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Organic hybrids are promising thermoelectric materials to convert thermal energy into electricity. In this chapter, we demonstrate a series of thermoelectric materials with novel hierarchical nanostructures consisting of zero-dimensional fullerene and two-dimensional organic nanosheets (graphene)/inorganic nanosheets (titanium disulfide). By carefully tuning the hierarchical structure, the engineered hybrids exhibit encouraging thermoelectric performance.

International audience; Flexible and lightweight printed thermoelectric devices are becoming increasingly attractive with the advent of ubiquitous sensing and within the context of an increasing energy demand and the associated environmental issues. In this study, flexible thermoelectric devices based on efficient solution-processed organic/hybrid thermoelectric materials have been successfully patterned. The n-type component hexylammonium titanium disulfide (TiS2(HA)x) nanocomposite reaches a ZT of 0.08 ± 0.06 at room temperature and was successfully printed on a flexible substrate using inkjet technology which yielded a functional device. The device operates in a near-ambient temperature range and retains its performance under mechanical bending, demonstrating thus the flexible properties of the device.

International audience; Single crystals of Ge-doped TiS2 polytypes, 1T, (4H)2, 12R, and their corresponding new a√3 × a√3 superstructure were grown by chemical vapor transport method. The crystals were characterized by combining X-ray diffraction and transmission electron microscopy techniques. The structures of these polytypes are all based on close packing layers of sulfur of CdI2-type structure. Except in the 1T polytype, the germanium atoms are observed to be equally distributed over both partial and complete occupancy layers. A significant distortion of the metal–sulfur distances is observed in the superstructure polytypes, as a consequence of metal–metal corrugated layers. The 12R-a√3 × a√3 superstructure is revealed by both electron diffraction and X-ray diffraction by the presence of satellite reflections. Electron diffraction patterns from the 12R polytype show highly structured diffuse scattering surrounding the main spots. These diffuse segments, which are arranged in triangles sharing vertices, correspond to a 2a* × 2a* superstructure and are attributed to the short-range order of metal atoms in the partially filled layers.

Metallic and complex hydrides may act as anode and solid electrolytes in next generation of lithium batteries. Based on the conversion reaction with lithium to form LiH, Mg- and Ti-based anode materials have been tested in half-cell configuration with solid electrolytes derived from the hexagonal high temperature modification of the complex hydride LiBH 4 . These anode materials show large first discharge capacities demonstrating their ability to react with lithium. Reversibility remains more challenging though possible for a few dozen cycles. The work has been extended to full-cell configuration by coupling metallic lithium with positive electrodes such as sulfur or titanium disulfide through complex hydride solid electrolytes. Beside pure LiBH 4 which works only above 120 °C, various strategies like substitution, nanoconfinement and sulfide addition have allowed to lower the working temperature around 50 °C. In addition, use of lithium closo-boranes has been attempted. These results break new research ground in the field of solid-state lithium batteries. Finally, operando and in-situ neutron scattering methods applied to full-cells are presented as powerful tools to investigate and understand the reaction mechanisms taking place in working batteries.

Role of Te doping in titanium disulfide using linear combination of atomic orbitals method and Compton spectroscopy is reported. The theoretical Compton profiles (CPs) of TiSTe derived using various exchange and correlation potentials like Perdew-Burke-Ernzerhof, Perdew-Wang generalized gradient approximation and von Barth-Hedin (VBH) are compared with corresponding experimental CP to check the applicability of considered potentials. From the total and partial density of states, we observe that doping of Te at S site vanishes the narrow band gap of TiS2 leading to metallic character of TiSTe. A good agreement between experimental and VBH potential based CP of TiSTe shows better performance of VBH approximation in this mixed metal-like dichalcogenide.

It is now almost 50 years since the first rechargeable lithium batteries, based on the reversible intercalation of lithium into layered structured titanium disulfide, were conceived. They were the precursor to the structurally related layered oxides that now dominate energy storage for electronics, the grid and vehicles.

