Search Results (50)

One-dimensional TiO₂ nanotube arrays (TNAs) were vertically aligned and obtained via the electrochemical anodization method. In this study, Bi₂S₃-TiO₂-SiO₂/TNA heterojunction photocatalysts were successfully prepared with different amounts of Bismuth(III) sulfide (Bi₂S₃) loading on the TNAs by the successive ionic layer adsorption and reaction (SILAR) method and characterized by X-ray diffraction (XRD) patterns, field-emission scanning electron microscope–energy-dispersive spectroscopy (FESEM-EDS), Fourier transform infrared (FTIR) spectra, ultraviolet-visible diffuse reflectance spectra (UV–Vis/DRS), and electrochemical impedance spectroscopy (EIS) techniques. The photocatalytic performances of the samples were investigated by degrading Basic Yellow 28 (BY 28) under visible-light irradiation. Optimization of the condition using the response surface methodology (RSM) and central composite rotatable design (CCRD) technique resulted in the degradation of BY 28 dye, showing that the catalyst with 9.6 mg/cm² (designated as Bi₂S_3(9.6)-TiO₂-SiO₂/TNA) showed the maximum yield in the degradation process. The crystallite size of about 17.03 nm was estimated using the Williamson–Hall method. The band gap energies of TiO₂-SiO₂/TNA and Bi₂S_3(9.6)-TiO₂-SiO₂/TNA were determined at 3.27 and 1.87 eV for the direct electronic transitions, respectively. The EIS of the ternary system exhibited the smallest arc diameter, indicating an accelerated charge transfer rate that favors photocatalytic activity. Full article

Thin films of bismuth(III) sulfide (Bi₂S₃) on fluorine doped tin oxide (FTO) coated glass slides were successfully formed by the chemical bath deposition (CBD) method. In this work, a new sulfur precursor L-cysteine was used instead of the typical sulfur precursors, such as urea, thiosulfate, or thioacetamide, used for the formation of the Bi₂S₃ films by the CBD method. The synthesized Bi₂S₃ thin film on the FTO substrate was subjected to characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and UV–Visible spectroscopy analysis. An X-ray diffraction analysis showed that, initially, Bi₂S₃ films of an amorphous structure with elemental sulfur impurities were formed on the FTO surface. During the annealing of the samples, amorphous Bi₂S₃ was transformed into its crystalline phase with an average crystallite size of about 22.06 nm. The EDS studies confirmed that some of the sulfur that was not part of the Bi₂S₃ was removed from the films during annealing. The influence of the morphology of Bi₂S₃ films on their optical properties was confirmed by studies in the UV-visible range. Full article

Exciton generation and separation play an important role in the photoelectric properties and the luminescence performance of materials. In order to tailor the defects and grain boundaries and improve the exciton separation and light harvesting of the graphitic carbon nitride (g-C₃N₄) nanosheets, a C₃N₄/bismuth sulfide (Bi₂S₃) nanocomposite was synthesized. The photoelectric properties of the 405, 532, 650, 780, 808, 980 and 1064 nm light sources were studied using Au electrodes and graphite electrodes with 4B and 5B pencil drawings. The results indicate that the C₃N₄/Bi₂S₃ nanocomposite exhibited photocurrent switching behavior in the broadband light spectrum range. It is noted that even with zero bias applied, a good photoelectric signal was still measured. The resulting nanocomposite exhibited good photophysical stability. Physical mechanisms are discussed herein. It is suggested that the interfacial interaction of C₃N₄ and Bi₂S₃ in the nanocomposite creates a strong built-in electric field, which accelerates the separation of excitons. Therefore, as a dynamic process of photoexcitation, fluorescence, the photoelectric effect, and scattering are three main competing processes; the separation of excitons and the extraction of free photogenerated charge can be used as a reference for the fluorescent materials or other photoelectric materials studies as photophysical properties. This study also serves as an important reference for the design, defect and grain boundary modulation or interdisciplinary application of functional nanocomposites, especially for the bandgap modulation and suppression of photogenerated carrier recombination. Full article

Monitoring hazardous gases is increasingly critical for environmental protection and human health. As a novel class of two-dimensional nanomaterials, layered metal chalcogenides have attracted substantial research attention in recent years. This is attributed to their unique physical and chemical characteristics, which endow them with remarkable potential for applications in gas sensing. In particular, bismuth sulfide (Bi₂S₃) has been extensively studied recently due to its cost-effectiveness, abundance, and eco-friendliness, aligning with the requirements of advanced sensing platforms. This article systematically summarizes recent advancements in gas sensors based on Bi₂S₃. Initially, the structural and functional properties of Bi₂S₃ are outlined, emphasizing its potential in detecting toxic gases. Subsequently, innovative methodologies aimed at enhancing room-temperature sensing efficiency are critically analyzed. The discussion concludes by addressing existing limitations and proposing future research directions to optimize Bi₂S₃ for practical applications. This review aims to systematically examine the design and optimization of next-generation gas detection nanomaterials, offering fundamental understanding of their performance enhancement mechanisms and exploring their potential implementation across multiple technological platforms. Full article

