Hydrothermally synthesized nanocrystalline photoactive SnS2 thin films: effect of surface directing agents

In the present work, we have synthesized tin disulphide (SnS2) thin films via a facile, low cost, single-step hydrothermal route using various surface directing agents.

SnS2 Nanocrystalline-Anchored Three-Dimensional Graphene for Sodium Batteries with Improved Rate Performance

Tin disulfide (SnS₂) is regarded as one of the most suitable candidates as the electrode material for sodium-ion batteries (SIBs). However, the easy restacking and volume expansion properties of SnS₂ during the charge/discharge process lead to the destruction of the electrode structure and a decrease in capacity. We successfully synthesized a SnS₂ nanocrystalline-anchored three-dimensional porous graphene composite (SnS₂/3DG) by combining hydrothermal and high-temperature reduction methods. The SnS₂ nanocrystalline was uniformly dispersed within the connected reduced graphene oxide matrix. The SnS₂/3DG battery showed a high reversible capacity of 430 mAh/g after 50 cycles at 100 mA/g. The SnS₂/3DG composite showed an excellent rate capability with the current density increasing from 100 mA/g to 2 A/g. The excellent performance of the novel SnS₂/3DG composite is attributed to the porous structure, which not only promoted the infiltration of electrolytes and hindered volume expansion for the porous structure, but also improved the conductivity of the whole electrode, demonstrating that the SnS₂/3DG composite is a prospective anode for the next generation of sodium-ion batteries.

Novel Two-Dimensional AgInS2/SnS2/RGO Dual Heterojunctions: High Spatial Charge and Toxicity Evaluation

A single semiconductor employed into photo(electro)catalysis is not sufficient for charge carrier separation. Designing a multiple heterojunction system is a practical method for photo(electro)catalysis. Herein, novel two-dimensional AgInS₂/SnS₂/RGO (AISR) photocatalysts with multiple junctions were prepared by a simple hydrothermal method. The synthesized AISR heterojunctions showed superior photoelectrochemical performance and photocatalytic degradation of norfloxacin, with a high degradation rate reaching 95%. More importantly, the toxicity of photocatalytic products decreased within the reaction process. High spatial separation efficiency of photogenerated electron-hole pairs was evidenced by optical and photoelectrochemical characterizations. Furthermore, a laser flash photolysis technique was carried on investigating the lifetime of the charge carrier of the fabricated dual heterostructures. In addition, sulfur and oxygen vacancies existed in AISR heterojunctions could largely constrain the recombination of electron-hole pairs. Density functional theory calculations were carried out to analyze the mechanism of photoinduced interfacial redox reactions, showing that reduced graphene oxide and AgInS₂ act as electron and hole trappers in the photocatalytic reaction, respectively. Due to the interfacial electric field formed from AISR dual heterojunctions, the effective spatial charge separation and transfer contributed to the boosting photo(electro)catalytic performance.

A novel electrochemical immunosensor based on CoS2 for early screening of tumor marker carcinoembryonic antigen

In this work, PANI–HRP nanoparticles integrate biometric recognition and signal amplification functions in one body, which can be converted to each other without consuming the material itself.

Sandwich-type electrochemical immunosensor constructed using three-dimensional lamellar stacked CoS2@C hollow nanotubes prepared by template-free method to detect carcinoembryonic antigen

Effective treatment of cancer depends on early detection of tumor markers. In this paper, an effective template-free method was used to prepare CoS₂@C three-dimensional hollow sheet nanotubes as the matrix of the immunosensor. The unique three-dimensional hybrid hollow tubular nanostructure provides greater contact area and enhanced detection limit. The CoS₂@C-NH₂-HRP nanomaterial was synthesized as a marker and had a high specific surface area, which can effectively improve the electrocatalytic ability of hydrogen peroxide (H₂O₂) reduction while increasing the amount of capture-fixed carcinoembryonic antigen antibody (anti-CEA). In addition, the co-bonded horseradish peroxidase (HRP) can further promote the redox of H₂O₂ and amplify the electrical signal. Carcinoembryonic antigen (CEA) was quantified by immediate current response (i-t), and the prepared immunosensor had good analytical performance under optimized conditions. The current signal and the concentration of CEA were linear in the range of 0.001-80 ng/mL, and the detection limit was 0.33 pg/mL (S/N = 3). The designed immunosensor has good selectivity, repeatability and stability, and the detection of human serum samples shows good performance. Furthermore, electrochemical immunosensor has broad application prospects in the clinical diagnosis of CEA.