TiO2/carbon composite-fiber anodes for lithium ion batteries were prepared through the centrifugal spinning of TiS2/polyacrylonitrile (PAN) precursor fibers and subsequent thermal treatment. The TiS2/PAN precursor solutions were prepared by mixing TiS2 nanoparticles (a 2-D layered structure) with PAN in N, N-dimethylformamide (DMF). The thermal treatment of the TiS2 in the centrifugally spun PAN fibers resulted in TiO2/carbon composite fibers. The structure of TiO2 nanoparticles embedded in the carbon-fiber matrix synthesized from the TiS2 starting material may accommodate high amounts of Li ions. The TiO2/C structure may lead to increased specific capacity, improved stability, and enhanced electrochemical performance of the TiO2/C composite electrode after prolonged charge/discharge cycles. The TiO2/C composite-fiber anode delivered discharge and charge capacities at the first cycle of 683 mAhg−1 and 356 mAhg−1, respectively, with a reversible charge capacity of 290 mAhg−1 after 100 cycles at a current density of 100 mAg−1. The TiO2/C composite fibers showed an improvement in the rate performance at higher current densities compared to the graphite anode alone.

State-of-the-art dye-sensitized solar cells (DSSCs) usually utilize noble and scarce Pt as counter electrodes to catalyze the reduction of triiodide in electrolyte, which largely hinders the practical applications of DSSCs. Accordingly, alternatives with low cost, excellent electrocatalytic activity, and superior electrochemical stability to Pt are highly sought after. Herein, we report novel two-dimensional titanium disulfide nanosheets assembled and decorated on graphene (TiS2–G) through an integrated strategy of ball milling and high temperature annealing process. Benefiting from combined characteristics, when firstly applied as counter electrode, the TiS2–G hybrids demonstrate superior electrocatalytic activity towards the triiodide reduction with a power conversion efficiency of 8.80%, outperforming the Pt reference (8.00%). The high catalytic activity of TiS2–G hybrids is ascribed to synergetic effects derived from the dual integration system of highly electroactive TiS2 species and G functioning as conductive matrix. Most importantly, the as-made TiS2–G hybrids also deliver outstanding electrochemical stability. The present work provides an effective strategy to engineer the highly active and low cost replacement to noble Pt.

Room temperature sodium-ion batteries are of great potential for large-scale energy storage applications because of the abundance and low cost of sodium resources. However, their future viability will largely hinge on the development of high-capacity and stable electrode materials. In this study, we report thin TiS2 nanoplates as a possible cathode material for sodium-ion batteries. These nanoplates possess nanoscale dimensions and large surface areas. Their interlayer galleries are open toward the edges, providing easy access to the large internal space. Electrochemical measurements and multiple ex-situ studies demonstrate that TiS2 nanoplates are capable of fast and reversible Na+ intercalation and deintercalation. They deliver a large capacity close to full Na+ intercalation (186 mAh/g), high rate capability (~100 mAh/g at 10 C) and satisfactory cycling stability at both low and high current rates. Our study suggest that with proper nanostructure engineering, two-dimensional layered materials may hold great promise as sodium ion battery electrode materials to enable fast and robust energy storage at low costs.

Direct ablation of large-area graphene-like two-dimensional (2D) materials, i.e., tantalum diselenide ( T a S e 2 ), stannic disulfide ( S n S 2 ), and titanium disulfide ( T i S 2 ), by the back ablation method with a femtosecond laser with a repetition rate of 50 MHz and pulse width of 200 fs is studied for the first time to our knowledge. The ablation thresholds of the three kinds of materials are discussed. In addition, the optimization and ablation of narrow grooves on the films are demonstrated. Our work demonstrates the direct femtosecond laser ablation processing of the graphene-like 2D-material films and the potential of 2D-material-film-based devices.

The various physical properties of titanium disulfide (TiS2) crystals with intercalated iron (Fe) are reported to be influenced by the distribution of Fe atoms in the van der Waals gap between TiS2...