The Jiaodong Peninsula is renowned for its significant gold reserves, which exceed 4500 tons. In this study, we conducted zircon SHRIMP U-Pb dating, ⁴⁰Ar/³⁹Ar geochronology, electron probe microanalysis (EPMA) analysis, and He-Ar isotope analysis on samples from the Shuigou gold deposit located in the Qixia-Penglai-Fushan metallogenic area of central Jiaodong. This quartz vein-type gold deposit is characterized by three mineralization stages: (I) the quartz-pyrite stage, (II) the quartz-polymetallic sulfide stage, and (III) the calcite stage. In stages I and II, gold primarily exists as native gold or electrum. Preliminary analysis suggests that the deposit contains rare critical metals, including bismuth (Bi), tellurium (Te), and antimony (Sb). The Sb is found as pyrargyrite in stage III, while the other critical elements occur as isomorphisms or nanoparticles within host minerals such as pyrite, native gold, and electrum. Geochronology data indicate that the pre-mineralization Guojialing monzogranite formed around 126 ± 1.6 Ma, the syn-mineralization muscovite formed at approximately 125 Ma, and the post-mineralization diorite porphyrite formed at 120.4 ± 1.8 Ma. The ³He/⁴He ratios of fluid inclusions in the main-stage pyrite range from 0.26 to 1.26 Ra, and the ⁴⁰Ar/³⁶Ar ratios vary from 383 to 426.6. These findings suggest that the Shuigou gold deposit formed during the destruction of the North China Craton (NCC), similar to other super-large gold deposits in the Jiaodong Mesozoic gold metallogenic province. Gold mineralization has been influenced by mantle, crustal, and meteoric fluids. Full article

Lithium-ion batteries (LIBs) are considered one of the most important solutions for energy storage; however, conventional graphite anodes possess limited specific capacity and rate capability. Bismuth sulfide (Bi₂S₃) and cobalt sulfide (Co_1−xS) with higher theoretical capacities have emerged as promising alternatives, but they face challenges such as significant volume expansion during electrochemical cycling and poor electrical conductivity. To tackle these problems, vanadium was doped into Bi₂S₃ to improve its electronic conductivity; subsequently, a vanadium-doped Bi₂S₃ (V-Bi₂S₃)@Co_1−xS heterojunction structure was synthesized via a facile hydrothermal method to mitigate volume expansion by the closely bonded heterojunction interface. Moreover, the built-in electric field (BEF) created at the heterointerfaces can significantly enhance charge transport and facilitate reaction kinetics. Additionally, the nanofiber morphology of the V-Bi₂S₃@Co_1−xS heterojunction structure further contributed to improved electrochemical performance. As a result, the V-Bi₂S₃ electrode exhibited better electrochemical performance than the pure Bi₂S₃ electrode, and the V-Bi₂S₃@Co_1−xS electrode showed a significantly enhanced performance compared to the V-Bi₂S₃ electrode. The V-Bi₂S₃@Co_1−xS heterojunction electrode displayed a high capacity of 412.5 mAh g⁻¹ after 2000 cycles at 1.0 A g⁻¹ with high coulombic efficiencies of ~100%, indicating a remarkable long-term cycling stability. Full article

An association of bismuth sulfosalts coexisting with native gold is described from a sulfide-rich copper vein in the Nistru area, Baia Mare metallogenetic district, NW Romania. This mineralization is hosted within a Neogene calc-alkaline subvolcanic porphyry quartz-micromonzodiorite stock on the southern border of the Gutâi Mountains. Cu+Au+Bi mineralization represents the inner part of a zoned vein of a type specific to the SE part of the Nistru orefield. The Pb-Zn and Au-Ag veins are located towards the external zone at the boundary of the stock with the surrounding rocks. Bismuth sulfosalts are mainly represented by bismuthinite derivatives and members of the lillianite homologous series. Cosalite, matildite and wittichenite are also present in subordinate amounts. Bi-rich members of the bismuthinite-aikinite series (from krupkaite to bismuthinite) are predominant. A phase with the empirical formula CuPbBi₇S₁₂ was also identified and could potentially be a new bismuthinite derivative. The lillianite homologous series is represented by phases with composition between Gus₇₃ and Gus₅₉, with a dominance of members closer to gustavite (Gus_97–79) and less abundant members closer to lillianite (Gus₄₉). Native gold and Bi-sulfosalts are closely associated with the main sulfides (pyrrhotite, pyrite, chalcopyrite) and quartz, indicating simultaneous crystallization. Fluid inclusion data for quartz indicate a temperature interval between 205 and 247 °C. The assemblage within this vein was deposited from a low-salinity fluid (0.4–2.6 wt.% NaCl equiv.) and density from 0.80 to 0.87 g/cm³. Full article

