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Titanium disulfide (TiS2) was synthesized by a simple solid phase method. The physical properties of TiS2 were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDX). Scanning and transmission electron microscopy (SEM and TEM) were used to study the structural and morphological characteristics. The synthesized TiS2 was applied as negative electrode material for TiS2/graphite electric storage devices with organic electrolytes based on Na+-ions. The electrochemical methods were used to characterize the charge storage mechanism of TiS2. The TiS2/graphite electric energy storage device possessed a working voltage of 3.5 V. The fabricated device showed relatively high performance rate and excellent cycle stability in electrochemical tests.

Based on femtosecond laser ablated processing, one-dimensional arrays with different line spacings were fabricated on titanium disulfide (TiS2) nanosheet. Optical modulated measurements with these devices were demonstrated. Photo-induced complex conductivity changes of the TiS2 nanosheet devices were studied by an optical-pump THz-probe (OPTP) measurement system. For the 700 μm line spacing device, the optically introduced modulation depth (MD) reached up to 70%. Our experimental results have demonstrated the ultrafast dynamics and photoconductivity for the TiS2 nanosheet devices in the THz frequency range. TiS2 nanosheet based devices would be suitable as the photoelectric modulators of THz wave.

Solid-state ionics, the study of fast ion transport in solids, expanded explosively after the discovery of sodium ion transport in β-alumina 50 years ago and has revolutionized energy storage. Lithium-ion batteries have come from a dream with titanium disulfide to enabling the communications revolution and are enabling renewable energy. Much can be learned from these early studies that will allow the attainment of a fossil-free society and a sustainable environment.

In this work, we study the electronic properties of mono- and multilayer titanium disulfide (TiS2) with the aid of first-principles calculations based on density functional theory. We find that the band gap can slightly be tuned as a function of the number (N) of stacked layers, ranging from 0.49 eV in the monolayer down to 0.40 eV in the bulk form—as a result of quantum confinement and the formation of sub-bands. However, the introduction of external agents such as biaxial strain and electric fields can significantly change the electronic properties of the system and induce strong gap modifications. Compressive strains and electrical fields are found to reduce the indirect band gap and induce a semiconductor to semimetal transition beyond a critical value, which is a decreasing function of N. In contrast, under tensile strains, the gap increases up to a maximum value and can reach about 0.90 eV under a 5% strain. Furthermore, we also report the optical properties of these systems, which display strong absorption peaks in both visible and UV regions of the spectrum, thus making the most of incident solar light. These properties also display a good tunability, as the peak intensities increase with N and the peak positions show a strong dispersion with strain. However, the spectra are less sensitive to electrical fields, despite their response being very similar to that found under compressive strains. Finally, k-resolved band structure calculations suggest the existence of both intralayer and interlayer excitons in optical transitions in the visible range. In light of these results, we believe that TiS2 can efficiently be explored in the design of novel vdW heterostructures in combination with other 2D materials, thus opening the way to novel applications in future nano- and optoelectronic devices.

The scalable and conformal synthesis of two-dimensional (2D) transition metal dichalcogenide (TMDC) heterostructures is apersisting challenge for their implementation in next-generation devices.In this work, we report the synthesis of nanometer-thick 2D TMDC heterostructures consisting of TiSx-NbSx on both planar and 3D structures using atomic layer deposition (ALD) at low temperatures (200−300 °C).To this end, a process was developed for the growth of 2D NbSx by thermal ALD using (tert-butylimido)-tris-(diethylamino)-niobium (TBTDEN) and H2S gas. This process complemented the TiSx thermal ALD process for the growth of 2D TiSx-NbSx heterostructures. Precise thickness control of the individual TMDC material layers was demonstrated by fabricatingmultilayer (5-layer) TiSx-NbSx heterostructures with independently variedlayer thicknesses. The heterostructures were successfully deposited on large-areaplanar substrates as well as over a 3D nanowire array for demonstrating the scalability and conformality of the heterostructure growth process. The current study demonstrates the advantages of ALD for the scalable synthesis of 2D heterostructures conformally over a 3D substrate with precise thickness control of the individual material layers at low temperatures. This makes the application of 2D TMDC heterostructures for nanoelectronics promising in both BEOLand FEOL containing high-aspect-ratio 3D structures.