The synthesis of large‐area TiS2 thin films is reported at temperatures as low as 500 °C using a scalable two‐step method of metal film deposition followed by sulfurization in an H2S gas furnace. It is demonstrated that the lowest‐achievable sulfurization temperature depends strongly on the oxygen background during sulfurization. This dependence arises because Ti-O bonds present a substantial kinetic and thermodynamic barrier to TiS2 formation. Lowering the sulfurization temperature is important to make smooth films, and to enable integration of TiS2 and related transition metal dichalcogenides—including metastable phases and alloys—into device technology., Office of Naval Research MURI (Grant N00014-17-1-2661)

Transition metal dichalcogenide layered structures have become the focus of special attention for electrochemical applications in recent years. Although various engineering strategies, including size reduction and composition manipulation, have been adopted to modulate the innate electrochemical features of these layered materials, there remains a great deal of work to satisfy the specific requirements for practical applications. In this work, we set forth to provide an insight into the impact of niobium (Nb) doping on the structural features of titanium disulfide (TiS2). In addition, we examine the influence of Nb dopant on the inherent electrochemistry and charge transfer kinetics of TiS2 and its implication for the hydrogen evolution, oxygen reduction and oxygen evolution reaction (HER, ORR, and OER) processes. It has been found that introducing an appropriate amount of Nb atom (>10%) results in the formation of titanium trisulfide (TiS3) belt-like structures on the surface of TiS2 polygonal discs. Nb doping marginally changes the inherent electroactivity of TiS2 through introducing a small trace of reducible species. Furthermore, Nb-doped TiS2 materials show improved electron transfer kinetics when compared to pure TiS2, with the fastest k obs 0 of 5.58 × 10−4 cm s−1 toward [Fe(CN)6]3−/4− redox probe recorded for Ti0.95Nb0.05S2. The same trend is also found in the HER activity of these materials whereby Nb-doped TiS2 materials exhibit better performance in the electrocatalytic hydrogen evolution.

There is an assortment of layered transition metal dichalcogenides (TMDs), about 40 reported compounds, each with its unique polymorph and properties. Group 4 TMD, titanium disulfide (TiS2), possess high electronic conductivity and light weight amongst other attractive features. In consideration for electrochemical and thermoelectrical applications, doping is a promising approach to enhance its practicability. The introduction of foreign atoms or compositional variance may improve existing properties or grant access to new ones. Moving away from the more intensively studied and successfully doped group 6 MoS2 and WS2, TiS2 is doped with varying levels of niobium (Nb) via controlled heating of stoichiometric amounts to yield Ti1-xNbxS2 where x = 0.05, 0.1, 0.2. Structural effects are discussed together with two doping parameters, nature and concentration of dopant. Characterisation data reveal retention of 1T-phase polymorph despite formation of TiS3 nanobelts upon doping. Fundamental electrochemical properties such as heterogenous electron transfer rates and its charge transfer resistance are compared amongst the materials of interest. A selective and sensitive 2nd generation electrochemical biosensor is prepared using Ti0.95Nb0.05S2/GOx/GTA since it is the most superior material in glucose detection.

TiS2 nanotubular structures were synthesized by a high temperature H2S treatment of anodized TiO2 nanotube layers, and their electrochemical activity for a use as counter electrodes in dye sensitized solar cells (DSSCs) was evaluated. During conversion to TiS2 compositional, morphological and structural transformations were monitored. The fully converted TiS2 nanostructures show a high electrocatalytic activity for the I−/I3− oxidation comparable to a nanoparticular platinum layer. For a simplified model a DSSC solar cell efficiency of 6.1% was obtained using the TiS2 nanotube layer as counter electrode, which is very close to values obtained for a Pt reference (6.2%).

By taking advantage of the layered structure and decent M–X bond strength of transition metal dichalcogenides (TMDCs), herein versatile Ti-MOFs were successfully prepared with layered titanium disulfide (TiS2) as the titanium source. In addition, the phase evolution mechanism, CO2 adsorption capacity and photocatalytic degradation performance of the prepared Ti-MOFs were investigated in detail.

