SnS2 Nanoflakes Research Articles

A Facile In Situ Sulfurization Strategy for Heterostructured SnS2@Graphene Scrolls Anode with Enhanced Initial Coulombic Efficiency for High‐Energy Lithium Storage

AbstractThe initial Coulombic efficiency (ICE) for anode materials is usually one of important parameters for the energy density improvement of batteries. However, due to the lack of effective regulatory methods, the excellent ICE is usually difficult to achieve for SnS2 systems based on alloying/conversion mechanisms in Li‐storage process. Herein, a heterostructure constructed from SnS2 nanoflakes in situ anchored on graphene scroll (SnS2@GS) is engineered and fabricated involving a facile in situ sulfurization strategy. The SnS2@GS anode benefiting from 1D open and organized ion diffusion pathways, along with rapid charge transfer in the heterogeneous interfaces, achieves improved reversibility and kinetics. This material exhibits a remarkable specific capacity coupled with a high ICE (≈88%) while yielding robust rate properties. These exceptional lithium storage properties derive from improved conductivity and reduced energy barriers for Li‐ion migration in the heterostructures, as indicated by the density functional theory calculations. Besides, the full‐cell (LiFePO4//SnS2@GS) and the lithium‐ion capacitor based on SnS2@GS anode are assembled and deliver superior energy densities of 330 and 349 W h kg−1, respectively. This proposed approach is also popularized for the fabrication about other metal sulfide wrapped in graphene scroll to construct the anodes with remarkable properties.

Enhanced response characteristics of NO2 gas sensor based on ultrathin SnS2 nanoplates: Experimental and DFT study

Layered-metal dichalcogenides with extraordinary characteristics of vast surface area, tunable bandgap and superior adsorption capability enable the potential for application in gas sensors. However, the synthesis of effective material for enhanced response performance remains a challenge. Herein, we exploited a fascinating sensitivity and selectivity towards NO2 gas detection using SnS2 nanoflakes prepared via the hydrothermal method. SnS2 nanoflakes with a thickness of 25 nm and an average diameter of approximately 500 nm show the potential for the detection of NO2 gas at low concentrations of ppb levels. The sensing properties of the SnS2 sensors were investigated for different concentrations of NO2 at various operating temperatures. The sensor exhibits the highest gas-sensing response of 161 at 250 οC upon exposure to 5 ppm of NO2 gas with fast response and recovery times. In addition, the sensor shows excellent selectivity with a low detection limit of ppb level. The electronic structure and gas-sensing mechanism are elucidated via finding density of states, charge density, and band structure based on DFT study which is calculated by the Vienna ab-initio simulation package (VASP). The considerable small adsorption energy reveals a physisorption of the NO2 molecules on the SnS2 surface (-0.174 eV), indicating the SnS2 nanoflakes are intriguing candidates for the speedy detection of NO2 gas.

Controlled growth of edge site enriched vertical SnS2 nanoflakes for highly sensitive room temperature detection of NO2 sensor

SnS2 (Tin sulfide), a 2D layered material has been recognized as the most promising material for gas sensing applications owing to its high surface-to-volume ratio. Controlling the growth orientation provides them with remarkably high catalytic activity and better adsorption properties. In this work, SnS2 is deposited on SiO2/Si by chemical vapor deposition (CVD) technique. The calculated peak intensity ratio from Raman A1gEg>EgA1g and HRSEM analysis confirms the vertical growth of SnS2. The band bending (qV) was found to be increased as a function of NO2 concentration, resulting in an excellent response (S%) of about 98 % towards 40 ppm of NO2 at room temperature (30 °C). It also has the characteristics of low limit of detection (LoD) of 1.29 ppm and long-term reliable stability of 28 days with 81 % retention of performance. The obtained sensing performance can be attributed towards the presence of voids, negative curvature and high adsorption of NO2 on edge sites of vertically grown SnS2. Thus, exploiting the inherent property of the layered materials using growth strategy will provide a way to develop the potential applicant for practical NO2 detector.

Battery-like supercapacitor electrodes utilizing porous hierarchical bush-like ZnO/SnS on nickel foam framework

This paper reports the electrochemical activity of mesoporous bush like ZnO/SnS nanocomposites, with a specific capacity of 523.60 C g−1, at a current density of 1 A g−1, which is higher than the specific capacities offered by pristine SnS (301.15 C g−1) and ZnO (32.67 C g−1) electrodes. The ZnO/SnS composite electrode exhibits a greater energy density of ~36.36 Wh kg−1with a power density of 250 W kg−1. The composite electrode has a cyclic stability with 56 % capacity retention for over 3500 cycles. The enhanced electrochemical performance of ZnO/SnS composite structure is attributed to its bush like morphology with a large surface area (204.4 m2 g−1) which provides a greater number of electro-active sites for the absorption of ions that leads to efficient charge transportation pathways. This type of morphology is attained only when the orthorhombic SnS nanoflakes are grown over hexagonal ZnO nanoparticles, by surfactant free homogenous precipitation method. These results demonstrate that ZnO/SnS composite is an emerging electrode material for supercapacitor application.