Doping engineering is an effective modification strategy to enhance the electrochemical performance of electrode materials. In this paper, the impacts of heteroatom doping in monolayer titanium disulfide (TiS2) by substituting the S atom with the heteroatoms (B, C, N, O, F, and P) on the adsorption and diffusion capabilities of alkali metals (Li, Na, and K) have been systematically investigated using first-principles calculations to evaluate the material performance for application in alkali metal-ion batteries. The doping of most heteroatoms can promote the adsorption capability of alkali metal atoms on monolayer TiS2 as their adsorption energies decrease compared with the pristine system, particularly for p-type doping with C, N, and P. The diffusion energy barriers decrease when alkali metals approach the doping site of most heteroatom-doped TiS2, and the barriers near the doping site are extremely small (0.00-0.08 eV), whereas they slightly increase as alkali metals move away from the doping site. P doping has the lowest overall diffusion energy barrier for each metal. Thus, monolayer TiS2 with heteroatom doping, especially P doping, can be used as a potential anode material for alkali metal-ion batteries. This study can help comprehend the impacts of heteroatom doping and design high-performance electrode materials for rechargeable batteries.

Recent experiments revealed the possibility of using titanium disulfide (TiS2) as the cathode material in capacitive deionization (CDI) devices for water desalination. Although it performed stably ...

2D semiconductors like Molybdenum disulfide (MoS2) still have issues in forming good metal electrode (Schottky and Ohmic) especially for mono layer (ML) to few layers thick due to strain and metallization issues. Here, we explore a 2D semi-metal, titanium disulfide (TiS2), for making different types of contacts with ML MoS2 using density functional theory (DFT). It is observed that ML TiS2 induces ML MoS2 to become p-type with a doping density of 3.85 × 1017 cm−3 which becomes larger with thicker TiS2. Thus, TiS2 can thus be utilized as a variable contact material ohmic if the MoS2 is p-type and as Schottky if the MoS2 is n-type with a Schottky barrier height ranging from 0.3 to 1.35 eV. One of the important results from the study is that compared to a traditional metal–MoS2 in a TiS2–MoS2 contact the bandgap is preserved where in contrast, a traditional metal contact metalizes the monolayer MoS2 and fill its bandgap with states. Hence, a clear path forward to make pristine contacts is to use 2D semi-metals in conjunction with 2D semiconductors.

Single layer crystalline materials, often termed two-dimension (2D) materials, have quickly become a popular topic of research interest due to their extraordinary properties. The intrinsic electrical, mechanical, and optical properties of graphene were found to be remarkably distinct from graphite, its bulk counterpart. In conjunction with newfound processing techniques, there is renewed interest in elucidating the structure-property relationships of other 2D materials like the transition metal dichalcogenides (TMDCs). The energy storage capability of 2D nanoplatelets of TiS2 and MoS2 are studied here providing a contrast with investigations of corresponding bulk materials in the early 1970s. TiS2 was synthesized into nanoplatelets using a hot injection route which provided a capacity of ~143mAhg-1 from thin film electrodes as determined by cyclic voltammetry measurements. Phase identification using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy to complement the electrochemical performance and impurity identification is presented. MoS2 thick films were created using a sulfonation reaction of synthesized MoO2 and were found to have a capacity of 220mAhg-1 using galvanostatic cycling measurements. Energy and power densities of these TMDCs are presented and shown to exceed the performance of commercial electrochemical capacitors.

A chemiresistive, 1T-TiS2 nanosheet (TNS) based gas sensor has been developed, and its ultrahigh sensitivity toward hydrogen sulfide (H2S) and oxygen (O2) gas at room temperature has been experimen...

