Bismuth sulfide based compounds: Properties, synthesis and applications

Low-Temperature Synthesis of Bi2S3 Hierarchical Microstructures via Co-Precipitation and Digestive Process in Aqueous Medium

Bismuth sulfide (Bi2S3) nanostructures have gained significant attention in the fields of catalysis, optoelectronics, and biomedicine due to their unique physicochemical properties. This paper introduces a simple and cost-effective method for producing Bi2S3 microstructures at low temperatures (25 and 70 °C). These microstructures are formed by the hierarchical self-assembly of Bi2S3 nanoparticles, which are typically 15-40 nm in size. The nanoparticles are synthesized by the co-precipitation of thioglycolic acid, thioacetamide, and bismuth nitrate in water. The study delves into the phase composition and morphological evolution of the microstructures, concerning the chemical composition of the solution and the synthesis temperature. X-ray analysis has confirmed the formation of single-phase bismuthinite Bi2S3. The synthesis process generates primary building blocks in the form of 15-40 nm Bi2S3 nanocrystals, which then go through a hierarchical self-assembly process to produce a range of micrometer-sized structures. A scanning electron microscopy examination revealed that the primary nanoparticles self-assemble into quasi-1D worm-like nanostructures, which then self-assemble to create sponge-shaped microstructures. These structures subsequently self-organize and refine into either flower- or dandelion-like microstructures, mostly depending on the synthesis temperature and the chemistry of the digestion medium.

Bismuth-Based Z-Scheme Heterojunction Photocatalysts for Remediation of Contaminated Water

Agricultural runoff, fuel spillages, urbanization, hospitalization, and industrialization are some of the serious problems currently facing the world. In particular, byproducts that are hazardous to the ecosystem have the potential to mix with water used for drinking. Over the last three decades, various techniques, including biodegradation, advanced oxidation processes (AOPs), (e.g., photocatalysis, photo-Fenton oxidation, Fenton-like oxidation, and electrochemical oxidation process adsorption), filtration, and adsorption techniques, have been developed to remove hazardous byproducts. Among those, AOPs, photocatalysis has received special attention from the scientific community because of its unusual properties at the nanoscale and its layered structure. Recently, bismuth based semiconductor (BBSc) photocatalysts have played an important role in solving global energy demand and environmental pollution problems. In particular, bismuth-based Z-scheme heterojunction (BBZSH) is considered the best alternative route to overhaul the limitations of single-component BBSc photocatalysts. This work aims to review recent studies on a new type of BBZSH photocatalysts for the treatment of contaminated water. The general overview of the synthesis methods, efficiency-enhancing strategies, classifications of BBSc and Z-scheme heterojunctions, the degradation mechanisms of Z- and S-schemes, and the application of BBZSH photocatalysts for the degradation of organic dyes, antibiotics, aromatics compounds, endocrine-disrupting compounds, and volatile organic compounds are reviewed. Finally, challenges and the future perspective of BBZSH photocatalysts are discussed.

Controlled synthesis of photoresponsive bismuthinite (Bi2S3) nanostructures mediated through a new 1D bismuth-pyrimidylthiolate coordination polymer as a molecular precursor

Bismuthinite (Bi2S3) nanostructures have garnered significant interest due to their appealing photoresponsivity which has positioned them as an attractive choice for energy conversion applications. However, to utilize their full potential, a simple and economically viable method of preparation is highly desirable. Herein, we present the synthesis and characterization including structural elucidation of a new air- and moisture-stable bismuth-pyrimidylthiolate complex. This complex serves as an efficient single-source molecular precursor for the facile preparation of phase-pure Bi2S3 nanostructures. Powder X-ray diffraction (PXRD), Raman spectroscopy, electron dispersive spectroscopy (EDS) and electron microscopy techniques were used to assess the crystal structure, phase purity, elemental composition and morphology of the as-prepared nanostructures. This study also revealed the profound effects of temperature and growth duration on the crystallinity, phase formation and morphology of nanostructures. The optical band gap of the nanostructures was tuned within the range of 1.9-2.3 eV, which is blue shifted with respect to the bulk bandgap and suitable for photovoltaic applications. Liquid junction photo-electrochemical cells fabricated from the as-prepared Bi2S3 nanostructure exhibit efficient photoresponsivity and good photo-stability, which project them as promising candidates for alternative low-cost photon absorber materials.