Flexible and Hand-Printed Photodetector Based on Mg–SnS Nanoflakes

Flexible and Hand-Printed Photodetector Based on Mg–SnS Nanoflakes

Construction of branched SnS2/Te heterostructure film for self-powered high-performance photodetector application

Effective design and construction of heterostructure can conduce to charges transportation/separation and simultaneously improve light absorption ability of photoelectrochemical (PEC) photoelectrode. In this work, the p-type Te nanorods were directly grown on the surface of ultra-thin SnS2 nanoflakes via a facile and low-cost electrochemical deposition (ED) method. The PEC performance of mixed-dimensional branched SnS2/Te nanoflakes/nanorods (NFRs) heterostructure composites film was optimized by varying the ED time. Under simulated light illumination of 40 mW/cm2, the optimal photocurrent density of the SnS2/Te NFRs photoanode significantly reached up to 0.95 mA/cm2, approximately 5.2 times and 3.5 times larger than those of bare SnS2 and Te film, respectively. The improved performance was attributed to appropriate energy band matching and intensive light absorption property. In particular, it presented good stability and high light on/off ratio of about 4.1 ×106 at the 0 bias voltages, suggesting an excellent self-powered characteristic of the device. Furthermore, the SnS2/Te NFRs photodetector exhibited photoresponsivity of 127 mA/W at 0.8 V bias and photodetectivity of 1.33 ×1011 Jones, respectively. This study presents a rational strategy to improve the photodetection performance of SnS2-based PEC-type photodetector and opens a new avenue for designing high-efficiency photoelectronics device.

SnS2 decorated biochar: a robust platform for the photocatalytic degradation and electrochemical sensing of pollutants

We report the decoration of biochar with self-assembled SnS2 nanoflakes for methylene blue degradation and electrochemical sensing of Hg2+ and Pb2+ ions.

Efficient and stable CO2 to formate conversion enabled by edge-site-enriched SnS2 nanoplates

Layered materials have been investigated in many different catalytic reactions due to their excellent functionalities. In particular, understanding the anisotropic properties of layered materials is important for the design of more efficient catalysts. Herein, SnS2 nanoflakes with abundant edge sites (E-SnS2) were synthesized and their catalytic properties towards the electrochemical CO2 reduction reaction (CO2RR) were studied. Combining experimental data and computational analysis, we found that the edge sites of SnS2 are more active for CO2 to formate conversion compared with the basal sites. Moreover, a CO2 reduction intermediates triggered activation mechanism at the edge sites is proposed, the formation of sulfur vacancies at the edges would generate more active sites for CO2RR. The as-synthesized E-SnS2 shows high selectivity, activity and robust stability for at least 12 h in a flow cell under a current density of − 200 mA·cm-2. This work may provide a new perspective on rational catalyst design for CO2RR.

Anchoring SnS nanoflakes on CuCo2O4 acicular sprouts for overall water splitting

Employing a bifunctional electrocatalyst capable of simultaneously performing Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) under the same conditions of temperature, pressure, and pH is beneficial for realizing compact and efficient electrolyzers. In the pursuit of cultivating the superior abilities of ternary transition metal oxides and sulphides in OER and HER, an Argyrophylla-like heterostructure electrode consisting of Copper Cobalt Oxide (CuCo2O4) and Tin Sulfide (SnS) have been fabricated through a facile two-pot hydrothermal method. The surface level morphology and electrochemical active sites of binder-free SnS/CuCo2O4/NF heterostructure bifunctional catalyst were modified to achieve lower overpotentials for both OER (315 mV @ 20 mA/cm2) and HER (98 mV @ 20 mA/cm2) in 1.0 M KOH electrolyte medium. The proclaimed efficiencies are attributed to the enhanced oxygen vacancies, interfacial bonds and surface sulfur sites in the heterostructure as evident from electrochemical and X-ray photoelectron spectroscopy (XPS) studies. Apart from that, the proposed heterostructure electrode attained a current density of 10 mA/cm2 with a very low cell voltage of 1.60 V when employed as a dual electrode in an electrolyser cell. The Sn–O bond at the interface of CuCo2O4 and SnS stabilizes the heterostructure that helped in maintaining the lower current degradation rate (CDR) in Chronoamperometry (CA) test.