Titanium disulfide (TiS2) with high electric conductivity, fast rate capability, and good cycling performance is a promising candidate for electrode material in sodium (Na)-ion batteries. Despite the well-studied electrochemical behaviors of TiS2 in Li-ion batteries, the detailed reaction mechanism of TiS2 in Na-ion batteries is not yet fully understood due to a more complex multi-phase conversion process. In this work, reactions of TiS2 in Na-ion batteries are investigated via a multi-modal synchrotron approach: operando X-ray Absorption Spectroscopy (XAS) – including X-ray Absorption Near-Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) – and ex situ X-ray Powder Diffraction (XPD), coupled with computational modeling. Operando XANES spectra indicate that the redox reactions occur in both Ti and S during the electrochemically driven phase transformation. Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) analysis of XAS suggests that different numbers of components are involved in the lithiation and sodiation of TiS2, with the sodiation including at least one intermediate phase in addition to the starting material and the final sodiation product. Ex situ XPD and Rietveld refinement further determined and quantified the unknown phases, showing that three phases, TiS2, Na0.55TiS2, and NaTiS2, participate in the sodiation of TiS2. Operando EXAFS results show the changes in the Ti–Ti coordination number and interatomic distance. This explains the coulombic efficiency decay due to the incomplete recovery of the coordination number of Ti after cycling. Overall, this work reveals the reaction mechanism occurring in Na–TiS2 batteries with a greater quantitative understanding of the structural evolution. By combining the multi-modal synchrotron approach and computational work, this study provides a framework for studying a broader range of electrochemically driven phase-transformation systems towards advanced energy storage and conversion applications.

Promoting the reversible structural transformation and carrier migration dynamics simultaneously in a multiple ion-involved process is vital for sulfide electrode materials. Herein, TiS2 with a sulfide cluster vacancy (CV–TiS2−x) has been calculated and prepared to explore a novel strategy to improve the electrochemistry reversibility of sulfide electrodes. It is found that the cluster vacancy can serve as an effective control factor for the improvement of the Fermi level, and enhances the electrochemical stability of CV–TiS2−x in the liquid organic electrolyte system. Moreover, owing to the plentiful positively charged S-vacancies, the CV–TiS2−x samples exhibit an extended interplanar spacing and retain their structural integrity during the lithium ion insertion process. The integrated HRTEM, in situ XRD, XPS analysis and electrochemical study reveal that the cluster vacancy is not only responsible for an increase in reversible performance, but also boosting the anionic redox reaction of (S2)2− species. Therefore, the CV–TiS2−x electrode delivers a reversible capacity of 650 mA h g−1 for 300 cycles at a current density of 1C (220 mA g−1). Our study provides a novel strategy of introducing sulfur cluster vacancies to improve the electrochemical activity of TiS2, which can be applied to other sulfide electrodes.

A relatively new and promising method to tune properties of monolayers is by forming a heterostructure of them. Here, the van der Waals heterostructure of graphene-like zinc oxide (g-ZnO) and 1-trigonal titanium disulfide (1T-TiS2) was formed and its structural, electronic, and optical properties were studied in the framework of density functional theory. The dynamical stability of the heterostructure was confirmed based on its phonon band structure. An indirect (Γ → M) bandgap of 0.65 eV, a large built-in electric field (or a large potential drop of 3.12 eV), a type-II (staggered) band alignment, and a large conduction band offset of 2.94 eV were found to form across the interface, which are all desirable for potentially efficient separation of charge carriers. We showed also that the formation of the heterostructure largely enhances the almost-zero optical absorption of g-ZnO in visible and near-infrared regions, which is desirable for optoelectronic applications. By applying a perpendicular electric field, we could tune the bandgap value and the band alignment type (type-II → type-I) of the heterostructure. Finally, we showed that by applying compressive strain, one can change the band alignment type (type-II → type-I) and by applying tensile strain, the bandgap value could be tuned and a crossover occurs in the bandgap type (indirect → direct → indirect).