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim While electrochemical supercapacitors often show high power density and long operation lifetimes, they are plagued by limited energy density. Pseudocapacitive materials, in contrast, operate by fast surface redox reactions and are shown to enhance energy storage of supercapacitors. Furthermore, several reported systems exhibit high capacitance but restricted electrochemical voltage windows, usually no more than 1 V in aqueous electrolytes. Here, it is demonstrated that vertically aligned carbon nanotubes (VACNTs) with uniformly coated, pseudocapacitive titanium disulfide (TiS2) composite electrodes can extend the stable working range to over 3 V to achieve a high capacitance of 195 F g−1in an Li-rich electrolyte. A symmetric cell demonstrates an energy density of 60.9 Wh kg−1—the highest among symmetric pseudocapacitors using metal oxides, conducting polymers, 2D transition metal carbides (MXene), and other transition metal dichalcogenides. Nanostructures prepared by an atomic layer deposition/sulfurization process facilitate ion transportation and surface reactions to result in a high power density of 1250 W kg−1with stable operation over 10 000 cycles. A flexible solid-state supercapacitor prepared by transferring the TiS2–VACNT composite film onto Kapton tape is demonstrated to power a 2.2 V light emitting diode (LED) for 1 min.

Here in this article, we report Li-intercalated titanium disulfide (TiS2) two-dimensional (2D) nanosheets, exfoliated in 1-methyl-2-pyrrolidinone (NMP) forming a quite stable dispersions of pale brownish color. As synthesized TiS2 nanosheets were characterized by transmission electron microscopy (TEM). Selected area electron diffraction (SAED) pattern confirmed the hexagonal lattice structure of the exfoliated nanosheets.

This chapter discusses the latest advances in the development of various two-dimensional (2D) metal dichalcogenides as a new direction in modern science and technology. The chapter begins with a review of the physical-chemical properties of transition metal dichalcogenides (TMDs) and how the tunable electronic structure of TMDs makes them attractive for a variety of applications. Most of the 2D TMDs are described in detail: molybdenum disulfide (MoS 2 ), titanium disulfide (TiS 2 ), tungsten disulfide (WS 2 ), molybdenum diselenide (MoSe 2 ), tungsten diselenide (WSe 2 ), and niobium diselenide (NbSe 2 ). Then, it is shown how to turn properties of 2D semiconductors through surface functionalization, and the new concept of UV photodetectors based on 2D semiconductors is investigated. The chapter concludes on the future impact of the combination of the 2D semiconductor nano-crystals into 3D structures.

Titanium disulfide, being one of the popular transition-metal dichalcogenide (TMD) materials, shows great properties. TiS2 nanodiscs have been synthesized by solid state reaction (SSR) method. FESEM images confirm the synthesis of TiS2 nanodiscs. XRD spectra suggest the crystalline structure of as-prepared TiS2 nanodiscs. Electrochemical properties of the synthesized nanodiscs were studied in 6 M KOH aqueous solution. The observed results indicates the promisibilty of TiS2 as electrode material in energy storage devices.

Lithium-intercalated titanium disulfide Li x TiS2 had been extensively studied as prototypical cathode material for high-energy-density reversible lithium batteries with moderate voltage. Today, this phase is one of the leading candidates for all-solid-state lithium batteries with durable high energy and high rate performance. However, fundamental knowledge of Li+ insertion into TiS2 is still incomplete; available information on the phase diagram of the Li–TiS2 system is limited by x = 1 due to difficulties in preparing lithium-rich equilibrated samples. The goals of this work were to re-examine Li x TiS2 single phase boundaries and to clarify the existence of lithium-rich intercalates with x > 1. А new preparation technique was developed to obtain 1T-Li x TiS2 samples as good-quality equilibrated products with desirable lithium content. Phase equilibria in a quasibinary Li–TiS2 system were studied by X-ray diffraction, emf measurements (25 °C) and thermal analysis (25–350 °C) over a wide range of Li:Ti ratios (0 to 4).

