Nanomechanical and nanotribological characterization of multilayer self-lubricating Ti/MoS2/Si/MoS2 nanocoating on aluminium-silicon substrate

Ti/MoS₂/Si/MoS₂ multilayer coating was fabricated by a pulse laser deposition method from a titanium, molybdenum disulphide, and silicon targets, and the coating was deposited in layers on aluminium-silicon substrates, at room temperature. The structural analysis and surface morphology of multilayer Ti/MoS₂/Si/MoS₂ coating were analysed using X-ray diffraction, Raman spectroscopy, and scanning electron microscopy integrated with energy dispersive X-ray spectroscopy. Nanomechanical tests were performed on Ti/MoS₂/Si/MoS₂ coating at small loads of 2000 to 6000 μN to study the effect of load on hardness and Young's modulus. Nanoscratch and nanowear tests were conducted on Ti/MoS₂/Si/MoS₂ coating at a low load of 1000 to 5000 μN and 100 to 500 μN, respectively, to study deformation and failure behaviours of coating/substrate system and also their nanotribological properties. The results show that hardness and Young's modulus of Ti/MoS₂/Si/MoS₂ coating decrease with increase in load. A low friction coefficient of 0.09 to 0.16 was observed, which proves that the Ti/MoS₂/Si/MoS₂ coating possesses self-lubricating property. The wear rate of Ti/MoS₂/Si/MoS₂ coating increases 3.3 × 10⁻¹⁰ to 7.8 × 10⁻¹⁰ mm³/Nm with increase in load. Ti/MoS₂/Si/MoS₂ multilayer coating shows a smooth wear track with no cracks and debris on the surface, which attributed plastic flow of softer coating material around the wear track.     

Ratiometric two-photon excited photoluminescence of quantum dots triggered by near-infrared-light for real-time detection of nitric oxide release in situ

Probe-donor integrated nanocomposites were developed from conjugating silica-coated Mn²⁺:ZnS quantum dots (QDs) with MoS₂ QDs and photosensitive nitric oxide (NO) donors (Fe₄S₃(NO)₇⁻, RBS). Under excitation with near-infrared (NIR) light at 808 nm, the Mn²⁺:ZnS@SiO₂/MoS₂-RBS nanocomposites showed the dual-emissive two-photon excited photoluminescence (TPEPL) that induced RBS photolysis to release NO in situ. NO caused TPEPL quenching of Mn²⁺:ZnS QDs, but it produced almost no impact on the TPEPL of MoS₂ QDs. Hence, the nanocomposites were developed as a novel QDs-based ratiometric TPEPL probe for real-time detection of NO release in situ. The ratiometric TPEPL intensity is nearly linear (R² = 0.9901) with NO concentration in the range of 0.01∼0.8 μM, which corresponds to the range of NO release time (0∼15 min). The detection limit was calculated to be approximately 4 nM of NO. Experimental results confirmed that this novel ratiometric TPEPL probe possessed high selectivity and sensitivity for the detection of NO against potential competitors, and especially showed high detection performance for NIR-light triggered NO release in tumor intracellular microenvironments. These results would promote the development of versatile probe-donor integrated systems, also providing a facile and efficient strategy to real-time detect the highly controllable drug release in situ, especially in physiological microenvironments.     

The H2S decomposition activity of supported MoS2 catalysts prepared via PFHS method

Silica-supported MoS₂ catalysts prepared via precipitation from homogeneous solution (PFHS) exhibited high surface areas (180–190 m² g^–1 and activities which were about twice those of the unsupported specimens. An 8% Mo catalyst showed optimum activity. The superior activity of the supported specimen was attributed to the higher population of active sites occasioned by the good dispersion during PFHS. TEM examination also confirmed the existence of small MoS₂ crystallites on the silica support.     