The rapid capacity loss caused by the shuttling effect of polysulfides is one of the great challenges of Li–S batteries. In this work, we adopted a simple solid-phase sintering method to synthesize titanium disulfide (TiS2) and further demonstrated it as a superior modifier of separators for Li–S batteries. Two commonly adopted modification processes of separators, including vacuum filtration (VF) and slurry casting (SC) have been used to prepare TiS2/Celgard separators. TiS2-VF/Celgard can better restrain the polysulfide shuttling effect compared with TiS2-SC/Celgard. A TiS2-VF/Celgard-based Li–S battery has a reversible capacity of 771.6 mA h g−1, with a capacity retention of 645.6 mA h g−1 after 500 cycles at 2.0 C, corresponding to a capacity fading rate of ∼0.033% per cycle. This study has shown the potential of TiS2 as a multifunctional modifier of separators for high performance and long cycle life Li–S batteries.

The surface morphology and electronic structure of layered semiconductor 1-trigonal phase titanium disulfide, i.e., 1T-TiS2(0001), with Sn intercalation, have been studied by scanning tunneling mic...

Two-dimensional (2D) metal sulfides show great promise for their potential applications as electrode materials of sodium ion-batteries because of the weak interlayer van der Waals interactions, which allow the reversible accommodation and extraction of sodium ions. The sodiation of metal sulfides can undergo a distinct process compared to that of lithiation, which is determined by their metal and structural types. However, the structural and morphological evolution during their electrochemical sodiation is still unclear. Here, we studied the sodiation reaction dynamics of TiS2 by employing in situ transmission electron microscopy and first-principles calculations. During the sodium-ion intercalation process, we observed multiple intermediate phases (phase II, phase Ib, and phase Ia), different from its lithiation counterpart, with varied sodium occupation sites and interlayer stacking sequences. Further insertion of Na ions prompted a multistep extrusion reaction, which led to the phase separation of Ti metal from the Na2S matrix, with its 2D morphology expanded to a 3D morphology. In contrast to regular conversion electrodes, TiS2 still maintained a compact structure after a full sodiation. First-principles calculations reveal that the as-identified phases are thermodynamically preferred at corresponding intercalation/extrusion stages compared to other possible phases. The present work provides the fundamental mechanistic understanding of the sodiation process of 2D transition metal sulfides.

Titanium disulfide (TiS2) was adopted as a negative electrode material for the asymmetric sodium-ion supercapattery of TiS2/activated carbon using Na+-based organic electrolytes. This type of supercapattery possesses a working voltage as high as 3 V. The physical properties of the negative electrode were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical performance tests revealed that the supercapattery had a relatively high rate performance and good cycle stability, displaying 77% capacity retention after 1000 cycles at a current density of 0.2 A g−1.

Unlike the vast majority of transition metal dichalcogenides which are semiconductors, vanadium disulfide is metallic and conductive. This makes it particularly promising as an electrode material in lithium-ion batteries. However, vanadium disulfide exhibits poor stability due to large Peierls distortion during cycling. Here we report that vanadium disulfide flakes can be rendered stable in the electrochemical environment of a lithium-ion battery by conformally coating them with a ~2.5 nm thick titanium disulfide layer. Density functional theory calculations indicate that the titanium disulfide coating is far less susceptible to Peierls distortion during the lithiation-delithiation process, enabling it to stabilize the underlying vanadium disulfide material. The titanium disulfide coated vanadium disulfide cathode exhibits an operating voltage of ~2 V, high specific capacity (~180 mAh g−1 @200 mA g−1 current density) and rate capability (~70 mAh g−1 @1000 mA g−1), while achieving capacity retention close to 100% after 400 charge−discharge steps., VS2 is a promising cathode material for lithium-ion batteries, but is susceptible to Peierls distortion during (de)lithiation. Here the authors show that VS2 cathodes can be stabilized by conformally coating them with a nanoscale TiS2 protective layer, leading to impressive electrochemical performance.

The saturable absorption characteristics of two-dimensional materials tin disulfide (SnS2) near 1.6 μm was studied and a passively Q-switched Er:YAG laser at 1645nm based on a home-made titanium disulfide was realized. 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 μs at a repetition rate of 43 kHz, corresponding to a pulse energy of 33.02 μJ.