A functional SnS2-engineered separator for durable and practical lithium metal battery

Lithium (Li) metal is one of the most promising anodes for next-generation high-energy-density batteries. However, the practical application of Li metal anodes (LMAs) is hindered by uncontrollable solid electrolyte interphase (SEI) formation and detrimental Li dendrites growth. Herein, a well-designed SnS2 nanoflakes coating is utilized to modify the commercial polypropylene (PP) separator (denoted as SnS2@PP), providing a solution to tackle above issues. Impressively, an artificial SEI consisting of Li2S, Li5Sn2, and Li7Sn2 species with high ionic conductivity and superior Li affinity is generated on the Li surface to regulate homogeneous Li plating/stripping. Consequently, the Li||Li symmetric cells exhibit a stable cycling behavior of over 2700 h at 1 mA cm−2 for 1 mAh cm−2. Remarkably, SnS2@PP enables over 600 cycles at 2 C with a capacity retention of ∼80% in a Li||LiFePO4 coin cell and more than 110 cycles at 0.3 C with a capacity retention of ∼97% in a Li||LiFePO4 pouch cell under high cathode loading (13 mg cm−2), ultrathin Li foil (50 µm), and lean electrolyte (2.8 g Ah−1 after sealed) conditions. This work extends the scalable technology into a platform to control Li deposition and SEI formation toward practical Li metal batteries (LMBs) with ultralong life spans.

Flexible ultrathin Nitrogen-Doped carbon mediates the surface charge redistribution of a hierarchical tin disulfide nanoflake electrode for efficient capacitive deionization

Constructing pseudocapacitive electrodes with high specific capacities is indispensable for increasing the large-scale application of capacitive deionization (CDI). However, the insufficient CDI rate and cycling performance of pseudocapacitive-based electrodes have led to a decline in their use due to the corresponding volumetric expansion and contraction that occurs during long-term CDI processes. Herein, hierarchical porous SnS2 nanoflakes are encapsulated inside an N-doped carbon (NC) matrix to achieve efficient CDI. Benefiting from the synergistic properties of the pseudocapacitive SnS2 nanoflakes and few-layered N-doped carbon, the heterogeneous interface simultaneously provides more available vigorous sites and demonstrates rapid charge-transfer kinetics, resulting in a superior desalination capability (49.86 mg g−1 at 1.2 V), rapid desalination rate (1.66 mg g−1 min−1) and better cyclic stability. Computational research reveals a work function-induced surface charge redistribution of the SnS2@NC heterojunction, which can lead to an auspicious surface electronic structure that reduces the adsorption energy to improve the diffusion kinetics toward sodium adsorption. This work contributes to providing a thoughtful understanding of the interface engineering between transition metal dichalcogenides and NC to construct high-performance CDI electrode materials for further industrialization.

Controllable and universal anisotropic vapor–solid growth of vertical 2D metal chalcogenide nanoflakes with enhanced photoelectric and electrocatalytic properties

Epitaxial growth and subsequent processing of 2D materials are mostly confined to xy plane parallel to the substrate. Introducing another degree of freedom, i.e., the vertical direction perpendicular to the base plane, is very intriguing, as the resulting vertically aligned 2D materials will intuitively have a high aspect ratio, anisotropic structure, and abundant edge sites, holding great promise in field emission, photoelectronics, piezoelectricity, clean energy catalysis, etc. However, the key factors governing the spatially anisotropic growth to selectively obtain vertically or horizontally aligned 2D nanoflakes remain elusive. Herein, we report a controllable and general strategy to vertically grow representative 2D metal chalcogenide materials, including but not limited to SnS, SnSe, Bi2Se3, MoO3, and MoS2 nanoflakes, via a rapid heating–cooling process on various optional substrates. The rapid heating–cooling process allows rapid desublimation and nucleation of highly-supersaturated precursor vapor, leading to ultrafast growth of vertically aligned nanoflakes with exposed side surfaces and edges. As an example, the vertically grown SnS nanoflakes exhibit anisotropic spectroscopic features, superior photoelectric properties and enhanced electrocatalytic performances for the nitrate reduction and CO2 reduction reactions. This work provides a feasible approach to controllably synthesize versatile vertically aligned 2D metal chalcogenide nanoflakes on various substrates, which can advance the mechanistic understanding of anisotropic growth and physicochemical properties of 2D materials towards photoelectric devices and clean energy conversion.