Much groundbreaking research in the field of lithium batteries occurred in the 1970s. Some of “the first” rechargeable lithium cells for commercial applications were fabricated by the Exxon Enterprises Battery Division in New Jersey. A small collection of 1978-era 25 mAh and 100 mAh button cells were preserved in the personal collections of the original researchers. This presented a unique opportunity to evaluate lithium cells after 35 years of storage. Cells were characterized for capacity, cycling, rate and impedance. Results were compared with original data as recovered from historical documents.

Highly crystalline hexagonal titanium disulfide (TiS2) sheets were synthesized at the gas/liquid interface between TiCl4 vapor and the dissolved Na2S in equimolar NaCl–KCl melts at temperatures between 700°C and 850°C. TiS2 sheets with sizes of about 10–20 μm and thicknesses of about 50–200 nm have been collected at 700°C–750°C, and much bigger (50–100 μm in sizes) and thicker (1–5 μm in thickness) TiS2 sheets were obtained at 850°C. The mass transfer preferential growth of an interphase layer and the thermodynamically preferential enlargement of the (001) plane of the hexagonal TiS2 crystal were thought to have led the formation of large and thin TiS2 sheets in this proposed gas/liquid interface process. Due to the density difference, the ripe TiS2 sheets sank into the melt allowing the continuing preparation of TiS2 sheets. These TiS2 sheets could spontaneously assemble to TiS2 membranes or be ultrasonically exfoliated to few-layer TiS2 sheets with thicknesses less than 5 nm. The presented approach should be potentially extendable to the synthesis of large and thin sheets of other layered metal dichalcogenides in large scale.

Bulk polycrystalline samples in the series Ti1+xS2 (x = 0 to x = 0.05) were prepared using high-temperature synthesis from the elements and spark plasma sintering. X-ray structure analysis shows that the lattice constant c expands as titanium intercalates between TiS2 slabs. A Seebeck coefficient close to −300 μV K−1 is observed for the first time in TiS2 compounds. The decrease in electrical resistivity and Seebeck coefficient that occurs upon Ti intercalation (Ti off stoichiometry) supports the view that charge carrier transfer to the Ti 3d band takes place and the carrier concentration increases. At the same time, the thermal conductivity is reduced by phonon scattering due to structural disorder induced by Ti intercalation. Optimum ZT values of 0.14 and 0.48 at 300 and 700 K, respectively, are obtained for x = 0.025.

Composite electrodes composed of amorphous titanium polysulfide (a-TiSx) and titanium disulfide (TiS2) were designed for application in all-solid-state batteries. The conductivity of the a-TiSx/TiS2-based working electrode was higher than that of the amorphous TiS4 (a-TiS4); the reversible capacity of the cell using a-TiSx/TiS2 electrode was higher than that of the cell using a-TiS4. Designing nanocomposite materials such as the a-TiSx/TiS2 described in this paper is an effective way to improve the performance of all-solid-state batteries.

Monolayered titanium disulfide TiS2, a prospective nanoelectronic material, was previously shown to be subject to an exothermic solid-state D3h -D3d reaction that proceeds via a newly discovered transition state. Here, we study the reaction in detail using topological methods of quantum chemistry (quantum theory of atoms in molecules and electron localization function analysis) and show how electron density and chemical bonding between the atoms change in the course of the reaction. The reaction is shown to undergo a series of topological catastrophes, associated with elementary chemical events such as break and formation of bonds (including the unexpected formation of S-S bonding between sulfur layers), and rearrangement of electron density of outer valence and core shells.

Phase evolution during a thorough Li + ion's insertion of electrode materials governs their battery performance during charge and discharge. Here we investigated the lithiation pathway of titanium disulfide using in situ TEM combined with synchrotron-based pair distribution function measurement and first-principles calculations. A 2D intercalation reaction proceeds along with a transition from van der Waals interaction between Ti–S slabs to the covalent bonding of S–Li–S, with no symmetry broken. Further lithiation triggers unconventionally multiple step conversion reactions as proved: LiTiS 2 →TiS→Ti 2 S→Ti. The conversion reaction pathway is also verified in fully discharged sample in coin-cell. The expanded conversion chemistry is supposed to increase the capacity of TiS 2 electrode and downgrade the cyclability, whereas the existence of intermediate phases shows the promise of improving the reversibility with a successful control of the state of charge.

