challenges in using bismuth radionuclides in targeted radioimmunotherapy, connected with choice of adequate radionuclide, targeting vector, proper bifunctional ligand and problems with 213Bi recoil daughters toxicity (derived from 92 papers). This review presents recent research trends on bismuth compounds in cancer chemo- and radiotherapy, suggesting directions for future research.

Cytotoxicity of 5-ALA-conjugated bismuth oxidenanoparticles on KB cell line

Introduction: In recent years, bismuth-based nanomaterials have been widely used in medical researches as imaging, drug delivery and x-ray radiosensitizing agents. Due to their anti-microbial effects against Helicobacter pylori (HP), bismuth colloidal compounds are used to treat various types of diseases such as chronic gastritis. Despite their advantages, bismuth-based compounds have shown many toxic effects in humans. There are few studies on cytotoxicity effects of bismuth (ΙΙΙ) oxide (Bi2O3) nanoparticles (NPs). Based on the natural high affinity of folate for the folate receptor protein (FR), which is commonly expressed on the surface of many human cancers, folate-drug conjugates bind tightly to the FR and trigger cellular uptake via endocytosis. Therefore, we aimed to investigate the cytotoxicity effects of 5-ALA-conjugated Bi2O3 NPs, 5-ALA-folate-conjugated Bi2O3 NPs and free 5-ALA on oral squamous carcinoma cell line (KB cells) for the first time. 5-ALA is used in photo dynamic detection and photodynamic surgery of cancer. Being a precursor of a photosensitizer, 5-ALA is also used as an add on agent for photodynamic therapy. Materials and Methods: Bi2O3 NPs were synthesized and conjugated with folate and 5- aminolevulinic acid (5-ALA). KB cells were cultured monolayer and incubated with 10, 20, 50, 100 and 200 μg/ml concentrations of free 5-ALA, 5-ALA-folate-conjugated Bi2O3 NPs and 5-ALA-conjugated Bi2O3 NPs for 24 hours. The survival of the cells obtained after 24 h of incubation with the materials using MTT assay. Results: Bi2O3 NPs were synthesized (~20 nm) and conjugated to folate and (5-ALA). Results indicated that the significant cellular death were noted at the concentrations more than of 50 μg/ml for all compounds that cell viability reduced to 37%, 49% and 63% in groups receiving 5-ALA-folate-conjugated NPs, 5-ALA-conjugated Bi2O3 NPs and free 5-ALA, respectively. The cytotoxicity of the materials on KB cells also increased with increasing concentrations of synthesized NPs. Conclusion:5-ALA-folate-conjugated NPs, 5-ALA-conjugated Bi2O3 NPs and free 5-ALA were easily taken up by the cells and showed cytotoxic effects at high concentrations. Folic acid conjugation facilitates selective targeting of the KB cells with the overexpression of the folate receptors and improves internalization of the drugs through receptor-mediated endocytosis

Enhanced visible-light-driven photocatalysis of Bi2YO4Cl heterostructures functionallized by bimetallic RhNi nanoparticles

Bismuth-based Sillen-Aurivillius compounds are being explored as efficient photocatalyst materials for the degradation of organic pollutants due to their unique layered structure that favours effective separation of electron-hole pairs. In this work, we synthesized Sillen-Aurivillius-related Bi2YO4Cl with the bandgap of 2.5 eV by a simple solid-state reaction and sensitized with rhodium nickel (RhNi) nanoparticles (NPs) to form the RhNi/Bi2YO4Cl heterostructure. Photocatalytic activities of BiOCl, Bi2YO4Cl and the RhNi/Bi2YO4Cl heterostructure were examined for the degradation of rhodamine- 6G under visible-light illumination. Results demonstrated that the photocatalytic dye degradation efficiency of RhNi/Bi2YO4Cl heterostructures is higher than those of BiOCl and Bi2YO4Cl, attributed to the synergistic molecular-scale alloying effect of bimetallic RhNi NPs. The plausible mechanism for the degradation of rhodamine-6G and the effective electron-hole pair utilization mechanism were discussed.

