Nanostructured Metal Sulfides Research Articles

Comprehensive reviews on the potential applications of inorganic metal sulfide nanostructures in biological, environmental, healthcare, and energy generation and storage

Abstract The versatile nature of metal sulfide nanostructures has led to their meteoric rise in popularity. The compositions, morphologies, and sizes of these nanostructures may be tuned, giving them distinct features. Here we look at the many uses of metal sulfide nanostructures, with an emphasis on their possible benefits in the fields of biology, ecology, and energy storage. Because of their remarkable optical characteristics and high degree of biocompatibility, metal sulfide nanostructures have great potential in the biological fields of bioimaging, medication administration, and photothermal treatment. Additionally, because of their large surface area and adsorption capability, these nanostructures show outstanding performance in environmental remediation, which includes pollutant removal and wastewater treatment. Because of their great conductivity and electrochemical activity, metal sulfide nanostructures are also in great demand for energy storage applications such supercapacitors, hydrogen storage, and lithium-ion batteries. This review provides a comprehensive analysis of recent progress in synthesizing various metal sulfides with transition metal elements. Effective physiochemical and biological approaches are employed in their production to control the structures, dimensions, and compositions of these sulfides.

Photocatalytic efficiency of PVDF based binary and ternary nanocomposites of metal sulfides: A comparative study

Our present research work aims in providing a simple and economical technique of developing an efficient visible light active photocatalyst. Polyvinylidene fluoride (PVDF) based binary and ternary nanocomposites of metal sulfide nanostructures namely ZnS/PVDF and ZnS/CdS/PVDF were synthesized using a simple solvent casting technique. The photocatalytic efficiencies of the prepared composite films were studied towards the degradation of Malachite green dye under UV and visible light irradiation. Effective incorporation of nanomaterial fillers on the PVDF matrix was confirmed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Fourier Transform Infrared (FTIR) and UV–Vis Diffused Reflectance spectroscopy. The energy band gap of ZnS/PVDF and ZnS/CdS/PVDF, calculated using the Kubelka Munk Function from the Reflectance data were observed to be 3.64 eV and 2.52 eV respectively. Photodegradation studies show that ternary nanocomposite is a better photocatalyst as compared to binary nanocomposite under both UV and visible light irradiation.

Influence of a One-Pot Approach on a Prepared CuS Macro/Nanostructure from Various Molecular Precursors

Nanostructured metal sulfides such as copper sulfide (CUS) form from single-source precursors (SSPs) and are cost-friendly materials that can be used in a one-pot approach with potential applications in dye-sensitizer solar cells (DSCs). This is an attractive pathway that allows the careful control of tailoring the design of the nanostructures with slight variations in the mixture conditions to form uniform nanoparticles and enhance the performance of DSCs. We report on the optical, structural, and morphological properties of CuS as photosensitizers and their application in QDSCs using characterization techniques such as cyclic voltammetry (CV), current–voltage (I-V), UV-Vis spectroscopy (UV-Vis), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), etc. The UV-Vis reveals that the band gap for the three samples is found at 2.05–2.87 eV, confirming them as suitable materials for solar cells. The XRD peaks for the three CuS nanoparticles harmonized very well with hexagonal CuS. The thermal gravimetric (TGA) suitability of the three complexes shows a two-step decomposition within the temperature range of 125–716 °C, with a final residue of 2–4%. CV curves for three samples show that none of the developed metal sulfides exhibits a peak indicative of limited catalytic activity in the iodine electrolyte. The I-V overall energy conversion efficiency (η%) of 4.63% for the CuSb photosensitizer is linked to the wide electronic absorption spectrum and better relative dye loading. The synthesis of photosensitizers from a trioctylphosphine oxide (TOPO) capping agent shows improved efficiency compared to our previous studies, which used hexadecylamine as a coordinating solvent.

Microwave-Assisted Fabrication of High Energy Density Binary Metal Sulfides for Enhanced Performance in Battery Applications.