Structural changes during water-mediated amorphization of semiconducting two-dimensional thio-stannates

Owing to their combined open-framework structures and semiconducting properties, two-dimensional thio-stannates show great potential for catalytic and sensing applications. One such class of crystalline materials consists of porous polymeric [Sn3S7 2-] n sheets with molecular cations embedded in-between. The compounds are denoted R-SnS-1, where R is the cation. Dependent on the cation, some R-SnS-1 thio-stannates transition into amorphous phases upon dispersion in water. Knowledge about the fundamental chemical properties of the thio-stannates, including their water stability and the nature of the amorphous products, has not yet been established. This paper presents a time-resolved study of the transition from the crystalline to the amorphous phase of two violet-light absorbing thio-stannates, i.e. AEPz-SnS-1 [AEPz = 1-(2-amino-ethyl)-piperazine] and trenH-SnS-1 [tren = tris-(2-amino-ethyl)-amine]. X-ray total scattering data and pair distribution function analysis reveal no change in the local intralayer coordination during the amorphization. However, a rapid decrease in the crystalline domain sizes upon suspension in water is demonstrated. Although scanning electron microscopy shows no significant decrease of the micrometre-sized particles, transmission electron microscopy reveals the formation of small particles (∼200-400 nm) in addition to the larger particles. The amorphization is associated with disorder of the thio-stannate nanosheet stacking. For example, an average decrease in the interlayer distance (from 19.0 to 15.6 Å) is connected to the substantial loss of the organic components as shown by elemental analysis and X-ray photoelectron spectroscopy. Despite the structural changes, the light absorption properties of the amorphisized R-SnS-1 compounds remain intact, which is encouraging for future water-based applications of such materials.

Rational Design of 3D Honeycomb-Like SnS2 Quantum Dots/rGO Composites as High-Performance Anode Materials for Lithium/Sodium-Ion Batteries

Structure pulverization and poor electrical conductivity of metal dichalcogenides result in serious capacity decay both in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). To resolve the above problems, a combination of metal dichalcogenides with conductive scaffolds as high-performance electrode materials has aroused tremendous interest recently. Herein, we synthesize a 3D honeycomb-like rGO anchored with SnS₂ quantum dots (3D SnS₂ QDs/rGO) composite via spray-drying and sulfidation. The unique 3D-ordered honeycomb-like structure can confine the volume change of SnS₂ QDs in the lithiation/delithiation and sodiation/desodiation processes, provide enough space for electrolyte reservoirs, promote the conductivity of the SnS₂ QDs, and improve the electron transfer. As a result, the 3D SnS₂ QDs/rGO composite electrode delivers a high capacity and long cycling stability (862 mAh/g for LIB at 0.1 A/g after 200 cycles, 233 mAh/g for SIB at 0.5 A/g after 200 cycles). This study provides a feasible synthesis route for preparing 3D-ordered porous networks in varied materials for the development of high-performance LIBs and SIBs in future.

Degradation of Methylene Blue Dye in the Presence of Visible Light Using SiO₂@α-Fe₂O₃ Nanocomposites Deposited on SnS₂ Flowers

Semiconductor materials have been shown to have good photocatalytic behavior and can be utilized for the photodegradation of organic pollutants. In this work, three-dimensional flower-like SnS₂ (tin sulfide) was synthesized by a facile hydrothermal method. Core-shell structured SiO₂@α-Fe₂O₃ nanocomposites were then deposited on the top of the SnS₂ flowers. The as-synthesized nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis Spectroscopy, Brunauer–Emmett–Teller (BET) surface area analysis, and photoluminescence (PL) spectroscopy. The photocatalytic behavior of the SnS₂-SiO₂@α-Fe₂O₃ nanocomposites was investigated by observing the degradation of methylene blue (MB). The results show an effective enhancement of photocatalytic activity for the degradation of MB especially for the 15 wt % SiO₂@α-Fe₂O₃ nanocomposites on SnS₂ flowers.