As the lightest member of transition metal dichalcogenides, 2D titanium disulfide (2D TiS) nanosheets are attractive for energy storage and conversion. However, reliable and controllable synthesis of single- to few-layered TiS nanosheets is challenging due to the strong tendency of stacking and oxidation of ultrathin TiS nanosheets. This study reports for the first time the successful conversion of TiCT MXene to sandwich-like ultrathin TiS nanosheets confined by N, S co-doped porous carbon (TiS@NSC) via an in situ polydopamine-assisted sulfuration process. When used as a sulfur host in lithium–sulfur batteries, TiS@NSC shows both high trapping capability for lithium polysulfides (LiPSs), and remarkable electrocatalytic activity for LiPSs reduction and lithium sulfide oxidation. A freestanding sulfur cathode integrating TiS@NSC with cotton-derived carbon fibers delivers a high areal capacity of 5.9 mAh cm after 100 cycles at 0.1 C with a low electrolyte/sulfur ratio and a high sulfur loading of 7.7 mg cm, placing TiS@NSC one of the best LiPSs adsorbents and sulfur conversion catalysts reported to date. The developed nanospace-confined strategy will shed light on the rational design and structural engineering of metal sulfides based nanoarchitectures for diverse applications.

Lithium-sulfur (Li-S) batteries have attracted considerable attention as one of the most promising next-generation energy storage system owing to the high theoretical specific capacity (1675 mAh g-1), low cost, natural abundance and environmentally benign nature of sulfur. However, the poor electrical conductivity of elemental S results in low utilization of S specific capacity, and hence, insufficient specific energy of Li-S batteries. Development of Li-S batteries is hindered by sluggish kinetics resulting from the intrinsic poor conductivity of sulfur and capacity degradation due to solubility of polysulfides intermediate. One strategy to overcome with these issues is to use of titanium disulfide (TiS2) as an additive to sulfur electrodes as it is a good electrical conductor and electrochemically active and also has the ability to adsorb polysulfide. Herein, we investigated TiS2 as additive with sulfur using hierarchical architectures of carbon as effective hosts for S/TiS2. By a facile one-step melting diffusion method, we synthesized S/TiS2@carbon nanofibers (CNFs) composites in which TiS2 was uniformly distributed over the S-CNFs. The hierarchical S/TiS2@CNFs (TiS2, 20 wt%) electrodes shows good initial discharge capacity of 1085 mAh g−1 at 0.05 C rate with high mass loading of material (~6-6.5 mg/cm2 of composite) and ~99% initial coulombic efficiency. The composite electrode shows stable cycling performance for more than 100 charge-discharge cycles with specific capacity of ~750 mAh g-1 at a rate of C/3 and coulombic efficiency over 99%. Thus, in the presence of TiS2 additive, long cycle life and improved sulfur utilization of Li-S cells under high current rate (C/3) are demonstrated with high sulfur mass-loading.

Based on a home-made titanium disulfide (TiS2) saturable absorber (SA), we demonstated a passively Q-switched Er:YAG laser at 1645 nm. Under an absorbed pump power of 10.75 W, a maximum average output power of 1.42 W was achieved with a pulse duration of 1.2 µs at a repetition rate of 38 kHz, corresponding to a pulse energy of 37.4 µJ. Our results indicate that TiS2-SAs have great potential to be the optical modulator in the eye-safe wavelength range.