Nanomaterials have found use in a number of relevant energy applications. In particular, nanoscale motifs of binary metal sulfides can function as conversion materials, similar to that of analogous metal oxides, nitrides, or phosphides, and are characterized by their high theoretical capacity and correspondingly low cost. This review focuses on structure-composition-property relationships of specific relevance to battery applications, emanating from systematic attempts to either (1) vary and alter the dimension of nanoscale architectures or (2) introduce conductive carbon-based entities, such as carbon nanotubes and graphene-derived species. In this study, we will primarily concern ourselves with probing metal sulfide nanostructures generated by a microwave-mediated synthetic approach, which we have explored extensively in recent years. This particular fabrication protocol represents a relatively facile, flexible, and effective means with which to simultaneously control both chemical composition and physical morphology within these systems to tailor them for energy storage applications.

Review of Metal Sulfide Nanostructures and their Applications

Review of Metal Sulfide Nanostructures and their Applications

FeCoS2/Co4S3/N-doped graphene composite as efficient electrocatalysts for overall water splitting

Transition metal sulfide is a kind of electrocatalyst with appropriate cost, high efficiency, and stability. However, introducing additional metal atoms into transition metal complexes to form ternary compounds can more effectively optimize the electronic structure and improve its catalytic performance. In this work, FeCoS2/Co4S3 nanoparticles were groundbreakingly synthesized and loaded on nitrogen-doped graphene foam (NGF) with a 3D network structure by facile hydrothermal synthesis and simple chemical vapor deposition (CVD) process. The transition metal sulfide nanoparticles were uniformly distributed on the surface of NGF substrates. The transition metal sulfide nanostructures can provide a larger surface area, enhance the interaction with the medium, and improve the electrocatalytic performance. The synthesized FeCoS2/Co4S3/NGF catalyst exhibits enhanced HER and OER catalytic performance in 1 M KOH, with overpotentials of 172 mV for the HER and 276 mV for the OER at a current density of 10 mA·cm−2. The performance of the FeCoS2/Co4S3/NGF hybrid catalyst could match the best Fe-Co-S bifunctional electrocatalysts reported in the literature. Strong evidence supports that the FeOOH/CoOOH species in situ formed on the surface of FeCoS2/Co4S3/NGF catalyst was the actual catalytic active substance towards OER. In addition, the Tafel slope, TOF, EIS, and stability test results collaboratively support that Fe-Co-S/NGF shows great potential to be used as a bifunctional electrocatalyst for large-scale overall water electrolysis.

Metal Sulfide Photocatalysts for Hydrogen Generation: A Review of Recent Advances

Metal-sulfide nanostructures have piqued the interest of researchers for decades due to their intriguing optoelectronic properties. Indeed, significant advances and improvements have been made in various fundamental aspects for cutting-edge applications, such as water splitting and hydrogen production. Furthermore, rising demand for low-dimensional materials due to lower material consumption and improved performance due to quantum size effects has spurred research on semiconducting metal sulfides. Consequently, size-controllable nanostructures with diverse morphologies have been fabricated and studied for potential applications. However, the photocatalytic hydrogen evolution rate is still limited mainly by fast recombination rate, poor solar energy utilization and lack of surface-active sites for H2 reduction. This review will highlight particularly recent findings in metal-sulfide-based photocatalysts for hydrogen evolution reactions, considering the swift development and excellent research in this field. Following a brief overview of fundamental properties, we will explore state-of-the-art strategies for enhancing H2 generation efficiencies over the pristine, heterostructured and co-catalayzed metal-sulfide photocatalysts.