Influence of polycrystalline MoS2 nanoflowers on mouse breast cancer cell proliferation via molten salt sintering

In this paper, polycrystalline molybdenum disulfide (MoS₂) nanoflowers were prepared by mixing ammonium molybdate tetrahydrate [(NH₄)₆Mo₇O₂₄·4H₂O] and potassium thiocyanate (KSCN) at 300 °C for 2 h via molten salt sintering method. Under scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM), MoS₂ showed popcorn-like shape, which surface distribution defects were easy to be further modified. MoS₂ as a nano-enzyme was used to inhibit the proliferation of mouse breast cancer cells (4 T1), which had 69.8 % inhibitory effect on 4 T1 cell proliferation. Electron spin resonance (ESR) analysis showed that MoS₂ could produce a large number of stable hydroxyl radicals (–OH). The disulfide bond in MoS₂ was highly sensitive to reactive oxygen species (ROS). High ROS level leads to the death of cancer cells under oxidative stress and inhibits the proliferation of 4 T1. This work demonstrates that MoS₂ is a potential anticancer drug or carrier for cancer treatment.     

Electrophoretically deposited L-cysteine functionalized MoS2@MWCNT nanocomposite platform: a smart approach toward highly sensitive and label-free detection of gentamicin

The exploitation of antibiotics has caused many side effects on the agriculture, environment, and human health. The existing methods have numerous shortcomings in determining gentamicin (GEN), a broad-spectrum antibiotic that causes nephrotoxicity and ototoxicity when found in excess. Here, an immunosensing platform to detect GEN using multiwalled carbon nanotubes (MWCNTs) and molybdenum disulfide (MoS₂) nanocomposite, deposited electrophoretically on indium tin oxide (ITO) glass has been developed. A novel 2-D graphene analog MoS₂@ MWCNTs nanocomposite was made via a facile and low-cost hydrothermal technique using l-cysteine to achieve remarkable electrochemical properties. Subsequently, a highly sensitive electrochemical immunosensor was fabricated by assembling monoclonal antibodies against gentamicin (anti-GEN) on a MoS₂@MWCNTs modified ITO electrode. The hetero-nanostructure formed on the immunosensor surface appeared relatively good conductor for accelerating the electron transfer. GEN was determined on anti-GEN modified electrodes by utilizing the differential pulse voltammetry technique by measuring the difference in current owing to the transfer of electrons directly between the redox species and immunoelectrodes. Under optimal experimental conditions, the fabricated immunosensor had a wide linear detection range of 1 × 10^?6–40 μg/mL, a high sensitivity of 13.55 μA (log μg/mL)^?1 and a low limit of detection and limit of quantification of 0.039 μg/mL and 0.130 μg/mL, respectively. The developed immunosensor also exhibits high reproducibility, repeatability, and good selectivity against various interferences. This electrochemical immunosensor having MoS₂ modified MWCNTs displays the excellent potential for the point-of-care device for GEN testing.     

An insight to catalytic synergic effect of Pd-MoS2 nanorods for highly efficient hydrogen evolution reaction

The electrocatalytic hydrogen evolution reaction (HER) is a sustainable energy production route using green chemistry. Transition metal dichalcogenides' application in catalytic hydrogen production is limited due to a lack of solutions that simultaneously address intrinsic activity, increased surface area, electrical conductivity, and stability problems. Herein we address these issues simultaneously by modifying the electronic structure of molybdenum disulfide (MoS₂) nanorods using a low content of Pd (1 wt% and 2 wt%) dopant via a facile colloidal solvothermal route. The resulting MoS₂ nanorods doped with (1 and 2 wt%) palladium demonstrate current density of 100 mA/cm² at quit lower over-potentials of 137 mV and 119 mV than 273 mV for pure MoS₂ nanorods, accompanied by high stability. This research proposes a strategy for designing high-performance HER electrocatalysts that work in acidic medium. In addition, the Tafel slop calculated for MoS₂ is 112 mV/dec whereas for 1 and 2 wt% Pd-MoS₂, the Tafel slopes are 70 mV/dec and 46 mV/dec.     