In our work, passively mode-locked and Q-switched Er-doped fiber lasers (EDFLs) based on titanium disulfide (TiS2) as a saturable absorber (SA) were generated successfully. Stable mode-locked pulses centred at 1531.69 nm with the minimum pulse width of 2.36 ps were obtained. By reducing the length of the laser cavity and optimizing the cavity loss, Q-switched operation with a maximum pulse energy of 67.2 nJ and a minimum pulse duration of 2.34 &micro, s was also obtained. Its repetition rate monotonically increased from 13.17 kHz to 48.45 kHz with about a 35 kHz tuning range. Our experiment results fully indicate that TiS2 exhibits excellent nonlinear absorption performance and significant potential in acting as ultra-fast photonics devices.

We have envisaged the hydrogen evolution and oxygen evolution reactions (HER and OER) on a two-dimensional (2D) noble-metal-free titanium disulfide (TiS2 ) monolayer, which belongs to the exciting family of transition metal dichalcogenides (TMDCs). Our theoretical investigation to probe the HER and OER on both the H and T phases of 2D TiS2 is based on electronic-structure calculations witihin the framework of density functional theory (DFT). Since TiS2 is the lightest compound among the group-IV TMDCs, it is worth exploring the catalytic activity of a TiS2 monolayer through the functionalization at the anion (S) site, substituting with P, N, and C dopants as well as by incorporating single sulfur vacancy defects. We have investigated the effect of functionalization and vacancy defects on the structural, electronic, and optical response of a TiS2 monolayer by determining the density of states, work-function, and optical absorption spectra. We have determined the HER and OER activities for the functionalized and defective TiS2 monolayers based on the reaction coordinate, which can be constructed from the adsorption free energies of the intermediates (H*, O*, OH* and OOH*, where * denotes the adosrbed state) in the HER and OER mechanisms. Finally, we have shown that TiS2 monolayers are emerging as a promising material for the HER and OER mechanisms under the influence of functionalization and defects.

Titanium disulfide is a promising material for a range of applications, including lithium-ion battery (LIB) anodes. However, its application potential has been severely hindered by the tendency of exfoliated TiS2 to rapidly oxidize under ambient conditions. Herein, we confirm that, although layered TiS2 powder can be exfoliated by sonication in aqueous surfactant solutions, the resultant nanosheets oxidise almost completely within hours. However, we find that upon performing the exfoliation in the solvent cyclohexyl-pyrrolidone (CHP), the oxidation is almost completely suppressed. TiS2 nanosheets dispersed in CHP and stored at 4 °C in an open atmosphere for 90 days remained up to 95% intact. In addition, CHP-exfoliated nanosheets did not show any evidence of oxidation for at least 30 days after being transformed into dry films even when stored under ambient conditions. This stability, probably a result of a residual CHP coating, allows TiS2 nanosheets to be deployed in applications. To demonstrate this, we prepared lithium ion battery anodes from nano : nano composites of TiS2 nanosheets mixed with carbon nanotubes. These anodes displayed reversible capacities (920 mA h g−1) close to the theoretical value and showed good rate performance and cycling capability.

Semimetallic-layered transition-metal dichalcogenides, such as TiS2, can serve as a platform material for exploring novel physics modulated by dimensionality, as well as for developing versatile applications in electronics and thermoelectrics. However, controlled synthesis of ultrathin TiS2 in a dry-chemistry way has yet to be realized because of the high oxophilicity of active Ti precursors. Here, we report the ambient pressure chemical vapor deposition (CVD) method to grow large-size, highly crystalline two-dimensional (2D) TiS2 nanosheets through in situ generating titanium chloride as the gaseous precursor. The addition of NH4Cl promoter can react with Ti powders and switch the solid-phase sulfurization reaction into a CVD process, thus enabling the controllability over the size, shape, and thickness of the TiS2 nanosheets via tuning the synthesis conditions. Interestingly, this semimetallic 2D material exhibits near-infrared surface plasmon resonance absorption and a memristor-like electrical behavior, both holding promise for further application developments. Our method hence opens a new avenue for the CVD growth of 2D metal dichalcogenides directly from metal powders and pave the way for exploring their intriguing properties and applications.