Engineering of Transition Metal Sulfide Nanostructures as Efficient Electrodes for High-Performance Supercapacitors

Engineering of Transition Metal Sulfide Nanostructures as Efficient Electrodes for High-Performance Supercapacitors

Visible light driven photocatalytic activities of metal sulfides synthesized by simple co-precipitation method

Simple co-precipitation method was employed for the successful preparation of metal sulfide nanostructures (ZnS and CdS). The structural properties of the samples were investigated using X-Ray Diffraction (XRD) technique. The crystallite size of CdS and ZnS were observed to be 3.2 nm and 3.3 nm respectively. The optical properties of the samples were examined using UV–Visible absorbance and FTIR spectroscopy. The elemental composition of the samples were characterized using EDX. The photocatalytic activities of the nanostructures were studied and compared towards the degradation of Malachite green dye under the action of different sources of light. Under visible light source, CdS shows higher photocatalytic efficiency which degrades 95% of the dye as compared to ZnS which degrades only 35% of the dye under 2 h of light irradiation. However, under UV light source, ZnS shows higher photocatalytic efficiency with degradation percentage of 63% as compared to CdS whose degradation percentage is 42% under the same experimental condition.

Recent advances in nanostructured transition metal sulfide based sensors for environmental applications

It is well said by the great writer Rumi that “Anything beyond what we need is a poison”. The adulteration of living conditions or the environment due to the presence of several toxic chemicals has adversely affected the quality of life. These chemicals can be anything like pesticide, industrial waste, organic contaminants, toxic gases, pharmaceuticals or even the common biomolecules. Even the slight perturbation in their concentration may have harmful consequence on human health. The development of sensors to monitor their levels in the environment is the first step to deal with them. Continuous efforts are being made to find suitable sensing materials as the need of hour. Nanostructured metal sulfides owing to their versatile properties are a suitable candidate for sensing applications. This review presents a recent perspective to the use of metal sulphide for sensing of a wide range of analytes.

Synthesis of metal sulfides via ionic liquid-mediated assembly strategy and their photocatalytic degradation of dyes in water

Metal sulfide nanomaterials have been extensively studied due to their attractive applications in various fields. Although various synthetic approaches have been developed, it remains a great challenge to establish a universal and green method for fabricating metal sulfide nanomaterials with tailorable structures (e.g., shapes and sizes). Here we report a ionothermal strategy to synthesize metal sulfide particles with diverse components and controllable architectures. Transition metal sulfide (TMS) nanostructures such as hierarchical Cu7S4 microspheres, ZnS and CdS nanoparticles, PdS polyhedrons, and Bi2S3 nanorods have been successfully synthesized with metal salts and amino acid-based ionic liquids, [TBP][Cys] (tetrabutyl-phosphonium cation and L-cysteine anion). We unveiled the structures, optical properties, and formation mechanism of TMSs. As a typical application of the as-prepared TMSs, the hierarchically structured Cu7S4 nanocrystals enable high-performance photocatalysis degradation of dyes (e.g., methylene blue) in water. Our study not only provides new insights into the ionic liquid-mediated assembly strategy but also achieves an efficient catalyst for photocatalytic degradation.

Enhanced efficiency of DSSC by lyophilized tin-doped molybdenum sulfide as counter electrode

The influence of lyophilization on the electrochemical properties of hydrothermally synthesized tin (Sn) doped molybdenum sulfide (MoS2) nanostructures are investigated thoroughly. The lyophilized tin doped MoS2 used as counter electrode (CE) in dye-sensitized solar cells (DSSCs) showed high efficiency and better stability. Power conversion efficiency (PCE) of 7.14% is achieved using lyophilized 2.5% Sn-doped MoS2 as CE in DSSCs, which is much higher than devices made of CE comprising oven air annealed samples (5.74%). The major enhancement of PCE is due to the large surface area of Sn-doped lyophilized MoS2 nanostructures as well as the high electrocatalytic activity of MoS2 towards reduction reaction, which are observed from BET, CV and EIS measurements. Sequential CV scanning further showed the high electrochemical stability of the Sn-doped MoS2 nanostructures. This indicates the useful application of lyophilizer technique to produce various other metal sulfide nanostructures to increase the porosity and overall surface area of the materials for optimum device performance.