The crystal structure of 3R-LiTiS2 was studied with com- bined experimental and theoretical approaches. The 3R polymorph of lithium titanium disulfide crystallizes rhombohedrally in the well- known NaCrS2 type with lattice parameters a = 352.98(1) pm, c = 1807.51(3) pm. The relative stability of 3R-LiTiS2 with respect to

Amorphous titanium trisulfide (TiS3) active materials were prepared by ball milling of an equimolar mixture of crystalline titanium disulfide (TiS2) and sulfur. A high-resolution transmission electron microscope image revealed no periodic lattice fringes on the amorphous TiS3. The all-solid-state lithium secondary batteries using a sulfide solid electrolyte and the amorphous TiS3 electrode showed high capacity of greater than 300 mAh g−1 for 10 cycles. The amorphous TiS3 had a higher capacity than the mixture of crystalline TiS2 and S, which was used as the starting material of amorphous TiS3. The X-ray diffraction patterns and the Raman spectra of the amorphous TiS3 electrode after the first and tenth charge–discharge measurements were similar to those before the measurement. The amorphous structure of TiS3 did not change greatly during the first few cycles. The all-solid-state cells with the amorphous TiS3 electrode showed higher initial coulombic efficiency because the amorphous TiS3 active material retained its structure during the initial electrochemical test.

Titanium disulfide (TiS2) powder was prepared by sulfurizing TiO2 powder with CS2 gas at 1073 K for 4 h. Because CS2 gas is a powerful sulfurizing agent for TiO2, CS2 sulfurization can be performed at a low temperature. The TiS2 powder thus prepared was first mixed with sulfur powder in a mass ratio of 1:0.04 and pressure sintered at 973 K for 1 h under a uniaxial pressure of 50 MPa in vacuum. The addition of a small amount of sulfur powder to the TiS2 powder prevents sulfur deficiency in the sintered compact, resulting in the formation of a near-stoichiometric Ti1.008S2 composition. X-ray diffraction patterns show that the crystalline ab-axis is preferentially oriented perpendicular to the pressing direction. The Seebeck coefficient, electrical resistivity and thermal conductivity of the oriented TiS2 sintered compacts with near-stoichiometric and sulfur-poor (titanium-rich) compositions were measured in the temperature range 300–723 K. The thermoelectric figure of merit ZT was enhanced by prevention of sulfur deficiency and formation of the oriented texture. The highest ZT of 0.34 was observed at 663 K in Ti1.008S2 for the direction perpendicular to the pressing axis.

International audience; Bulk polycrystalline samples in the series Ti1-xNbxS2 (0 ≤ x ≤ 0.075) were prepared using mechanical alloying synthesis and spark plasma sintering. X-ray diffraction analysis coupled with high resolution transmission electron microscopy indicates the formation of trigonal TiS2 by high energy ball-milling. The as-synthesized particles consist of pseudo-ordered TiS2 domains of around 20-50 nm, joined by bent atomic planes. This bottom-up approach leads, after spark plasma sintering, to homogeneous solid solutions, with a niobium solubility limit of x = 0.075. Microstructural observations evidence the formation of small crystallites in the bulk compounds with a high density of stacking faults. The large grain boundary concentration coupled with the presence of planar defects, leads to a substantial decrease in the thermal conductivity to 1.8 W/mK at 700 K. This enables the figure of merit to reach ZT = 0.3 at 700 K for x = 0.05, despite the lower electron mobility in mechanically alloyed samples due to small crystallite/grain size and structural defects. © 2015 Elsevier Ltd.

Single crystals of titanium disulfide TiS2 were synthesized by chemical vapor synthesis and subsequently intercalated with n-butyl lithium (BuLi) in n-hexane. Experiments were carried out using a butyl lithium concentration between 0.8 and 10 mol L-1 and the temperature range was from 248 K to 328 K. The duration of the intercalation was varied from 2 h to 30 d. After the intercalation experiments concentration profiles of lithium, titanium and sulfur were measured parallel to the ab-plane of the crystal by LA-ICP-OES (LASER Ablation — Inductively Coupled Plasma - Optical Emission Spectroscopy). Chemical diffusion coefficients (D) were determined by fitting of the profiles to the specific solution of Fick's 2 nd law for the given boundary conditions. The measured diffusivity in the ab-plane (D|| a/b ) varies between 10-13 and 10-15 m2 s-1 at room temperature. These variations of D cannot be correlated to the reaction time. On the other hand a systematic increase of D|| a/b with the concentration of butyl lithium (cBuLi ) was observed, with a corresponding decrease in activation energy from 59.6 ± 7.6 kJ mol-1 (cBuLi=1.6 mol L-1 ) to 42.6 ± 11.7 kJ mol-1 (cBuLi=10 mol L-1 ). Furthermore, profiles measured on the same crystals reveal D|| a/b values differing by up to a factor of 3. ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectromety) images gave evidence of inhomogenous insertion of lithium along crystal edges. These findings indicate that stress induced by widening of the crystal layers plays a crucial role in the intercalation kinetics. SIMS profiling perpendicular to the ab-plane gives evidence that D⊥ a/b is at least four orders of magnitude lower than D|| a/b .