We demonstrate the mixed antimony telluride-molybdenum disulfide/tungsten disulfide/titanium disulfide as saturable absorber for efficient passively Q-switching of Nd:GYSGG laser. Sb2Te3-MoS2, Sb2Te3-WS2 and Sb2Te3-TiS2 dispersions with large populations of few layers were prepared by liquid-phase exfoliation. At the pump power of 5 W, dual-wavelength Q-switched operation were obtained with the output power of 0.46W, 0.42 W and 0.35W by using the mixed Sb2Te3-TiS2, Sb2Te3-WS2 and Sb2Te3-MoS2 SAs. The minimum pulse width was 254 ns with a pulse repetition rate of 72.4 kHz was obtained by using the Sb2Te3-MoS2 SA. Obviously, all the mixed saturable absorber shows better SA response. It also allows to generate laser pulse at two different wavelengths simultaneously.

The selective removal of ions by an electrochemical process is a promising approach to enable various water-treatment applications such as water softening or heavy-metal removal. Ion intercalation materials have been investigated for their intrinsic ability to prefer one specific ion over others, showing a preference for (small) monovalent ions over multivalent species. In this work, we present a fundamentally different approach: tunable ion selectivity not by modifying the electrode material, but by changing the operational voltage. We used titanium disulfide, which shows distinctly different potentials for the intercalation of different cations and formed binder-free composite electrodes with carbon nanotubes. Capitalizing on this potential difference, we demonstrated controllable cation selectivity by online monitoring the effluent stream during electrochemical operation by inductively coupled plasma optical emission spectrometry of aqueous 50 mm CsCl and MgCl2 . We obtained a molar selectivity of Mg2+ over Cs+ of 31 (strong Mg preference) in the potential range between -396 mV and -220 mV versus Ag/AgCl. By adjusting the operational potential window from -219 mV to +26 mV versus Ag/AgCl, Cs+ was preferred over Mg2+ by 1.7 times (Cs preference).

Titanium disulfide (TiS2) material has been interest in an optics nonlinear due to its perfect optical, physical and chemical properties. However, there are few studies on TiS2 material as saturable absorber (SA) for ultrafast solid-state laser operating at 2-μm range. In this paper, we prepared TiS2 SA by using an ultrasonic thermolysis technique and demonstrated its saturable absorption characteristics by passively mode-locked (PML) technology. Under PML mode, Tm:YAG laser produced the maximum average output power of 102 mW at 2011.4 nm, corresponding to a shortest pulse duration of 224.0 ps at 208.5 MHz. To our knowledge, that is the narrowest pulse width from a PML Tm:YAG laser with a TiS2 SA.

This paper aims to study the dry sliding wear characteristics of LM13 aluminum alloy matrix containing titanium disulfide (TiS2) as the reinforcement (10 wt%, average size 37 µm) fabricated...

We report the synthesis of TiS2 by chemical vapour transport and evaluated as insertion host for Na-ion battery. The half-cell assemblies are fabricated to study the Na-insertion properties. The Na/TiS2 cell displayed a reversible capacity of ∼146 mAh g–1 at 0.1 C rate which corresponds to ∼0.61 mol. Na. Excellent cycling stability, and rate performance are noted for TiS2. Cyclic voltammetry and impedance measurements supports the charge storage mechanism and interfacial properties, respectively. Operando studies are also conducted to ensure the structural stability of the insertion host. Furthermore, the Li-insertion properties are also conducted to support the electrochemical activity of the host matrix prepared by chemical vapour transport.

Magnesium rechargeable batteries potentially offer high-energy density, safety, and low cost due to the ability to employ divalent, dendrite-free, and earth-abundant magnesium metal anode. Despite recent progress, further development remains stagnated mainly due to the sluggish scission of magnesium-chloride bond and slow diffusion of divalent magnesium cations in cathodes. Here we report a battery chemistry that utilizes magnesium monochloride cations in expanded titanium disulfide. Combined theoretical modeling, spectroscopic analysis, and electrochemical study reveal fast diffusion kinetics of magnesium monochloride cations without scission of magnesium-chloride bond. The battery demonstrates the reversible intercalation of 1 and 1.7 magnesium monochloride cations per titanium at 25 and 60 °C, respectively, corresponding to up to 400 mAh g−1 capacity based on the mass of titanium disulfide. The large capacity accompanies with excellent rate and cycling performances even at room temperature, opening up possibilities for a variety of effective intercalation hosts for multivalent-ion batteries., Magnesium rechargeable batteries potentially offer high-energy density, safety, and low cost. Here the authors show a battery that reversibly intercalates magnesium monochloride cations with excellent rate and cycle performances in addition to the large capacity.