Efficient Separation and Purification Method for Recovering Valuable Elements from Bismuth Telluride Refrigeration Chip Waste

Bismuth telluride and its alloys are widely utilized in thermoelectric refrigeration and power generation devices. Waste bismuth telluride-based cooling chips contain valuable elements; however, recycling processes for these materials remain underdeveloped due to their complexity. In this study, we developed a concise and efficient chemical method that does not require expensive reagents or equipment, enabling the separation and purification of tellurium, bismuth, selenium, and antimony from waste bismuth telluride-based cooling chips. Initially, the waste was leached with HCl and NaClO3 to dissolve primary elements and recover 99.9% of selenium using hydroxylamine hydrochloride. Subsequently, Na2S and NaOH were employed for precipitation and leaching, resulting in a solution containing tellurium. The precipitated residue was treated with HNO3 to oxidize antimony into insoluble SbOHN and dissolve bismuth completely. 99.8% of the bismuth telluride waste was dissolved via oxidative leaching through hydrolysis. A small amount of sodium sulfide reduced the precipitation percentage of tellurium from 11.9% to 7.5% in an alkaline solution, and the direct recovery percentage of tellurium in the form of TeO2 exceeded 90%, while the purity of TeO2 reached 99.9%. By adjusting the pH of the bismuth solution to 0.15, 98.9% of the bismuth was able to precipitate and be recovered as BiOCl, with the purity also reaching 99.9%. In summary, this study presents an efficient hydrometallurgical method for treating bismuth telluride waste and provides theoretical guidance for reagent dosage, demonstrating the significant potential for industrial applications.

Visible light-driven photocatalytic thiol-ene/yne reactions using anisotropic 1D Bi2S3 nanorods: a green synthetic approach

Thiol-ene/yne click reactions play a significant role in creating carbon-sulfur (C-S) bonds, and there has been a growing interest in using visible-light photoredox catalysis for their formation. In this study, anisotropic 1D Bi2S3 nanorods were prepared using a simple polyol-assisted reflux method, and they were used as catalysts for the thiol-ene/yne click reactions under visible light irradiation. The developed protocol is highly compatible and tolerant to various substrates with excellent product yields. Also, thiol-ene and -yne reactions achieved maximum TONs of 93 and 95, respectively. Detailed mechanistic studies were conducted and supported by NMR studies, radical trapping utilizing TEMPO, and ESI-MS product analysis. The ability of Bi2S3 nanorods to catalyze thiol-ene/yne reactions is primarily due to the creation of photoexcited holes, which aid in the formation of thiyl radicals. This method can be scaled up to the gram-scale synthesis of benzyl styryl sulfide with an excellent chemical yield of 90%. The 1D Bi2S3 nanorods also demonstrated structural and morphological stability throughout five reaction cycles while maintaining a favorable photocatalytic activity. The developed methodology had the advantages of broad substrate scope, mild reaction conditions, scaled-up synthesis, and nonrequirement of free radical initiators.

Novel data on genotoxic assessment of bismuth sulfide nanoflowers in common carp Cyprinus carpio

The environmental impacts and risks of nanomaterials that are commonly used in different technologies are of great concern as their toxic effects on the aquatic ecosystem remain unclear. In this study, bismuth sulfide (Bi2S3) nanoflowers (nfs) were synthesized using a microwave-based hydrothermal process, and their genotoxic effects were investigated in the common carp, Cyprinus carpio. Bi2S3 nanoflowers were applied to common carp for 96 h. LC50 value (LC50 = 350 mg/L-1) was determined for acute toxicity with probit analysis, and three sublethal concentrations (35, 87, and 175 mg/L-1) were selected accordingly for genotoxicity tests. Such LC50 value - 350 mg L-1 for the common carp makes these nanoflowers non-toxic to aquatic organisms according to the EU-Directive 93/67/EEC classification scheme. Toxicological evaluations of the sublethal concentrations of Bi2S3 nanoflowers demonstrated that the 35 and 87 mg L-1 Bi2S3nfs groups were generally harmless and similar to the control group. Only the 175 mg L-1 Bi2S3nfs group had significant DNA damage frequency and nuclear abnormalities than the control and other Bi2S3nfs groups. To the best of our knowledge, this is a novel data on genotoxicity reported for fish species exposed to Bi2S3 nanoflowers; however, further systematic studies need to be performed to fully estimate the effects of Bi2S3 nanoflowers on aquatic life.