Investigating the Cytotoxicity of Folate-Conjugated Bismuth Oxide Nanoparticles on KB and A549 Cell Lines.

Purpose: Lately, bismuth-based nanomaterials have been widely utilized in medical researches such as imaging, drug delivery and radio-sensitization. Despite their advantages, bismuth-based compounds have shown toxic effects in humans. There are few studies on cytotoxicity effects of bismuth oxide (Bi2O3) nanoparticles (NPs) in-vitro. In this study, we aimed to investigate cytotoxicity of bare and also folate and 5-aminolevulinic acid (5-ALA)-conjugated Bi2O3 NPs on nasopharyngeal carcinoma (KB) and lung cancer (A549) cell lines.Methods: Bi2O3 NPs were synthesized and conjugated with folate and 5-ALA. KB and A549 cells were cultured and incubated with 10, 20, 50 and 100 μg/ml concentrations of bare and folate-5-ALA-conjugated NPs. The survival rates were obtained after 2 and 24 hours incubation of the cells with NPs using MTT assay. Also, apoptosis and ROS generation induced by the NPs in the treated cells were obtained using Caspases-3 activity assay and flow cytometry analysis, respectively.Results: Bi2O3 NPs were successfully synthesized with average size of 19.2 ± 6.5 nm, then conjugated with 5-ALA and folate. Either naked or folate-conjugated NPs were easily taken up by the cells in a concentration-dependent manner and showed cytotoxic effects. The significant cell death was noted at the concentrations more than 50 μg/ml for both compounds.Conclusion: Results indicated low cytotoxicity of the prepared NPs at lower incubation periods, which is very important for their further applications. However, 24 hours incubation of the cells with both forms of NPs caused more cell killing and the cytotoxicity increased with increasing concentrations of the NPs.

Do bismuth complexes hold promise as antileishmanial drugs?

Even after 70years, pentavalent antimonials sodium stibogluconate and meglumine antimoniate remain the most important and cost-effective antileishmanial drugs. However, the drugs cannot be delivered orally and treatment involves intravascular or intramuscular injections for 28days under strict medical monitoring due to the toxicity of Sb(III). The main alternatives, amphotericin B, pentamidine and miltefosine, are expensive and not without their own problems. Bismuth sits below antimony in the periodic table and is considered to be relatively nontoxic to humans while being capable of providing powerful antimicrobial activity. This review describes recent efforts into developing antileishmanial Bi(III) and Bi(V) drugs, which may resemble Sb analogs in effect and mode-of-action while providing lower mammalian cell toxicity and opportunities of oral delivery.Within the last 10 years, various studies concerning bismuth-based compounds as potential antileishmanial agents have been published. This review seeks to summarize the relevant studies and draw a conclusion as to whether bismuth complexes have the potential to be effective drugs.

Research Update: Bismuth-based perovskite-inspired photovoltaic materials

Bismuth-based compounds have recently gained interest as solar absorbers with the potential to have low toxicity, be efficient in devices, and be processable using facile methods. We review recent theoretical and experimental investigations into bismuth-based compounds, which shape our understanding of their photovoltaic potential, with particular focus on their defect-tolerance. We also review the processing methods that have been used to control the structural and optoelectronic properties of single crystals and thin films. Additionally, we discuss the key factors limiting their device performance, as well as the future steps needed to ultimately realize these new materials for commercial applications.

Exploring bismuth-based alternatives to lead-halide perovskites

Bismuth-based photovoltaic compounds show possibilities as lead-halide analogs without the toxicity risks.