Lithium–sulfur (Li–S) batteries show significant advantages for next-generation energy storage systems owing to their high energy density and cost effectiveness. The main challenge in the development of long-life and high-performance Li–S batteries is to simultaneously facilitate the redox kinetics of sulfur species and suppress the shuttle effect of polysulfides. In this contribution, we present a general and green water-steam-etched approach for the fabrication of H- and O-incorporated porous TiS2 (HOPT). The conductivity, porosity, chemisorptive capability, and electrocatalytic activity of HOPT are enhanced significantly when compared with those of raw TiS2. The synthetic method can be expanded to the fabrication of other highly conductive transition metal dichalcogenides such as porous NbS2 and CoS2. The as-obtained HOPT can serve as both a substitute of conductive agents and an additive of interlayer materials. The optimal electrode delivers discharge capacities of 950 mA h g–1 after 300 cycles at 0....

Sulfur-doped anatase TiO 2 nanoparticles with sulfur atoms occupying oxygen sites were realized by low-temperature hydrothermal oxidation of titanium disulfide (TiS 2 ) with deionized water as the solvent. S doping can effectively narrow the bandgap of TiO 2 due to the fact that S 3 p level is higher than O 2p orbital. The large surface area caused by this doping method induces higher photocatalytic activity in the visible regime compared with S-TiO 2 oxidized at high temperature. The low-temperature hydrothermal oxidation of TiS 2 in pH neutral solvent is an environmental-friendly method to obtain S-TiO 2 with high photocatalytic activity, which can be extended to other nonmetal doping of TiO 2 or other semiconductors for bandgap engineering.

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.

A subcellular organelle-targeted delivery of anti-cancer drugs is a promising strategy to maximize the anti-cancer effects and minimize the adverse effects. Herein, we prepared a mitochondria-targeted drug delivery nanoplatform based on IR780 iodide (IR780) and titanium disulfide (TiS2) nanosheets. Due to the large specific surface area of TiS2 nanosheets, the nanoplatform could highly load anti-cancer drug resveratrol (RV). The as-prepared nanocomposite (IR780-TiS2/RV) was used for an efficacious photothermal-triggered tumor chemotherapy. IR780-TiS2/RV showed satisfactory stability and biocompatibility, and the loading ratio of RV and IR780 was about 112% and 56%, respectively. Upon the near-infrared (NIR) irradiation, the heat generated by IR780-TiS2/RV could trigger the RV release. Due to the conjugation with the mitochondria-specific IR780, IR780-TiS2/RV could target and accumulate in mitochondria and release RV when triggered by NIR to decrease the mitochondrial membrane potential, rapidly induce the upregulation of key intrinsic apoptotic factors such as cytochrome c, and initiate the caspase cascade, thereby achieving the chemotherapeutic effect. The IR780-TiS2/RV nanocomposite was demonstrated to have a high anti-tumor efficacy in vitro and in vivo as well as no remarkable tissue toxicity. We believe our study demonstrates that the NIR-triggered IR780-TiS2/RV nanoplatform could be a promising chemotherapeutic agent in clinical practice. Electronic supplementary material The online version of this article (10.1186/s11671-019-3044-5) contains supplementary material, which is available to authorized users.

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.

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.

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.

