Metal Sulfide Nanoparticles Research Articles

Biosynthesis of Nanoparticles by Microorganisms and Their Applications

The development of eco-friendly technologies in material synthesis is of considerable importance to expand their biological applications. Nowadays, a variety of inorganic nanoparticles with well-defined chemical composition, size, and morphology have been synthesized by using different microorganisms, and their applications in many cutting-edge technological areas have been explored. This paper highlights the recent developments of the biosynthesis of inorganic nanoparticles including metallic nanoparticles, oxide nanoparticles, sulfide nanoparticles, and other typical nanoparticles. Different formation mechanisms of these nanoparticles will be discussed as well. The conditions to control the size/shape and stability of particles are summarized. The applications of these biosynthesized nanoparticles in a wide spectrum of potential areas are presented including targeted drug delivery, cancer treatment, gene therapy and DNA analysis, antibacterial agents, biosensors, enhancing reaction rates, separation science, and magnetic resonance imaging (MRI). The current limitations and future prospects for the synthesis of inorganic nanoparticles by microorganisms are discussed.

Hollow Nanoparticles of Metal Oxides and Sulfides: Fast Preparation via Laser Ablation in Liquid

In this work, diverse hollow nanoparticles of metal oxides and sulfides were prepared by simply laser ablating metal targets in properly chosen liquids. The Kirkendall voiding and the selective heating with an infrared laser were shown to work as two independent mechanisms for the formation of such hollow nanoparticles in only one- or two-step synthesis approaches. One of the prepared materials, ZnS hollow nanoparticles, showed high performance in gas sensing. The simple, fast, inexpensive technique that is proposed demonstrates very promising perspectives.

Growth kinetics and long-term stability of CdS nanoparticles in aqueous solution under ambient conditions

The ubiquity of naturally occurring nanoparticles in the aquatic environment is now widely accepted, but a better understanding of the conditions that promote their formation and persistence is needed. Using cadmium sulfide (CdS) as a model metal sulfide species, thiolate-capped CdS nanoparticles were prepared in the laboratory to evaluate how aquatic conditions influence metal sulfide nanoparticle growth and stability. This work examines CdS nanoparticle growth directly in aqueous solution at room temperature by utilizing the size-dependent spectroscopic properties of semiconductors detectable by UV/vis. CdS nanoparticle growth was governed by oriented attachment, a non-classical mechanism of crystallization in which small precursor nanoparticles coalesce to form larger nanoparticle products. Nanoparticle growth was slowed with increasing capping agent and decreasing ionic strength. In addition to examining the short-term (hours) growth of the nanoparticles, a long-term study was conducted in which cysteine-capped CdS nanoparticles were monitored over 3 weeks in solutions of various ionic strengths. The long-term study revealed an apparent shift from small nanoparticles to nanoparticles twice their original size, suggesting nanoparticle growth may continue through oriented attachment over longer time scales. High-ionic strength solutions resulted in salt-induced aggregation and eventual settling of nanoparticles within days, whereas low-ionic strength solutions were stable against settling over the course of the experiment. Sulfide recovery from cysteine-capped CdS nanoparticles as acid volatile sulfide was nearly quantitative after 2 weeks in fully oxygenated water, demonstrating significantly slowed oxidation of sulfide when complexed to Cd(II) within CdS nanoparticles. The nanoparticles were also shown to be resistant to oxidation by Fe(III) (hydr)oxide. This study illustrates that aggregation, rather than chemical oxidation, is likely more important to the lifetime of many metal sulfide nanoparticles in the aquatic environment.

One-step large scale gas phase synthesis ofMn2 + doped ZnS nanoparticles in reducing flames

Metal sulfide nanoparticles have attracted considerable interest because of their uniquesemiconducting and electronic properties. In order to prepare these fascinatingmaterials at an industrial scale, however, solvent-free, dry processes would bemost advantageous. In the present work, we demonstrate how traditionaloxide nanoparticle synthesis in flames can be extended to sulfides if we applya careful control on flame gas composition and sulfur content. The ultra-fast (<1 ms) gas phase kinetics at elevated temperatures allow direct sulfidization of metals inflames (). As a representative example, we prepared air-stableMn2 + doped zinc sulfide nanoparticles. Post-sintering of the initially polycrystalline nanopowderresulted in a material of high crystallinity and improved photoluminescence. An analysis ofthe thermodynamics, gas composition, and kinetics in these reducing flames indicates thatthe here-presented extension of flame synthesis provides access to a broad range of metalsulfide nanoparticles and offers an alternative to non-oxide phosphor preparation.

