A simple chemical route to Bi2S3 hierarchical columniform structures assembled by nanorod-based lamellae

Bi₂S₃ hierarchical columniform structures assembled by nanorod-built lamellae have been first synthesized by a simple wet chemical method through the reaction between Bi(NO₃)₃?5H₂O and CS₂ at 80 °C for 14 h using DMSO as solvent without any surfactants. These new Bi₂S₃ structures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Compared to ethylene glycol and DMF, DMSO supplied an excellent chemical environment favorable to the generation of Bi₂S₃ quickly in heterogeneous condition. The influences of the synthetic parameters were discussed and a possible growth mechanism for the formation of these complex structures was proposed.     

Preparation of Bi2S3 nanorods via a hydrothermal approach

Large-scale bismuth sulfide (Bi₂S₃) nanorods with uniform size have been prepared by hydrothermal method using bismuth chloride (BiCl₃) and sodium sulfide (Na₂S·9H₂O) as raw materials at 180 °C and pH = 1-2 for 12 h. The powder X-ray diffraction (XRD) pattern shows the Bi₂S₃ crystal belongs to the orthorhombic phase with calculated lattice constants a = 1.1187 nm, b = 1.1075 nm and c = 0.3976 nm. Furthermore, the quantification of X-ray photoelectron spectra (XPS) analysis peaks gives an atomic ratio of 1.9:3.0 for Bi:S. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopic (TEM) studies reveal that the appearance of the as-prepared Bi₂S₃ is rod-like with typical lengths in the range of 2-5 μm and diameters in the range of 10-30 nm. Finally the influences of the reaction conditions are discussed and a possible mechanism for the formation of Bi₂S₃ nanorods is proposed.     

Novel flower-like (Bi(Bi2S3)9I3)2/3 nanostructure as efficient photocatalyst for photocatalytic desulfurization of benzothiophene under visible light irradiation

Here, we report the preparation of hierarchical flower-like (Bi(Bi₂S₃)₉I₃)_2/3 nanostructures that acts as a strong photocatalyst in the desulfurization of benzothiophene. We optimized the reaction time, type of capping agent and reflux temperature to tune the shape of porous flower-like (Bi(Bi₂S₃)₉I₃)_2/3 nanostructures to achieve the highest desulfurization performance. We investigated the characteristic shape, size, purity, and optical response of the flower-shape nanostructures using XRD, EDS, FESEM, UV–Vis-DRS analysis. The flower-like (Bi(Bi₂S₃)₉I₃)_2/3 nanostructures showed a significant photocatalytic property in desulfurization of benzothiophene as a model fuel. The hierarchical flower-like (Bi(Bi₂S₃)₉I₃)_2/3 photocatalyst with an energy gap of 1.15 eV, exhibits a 92% photocatalytic desulfurization performance after 2 h of visible light irradiation. The (Bi(Bi₂S₃)₉I₃)_2/3 nanostructures show a high photocatalytic reproducibility after 4 rounds of exposure. We proposed a photo-oxidation mechanism based on the active species scavenging, which revealed the role of photo-produced h⁺ and O₂^? species as essential in the photocatalytic desulfurization process. These findings provide a new prospect and design strategy for the development of efficient photocatalysts in desulfurization process.     

Spatiotemporally Synchronous Oxygen Self-Supply and Reactive Oxygen Species Production on Z-Scheme Heterostructures for Hypoxic Tumor Therapy

Photodynamic therapy (PDT) efficacy has been severely limited by oxygen (O₂) deficiency in tumors and the electron–hole separation inefficiency in photosensitizers, especially the long-range diffusion of O₂ toward photosensitizers during the PDT process. Herein, novel bismuth sulfide (Bi₂S₃)@bismuth (Bi) Z-scheme heterostructured nanorods (NRs) are designed to realize the spatiotemporally synchronous O₂ self-supply and production of reactive oxygen species for hypoxic tumor therapy. Both narrow-bandgap Bi₂S₃ and Bi components can be excited by a near-infrared laser to generate abundant electrons and holes. The Z-scheme heterostructure endows Bi₂S₃@Bi NRs with an efficient electron–hole separation ability and potent redox potentials, where the hole on the valence band of Bi₂S₃ can react with water to supply O₂ for the electron on the conduction band of Bi to produce reactive oxygen species. The Bi₂S₃@Bi NRs overcome the major obstacles of conventional photosensitizers during the PDT process and exhibit a promising phototherapeutic effect, supplying a new strategy for hypoxic tumor elimination.     