The conventional lithium-ion batteries (LIBs) have dominated the portable electronics markets; however, inherent limitations have raised concerns over their cost, safety, and greenness in large scale energy storage applications. Taking advantage of the recently developed “Water-in-Salt” electrolyte (WiSE), an aqueous lithium-ion battery of TiS2/LiFePO4 (LFP) is demonstrated. The effects of potential window, addition of tris(trimethylsilyl) borate (TMSB) salt, and the choice of current collector on cell performance are investigated. The aqueous TiS2/LFP cell delivers an energy density of 65 Wh kg−1, based on the total mass of electrodes. The presence of TMSB additive enhances the capacity, stability, and efficiency of the cell. Compared to the control cell, the capacity increases by 34%, SEI layer resistance decreases by 1.7 times, and the charge transfer resistance decreases by 7 times, yielding high coulombic efficiency of 99.9% and capacity retention of 70% after 100 cycles. A safe potential window of 0.01–1.6 V, 0.1 wt% TMSB in WiSE, and stainless-steel current collector on the cathode and titanium on the anode offer the most stable cycling. The combination of low-cost electrodes, safer and greener electrolyte, and high coulombic efficiency make this new aqueous battery promising for large scale energy storage systems.

The impacts of point defects including single- and few-atom vacancies (VS, VTi, VS2, VTiS3, VTiS6) and antisites (STi, TiS) on the Li adsorption and diffusion in monolayer titanium disulfide (TiS2) are systematically investigated through first-principles calculations based on density functional theory for their underlying functions in Li-ion batteries. The calculations imply that Li adsorption and diffusion capabilities are strongly dependent on the defect types of TiS2. For example, defects VTi, VTiS3 and STi improve Li adsorption capability as their adsorption energies increase compared with the pristine TiS2, and VTi has the largest increase. VS, VS2 and VTi exhibit approximate Li diffusion energy barriers with the pristine TiS2 (0.21 eV), signifying that a neglected impact on the rate capability. More importantly, sulfur antisite STi reduces Li diffusion barrier by 0.03 eV, and thus enhances diffusion rates by 3.2 times. Interestingly, STi simultaneously enhances Li adsorption and diffusion capabilities in monolayer TiS2 to some degree, and VTi considerably favors Li adsorption without compromising diffusion rates, suggesting that the introduction of defects STi and VTi in TiS2 displays excellent properties for energy storage systems. This study benefits for comprehending the impacts of point defects and designing high-performance electrode materials for rechargeable 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.

Pseudocapacitive materials offer an opportunity to bridge the energy storage gap between supercapacitor and battery technologies. Herein is chronicled the first report of pseudocapacitance in a system devoid of liquid electrolytes, using the cathode material LiTiS2. It is demonstrated that due to extreme crystallite reduction to less than 3 nm, additional charge storage is derived by reducing surface Ti3+ to Ti2+ at higher voltages and more reversibly than traditionally shown. Due to facile diffusion pathways in 3-fold coordinated lithium along the TiS2 surfaces, disordered LiTiS2 can be used as a singular cathode without conductive additives. The result is a system exhibiting nearly 300 mA h g−1 at a rate of C/2 for 1000 cycles. Whereas active materials in liquid cells typically have size limitations before irreversibilities appear, the high pseudocapacitance demonstrated in this report indicates that active materials used in the solid-state could benefit from size reduction. Hopefully, a new avenue of research stems from this work to investigate mixed conductor nano-domains for solid-state battery/capacitor hybrids. The prospect of a solid-state pseudocapacitor unlocks a series of new applications that offer long shelf life, high temperature capabilities, and enhanced safety.

Although the LiMn1.5Ni0.5O4 spinel operating at 4.7 V presents some beneficial characteristics over more traditional positive electrode materials, instability issues at elevated temperature have limited its practical use so far. While we previously proposed Li1+yMn1.5Ni0.5O4−xFx (LMNOF) spinel that is intrinsically stable at elevated temperatures in Li-excess half-cell configuration, we investigate herein fixed, non-excess Li-content window-shifted Li-ion systems. By utilizing Li4Ti5O12 (LTO) or TiS2 negative electrodes stable in broad electrolyte compositions instead of carbonaceous electrodes, we aim at limiting the Li-consuming side reactions such as the formation of solid-electrolyte interphase and enable a focus on the exploration of electrolyte compositions including additives. Utilizing such an approach, excellent fundamental stability of LMNOF in a fixed Li-content Li-ion environment is demonstrated at 55 °C with the use of relatively common electrolyte components.

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.

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.

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.