Size confinement and magnetization improvement by La3+ doping in BiFeO3 quantum dots

Nanometric multiferroic samples Bi_1−xLa_xFeO₃; 0.05 ≤ x ≤ 0.40 were prepared using ceramic method. Structural and magnetic properties were investigated using XRD, TEM, magnetic susceptibility and M–H loop. The decrease in the lattice parameters is due to the difference between the ionic radii of Bi and La and this effect is compensated by the change in the atomic weight of the two elements which is reflected as a decrease in the density. The obtained results showed that all samples were antiferromagnetic in character. The small values of remnant and saturation magnetization indicated the canted type antiferromagnetism. Maximum coercivity H_c = 5265 Oe was obtained at x = 0.25. The magnetic susceptibility measurements show its size dependence due to long range spin arrangement. Improvement of the magnetization of BiFeO₃ is achieved by La³⁺ at different doping levels. The obtained quantum dot size of the crystallites enhances their use in spintronic devices.     

Preparation of nanocrystalline TiO<Subscript>2</Subscript> powders for photocatalytic oxidation of phenol

Nanocrystalline TiO₂ powders in the anatase, rutile, and mixed phases prepared by hydrolysis of TiCl₄ solution were of ultrafine size (<7.2 nm) with high specific surface areas in the range 167 to 388 m²/g. In the photocatalytic degradation of phenol as model reaction, the photocatalytic properties of TiO₂ nanoparticles were evaluated by use of UV–vis absorption spectroscopy and total organic carbon (TOC) content. The synthetic mixed-phase TiO₂ powder calcined at 400 °C had higher activity than pure anatase or rutile; it degraded more than 90% phenol to CO₂ (evaluated by TOC) after irradiation with near UV light for 90 min at a catalyst loading of 0.4 g/L. The TOC results indicated that rutile TiO₂ crystallites of particle size 7.2 nm resulted in much better photocatalytic performance than particles of larger size. This result suggested that some intermediates, not determined by UV–vis absorption spectroscopy, existed in the solution after the photocatalytic process over the rutile TiO₂ photocatalysts of larger crystallite size.     

Thermal and hydrothermal stability of flame hydrolytically synthesized SiO2/TiO2 mixed oxides

The phase stability of the two TiO₂ modifications (anatase and rutile) in fumed SiO₂/TiO₂ nano-composites (0–24.8 wt-% silica) under thermal and hydrothermal conditions was investigated by X-ray powder diffraction, transmission electron microscopy (TEM) and gas adsorption methods (BET). The results show that the phase transformation from anatase to rutile type of structure and the growth of anatase crystallites are significantly retarded by mixing small amounts of SiO₂ into TiO₂, while the specific surface area is maintained. The SiO₂/TiO₂-composites reveal a remarkable shift in the anatase to rutile transformation temperature from approx. 500 °C (pure TiO₂) to approx. 1000 °C (samples with SiO₂ contents of more than 10%). The rate of phase transformation from anatase to rutile is enhanced under hydrothermal conditions compared to conventional thermal treatment, e.g. pure titania (AEROXIDE^® TiO₂ P25) annealed under hydrothermal conditions (100 g/m³ absolute humidity, 4 h at 600 °C) had a rutile content of 85%, while the same specimens annealed in absence of humidity contained only 46% rutile. However, the difference in rate of phase transformation became less pronounced when the silica content in SiO₂/TiO₂-composites was further increased.TEM results showed that the surface of the anatase crystallites was covered with silica. This averts coalescence of anatase crystallites and keeps them under a critical size during the annealing process. When the crystal domains grew larger, a rapid conversion to rutile took place. The critical size of anatase crystallites for the phase transformation was estimated to be 15–20 nm.     