Bi2S3 nanotubes: Facile synthesis and growth mechanism

Synthesis of tubular nanomaterials has become a prolific area of investigation due to their wide range of applications. A facile solution-based method has been designed to fabricate uniform Bi₂S₃ nanotubes with average size of 20 nm × 160 nm using only bismuth nitrate (Bi(NO₃)₃·5H₂O) and sulfur powder (S) as the reactants and octadecylamine (ODA) as the solvent. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and energy dispersive spectroscopy (EDX) experiments were employed to characterize the resulting Bi₂S₃ nanotubes and the classic rolling mechanism was applied to explain their formation process.      

Characterization of Bi2S3 with different morphologies synthesized using microwave radiation

Bi₂S₃ with different morphologies (nanoparticles, nanorods and nanotubes) was synthesized using bismuth nitrate pentahydrate (Bi(NO₃)₃·5H₂O) and two kinds of sulfur sources (CH₃CSNH₂ and NH₂CSNH₂) in different solvents (water, ethylene glycol and propylene glycol) via a microwave radiation method at 180 W for 20 min. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that all of the products are orthorhombic Bi₂S₃ phase of nanoparticles, nanorods and nanotubes, influenced by the sulfur sources and solvents. Formation mechanisms of the products with different morphologies are also proposed.     

Uniform Bi2S3 nanowires: Structure, growth, and field-effect transistors

Large-scale single-crystalline Bi₂S₃ nanowires were prepared by a simple one-step hydrothermal reaction between Bi(NO₃)₃ and Na₂S₂O₃, without using any organics in the experiment. These Bi₂S₃ nanowires have uniform size diameters which are about 60 nm. The structure of the nanowires is determined to be of the orthorhombic phase, and the growth direction is along the [001] direction. The growth mechanism of the nanowires was investigated based on high-resolution transmission electron microscopy observations. The field-effect transistors (FETs) have been fabricated using a single Bi₂S₃ nanowire, n-type semiconductor behavior has been observed, and high on/off ratio of about 3 orders of magnitude has been achieved.     

The LP-MOCVD of CdS/Bi2S3 bilayers using single-molecule precursors

The single-molecule precursors [Cd(S₂CNMe n-Hex)₂] and [Bi(S₂CNMe n-Hex)₃] (Me=methyl; n-Hex=n-hexyl) were used to prepare CdS/Bi₂S₃ layers by low-pressure metal organic chemical vapour deposition (LP-MOCVD). The bilayers were deposited onto glass substrates at 400–450 °C for varying growth conditions. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical measurements. The results were compared with those obtained for the single phases.     

Rapid synthesis of Bi2S3 nanocrystals with different morphologies by microwave heating

Single-crystalline Bi₂S₃ nanocrystals with urchinlike and rod-like morphologies have been successfully synthesized using Bi₂O₃, HCl, Na₂S₂O₃ and ethylene glycol (EG) by a simple and fast microwave heating method. Both urchinlike and rod-like Bi₂S₃ nanostructures could be formed under microwave heating at 190 °C for 30 s. Urchin-like Bi₂S₃ nanostructures were prepared using sodium dodecyl sulfate (SDS) or in the absence of any surfactant. However, Bi₂S₃ nanorods were obtained in the presence of cetyltrimethylammonium bromide (CTAB). The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED) and ultraviolet-visible (UV-Vis) absorption spectra.     

Photochemical synthesis of Bi2Se3 nanosphere and nanorods

A photochemical reaction route was developed to synthesize bismuth selenide (Bi₂Se₃) nanoparticles and nanorods. In an aqueous solution, bismuth nitrate (Bi(NO₃)₃) reacted with sodium selenosufate in the presence of reducing agent and complexing agent, and the dispersed Bi₂Se₃ nanoparticles were obtained with the average size of 35 nm. The nanorods were prepared via an alumina template route in the same solution. We carried out experiments to study the formation mechanism in the morphology control of the products and found that series of factors played an effective role including the irradiation time, pH value, the reducing agents and the species of complexing agents. The products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM).     