Two-dimensional (2D) nanomaterials have recently received significant attention because of their attractiveness for use in many nanostructured devices. Layered transition-metal dichalcogenides are of particular interest because reducing their dimensionality causes changes in their already anisotropic physical and chemical properties. The present study describes the first bottom-up solution-phase synthesis of thin highly crystalline titanium disulfide (TiS2) nanosheets (NSs) using abundant low-cost molecular precursors. The obtained TiS2 NSs have average dimensions of ∼500 nm × 500 nm in the basal plane and have thicknesses of ∼5 nm. They exhibit broad absorption in the visible that tails out into the near-infrared. The obtained results demonstrate new opportunities in synthesizing low-dimensional 2D nanomaterials with potential use in various photochemical energy applications.

We fabricate titanium disulfide (TiS2) using a liquid exfoliation method and subsequently a TiS2-based device by optically depositing the TiS2 material onto the microfiber. This device exhibits a strong nonlinear saturable absorption property with an optical modulation depth of 8.3% at 1560 nm. With the implementation of this all-fiber TiS2-based saturable absorber, we demonstrate that both mode-locking and Q-switching operation can be obtained in a turn-key all-fiber erbium-doped laser cavity. Our findings constitute the first example, to the best of our knowledge, of a TiS2-based saturable absorber for ultrashort pulse generation and highlight the great potential of such devices in two-dimensional nanomaterials-related photonics.

Titanium disulfide (TiS2) is investigated as an advanced conversion electrode for sodium (Na)-ion batteries (NIB) in an ether-based electrolyte (NaPF6/glyme (DME)). The as-prepared TiS2 demonstrates a high reversible capacity of 1040 mA h g-1 at 0.2 A g-1 with the capacity contribution of 521 mA h g-1 in the voltage region below 1.0 V (vs Na/Na+), remarkable initial coulombic efficiency of 95.9% and superior rate capability of 621 mA h g-1 at 40 A g-1. The high conductivity of the Ti-based compounds and nanosized particles generated by chemical conversion reactions could minimize the entropic barrier for the reversible conversion, resulting in high reversibility and ultrafast charge/discharge ability of the electrode. Moreover, with its strong ability to adsorb soluble polysulfide intermediates, the as-prepared TiS2 electrode exhibits superior cycling stability over 9000 cycles, serving as a stable and ultra-high capacity conversion electrode for NIBs.

Titanium disulfide, being one of the popular transition-metal dichalcogenide (TMD) materials, shows wonderful properties owing to tunable optical band gap. Pure and PbSe doped titanium disulfide nanodiscs have been synthesized by solid-state reaction method. FESEM, TEM and Raman images confirm the synthesis of nanodiscs. XRD spectra suggest the polycrystalline structure of as-prepared as well as PbSe doped TiS2 nanodiscs. PL spectra of the as-synthesized nanodiscs has been studied in the wavelength range of (300–550 nm), at room temperature. The position of the peak shifts towards the lower wavelength (blue shift) and intensity of the PL increases after the doping of PbSe, which may be due to a broadening of the optical band gap. UV–vis spectra has been used to calculate optical band gap of pure and PbSe doped titanium disulfide nanodiscs. The calculated value are found to be 1.93 eV and 2.03 eV respectively. Various optical constants such as n and k have been calculated. The value of extinction coefficient (k) of pure and doped titanium disulfide increases while the value of the refractive index (n) decreases with increase in photon energy.