Multianalyte Electrochemical Biosensor Based on Aptamer‐ and Nanoparticle‐Integrated Bio‐Barcode Amplification

In the present work, a signal-on electrochemical sensing strategy for the simultaneous detection of adenosine and thrombin is developed based on switching structures of aptamers. An Au electrode as the sensing surface is modified with two kinds of thiolated capture probes complementary to the linker DNA that contains either an adenosine aptamer or thrombin aptamer. The capture probes hybridize with their corresponding linker DNA, which has prehybridized with the reporter DNA loaded onto the gold nanoparticles (AuNPs). The AuNP contained two kinds of bio-barcode DNA: one is complementary to the linker DNA (reporter), whereas the other is not (signal) and is tagged with different metal sulfide nanoparticles. Thus a "sandwich-type" sensing interface is fabricated for adenosine and thrombin. With the introduction of adenosine and thrombin, the aptamer parts bind with their targets and fold to form the complex structures. As a result, the bio-barcoded AuNPs are released into solution. The metal sulfide nanoparticles are measured by anodic stripping voltammetry (ASV), and the concentrations of adenosine and thrombin are proportional to the signal of either metal ion. With the dual amplification of the bio-barcoded AuNP and the preconcentration of metal ions through ASV technology, detection limits as low as 6.6 x 10(-12) M for adenosine and 1.0 x 10(-12) M for thrombin are achieved. The sensor exhibits excellent selectivity and detectability in biological samples.

A chemo-biological treatment of scrubbing water from power plants with recovery of value-added products

A chemo-biological approach for treating sulphate-rich effluent generated during wet scrubbing of flue gas emissions from fossil fuel fired power plants has been discussed. Microbial sulphate reduction was carried out in an anaerobic up-flow packed bed bioreactor (R1) using ethanol as carbon source. More than 90% of Total Equivalent Sulphate (TES) present in the effluent was reduced to sulphide at HRT of 17 h in the tested loading range of 0.58?3.10 kg SO4/m³/day. Mass balance revealed that more than 88% of sulphate reduced was present as dissolved sulphide (HS−) and while only 0.01% was present as H2S(g). The paper discusses the feasibility of converting both H2S(g) and HS− into value-added products such as elemental sulphur and metal sulphide nanoparticles, respectively. Since the amount of H2S generated is very low (0.01%), this paper also suggests recovery of dissolved sulphide from the R1 effluent, as transition metal sulphide nanoparticles.

Synthesis and characterization of low dimensional ZnS- and PbS-semiconductor particles on a montmorillonite template

Low dimensional metal sulfide particles have been prepared in the interlayers of montmorillonites via reactions of the metal ion-exchanged clay minerals in aqueous dispersions with gaseous hydrogen sulfide. The montmorillonites separated from the Wyoming (USA) and Jelšový Potok (Slovakia) bentonites were saturated with Pb(2+) or Zn(2+). In the final nanohybrids, the smectite mineral can be incorporated with metal sulfide pillars and/or nanoparticles. Properties of the prepared materials were investigated by various analytical techniques. The formation of metal sulfide nanoparticles in the interlayer galleries was indicated by X-ray diffraction and energy dispersive X-ray analysis. About 50% of Pb(2+) or Zn(2+) present in montmorillonite has formed metal sulfide semiconducting units. Infrared spectroscopy and thermogravimetric analysis were used for characterization of starting materials and products. Ultraviolet-visible absorption and photoluminescence spectroscopies confirmed that final composite systems acquired the optical properties of the incorporated quantum low dimensional systems exhibiting blue shift of the energy gap and higher oscillator strength excitonic peaks. Larger amounts of metal sulfide nanoparticles were formed in montmorillonite Jelšový Potok probably as a consequence of its higher cation exchange capacity.

Metal complexes of thiobiurets and dithiobiurets: Novel single source precursors for metal sulfide thin film nanostructures

A series of new metal complexes of thiobiurets and dithiobiurets have been synthesized and characterized. The compounds are potentially useful as novel single source precursors for the deposition of metal sulfide thin films or nanoparticles.

Thermal Decomposition Mechanism of Single-Molecule Precursors Forming Metal Sulfide Nanoparticles

Several zinc alkyldithiocarbamates [Zn(S(2)CNR(2))(2)] were synthesized, and their thermal decomposition in the presence of alkylamines was studied in order to understand the formation of metal sulfide nanoparticles. The major intermediates and side products were isolated under various conditions and characterized by NMR spectroscopy and LC-MS. The analysis results showed that nucleophilic attack of the metal-coordinated amine on the most electron-deficient thiocarbonyl carbon of the alkyldithiocarbamate ligands at high temperature initiated the decomposition to generate thiourea, hydrogen sulfide, and solid metal sulfide nanoparticles. From the proposed decomposition mechanism, the role of amines in thermolysis was studied, and methods for synthesizing various metal sulfide nanoparticles were generalized. Formation of the desired products was confirmed by carrying out model experiments.