Synthesis and characterization of bismuth sulfide nanowires through microwave solvothermal technique

One-dimensional (1D) bismuth sulfide (Bi₂S₃) semiconducting nanowires have been successfully synthesized through mircrowave assisted solvothermal technique. The obtained product was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometry. The result shows that the Bi₂S₃ nanowires are single crystals grown along the [001] (c-axis) direction. The growth of Bi₂S₃ nanofibers with a preferential direction of c-axis can be ascribed to its particular structure. The optical measurement shows a blue shift relative to the bulk orthorhombic Bi₂S₃, which might be ascribed to the high aspect ratio of the nanowires.     

Hydrothermal synthesis and characterization of Bi2O3 nanowires

An alternative two-step method has been proposed for the synthesis of Bi₂O₃ nanowires with a diameter of about 40 nm from common and cost-effective Bi(NO₃)₃·5H₂O, Na₂SO₄, and NaOH. That is, first, Bi₂O(OH)SO₄ nanowires were prepared through the precipitation reaction of Bi(NO₃)₃·5H₂O and Na₂SO₄ in distilled water under the ambient condition and second, monoclinic phase Bi₂O₃ nanowires were prepared via the hydrothermal reaction of Bi₂O(OH)SO₄ and NaOH at 120 °C for 12 h. The resultant products were characterized by X-ray diffraction, field emission scanning electron microscope, and high resolution transmission electron microscopy. In addition, the photocatalytic studies indicated that the as-synthesized Bi₂O₃ nanowires were a kind of promising photocatalyst in remediation of water polluted by some chemically stable azo dyes.     

Bismuth Sulfide Nanorods with Retractable Zinc Protoporphyrin Molecules for Suppressing Innate Antioxidant Defense System and Strengthening Phototherapeutic Effects

Bismuth (Bi)‐based nanomaterials (NMs) are widely used for computed tomography (CT) imaging guided photothermal therapy, however, the photodynamic property is hardly exhibited by these NMs due to the fast electron–hole recombination within their narrow bandgap. Herein, a sophisticated nanosystem is designed to endow bismuth sulfide (Bi₂S₃) nanorods (NRs) with potent photodynamic property. Zinc protoporphyrin IX (ZP) is linked to Bi₂S₃ NRs through a thermoresponsive polymer to form BPZP nanosystems. The stretching ZP could prebind to the active site of heme oxygenase‐1 overexpressed in cancer cells, suppressing the cellular antioxidant defense capability. Upon NIR laser irradiation, the heat released from Bi₂S₃ NRs could retract the polymer and drive ZP to the proximity of Bi₂S₃ NRs, facilitating an efficient electron–hole separation in ZP and Bi₂S₃ NRs, and leading to reactive oxygen species generation. In vitro and in vivo studies demonstrate the promising photodynamic property of BPZP, together with their photothermal and CT imaging performance.     

Growth of Bi2S3 film using a solution-gas interface technique

Uniform large-area Bi₂S₃ films about 0.3 μm thick were prepared using a solution-gas interface technique. The surface of a Bi(NO₃)₃ solution was exposed to H₂S gas and a thin solid film was formed. The electrical and optical properties of films prepared in this way were studied. The band gap energy of Bi₂S₃ films estimated from electrical measurements was found to be in fair agreement with the value estimated from the optical measurements.     

Preparation and photoluminescence properties of Y2O3:Eu, Bi phosphors by molten salt synthesis for white light-emitting diodes

Y₂O₃:Eu, Bi red phosphors were first prepared by molten salt synthesis (MSS) method at a low temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM), and fluorescence spectrophotometer were used to characterize the as-synthesized phosphors. The results show that as-obtained Y₂O₃:Eu, Bi phosphors have good cubic crystallinity, presenting octahedral morphology with smooth surface and relatively uniform particle size. Bi³⁺ ion as a sensitizer plays a significant effect on the emission intensity of Y₂O₃:Eu, Bi by energy transfer from Bi³⁺ to Eu³⁺ and the optimal concentration of Bi³⁺ is 1.5 mol%. Y₂O₃:Eu, Bi emits excellent red light as the excitation wavelength is between 330 and 420 nm or excited by 254, 466 nm. Meanwhile, its emission intensity is as strong as that of sample prepared by solid-state reaction. So the as-fabricated red phosphors by MSS method would have a promising application in the area of white light-emitting diodes.     