Electronic structure studies of bismuth compounds using high energy resolution X-ray spectroscopy and ab initio calculations

Bismuth-based compounds are widely used as superconductors, catalysts and materials for optical devices. Their properties, and the possibility of controlling these properties, are determined by their electronic structure and the local environment of the Bi-centres. Although X-ray spectroscopy is a powerful method for revealing crystal and electronic structure, the results obtained so far have been limited by the energy resolution of the experimental data. Here, for the first time, we report X-ray absorption near edge structure (XANES) data, recorded in high energy resolution fluorescence detection (HERFD) mode at the Bi LIII and LI edges for a number of bismuth compounds. Experimental data are analysed using ab initio calculations based on a finite difference method (FDMNES) code, for metallic Bi, Bi2O3, BiPO4, Bi4(GeO4)3 and NaBiO3 compounds. It was observed that both the oxidation state and the length of the Bi-ligand bonds determine the exact position of the absorption edge, and this is in good agreement with other studies. Additionally, due to the high energy resolution, spectral features corresponding to strong Bi p-d orbital mixing were resolved. The results obtained here can be used as input for further investigations of the electronic structure of bismuth compounds in different chemical states.

Solvent-Engineering Method to Deposit Compact Bismuth-Based Thin Films: Mechanism and Application to Photovoltaics

Bismuth-based materials have been studied as alternatives to lead-based perovskite materials for photovoltaic applications. However, poor film quality has limited device performance. In this work, we developed a solvent-engineering method and show that it is applicable to several bismuth-based compounds. Through this method, we obtained compact films of methylammonium bismuth iodide (MBI), cesium bismuth iodide (CBI), and formamidinium bismuth iodide (FBI). On the basis of film growth theory and experimental analyses, we propose a possible mechanism of film formation. Additionally, we demonstrate that the resultant compact MBI film is more suitable to fabricate efficient and stable photovoltaic devices compared to baseline MBI films with pinholes. We further employed a new hole-transporting material to reduce the valence-band offset with the MBI. The best-performing photovoltaic device exhibits an open-circuit voltage of 0.85 V, fill factor of 73%, and a power conversion efficiency of 0.71%, the highest r...

Structural and Galvanomagnetic properties in Mn-Bi2Te3 thin films

Bismuth-based binary chalcogenide compounds such as Bi2Te3 and Bi2Se3 are well known materials for their excellent thermoelectric properties due to their near-gap electronic structure. In the last few years these materials have received attention for exhibiting new physics of 3D topological insulators (TI). Possible applications of TI based devices range from quantum computing, spin based logic and memory to electrodynamics. The 3D TIs present spin-momentum-locked surface states by time reversal symmetry (TRS). Introducing magnetic doping in a TI, brakes the TRS and is predicted to open the gap at Dirac point, resulting in exotic quantum phenomena. This interaction between magnetism and topologically protected states is of potential attention for applications in modern spintronics. Quantum phenomena such as weak antilocalization observed in these nanostructures are described. In this work, granular Mn-Bi2Te3 thin films were grown by DC magnetron sputtering on Si(111) substrates and were submitted to ex situ annealing. We present results for the crystal structure of sputtered and annealed films characterized with X-ray diffraction and high-resolution scanning electron microscopy (HRSEM). The surface analysis was studied with atomic force microscopy (AFM). Magnetotransport measurements were performed using standard four probe technique with Hall and MR configurations, with perpendicular magnetic fields up to 9T and temperatures from 300 to 3K.

Lattice dynamics and force constant calculation for the Raman and infra-red wave numbers of cubic bismuth-based pyrochlore compounds

Lattice dynamics computations utilizing a short-range electrostatic force-field model have been performed for the first time to investigate the fundamental Raman and infra-red wave numbers in some cubic bismuth-based composites, namely, BMN, BZN, BMT and BZT pyrochlores. The calculations of phonons involve three stretching and four bending force-field constants in Wilson GF-matrix method. The calculated phonon wave numbers agree satisfactorily with the observed spectra in the infra-red and Raman excitation zones for all these compounds. A Raman Eg mode has been assigned within the wave number range of 360–375 cm−1. The significant contributions of each force constant towards the calculated Raman and IR wave numbers have also been obtained through investigating the potential energy distribution (PED). The PED mapping for these compounds shows that the lattice dynamical properties of the Nb5+-compounds, BMN and BZN, are remarkably different from the Ta5+-compounds, BMT and BZT. This difference may be attributed to the different degree of orientational dipole disorder caused by the local hopping of the disordered atoms at the A and O′ sites in the A2O′ sub-structure as well as electro-negativity of B5+-cations in these bismuth pyrochlores.