Physio-chemical influence of high electron-phonon coupling induced by 120 MeV Ag9+ SHI irradiation on exfoliated MoS2 - PVA nanocomposite films for achieving remarkable electrical conductivity for potential application in organic electronics

Swift heavy ion (SHI) irradiation technology is known to enhance the optical, electronic, mechanical, and electrical properties in polymer nanocomposites by the virtue of electron-phonon coupling. In the present work, Molybdenum disulphide (MoS₂), a two-dimensional metal dichalcogenide, has been exfoliated via liquid-phase exfoliation using N-methyl-2- pyrrolidone (NMP) as the solvent that yielded nanosheets of around 2–4 layers as depicted by HR-TEM images. MoS₂ - PVA free-standing films were prepared by wet chemical technique i.e. solution casting method and irradiated by focussed high-energy Ag⁹⁺ ion beam at fluence range of 1E10 - 3E11 ions/cm². As a consequence, the structural modification was observed by X-Ray diffraction studies that showed the shift of (002) plane of MoS₂ while Raman studies indicated the decrease of degree of disorderness at fluence 1E10 ions/cm². SHI irradiation has found to induce a two-order increase in the electrical conductivity yielding a 9.7 E-3 S/cm against that of the pristine films at 2.6E-5 S/cm. The enhanced conductivity is attributed to the induced dispersion and annealing of MoS₂ nanosheets in the PVA matrix due to the interaction of 120 MeV Ag⁹⁺ ion beam irradiation as explained by Thermal spike model.     

TiO2 nanorods based self-supported electrode of 1T/2H MoS2 nanosheets decorated by Ag nano-particles for efficient hydrogen evolution reaction

Molybdenum disulfide (MoS₂) has shown significant promise as an economic hydrogen evolution reaction (HER) catalyst for hydrogen generation, but its catalytic performance is still lower than noble metal-based catalysists. Herein, a silver nanoparticles (Ag NPs)-decorated 1T/2H phase layered MoS₂ electrocatalyst grown on titanium dioxide nanorod arrays (Ag NPs/1T(2H) MoS₂/TNRs) was prepared through acid-tunable ammonium ion intercalation. Taking advantage of MoS₂ layered structure and crystal phase controllability, as-prepared Ag NPs/1T(2H) MoS₂/TNRs exhibited ultrahigh HER activity. As-proposed strategy combines facile hydrogen desorption (Ag NPs) with efficient hydrogen adsorption (1T/2H MoS₂) effectively circumventes the kinetic limitation of hydrogen desorption by 1T/2H MoS₂. The as-prepared Ag NPs/1T(2H) MoS₂/TNRs electrocatalyst exhibited excellent HER activity in 0.5 mol/L H₂SO₄ with low overpotential (118 mV vs. reversible hydrogen electrode (RHE)) and small Tafel slope (38.61 mV/dec). The overpotential exhibts no obvious attenuation after 10 h of constant current flow. First-principles calculation demonstrates that as-prepared 1T/2H MoS₂ exhibit a large capacity to store protons. These protons can be subsequently transferred to Ag NPs, which significantly increases the hydrogen coverage on the surface of Ag NPs in HER process and thus change the rate-determining step of HER on Ag NPs from water dissociation to hydrogen recombination. This study provides a unique strategy to improve the catalytic activity and stability for MoS₂-based electrocatalyst.     

Antimony anchored in MoS2 nanosheets with N-doped carbon coating to boost potassium storage performance

Potassium ions batteries (PIBs) have been considered as promising energy storage systems owning to potassium rich natural abundances. However, the difficult reaction kinetics and poor cycling of electrode restrict the further development of PIBs. In this work, antimony anchored in MoS₂ nanosheets with N-doped carbon coating (Sb/MoS₂/NCs) are prepared and evaluated as anode for PIBs. In the unique Sb/MoS₂/NCs structure, the volume expansion of Sb particles could be effectively buffered by the around MoS₂ structure. The defects in MoS₂ nanosheets provide more electrochemical reaction sites for sufficient K⁺ insertion/extraction. Furthermore, the N-doped carbon can further accommodate the volume expansion and improve the electronic conductivity of Sb/MoS₂/NCs composites. Due to the above advantages, the Sb/MoS₂/NCs anode delivers a capacity of 235 mAh/g at 50 mA/g after 78 cycles. This work provides a prospective strategy to design advanced anode materials for PIBs using MoS₂ and antimony composites.     