Depositing Ordered Arrays of Metal Sulfide Nanoparticles in Nanostructures Using Supercritical Fluid Carbon Dioxide

Silver sulfide and cadmium sulfide nanoparticles of controllable sizes are synthesized using a water-in-hexane microemulsion method and stabilized by dodecanethiol. The stabilized metal sulfide nanoparticles can be deposited homogenously on flat substrates forming ordered 2-D arrays in supercritical fluid carbon dioxide (Sc-CO(2)). The use of Sc-CO(2) leaves the particles unaffected by dewetting effects caused by traditional solvents and produces uniform arrays. The Sc-CO(2) deposition technique is capable of filling nanoparticles in nanostructures of silicon wafers which is difficult to accomplish by conventional solvent evaporation methods.

Green synthesis of metal sulfide nanocrystals through a general composite-surfactants-aided-solvothermal process

In this paper, we developed a generalized and greener composite-surfactants-assisted-solvothermal process (CSSP) to produce colloidal nanoparticles of metal sulfides. X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS) revealed that single-molecular-layer type of MoS 2 nanoparticles with diameter 6–10 nm were successfully synthesized. The molecular structure model of the capped MoS 2 nanoparticles was suggested through further examination by infrared spectra. Hexagonal CdS nanocrystals with spherical, triangle, and hollow sphere shapes were controllably synthesized by varying the experimental conditions. A possible in-situ reduction–sulfidation mechanism was proposed for the formation of Ag 2S nanocrystals, where the metal ions were reduced to metallic nanoparticles before the generation of sulfides. The obtained nanocrystals through this CSSP approach could provide the building blocks for the bottom-up approach to nanoscale fabrication in nanoscience and nanotechnology.

Thermal hysteresis in the dielectric properties of composites based on transition metal oxide and sulfide nanoparticles stabilized in a low-density polyethylene matrix

We have studied the temperature dependence of the complex dielectric permittivity of composites based on a low-density polyethylene matrix containing dispersed nanoparticles of zinc oxide and manganese oxide and an analogous composite with nanoparticles of cadmium sulfide. Laws governing the electric conduction and dielectric polarization as functions of the temperature and the size of nanoparticles are established and a possible mechanism responsible for the appearance of thermal hysteresis of the dielectric properties in the materials studied is proposed.

Precise Structural Control of Plasmonic and Metal Sulfide Nanoparticles for Energy Conversion

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Graphene–nanocrystalline metal sulphide composites produced by a one-pot reaction starting from graphite oxide

Graphene–nanocrystalline metal sulphide composites were prepared by a one-pot reaction. A dispersion of graphite oxide layers in an aqueous solution of metal ions (Cd 2+/Zn 2+) was reacted with H 2S gas, which acts as a sulphide source as well as a reducing agent, resulting in the formation of metal sulphide nanoparticles and simultaneous reduction of graphite oxide sheets to graphene sheets. The surface defect related emissions shown by free metal sulphide particles are quenched in the composites due to the interaction of the surface of the nanoparticles with graphene sheets.

Photocatalytic growth of CdS, PbS, and Cu xS nanoparticles on the nanocrystalline TiO 2 films

The CdS/TiO 2, PbS/TiO 2, and Cu x S/TiO 2 nanocomposites were synthesized via the photocatalytic reduction of sulfur on the surface of nanocrystalline TiO 2 films. The photocatalytic synthesis produced smaller CdS nanoparticles in the comparison with the conventional chemical deposition of cadmium sulfide. The mean size of CdS nanoparticles can be varied by changing the illumination intensity and the TiO 2 film calcination temperature. An AFM study of the surface structure of CdS/TiO 2 and PbS/TiO 2 nanocomposites showed that the photocatalytic deposition results in formation of the polycrystalline 7–80 nm (CdS) or 20–30 nm (PbS) long nanorods. Spatial separation of the photogenerated charge carriers in CdS/TiO 2 and PbS/TiO 2 nanocomposites was assumed to be the driving force of the formation of such elongated metal sulfide nanoparticle agglomerates.

Deposition of Ordered Arrays of Metal Sulfide Nanoparticles in Nanostructures Using Supercritical Carbon Dioxide

AbstractSilver sulfide (Ag2S) and cadmium sulfide (CdS) nanoparticles of adjustable sizes are synthesized using a water-in-hexane microemulsion method and stabilized by dodecanethiol. The stabilized metal sulfide nanoparticles can be deposited homogenously on flat substrates forming ordered 2D arrays in supercritical fluid carbon dioxide (Sc-CO2). The use of Sc-CO2 leaves the particles unaffected by de-wetting effects and surface tension caused by traditional solvents and produces uniform arrays. The Sc-CO2 deposition technique can effectively fill the metal sulfide nanoparticles into nanoscale features, which is difficult to achieve by conventional solvent evaporation methods.