Strongly Enhanced Photovoltaic Performance and Defect Physics of Air-Stable Bismuth Oxyiodide (BiOI).

Bismuth-based compounds have recently gained increasing attention as potentially nontoxic and defect-tolerant solar absorbers. However, many of the new materials recently investigated show limited photovoltaic performance. Herein, one such compound is explored in detail through theory and experiment: bismuth oxyiodide (BiOI). BiOI thin films are grown by chemical vapor transport and found to maintain the same tetragonal phase in ambient air for at least 197 d. The computations suggest BiOI to be tolerant to antisite and vacancy defects. All-inorganic solar cells (ITO|NiOx |BiOI|ZnO|Al) with negligible hysteresis and up to 80% external quantum efficiency under select monochromatic excitation are demonstrated. The short-circuit current densities and power conversion efficiencies under AM 1.5G illumination are nearly double those of previously reported BiOI solar cells, as well as other bismuth halide and chalcohalide photovoltaics recently explored by many groups. Through a detailed loss analysis using optical characterization, photoemission spectroscopy, and device modeling, direction for future improvements in efficiency is provided. This work demonstrates that BiOI, previously considered to be a poor photocatalyst, is promising for photovoltaics.

Bi2O(XO4)(IO3)2 (X = S, Se, Cr): Three-dimensional frameworks containing [Bi4O2]8+ clusters

Three new bismuth-based compounds, Bi2O(XO4)(IO3)2 (X = S, Se, Cr) have been synthesized by hydrothermal method and characterized by single-crystal X-ray diffraction. Title compounds crystallize in the monoclinic space group P21/n (No.14) with lattice parameters: a = 7.2391(5), b = 17.9074(12), c = 7.7964(5) Å, β = 109.6521(15) °, Z = 4 for Bi2O(SO4)(IO3)2; a = 7.2665(4), b = 18.0115(10), c = 7.9310(5) Å, β = 109.7480(10) °, Z = 4 for Bi2O(SeO4)(IO3)2; and a = 7.2708(6), b = 17.9967(14), c = 7.8998(6) Å, β = 109.799(2) °, Z = 4 for Bi2O(CrO4)(IO3)2, respectively. All compounds exhibit three-dimensional frameworks that are composed of [Bi4O2]8+ clusters, [IO3]− and [XO4]2− (X = S, Se, Cr) groups. Bi atoms occur in two different coordination types, showing the stereochemical influence of the Bi3+ lone electron pair. Title compounds were characterized by infrared spectra, solid state UV–vis–NIR diffuse reflectance spectroscopy and thermogravimetric analysis.

Giant Polarization and High Temperature Monoclinic Phase in a Lead-Free Perovskite of Bi(Zn0.5Ti0.5)O3-BiFeO3.

Lead-free piezoelectrics have attracted increasing attention because of the awareness of lead toxicity to the environment. Here, a new bismuth-based lead-free perovskite, (1 - x)Bi(Zn0.5Ti0.5)O3-xBiFeO3, has been synthesized via a high-pressure and high-temperature method. It exhibits interesting properties of giant polarization, morphotropic phase boundary (MPB), and monoclinic phase. In particular, large tetragonality (c/a = 1.228) and giant spontaneous polarization of 110 μC/cm2 has been obtained in 0.6 Bi(Zn0.5Ti0.5)O3-0.4BiFeO3, which is much higher than most available lead-free materials and conventional Pb(Zr,Ti)O3. MPB is clearly identified to be constituted of tetragonal and monoclinic phases at x = 0.5. Notably, a single monoclinic phase has been observed at x = 0.6, which exhibits an intriguing high-temperature property. The present results are helpful to explore new lead-free MPB systems in bismuth-based compounds.