Enhanced electrochemical performance of the MoS2/Bi2S3 nanocomposite-based electrode material prepared by a hydrothermal method for supercapacitor applications

Supercapacitors are widely used energy storage systems in the modern world due to their excellent electrochemical performance, fast charging capability, easy handling, and high power density. In the present work, pure MoS2 and MoS2/Bi2S3 nanocomposites with different compositions of bismuth were synthesized by the hydrothermal method. The structural properties of the electrode materials were studied using the XRD technique, which confirmed the formation of MoS2 and the secondary phase of Bi2S3 while increasing Bi substitution. The morphological studies of the synthesized electrode materials were performed using SEM, TEM, and HRTEM techniques, which indicated the 3D layered hierarchical structure of MoS2 nanospheres and the nanosheet-like structure of Bi2S3. The electrochemical properties of pristine MoS2 and MoS2/Bi2S3 nanocomposites were analysed by CV, CP, and EIS techniques using a 2 M KOH electrolyte in a three-electrode system. The CV curves show evidence of significant improvement in the electrochemical performance of MoS2/Bi2S3 composites compared to that of pure MoS2. The calculated specific capacitances of MoS2/Bi2S3 nanocomposites were relatively higher than those of pristine MoS2. The 20 mol% Bi added sample showed a maximum specific capacitance of 371 F g-1, compared to pristine MoS2 and other samples at a current density of 1 A g-1. The kinetics of the electrochemical process was studied. The Nyquist plots indicated that the Bi-added nanocomposites had lower Resr and RCT values, which resulted in high electrochemical performance. The experimental results revealed that Bi-substitution can further enhance the electrochemical energy storage performance of MoS2 for supercapacitor applications.

A new class of layered Bi2O2S nanopetals by one-pot supercritical-CO2 approach: A reliable electrocatalyst for analgesic bioflavonoid detection

Nanomaterials frequently draw a lot of interest in a variety of disciplines, including electrochemistry. Developing a reliable electrode modifier for the selective electrochemical detection of the analgesic bioflavonoid i.e., Rutinoside (RS) is a great challenge. Here in, we have explored the supercritical-CO₂ (SC-CO₂) mediated synthesis of bismuth oxysulfide (SC-BiOS) and reported it as a robust electrode modifier for the detection of RS. For a comparison study, the same preparation procedure was carried out in the conventional approach (C-BiS). The morphology, crystallography, optical, and elemental contribution analyses were characterized to understand the paradigm shift in the physicochemical properties between SC-BiOS and C-BiS. The results exposed the C-BiS had a nano-rod-like structure with a crystallite size of 11.57 nm; whereas the SC-BiOS had a nano-petal-like structure with a crystallite size of 9.03 nm. The B_2g mode in the optical analysis confirms the formation of bismuth oxysulfide by the SC-CO₂ method with the Pmnn space group. As an electrode modifier, the SC-BiOS achieved a higher effective surface area (0.074 cm²), higher electron transfer kinetics (0.13 cm s^-1), and lower charge transfer resistance (403 Ω) than C-BiS. Further, it provided a wide linear range of 0.1-610.5 μM L^-1 with a low detection and quantification limit of 9 and 30nM L^-1 and an appreciable sensitivity of 0.706 μA μM^-1 cm^-2. The selectivity, repeatability, and real-time application towards the environmental water sample with a recovery of 98.87% were anticipated for the SC-BiOS. This SC-BiOS unlocks a fresh avenue to construct a design for the family of electrode modifiers utilized in electrochemical applications.