Synthesis of TiO2/Bi2S3 heterojunction with a nuclear-shell structure and its high photocatalytic activity

TiO₂/Bi₂S₃ heterojunctions with a nuclear-shell structure were prepared by the coprecipitation method. The products were characterized by X-ray diffraction analysis, Raman spectra, transmission electron microscope images and energy dispersion X-ray spectra. Results showed that as-prepared Bi₂S₃ was urchin-like, made from many nanorods, and TiO₂/Bi₂S₃ heterojunctions have a similar nuclear-shell structure, with Bi₂S₃ as the shell and TiO₂ as the nuclear. The photocatalytic experiments performed under UV irradiation using methyl orange as the pollutant revealed that the photocatalytic activity of TiO₂ could be improved by introduction of an appropriate amount of Bi₂S₃. However, excessive amount of Bi₂S₃ would result in the decrease of photocatalytic activity of TiO₂. The relative mechanism was proposed.     

Bi2S3-modified TiO2 nanotube arrays: easy fabrication of heterostructure and effective enhancement of photoelectrochemical property

A novel heterostructure of Bi₂S₃ nanoparticles (NPs) and TiO₂ nanotube arrays (NAs) was fabricated by a conventional hydrothermal method. The morphological features and the X-ray diffractogram of the obtained Bi₂S₃/TiO₂ NAs were characterized by field-emission scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. The photoelectrochemical property of Bi₂S₃/TiO₂ NAs was also evaluated. The results demonstrated that photoelectrochemical solar cells based on Bi₂S₃/TiO₂ NAs had a short-circuit current of 4.54 mA/cm² and photoelectric conversion efficiency of 1.86 %. Surface photovoltage spectroscopy and field-induced surface photovoltage spectroscopy data indicated the existence of a strong interfacial electronic field between the two components Bi₂S₃ NPs and TiO₂ NAs, which can enhance the separation of photogenerated charge carriers.     

Enhancement of photosensitivity by annealing in Bi2S3 thin films grown using SILAR method

Bi₂S₃ thin films were grown by successive ionic layer adsorption and reaction method (SILAR) onto the glass substrates at room temperature. The as prepared thin film were annealed at 250 °C in air for 30 min. These films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrical measurement systems. The X-ray diffraction patterns reveal that Bi₂S₃ thin film have orthorhombic crystal structure. SEM images showed uniform deposition of the material over the entire glass substrate. The optical energy band gap observed to be decreased from 1.69 to 1.62 eV for as deposited and annealed films respectively. The I–V measurement under dark and illumination condition (100 W) show annealed Bi₂S₃ thin film gives good photoresponse as compared to as deposited thin film and Bi₂S₃ thin film exhibits photoconductivity phenomena suggesting its useful in sensors device. The thermo-emf measurements of Bi₂S₃ thin films revealed n-type electrical conductivity.     

Influence of gamma irradiation on structural,optical, and electrical characterization of Bi2S3 thin films

The induced effects of the gamma rays on properties of bismuth sulfide (Bi₂S₃) thin films synthesized using successive ionic layer adsorption and reaction (SILAR) have been investigated in details in this work. The Bi₂S₃ thin films are prepared on glass substrate and then exposed with low gamma radiation dose in the range of 0–1000 Gy. X-ray diffraction (XRD) confirmed the orthorhombic structural phase. Also, it was noticed in the XRD result that the crystallite size decreased from 115.29 to 73.63 nm with increasing gamma rays doses. For surface properties as well as stoichiometry of the prepared and irradiated thin film have been studied by field emission scanning electron microscope (FESEM). The optical transmission of irradiated samples increased and the energy band gap (E) decreased from 2.78 to 2.52 eV with gamma dose. Photoluminescence (PL) spectra revealed the improvement in the emission characteristics of Bi₂S₃ thin films with irradiation in the range of 250–1000 Gy. Impedance spectroscopy investigation exhibited that the resistance due to grain boundaries meaningfully contributed to the electrical characteristics of the Bi₂S₃ thin films. The achieved results suggested that Bi₂S₃ thin films are a good tool for further study of dosimetry and radiation sensing application.

     

D-penicillamine assisted hydrothermal synthesis of Bi2S3 nanoflowers and their electrochemical application

Single crystalline flower-like Bi₂S₃ nanostructures were successfully synthesized via a simple, facile and green hydrothermal method, with the assistance of D-penicillamine. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and found their morphologies mainly depend on the ratios of Bi^3 + to D-penicillamine, as well as the reaction temperature and time. And the possible growth mechanism has been discussed in some detail. In addition, the as-prepared Bi₂S₃ nanoflowers show good hydrogen storage ability. This strategy can be potentially expanded to prepare other metal chalcogenides materials.