Fe2O3/SnSSe Hexagonal Nanoplates as Lithium-Ion Batteries Anode

Novel two-dimensional (2D) Fe₂O₃/SnSSe hexagonal nanoplates were prepared from hot-inject process in oil phase. The resulted hybrid manifests a typical 2D hexagonal nanoplate morphology covered with thin carbon layer. Serving as anode material of lithium-ion battery (LIB), the Fe₂O₃/SnSSe hybrid delivers an outstanding capacity of 919 mAh g^-1 at 100 mA g^-1 and a discharge capacity of 293 mAh g^-1 after 300 cycles at the current density of 5 A g^-1. Compared with pristine SnSSe nanoplates, the Fe₂O₃/SnSSe hybrid exhibits both higher capacity and better stability. The enhanced performance is mainly attributed to the 2D substrate together with the synergistic effects offered by the integration of SnSSe with Fe₂O₃. The 2D Fe₂O₃/SnSSe hybrid can afford highly accessible sites and short ion diffusion length, which facilitate the ion accessibility and improves the charge transport. The novel structure and high performance demonstrated here afford a new way for structural design and the synthesis of chalcogenides as LIB anodes.

Ultrathin Nanosheet Assembled Sn0.91 Co0.19 S2 Nanocages with Exposed (100) Facets for High-Performance Lithium-Ion Batteries

Ultrathin 2D inorganic nanomaterials are good candidates for lithium-ion batteries, as well as the micro/nanocage structures with unique and tunable morphologies. Meanwhile, as a cost-effective method, chemical doping plays a vital role in manipulating physical and chemical properties of metal oxides and sulfides. Thus, the design of ultrathin, hollow, and chemical doped metal sulfides shows great promise for the application of Li-ion batteries by shortening the diffusion pathway of Li ions as well as minimizing the electrode volume change. Herein, ultrathin nanosheet assembled Sn_0.91 Co_0.19 S₂ nanocages with exposed (100) facets are first synthesized. The as-prepared electrode delivers an excellent discharge capacity of 809 mA h g^-1 at a current density of 100 mA g^-1 with a 91% retention after 60 discharge-charge cycles. The electrochemical performance reveals that the Li-ion batteries prepared by Sn_0.91 Co_0.19 S₂ nanocages have high capacity and great cycling stability.

Novel Ag2S quantum dot modified 3D flower-like SnS2 composites for photocatalytic and photoelectrochemical applications

Novel Ag₂S quantum dot modified 3D flower-like SnS₂ composites exhibit highly efficient photodegradation of MO and photocatalytic H₂ production.

Unlocking the potential of SnS2: Transition metal catalyzed utilization of reversible conversion and alloying reactions

The alloying-dealloying reactions of SnS₂ proceeds with the initial conversion reaction of SnS₂ with lithium that produces Li₂S. Unfortunately, due to the electrochemical inactivity of Li₂S, the conversion reaction of SnS₂ is irreversible, which significantly limit its potential applications in lithium-ion batteries. Herein, a systematic understanding of transition metal molybdenum (Mo) as a catalyst in SnS₂ anode is presented. It is found that Mo catalyst is able to efficiently promote the reversible conversion of Sn to SnS₂. This leads to the utilization of both conversion and alloying reactions in SnS₂ that greatly increases lithium storage capability of SnS₂. Mo catalyst is introduced in the form of MoS₂ grown directly onto self-assembled vertical SnS₂ nanosheets that anchors on three-dimensional graphene (3DG) creating a hierarchal nanostructured named as SnS₂/MoS₂/3DG. The catalytic effect results in a significantly enhanced electrochemical properties of SnS₂/MoS₂/3DG; a high initial Coulombic efficiency (81.5%) and high discharge capacities of 960.5 and 495.6 mA h g⁻¹ at current densities of 50 and 1000 mA g⁻¹, respectively. Post cycling investigations using ex situ TEM and XPS analysis verifies the successful conversion reaction of SnS₂ mediated by Mo. The successful integration of catalyst on alloying type metal sulfide anode creates a new avenue towards high energy density lithium anodes.

Ag2S quantum dots in situ coupled to hexagonal SnS2 with enhanced photocatalytic activity for MO and Cr(vi) removal

A highly efficient visible-light-driven composite photocatalyst of Ag₂S quantum dots coupled to hexagonal SnS₂ exhibited considerably increased photocatalytic activity for MO and Cr(vi) removal.

Effect of an external electric field on the electronic properties of SnS2/PbI2 van der Waals heterostructures

The future development of optoelectronic devices will require an advanced control technology in electronic properties, for example by an external electric field (E_field).