Biomedical applications of biodegradable polycaprolactone-functionalized magnetic iron oxides nanoparticles and their polymer nanocomposites

Magnetic nanoparticles (MNPs) have gained significant attention among several nanoscale materials during the last decade due to their unique properties. These properties make them successful nanofillers for drug delivery and a number of new biomedical applications. MNPs are more useful when combined with biodegradable polymers. In this review, we discussed the synthesis of polycaprolactones (PCL) and the various methods of synthesizing magnetic iron oxide nanoparticles. Then, the synthesis of composites that is made of PCL and magnetic materials (with special focus on iron oxide nanoparticles) were highlighted. In addition, we comprehensively reviewed their application in drug delivery, cancer treatment, wound healing, hyperthermia, and bone tissue engineering. Other biomedical applications of the magnetic PCL such as mitochondria targeting are highlighted. Moreover, biomedical applications of magnetic nanoparticles incorporated into other synthetic polymers apart from PCL are also discussed. Thus, great progress and better outcome with functionalized MNPs enhanced with polycaprolactone has been recorded with the biomedical applications of drug delivery and recovery of bone tissues.

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

Development of Bi2S3/Cu2S hetrojuction as an effective photocatalysts for the efficient degradation of antibiotic drug and organic dye

Herein, a Bi₂S₃/Cu₂S was successfully synthesized via a simple one-step wet impregnation process. The compositional behavior and electrical and optical properties of photocatalysts were investigated in detail. Photocatalytic technology has shown great promise in wastewater treatment, splitting water to hydrogen, and converting CO₂ to fuel. Researchers or scientist are attempting to design sulfate-based heterojunction photocatalytic systems in order to develop novel photocatalysts with excellent performance. Photodegradation of methylene blue (MB) dye and tetracycline (TC) drug under visible light irradiation was used to assess the photocatalytic activity of as-prepared samples. As a result, 2:1% wt of Bi₂S₃/Cu₂S heterostructure composite revealed superior visible light degradation performing of MB dye, and TC drug efficiency as 90.2% and 87.5%, respectively. The prepared hybrid photocatalyst has demonstated a potential for use in the photocatalytic degradation of antibiotic durgs and dyes, indicating a promissing future for its application.

Adsorptive remediation of aqueous inorganic mercury with surfactant enhanced bismuth sulfide nanoparticles

Heavy metal contamination in water is a growing threat, endangering the environmental stability. Mercury (Hg) is one of the most lethal heavy metals damaging the immune and nervous system irreversibly. A novel synthetic route to prepare bismuth sulfide (Bi₂S₃) nanoparticles in presence of the surfactant Pluronic (P123) was illustrated in this work. The sorption of Hg (II) by the nanoparticles was investigated. The surfactant assisted nanoparticles showed enhanced surface area and potential compared to the unmodified ones. The effects of adsorbent dose, pH, initial concentration, and temperature were investigated. The maximum Hg (II) adsorption capacity for the surfactant enhanced Bi₂S₃ was 832 mg/g at 303 K and pH 5. The distribution coefficient (K_d) of the order ∼10⁶ ml/g indicated high selectivity of the synthesized adsorbent toward mercury ions. Chemisorption was identified to be the dominant mechanism of adsorption. The adsorbent also showed excellent reusability (>95%) after 5 cycles. The transport parameters involved in the adsorption, the effective pore diffusivity (D_p: 7.36 × 10^-12 m²/s) and the mass transfer coefficient (k_f: 1.52 × 10^-6 m/s) were estimated from a first principle-based model.