In the present study, a green, scalable, and environmentally friendly approach was developed for the fabrication of Bi₂S₃-decorated CdS nanoparticles with an efficient hydrogen generation ability from the water. As a sulfur source, thiourea was used. The process was completed in two stages: mechanical activation and thermal annealing. The presence of spherical CdS nanoparticles and Bi₂S₃ nanorods in the CdS/Bi₂S₃ nanocomposite was confirmed and proved by XRD, Raman spectroscopy, SEM-EDS, and TEM. The synthesized CdS/Bi₂S₃ nanocomposites were evaluated for their photocatalytic hydrogen evolution capabilities. The CdS/Bi₂S₃ photocatalyst exhibited 25% higher photocatalytic activity compared to CdS, reaching a hydrogen evolution rate of 996.68 μmol h⁻¹g⁻¹ (AQE 0.87%) after 3.5 h under solar-light irradiation. Full article

In this work, bismuth sulfide (Bi₂S₃) thin films were deposited by a chemical bath deposition (CBD) technique (called soft chemistry), while titanium dioxide (TiO₂) nanoparticles were synthesized by sol–gel and zinc oxide (ZnO) nanoparticles were extracted from alkaline batteries. The resulting nanoparticles were then deposited on the Bi₂S₃ thin films by spin coating at 1000 rpm for 60 s each layer to create heterojunctions of Bi₂S₃/ZnO and Bi₂S₃/TiO₂. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The optical and contact angle analyses were undertaken by UV–Vis spectroscopy and a contact microscopy angle meter, respectively. The calculated band gap values were found to be between 1.9 eV and 2.45 eV. The Bi₂S₃ presented an orthorhombic structure, the TiO₂ nanoparticles presented an anatase structure, and the ZnO nanoparticles presented a wurtzite hexagonal crystal structure. Furthermore, heterogeneous solar photocatalysis was performed using the Bi₂S₃, Bi₂S₃/ZnO, and Bi₂S₃/TiO₂ thin film combinations, which resulted in the degradation of Congo red increasing from 8.89% to 30.80% after a 30 min exposure to sunlight. Full article

Colloidal quantum dots (CQDs) show unique properties that distinguish them from their bulk form, the so-called quantum confinement effects. This feature manifests in tunable size-dependent band gaps and discrete energy levels, resulting in distinct optical and electronic properties. The investigation direction of colloidal quantum dots (CQDs) materials has started switching from high-performing materials based on Pb and Cd, which raise concerns regarding their toxicity, to more environmentally friendly compounds, such as AgBiS₂. After the first breakthrough in solar cell application in 2016, the development of AgBiS₂ QDs has been relatively slow, and many of the fundamental physical and chemical properties of this material are still unknown. Investigating the growth of AgBiS₂ QDs is essential to understanding the fundamental properties that can improve this material’s performance. This review comprehensively summarizes the synthesis strategies, ligand choice, and solar cell fabrication of AgBiS₂ QDs. The development of PbS QDs is also highlighted as the foundation for improving the quality and performance of AgBiS₂ QD. Furthermore, we prospectively discuss the future direction of AgBiS₂ QD and its use for solar cell applications. Full article

Gold occurrence Maljavr is the first Archean conglomerate-hosted gold mineralization found in the Fennoscandian Shield. Gold-mineralized metasomatic rocks form a set of lenses within a 10 m thick linear zone, conformable to the bedding of host conglomerates. The lenses are up to 10 m long and up to 1 m thick and they clearly exhibit three alteration envelopes: the rock in the central part consists of garnet and quartz or garnet-only; biotite, garnet, and quartz make the intermediate biotite–garnet envelope; hornblende, hedenbergite, and quartz are the principal rock-forming minerals in the outer zone of the lenses. All metasomatic rocks contain sulfide mineralization up to 15–20 vol.% and up to 0.6 g/t Au. The main ore mineral is pyrrhotite, and the minor minerals are arsenopyrite, chalcopyrite, pentlandite, löllingite, and troilite. The age of zircon from biotite gneiss in the zone of alteration is 2664 ± 18 Ma, this is considered as the time of formation of lenses of metasomatic rocks. Biotite gneiss-conglomerate and metasomatic rocks were later intruded by tourmaline granite pegmatite 2508 ± 7 Ma. The injection of pegmatite caused re-crystallization of sulfides (mainly arsenopyrite and löllingite) and redistribution of gold. Visible gold in association with Bi minerals native bismuth, ehrigite, maldonite, bismuthinite, joseite-B, and hedleyite was found in inclusions in recrystallized arsenopyrite and löllingite. Au content in the rocks with recrystallized arsenopyrite and löllingite is >1 g/t, up to 30 g/t in hand samples. The 2508 Ma pegmatite is interpreted as synchronous with formation of gold mineralization in its present form. The linkage of gold mineralization with pegmatite and geochemical association Au-As-Se-Te-Bi in the mineralized rocks agree with characteristics of intrusion-related gold deposits worldwide. Biotite gneiss–metaconglomerate, hosting the mineralized altered rocks, was the probable primary source of arsenic and gold for mineralization. Full article