Nanostructured MoS2‐, SnS2‐, and WS2‐Based Anode Materials for High‐Performance Sodium‐Ion Batteries via Chemical Methods: A Review Article

In the current age, electric‐driven products based on large‐scale stationary energy‐storage devices, sodium‐ion batteries (SIBs) are good promising candidates due to their comparable low cost, environment friendliness, high efficiency, and relatable huge abundance. An anode plays a vital role in the high performance of rechargeable batteries, so it becomes necessary to focus on the research on high‐performance anode materials. Recently, a number of researchers developed advanced host materials for SIBs to boost their energy density, cycle efficiency, and safety measures. In recent years, nanostructured metal sulfides like MoS2, SnS2, and WS2 with their novel structure‐based anode materials are the focus of the key research in sodium‐storage applications because of their comparable high conductivity, high capacity, good cycle life, and unmatched chemical and physical properties. In addition, these metal sulfides exhibit high mechanical, thermal, and structural stability, which supports them to find their place as an anode material for high‐performance SIBs in large‐scale energy storage production. Herein, the selected metal sulfide‐based nanostructures synthesized by chemical routes are extensively reviewed and their electrochemical properties for application as a high‐performance anode material in the SIBs are explored.

Synthesis of Nano-Structured Transition Metal Oxides and Sulfides for Overall Water Splitting and Supercapacitors

In contemporary society, there are many different ways that energy is used in daily life. From applications that require a high energy density to long term storage in a stable manner, the requirements for energy usage are diverse. Therefore, the greater the number of uses a designed material exhibits the more practical it may be for wide-scale manufacture. Two areas of particular interest for energy applications are fuel cells (to generate energy) and supercapacitors (to store energy). To provide cheaper and more durable alternatives for energy storage electrodes containing CoMoO4, NiMoO4, CoMoS4, and NiMoS4 were synthesized. The electrodes were synthesized through a hydrothermal method using Ni-foam as the substrate then tested as electrocatalysts for water splitting and electrodes for supercapacitors. As an electrocatalyst for hydrogen evolution reaction, NiMoS4 displayed the lowest overpotential of 148 mV with a Tafel slope of 159 mV/dec. On the other hand, CoMoS4 showed the lowest overpotential of 189 mV with a Tafel slope of 78 mV/dec among all four samples for oxygen evolution reactions. In terms of energy storage, the CoMoO4 had the highest specific capacitance of 2652 F/g at a current density of 0.5 A/g with an averaged charge retention of 91% and a Coulombic efficiency of 99% after 10,000 cycles.

Hydrometallurgical Synthesis of Nickel Nano-Sulfides from Spent Lithium-Ion Batteries

By developing technologies, spent lithium-ion batteries (LIBs) are considered a great source of nickel-cobalt ions to fabricate metal sulfide nanoparticles. However, the presence of unnecessary ions such as manganese and lithium may hamper the formation of pure metal sulfide nanostructures where the utilization of proper ligand(s) can be very critical. For this reason, the present study initially introduces a promising and cost-effective acidic leaching followed by precipitation and thermal treatment (~250 °C, 1 h) processes to fabricate pure NiS nanopowders from the LIBs, while considering potassium amyl xanthate as the precipitating agent. The produced nanoparticle’s size and structure were characterized by commonly used and advanced analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS), and inductively coupled plasma optical emission spectrometry (ICP-OES). The elemental distributions and functional groups were analyzed through energy dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR) methods. The characteristic analyses of the spherical-like NiS particles showed a mean particle size of 61 ± 2 nm (by TEM) and 64 nm (through the PCS method) with high purities approved via XRD and EDS analyses. Moreover, comparing the obtained XRD data with the standard ones showed a perfect match with the hexagonal structure of the NiS phase. We finally concluded that such a presented approach is very practical and efficient for converting the LIBs to an extremely valuable product. Future studies are suggested for the fundamental conceptualization of the processes.