Impacts of Binary Oxide Nanoparticles on the Soybean Plant and Its Rhizosphere, Associated Phytohormones, and Enzymes

The utilization of binary oxide nanoparticles is geometrically increasing due to their numerous applications. Their intentional or accidental release after usage has led to their omnipresence in the environment. The usage of sludge or fertilizer containing binary oxide nanoparticles is likely to increase the chance of the plants being exposed to these binary oxide nanoparticles. The aim of the present review is to assess the detailed positive and negative impacts of these oxide nanoparticles on the soybean plants and its rhizosphere. In this study, methods of synthesizing binary oxide nanoparticles, as well as the merits and demerits of these methods, are discussed. Furthermore, various methods of characterizing the binary oxide nanoparticles in the tissues of soybean are highlighted. These characterization techniques help to track the nanoparticles inside the soybean plant. In addition, the assessment of rhizosphere microbial communities of soybean that have been exposed to these binary oxide nanoparticles is discussed. The impacts of binary oxide nanoparticles on the leaf, stem, root, seeds, and rhizosphere of soybean plant are comprehensively discussed. The impacts of binary oxides on the bioactive compounds such as phytohormones are also highlighted. Overall, it was observed that the impacts of the oxide nanoparticles on the soybean, rhizosphere, and bioactive compounds were dose-dependent. Lastly, the way forward on research involving the interactions of binary oxide nanoparticles and soybean plants is suggested.

Bismuth-Based Multi-Component Heterostructured Nanocatalysts for Hydrogen Generation

Developing a unique catalytic system with enhanced activity is the topmost priority in the science of H2 energy to reduce costs in large-scale applications, such as automobiles and domestic sectors. Researchers are striving to design an effective catalytic system capable of significantly accelerating H2 production efficiency through green pathways, such as photochemical, electrochemical, and photoelectrochemical routes. Bi-based nanocatalysts are relatively cost-effective and environmentally benign materials which possess advanced optoelectronic properties. However, these nanocatalysts suffer back recombination reactions during photochemical and photoelectrochemical operations which impede their catalytic efficiency. However, heterojunction formation allows the separation of electron–hole pairs to avoid recombination via interfacial charge transfer. Thus, synergetic effects between the Bi-based heterostructured nanocatalysts largely improves the course of H2 generation. Here, we propose the systematic review of Bi-based heterostructured nanocatalysts, highlighting an in-depth discussion of various exceptional heterostructures, such as TiO2/BiWO6, BiWO6/Bi2S3, Bi2WO6/BiVO4, Bi2O3/Bi2WO6, ZnIn2S4/BiVO4, Bi2O3/Bi2MoO6, etc. The reviewed heterostructures exhibit excellent H2 evolution efficiency, ascribed to their higher stability, more exposed active sites, controlled morphology, and remarkable band-gap tunability. We adopted a slightly different approach for reviewing Bi-based heterostructures, compiling them according to their applicability in H2 energy and discussing challenges, prospects, and guidance to develop better and more efficient nanocatalytic systems.

Characterization of Magnetron Sputtered BiTe-Based Thermoelectric Thin Films

Thermoelectric (TE) technology attracts much attention due to the fact it can convert thermal energy into electricity and vice versa. Thin-film TE materials can be synthesized on different kinds of substrates, which offer the possibility of the control of microstructure and composition to higher TE power, as well as the development of novel TE devices meeting flexible and miniature requirements. In this work, we use magnetron sputtering to deposit N-type and P-type BiTe-based thin films on silicon, glass, and Kapton HN polyimide foil. Their morphology, microstructure, and phase constituents are studied by SEM/EDX, XRD, and TEM. The electrical conductivity, thermal conductivity, and Seebeck coefficient of the thin film are measured by a special in-plane advanced test system. The output of electrical power (open-circuit voltage and electric current) of the thin film is measured by an in-house apparatus at different temperature gradient. The impact of deposition parameters and the thickness, width, and length of the thin film on the power output are also investigated for optimizing the thin-film flexible TE device to harvest thermal energy.