Investigation of the photovoltaic efficiency of dye-sensitized solar cells using transition metal (Cu, Mo, and Ni)-doped 2D SnS2 nanoflakes counter-electrodes

Investigation of the photovoltaic efficiency of dye-sensitized solar cells using transition metal (Cu, Mo, and Ni)-doped 2D SnS2 nanoflakes counter-electrodes

Breathable MOFs Layer on Atomically Grown 2D SnS2 for Stable and Selective Surface Activation.

2D transition metal dichalcogenides (TMDs) have significant research interests in various novel applications due to their intriguing physicochemical properties. Notably, one of the 2D TMDs, SnS2 , has superior chemiresistive sensing properties, including a planar crystal structure, a large surface-to-volume ratio, and a low electronic noise. However, the long-term stability of SnS2 in humid conditions remains a critical shortcoming towards a significant degradation of sensitivity. Herein, it is demonstrated that the subsequent self-assembly of zeolite imidazolate framework (ZIF-8) can be achieved in situ growing on SnS2 nanoflakes as the homogeneous porous materials. ZIF-8 layer on SnS2 allows the selective diffusion of target gas species, while effectively preventing the SnS2 from severe oxidative degradation. Molecular modeling such as molecular dynamic simulation and DFT calculation, further supports the mechanism of sensing stability and selectivity. From the results, the in situ grown ZIF-8 porous membrane on 2D materials corroborates the generalizable strategy for durable and reliable high-performance electronic applications of 2D materials.

Investigations of Vacancy-Assisted Selective Detection of NO2 Molecules in Vertically Aligned SnS2.

Two important methods for enhancing gas sensing performance are vacancy/defect and interlayer engineering. Tin sulfide (SnS2) has recently attracted much attention for sensing of the NO2 gas due to its active surface sites and tunable electronic structure. Herein, SnS2 has been synthesized by the chemical vapor deposition (CVD) method followed by nitrogen plasma treatment with different exposure times for fast detection of NO2 molecules. Plasma treatment created a substantial number of surface vacancies on SnS2 flakes, which were controlled by the exposure period to modify the surface of flakes. After 12 min of nitrogen plasma treatment, SnS2 nanoflakes show considerable improvement in NO2 sensing characteristics, including a high sensing response of ∼264% toward 100 ppm NO2 at 120°C. The enhancement in the relative response of the sensor is due to the electronic interaction between NO2 molecules and the S vacancies on the surface of SnS2. Density functional theory (DFT) computations indicate that the S-vacancy defects on the surface dominate the effective NO2 detection and the NO2 adsorption mechanism transition from physisorption to chemisorption. Adsorption kinetics of the NO2 gas over SnS2 nanoflake-based chemiresistor sensors were studied using the Lee and Strano model [ Langmuir 2005, 21(11), 5192-5196]. The irreversible rate of the reaction for various NO2 concentrations exposed to the gas sensor is extracted using this model, which also appropriately describes the response curves. The forward rate constant of the irreversible gas sensor increased with the increase of the N2 plasma treatment time and reached the maximum in the 12 min plasma-treated sample. Through defect engineering, this research may open up new vistas for the design and synthesis of 2D materials with enhanced sensing properties.

Coaxial SnS2/SnS Nanostructures on the Ag Fiber Substrate for Flexible Self-Powered Photodetectors

Sustainable and stable photodetectors with self-powering nature and superior performance are necessary to address the growing demand for flexible and wearable optoelectronic devices. This work demonstrates a flexible, self-powered, coaxial p–n heterojunction photodetector using SnS2/SnS on an Ag fiber substrate by coupling the photoexcitation property, semiconductor nature, and piezoelectric effect. Detailed characterization studies confirm the formation of hexagonal and orthorhombic crystal planes of SnS2 and SnS nanoflakes, respectively, with a piezoelectric coefficient (d33) of 175 pm/V for SnS2. The photoabsorption is maximum in the visible region with a direct band gap of 2.1 eV. The electrical studies display a tunable photoresponse under zero-bias conditions. Upon compressive strain of 0.43%, the photoresponse increases by 36%. The Ion/Ioff ratio of the fabricated photodetector was 102 at a zero bias, and the rise and decay times shorter than 1 s were obtained. The maximum external quantum efficiency of the fabricated photodetector was found to be 54.2%, owing to the superior piezo-phototronic properties. The band diagram and the charge transfer mechanism are studied to investigate the piezo-phototronic effect. The uniform strain on the Ag fiber substrate and the piezo-potential distribution upon compressive and tensile strain promotes carrier separation in the coaxial interfaces of the p–n junction. The demonstrated strategy provides a direction for developing fiber-based photodetectors with self-powering behavior and enhanced photoresponsivity for next-generation smart wearable textile-based applications.