Precipitation and Growth of Zinc Sulfide Nanoparticles in the Presence of Thiol-Containing Natural Organic Ligands

In sulfidic aquatic systems, metal sulfides can control the mobility and bioavailability of trace metal pollutants such as zinc, mercury, and silver. Nanoparticles of ZnS and other metal sulfides are known to exist in oxic and anoxic waters. However, the processes that lead to their persistence in the aquatic environment are relatively unknown. The objective of this study was to evaluate the importance of dissolved natural organics in stabilizing nanoparticulate ZnS that precipitates under environmentally relevant conditions. Precipitation and growth of ZnS particles were investigated in the presence of dissolved humic acid and low-molecular weight organic acids that are prevalent in sediment porewater. Dynamic light scattering was used to monitor the hydrodynamic diameter of particles precipitating in laboratory solutions. Zn speciation was also measured by filtering the ZnS solutions (< 0.2 microm) and using anodic stripping voltammetry to confirm that Zn was coordinated to sulfide during the precipitation experiments and not to the dissolved organic ligands. X-ray photoelectron spectroscopy and electron microscopy were used to confirm that amorphous particles containing Zn and S were precipitating in the suspensions. Observed growth rates of ZnS particles varied by orders of magnitude, depending on the type and concentration of organic ligand in solution. In the presence of humic acid and thiol-containing ligands (cysteine, glutathione, and thioglycolate), observed growth rates decreased by 1-3 orders of magnitude relative to controls without the ligands. In contrast, growth rates of the particles were consistently within 1 order of magnitude of the ligand-free control when oxygen- and amine-containing ligands (oxalate, serine, and glycolate) were present Furthermore, particle growth rates decreased with an increase in thiol concentration and increased with NaNO3 electrolyte concentration. These studies suggest that specific surface interactions with thiol-containing organics may be one factor that contributes to the persistence of naturally occurring and anthropogenic nanoparticles of ZnS and other metal sulfides in the aquatic environment.

In air liquid–solid phase synthesis of metal sulfide nanoparticles from metal acetates and thiourea

Cubic phase ZnS nanoparticles of several nanometers were synthesized directly via the liquid–solid reaction between zinc acetate and thiourea in air at 190 °C for 3 h. The structure, composition and optical property of the resultant product were characterized by means of X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectrum (EDX), Raman and UV–vis absorption spectra. The proposed method has also been successfully extended to synthesize MnS, CuS, CdS, PbS nanoparticles, etc., and may serve as a general kind of simple, mild and cheap way to synthesize semiconducting metal sulfide nanomaterials on a large scale.

Organic/inorganic hybrid nanospheres coated with palladium/P4VP shells from surface‐initiated atom transfer radical polymerization

AbstractCrosslinked poly(4‐vinylbenzyl chloride) (PVBC) nanospheres of about 160 nm were first synthesized by emulsion copolymerization of 4‐vinylbenzyl chloride (VBC) in the presence of a crosslinking agent, p‐divinylbenzene. Subsequent modification of the nanosphere surfaces via surface‐initiated atom transfer radical polymerization of 4‐vinylpyridine, using the VBC units of PVBC on the nanosphere surface as the macroinitiators, produced a well‐defined and covalently tethered poly(4‐vinylpyridine) (P4VP) shells of 24–27 nm in thickness. Activation of the P4VP shells in a PdCl2 solution, followed by reactions with CO or H2S gas, gave rise to the corresponding P4VP composite shells containing densely dispersed palladium metal or palladium sulfide nanoparticles. The chemical composition of the nanosphere surfaces at various stages of surface modification was characterized by X‐ray photoelectron spectroscopy. Field emission scanning electron microscopy and transmission electron microscopy were used to characterize the morphology of the organic/inorganic hybrid nanospheres coated with palladium/P4VP shells. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2119–2131, 2008

Gallium(III) and indium(III) dithiolate complexes: Versatile precursors for metal sulfides

The chemistry of classical and organometallic complexes of gallium and indium with dithiolate ligands, i.e., dithiocarboxylates, xanthates, dithiocarbamates, dithiophosphates, dithiophophinates and dithioarsenates, has been reviewed. Synthesis, spectroscopic and structural aspects of these complexes are described. Their emerging role as single source molecular precursors for the preparation of metal sulfide thin films and nano-particles has been discussed.