Integration of Bismuth sulfide/functionalized halloysite nanotube composite: An electrochemical tool for diethofencarb analysis

Diethofencarb (DFC) is a fungicide used in agricultural fields and it's overe use makes a negative impact in the real-time environment. Here in this work, a semi-conductive urchin like Bismuth sulfide (Bi₂S₃) anchored with tubular structure functionalized halloysite nanotube (F-HNT) was hydrothermally synthesized and used for the electrochemical detection of DFC. Various analytical and microscopic techniques were used to analyze the structure, crystalline nature, and purity of the as-prepared F-HNT@Bi₂S₃. Moreover, the cyclic voltammetry technique was used to analyze the electrochemical studies of the F-HNT@Bi₂S₃ modified glassy carbon electrode (GCE). A high synergetic relationship between the Bi₂S₃ and F-HNT provides a large surface area and better detection of DFC. The amperometry i-t technique result shows that the prepared composite exhibits a wide linear range of 0.0053-526.62 μg L^-1, a low detection limit of 0.0032 μg L^-1, and very good stability over 2000 s. Notably, our proposed sensor can determine the DFC spiked tomato and water samples with a high recovery range and proven the viability for real-time analysis. Finally, all the above-mentioned study results prove that the F-HNT@Bi₂S₃ could be used as an electrochemical probe for the detection of DFC.

Simplified Route for Deposition of Binary and Ternary Bismuth Sulphide Thin Films for Solar Cell Applications

For photovoltaic applications, undoped and Ni2+ doped Bi2S3 thin films were chemically deposited onto glass substrates at room temperature. Elemental diffraction analysis confirmed the successful Ni2+ incorporation in the range of 1.0 to 2.0 at. %, while X-ray Diffraction analysis revealed that orthorhombic crystal lattice of Bi2S3 was conserved while transferring from binary to ternary phase. Scanning electron microscopy images reported homogeneous and crack-free morphology of the obtained films. Optoelectronic analysis revealed that the bandgap value was shifted from 1.7 to 1.1 eV. Ni2+ incorporation also improved the carrier concentration, leading to higher electrical conductivity. Resultant optoelectronic behavior of ternary Bi2−x NixS3 thin films suggests that doping is proved to be an effectual tool to optimize the photovoltaic response of Bi2S3 for solar cell applications.

Photodynamic Therapeutic Effect of Nanostructured Metal Sulfide Photosensitizers on Cancer Treatment

Photodynamic therapy (PDT) utilizes photosensitizers (PSs) to produce reactive oxygen species (ROSs) upon irradiation, which causes the shutdown of vessels and deprives the tumor of nutrients and oxygen, and in turn induces adverse effects on the immune system. However, significant efforts are needed to increase the efficiency in PDT in terms of light delivery to specific PSs for the clinical treatment of tumors located deep under the skin. Even though PDT offers a disease site-specific treatment modality, current efforts are directed to improve the solubility (in body fluids and injectable solvents), photostability, amphiphilicity (for tissue penetration), elimination, and systemic toxicity of traditional PSs based on porphyrin derivatives. Nanostructured materials show promising features to achieve most of such combined efforts. They can be artificially engineered to carry multiple theranostic agents onto targeted tumor sites. However, recent studies on photosensitive Cd-based nanostructures, mostly used in PDT, indicate that leeching of Cd²⁺ ions is stimulated when they are exposed to harsh biological conditions for continuous periods of time, thus making them acutely toxic and hindering their applications in in vivo settings. Since nanostructured materials are not completely immune to degradation, great strides have been made to seek new alternatives. In this review, we focus on the latest advances of Cd-free nanostructured metal transition sulfides (MTSs) as alternative PSs and study their high-energy transfer efficiency, rational designs, and potential applications in cancer-targeted PDT. Nanostructured MTSs are discussed in the context of their versatility to serve as phototherapy agents and superior properties, including their strong absorption in the NIR region, excellent photothermal conversion efficiency, controlled reactive oxygen species (ROS) production, versatile surface chemistry, high fluorescence, and structural and thermal stability. We discuss the latest advancements in correlating the self-aggregation of MTSs with their passive tumor cell targeting, highlighting their ability to efficiently produce ROSs, and mitigating their dark toxicity through polymeric functionalization. Treatment of deep-seated tumors by using these PSs upon preferential uptake by tumor tissues (due to the enhanced permeability and retention effect) is also reviewed. We finally summarize the main future perspectives of MTSs as next-generation PSs within the context of cancer theranostics.