SnS2/Ti3C2Tx hybrids for conductometric triethylamine detection at room temperature

Transition metal carbides/nitrides (MXenes) and transition metal dichalcogenides (TMDs) have received much attention for gas sensors due to their large surface area, versatile surface chemistry, and unique gas detection capability. With distinct electrical conductivity and abundant surface chemical groups, titanium carbide (Ti3C2Tx) displays great potential in detecting volatile organic compounds (VOCs) at room-temperature. As a TMD with large electronegativity, tin disulfide (SnS2) is advantageous to outstanding sensing performance. Still, the poor intrinsic conductivity and slow response/recovery speeds impede their applications in room-temperature (RT) gas sensors. Herein, SnS2 nanoflakes were integrated with Ti3C2Tx skeleton platforms as the sensitive channels for VOC detection. The normalized response of the SnS2/Ti3C2Tx sensor was 38% to 50 ppm triethylamine (TEA) at RT, and the sensitivity at 2–20 ppm TEA was 1.2% ppm−1. Moreover, SnS2/Ti3C2Tx sensor exhibited fast response/recovery times of 12/8.5 s, a theoretical LOD of 0.49 ppm, excellent selectivity, and reliable long-term stability. The superior sensing performance is attributed to the formed heterojunctions and the unique microstructures of SnS2/Ti3C2Tx hybrids. These achievements of the heterostructured SnS2/Ti3C2Tx sensors demonstrate a novel strategy to realize effective VOC detection at RT.

Ultrafast Photocarrier Dynamics in Vertically Aligned SnS2 Nanoflakes Probing with Transient Terahertz Spectroscopy.

By employing optical pump Terahertz (THz) probe spectroscopy, ultrafast photocarrier dynamics of a two-dimensional (2D) semiconductor, SnS2 nanoflake film, has been investigated systematically at room temperature. The dynamics of photoexcitation is strongly related to the density of edge sites and defects in the SnS2 nanoflakes, which is controllable by adjusting the height of vertically aligned SnS2 during chemical vapor deposition growth. After photoexcitation at 400 nm, the transient THz photoconductivity response of the films can be well fitted with bi-exponential decay function. The fast and slow processes are shorter in the thinner film than in the thicker sample, and both components are independent on the pump fluence. Hereby, we propose that edge-site trapping as well as defect-assisted electron-hole recombination are responsible for the fast and slow decay progress, respectively. Our experimental results demonstrate that the edge sites and defects in SnS2 nanoflakes play a dominant role in photocarrier relaxation, which is crucial in understanding the photoelectrochemical performance of SnS2 nanoflakes.

Immobilization of gaseous elemental mercury using SnS2-Wrapped magnetic Fe3O4 microspheres

A SnS2@Fe3O4 composite has been easily synthesized via a KSCN fused salt approach and adopted for capturing elemental mercury at low temperature. Calcination temperature significantly impacts the mercury capture performance of SnS2-T. The optimal synthesis temperature for SnS2-T is 250 °C. Pristine SnS2-250 obtained at 250 °C exhibits a moderate Hg0 adsorption capability with mercury removing efficiency less than 65% within 80–120 °C. Fe3O4 incorporation can notably improve the mercury capture ability of SnS2-250 probably due to the cooperative effect between SnS2 nanoflakes and magnetic Fe3O4 microspheres. SnS2-250@Fe3O4 holds a good magnetism (saturation magnetization: 23 emu/g), which performs optimally at 100 °C with Hg0 capture efficiency of 95.2%. Sn4+, S2−, Fe3+ ions and chemisorbed oxygen species are principal active sites for Hg0 capture over SnS2-250@Fe3O4, which convert adsorbed Hg0 into HgO, HgS, and HgSO4.

Photocatalytic performance for palm-fiber-like SnS2 nanoflakes with full solar spectrum light response

A palm-fiber-like SnS2 with multilayer structure has been hydrothermally synthesized by anion exchange process from vertically-aligned Sn3O4 nanoflake arrays precursors. Compared to monolayer SnS2, the multilayer SnS2 exhibits obvious photothermal effect and displays excellent photocatalytic activity for RhB degradation and CO2 reduction under full solar spectrum. The multilayer SnS2 is found to have a larger electrochemically active surface area, and increased absorption for full solar spectrum with the merits of micron- and nanometer-scale structure favors to absorb the full spectrum of sunlight. The combined effect for the UV–vis absorption by the nanoscale primary structure and NIR absorption by the secondary micron-structure likely play an important role for its superior absorption capability and photocatalytic activity. This work is expected to provide a foundation to develop photocatalysts, photodetectors, solar cells and other solar energy conversion devices with full solar spectrum light response.