Synthesis of Size‐Controllable NiCo2S4 Hollow Nanospheres Toward Enhanced Electrochemical Performance

Although the synthesis of novel nanostructured metal sulfides has been well established, further size‐controllable optimization is still valuable to enhance their performance for various applications. Herein, a self‐template method to size‐controllably synthesize the hollow NiCo2S4 nanospheres is reported. Uniformly monodisperse NiCo precursors with diameter widely ranging from 97 to 550 nm are controllably synthesized and subsequently transformed into hollow NiCo2S4 nanospheres through in situ sulfidation. Smaller nanoparticles' diameter results in the hollow NiCo2S4 nanospheres larger surface area and thinner shell thickness and hence provides much more electrochemical active sites as well as facilitate the ion and electron transfer. Consequently, the hollow NiCo2S4 nanospheres—used as the electrode materials in supercapacitors—achieve 19% enhancement of specific capacity from 484.8 to 575.1 C g−1 through lowering the 42.5% diameter of hollow NiCo2S4 nanospheres from 407 to 234 nm. Moreover, the hollow NiCo2S4 nanospheres with 234 nm diameter exhibit superior rate capacity indicated by 49% capacity retention from 1 to 50 A g−1 and excellent cycling stability (77% after 2000 cycles). Furthermore, this method is a potentially general strategy in the size‐controllable synthesis of the metal sulfides hollow nanostructures and results in the remarkable electrochemical applications.

(Invited) Nanostructured Metal Sulfides for Solar Cells to Improve the Photovoltaic Performance

Nanostructured metal sulfides such as Sb2S3 [1-3], AgInS2 [4], and PbS [5] have been prepared as nanosheet, nanorods, quantum dots (QDs) as electron transporting, light harvesting, and/or stabilizing parts for solar cells to improve their photovoltaic performance and durability.For further improvement of the metal sulfide–based solar cells, nanostructured Sb2S3 with relatively high crystallinity and appropriate energy diagrams will bring decrease of the interfacial barrier for easy electron extraction and declination of charge recombination. In this context, Sb2S3 nanorods were newly prepared by solvothermal method using antimony chloride with two different sources of sulfur of thioacetamide or potassium o–benzyldithiocarbonate (C7H7OCSSK) in two different solvents of water or ethylene glycol. XRD patterns of the obtained powders were assigned to be Sb2S3, and their crystalline sizes were ranged in 0.2–0.8 nm. It was confirmed by the SEM observations that the minimum sized nanorods of Sb2S3 with their averaged length of 680 nm were obtained when C7H7OCSSK and water were used. Others were ranged in 2–5 mm length. From the uv–vis absorption spectra and the photoelectron yield spectra in air of the thin-films, their band gap, valence band and conduction band were estimated to be ranged in 1.6–1.8 eV, 5.5–5.8 eV, and 3.9–4.1 eV, respectively. Utilization of Sb2S3 nanorods for the planar solar cells composed of glass/F-doped SnO2/TiO2/Sb2S3/poly [(3–hexylthiophene)–2,5–diyl]+Sb2S3 nanorods/MoO3/Ag resulted in 3.5 times enhancement of power conversion efficiency (PCE) through the increment of short circuit current density since the interfacial contacting area of the polymer with Sb2S3 was increased with the use of nanorods as compared to that without the nanorods.In order to harvest more light both of uv-visible and infrared regions effectively, PbS QDs were prepared and applied as the active layer and/ or the hole transporting layer of solar cells. PbS QDs were prepared by hot injection technique. By varying the injection temperature at 343 K, 353 K, and/or 373 K, the absorption peak was shifted from 917 nm (at 343 K) to 1035 nm (at 373 K), which corresponds to specific band gap of the quantum dots. In addition, with the increase of the injection temperature, sizes of the crystallite and lattice were increased. XRD patterns which were assigned to nanosized crystal of PbS without any other additional peak was observed. The evaluations of solar cell parameters by using the above samples were examined. The superiority of device made of PbS quantum dots from low injection temperature was confirmed. The device made of 6 layers of PbS with methylammonium iodide (MAI) or tetrabutylammonium iodide (TBAI) ligands as active layer, resulted in PCE of 6.87% with short circuit current density of 23 mA cm-2, as the highest among the devices. In addition, comparison of solar cell performance by using the same type of PbS sample before and after ligand exchange with MAI was also examined and resulted in improvement of photovoltaic parameters of open circuit voltage, short circuit current density, and PCE after the ligand exchange with MAI on the PbS quantum dots. The effect of silver doping on PbS as the hole transporting layer for solar cell was also investigated. It was confirmed that the Ag–doped device has better performance for both PbS with TBAI and PbS with 1, 2–ethanedithiol though the device with MAI treatment did not have long stability.[1] Hayakawa, A.; Yukawa, M.; Sagawa, T., ECS J. Solid-State Technology, 2017, 6, Q35-Q38.[2] Yukawa, M.; Hayakawa, A.; Sagawa, T., ECS Trans., 2017, 77, 653-659.[3] Yukawa, M.; Hayakawa, A.; Sagawa, T., ECS Trans., 2018, 85, 551-555.[4] Kaewprajak, A.; Kumnorkaew, P.; Sagawa, T. Org. Electron., 2019, 69, 26-33.[5] Shi, G.; Kaewprajak, A.; Ling, X.; Hayakawa, A.; Zhou, S.; Song, B.; Kang, Y.-w.; Hayashi, T.; Altun, M. E.; Nakaya, M.; Liu, Z.; Wang, H.; Sagawa, T.; Ma, W. ACS Energy Lett., 2019, 4, 960-967.