Simple Synthesis of Nanocrystalline Tin Sulfide/N-Doped Reduced Graphene Oxide Composites as Lithium Ion Battery Anodes

Composites of nitrogen-doped reduced graphene oxide (NRGO) and nanocrystalline tin sulfides were synthesized, and their performance as lithium ion battery anodes was evaluated. Following the first cycle the composite consisted of Li₂S/Li_xSn/NRGO. The conductive NRGO cushions the stress associated with the expansion of lithiation of Sn, and the noncycling Li₂S increases the residual Coulombic capacity of the cycled anode because (a) Sn domains in the composite formed of unsupported SnS₂ expand only by 63% while those in the composite formed of unsupported SnS expand by 91% and (b) Li percolates rapidly at the boundary between the Li₂S and Li_xSn nanodomains. The best cycling SnS₂/NRGO-derived composite retained a specific capacity of 562 mAh g^-1 at the 200th cycle at 0.2 A g^-1 rate.

SnS2nanoflakes for efficient humidity and alcohol sensing at room temperature

We report a one step facile hydrothermal synthesis of layered SnS₂nanoflakes and its application as humidity and alcohol sensor.

Flexible additive-free CC@TiOxNy@SnS2 nanocomposites with excellent stability and superior rate capability for lithium-ion batteries

The free-standing CC@TiO_xN_y@SnS₂ nanocomposites have been synthesized via two steps hydrothermal process and exhibited excellent lithium storage performance.

A General Strategy to Fabricate Carbon-Coated 3D Porous Interconnected Metal Sulfides: Case Study of SnS/C Nanocomposite for High-Performance Lithium and Sodium Ion Batteries

Transition metal sulfides have a great potential for energy storage due to the pronouncedly higher capacity (owing to conversion to metal or even alloy) than traditional insertion electrode materials. However, the poor cycling stability still limits the development and application in lithium and sodium ion batteries. Here, taking SnS as a model material, a novel general strategy is proposed to fabricate a 3D porous interconnected metal sulfide/carbon nanocomposite by the electrostatic spray deposition technique without adding any expensive carbonaceous materials such as graphene or carbon nanotube. In this way, small nanorods of SnS are generated with sizes of ≈10-20 nm embedded in amorphous carbon and self-assembled into a 3D porous interconnected nanocomposite. The SnS:C is directly deposited on the Ti foil as a current collector and neither conductive additives nor binder are needed for battery assembly. Such electrodes exhibit a high reversible capacity, high rate capability, and long cycling stability for both lithium and sodium storage.

Carbon nanotube-assisted growth of single-/multi-layer SnS2 and SnO2 nanoflakes for high-performance lithium storage

Composite of ultrathin SnS₂ and SnO₂ nanoflakes with conducting multiwalled carbon nanotube matrix as superior anode materials for lithium-ion batteries.

Nanostructured metal sulfides for energy storage

Advanced electrodes with a high energy density at high power are urgently needed for high-performance energy storage devices, including lithium-ion batteries (LIBs) and supercapacitors (SCs), to fulfil the requirements of future electrochemical power sources for applications such as in hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles. Metal sulfides with unique physical and chemical properties, as well as high specific capacity/capacitance, which are typically multiple times higher than that of the carbon/graphite-based materials, are currently studied as promising electrode materials. However, the implementation of these sulfide electrodes in practical applications is hindered by their inferior rate performance and cycling stability. Nanostructures offering the advantages of high surface-to-volume ratios, favourable transport properties, and high freedom for the volume change upon ion insertion/extraction and other reactions, present an opportunity to build next-generation LIBs and SCs. Thus, the development of novel concepts in material research to achieve new nanostructures paves the way for improved electrochemical performance. Herein, we summarize recent advances in nanostructured metal sulfides, such as iron sulfides, copper sulfides, cobalt sulfides, nickel sulfides, manganese sulfides, molybdenum sulfides, tin sulfides, with zero-, one-, two-, and three-dimensional morphologies for LIB and SC applications. In addition, the recently emerged concept of incorporating conductive matrices, especially graphene, with metal sulfide nanomaterials will also be highlighted. Finally, some remarks are made on the challenges and perspectives for the future development of metal sulfide-based LIB and SC devices.

Facile preparation of CuO@SnO2 nanobelts as a high-capacity and long-life anode for lithium-ion batteries

CuO@SnO₂ nanobelts exhibits much higher capacities and markedly improved cycling stability compared with single CuO and SnO₂ counterparts.