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. Full article

The bismuth sulfide nanostructure has become a promising gas sensing material thanks to its exceptional intrinsic properties. However, pristine Bi₂S₃ as a room-temperature sensing material cannot achieve the highly sensitive detection of ppb-level NO₂ gas. Herein, 1D nanorods with self-assembled hierarchical Bi₂S₃ nanostructures were obtained via a simple hydrothermal process. The as-prepared hierarchical Bi₂S₃ nanostructures exhibited outstanding NO₂ sensing behaviors, such as a high response value (R_g/R_a = 5.8) and a short response/recovery time (τ₉₀ = 28/116 s) upon exposure to 1 ppm NO₂. The limit of detection of hierarchical Bi₂S₃ was down to 50 ppb. Meanwhile, the sensor exhibited excellent selectivity and humidity tolerance. The improved NO₂ sensing properties were associated with the self-assembled hierarchical nanostructures, which provided a rich sensing active surface and accelerated the diffusion and adsorption/desorption processes between NO₂ molecules and Bi₂S₃ materials. Additionally, the sensing response of hierarchical Bi₂S₃ nanostructures is much higher at 100% N₂ atmosphere, which is different from the chemisorption oxygen model. Full article

Uncontrolled coal fires present a nearly unparalleled environmental and human health disaster. These fires can cause the destruction of the ecosystem, ignite forest fires, become a source of windblown dust and siltation of streams, and pollute surface water, ground water, and crops. They can cause significant disruption of families and communities resulting from physical hazards of collapse or explosion, excessive heat, visual blight and loss of potentially valuable acreage, deterioration of cultural infrastructure, personal and public property, and loss of a valuable energy resource. The emission of CO₂ and other greenhouse gases presents a significant health hazard due to respiration of dust and aerosols, and exposure to acidic gases, potentially toxic trace elements, and organic compounds. Numerous studies have described many dozens of phases that have condensed from the effluents of these fires. However, many of these studies may have overlooked the nano- and ultra-fine particles that exist beside, in, and under the brightly colored, often spectacular crystalline macro phases. Using a scanning electron microscope with an energy dispersive X-ray detector we examined a small (30 mm × 10 mm) piece of condensate from an uncontrolled coal fire in the Jharia region of India and found more than 30 different phases in this one small piece. The phases included ammonium, copper, iron, lead, bismuth chlorides; bismuth, lead, and ammonium silici-fluorides; ammonium and lead iodates; iron, barium, lead, copper, and zinc sulfides; iron and silicon oxides; and others. Broken fragments revealed multiple generations of phases. Though not strictly nanoparticles (smaller than 0.1 μm), many of these particles are in the micrometer to sub-micron range and it is likely that there are phases present in the nanoparticle size range. Certainly, particulates in the nanoparticle and ultra-fine particle range are being released from the uncontrolled coal fires and may be impacting the environment and the health of the mine workers and nearby residents, an issue that should be investigated. Full article

Photocatalytic degradation plays a crucial role in wastewater treatment, and the key to achieving high efficiency is to develop photocatalytic systems that possess excellent light absorption, carrier separation efficiency, and surface-active sites. Among various photocatalytic systems, S-type heterojunctions have shown remarkable potential for efficient degradation. This work delves into the construction of S-type heterojunctions of ternary indium metal sulfide and bismuth ferrite nanofibers with the introduction of sulfur vacancy defects and morphology modifications to enhance the photocatalytic degradation performance. Through the impregnation method, BiFeO₃/ZnIn₂S₄ heterojunction materials were synthesized and optimized. The 30% BiFeO₃/ZnIn₂S₄ heterojunction exhibited superior photocatalytic performance with higher sulfur vacancy concentration than ZnIn₂S₄. The in-situ XPS results demonstrate that the electrons between ZnIn₂S₄ and BFO are transferred via the S-Scheme, and after modification, ZnIn₂S₄ has a more favorable surface morphology for electron transport, and its flower-like structure interacts with the nanofibers of BFO, which has a further enhancement of the reaction efficiency for degrading pollutants. This exceptional material demonstrated a remarkable 99% degradation of Evans blue within 45 min and a significant 68% degradation of ciprofloxacin within 90 min. This work provides a feasible idea for developing photocatalysts to deal with the problem of polluted water resources under practical conditions. Full article