Controlled Growth and Bandstructure Properties of One Dimensional Cadmium Sulfide Nanorods for Visible Photocatalytic Hydrogen Evolution Reaction.

One dimensional (1D) metal sulfide nanostructures are one of the most promising materials for photocatalytic water splitting reactions to produce hydrogen (H2). However, tuning the nanostructural, optical, electrical and chemical properties of metal sulfides is a challenging task for the fabrication of highly efficient photocatalysts. Herein, 1D CdS nanorods (NRs) were synthesized by a facile and low-cost solvothermal method, in which reaction time played a significant role for increasing the length of CdS NRs from 100 nm to several micrometers. It is confirmed that as the length of CdS NR increases, the visible photocatalytic H2 evolution activity also increases and the CdS NR sample obtained at 18 hr. reaction time exhibited the highest H2 evolution activity of 206.07 μmol.g−1.h−1. The higher H2 evolution activity is explained by the improved optical absorption properties, enhanced electronic bandstructure and decreased electron-hole recombination rate.

Supporting bimetallic sulfide on 3D TiO2 hollow shells to boost photocatalytic activity

Integrating two-dimensional (2D) transition metal sulfide (TMS) nanostructures with the semiconductor materials is one strategy to improve their photocatalytic performance. Herein, for the first time, supporting noble-metal-free Co1.62Mo6S8 (CMS) with a 2D structure on three-dimensional (3D) TiO2 hollow shells (THS) is developed to construct the special CMS/THS 2D-3D film-shell photocatalyst. Based on a range of spectroscopic and electrochemical techniques, such structure can accelerate charge separation and transfer, provide abundant active sites for water reduction, and enhance light harvesting capacity through light scattering and slow photon effects. As expected, the optimized CMS/THS photocatalyst exhibits excellent photocatalytic H2 evolution activity and good stability under simulated solar light irradiation, whose rate is 39 times higher than that of THS and even much better than those of CoS2/THS and MoS2/THS. This strategy may be applicable to construct other various 2D-3D integrated nanostructures for excellent performance.

Rational Design of Bimetal–Organic Framework-Derived ZnSnS3 Nanodots Incorporated into the Nitrogen-Doped Graphene Framework for Advanced Lithium Storage

Owing to their abundant resources and high theoretical capacities, nanostructured metal sulfides exhibit attractive potential to be used as anode materials for lithium-ion batteries. However, engin...