Magnetically separable and recyclable photocatalyst MoS2-SrFe12O19 with p-n heterojunction: Fabrication,characterization, and photocatalytic mechanism

A novel magnetic photocatalyst MoS₂-SrFe₁₂O₁₉ was successfully synthesized via a facile and reliable hydrothermal method. Flower-shaped nanospheres MoS₂ was compactly decorated with hexagon nanoplate SrFe₁₂O₁₉, which formed a new p-n heterojunction. The superiority of this heterojunction structure has validated by characterizations and spectroscopic technique. Importantly, the MoS₂-SrFe₁₂O₁₉ composite presents remarkable photocatalytic activity for the degradation of organic dyes (RhB and MB), far exceeding those for the pure MoS₂ and SrFe₁₂O₁₉. In particular, the degradation rate of RhB reached to 96.5% after only 120 min photocatalytic reaction for the composite MoS₂-SrFe₁₂O₁₉ (10 wt%). Based on the experiments and mechanism research, this magnetic photocatalyst can facilitate the separation of photogenerated electron-hole pairs, inhibit the recombination and prolong lifespan of charge. It is attributed to its unique composite structure and intimate interfacial contact, which can obtain a higher light utilization and electron transit path. In addition, MoS₂-SrFe₁₂O₁₉ can be rapidly separated (5–10 seconds) and recycled under an external magnetic field, which verifies the satisfactory magnetism and reusability of the composite (Ms = 10.1 emu g^–1, Mr = 3.5 emu g^–1, Hci = 1407.7 Oe). Overall, this work provides a new insight for the recyclable photocatalytic systems with multi-functionalities.     

In-situ formation of 2H phase MoS2/cerium-zirconium oxide nanohybrid for potential electrochemical detection of an anticancer drug flutamide

The developing field of sensors is highly motivated and attracted by two-dimensional transition metal dichalcogenides (TMDs) with transition metal oxide integration. Initially, molybdenum disulfide (MoS₂), one among the TMDs with cerium-zirconium oxide (CZO), was one-pot synthesized via hydrothermal method for sensing flutamide (FLD). The as-synthesized hybrid nanocomposite was characterized to understand their physical and chemical presence. MoS₂-CZO was well assigned with crystalline nature observed from X-ray powder diffraction and X-ray photoelectron spectroscopy. High-resolution transmission electron microscopy confirms the irregularly arranged nanoparticles wrapped with MoS₂ sheets. The wide surface area with more electroactive sites has provided higher conductance of the MoS₂-CZO/glassy carbon electrode. The limit of detection was 0.005 μM with a linear range of 0.019 μM to 668.5 μM, sensitivity 0.353 μA μM?1 cm^?2. The practical feasibility was analyzed with human urine and river water samples, whereas the obtained results showed excellent FLD detection. The fabricated MoS₂-CZO with all these distinguished analyses will be an outbreak in the field of electrochemical sensors.     

Direct formation of SiO<Subscript>2</Subscript>/SnO<Subscript>2</Subscript> composite nanoparticles with high surface area and high thermal stability by sol–gel-hydrothermal process

SnO₂/SiO₂ composite nanoparticles were prepared by sol–gel-hydrothermal process and their physico-chemical structure and photocatalytic property were investigated. The results of XRD, TEM and FT-IR indicated that SnO₂ crystallites with the tetragonal rutile structure were well-developed directly during hydrothermal process. The SnO₂/SiO₂ composite nanoparticles owned narrow size distribution, large specific surface area, and good thermal stability. As the presence of 25.0 wt% SiO₂, the SnO₂ nanoparticles were about 4.0 nm in diameter and the specific surface area was 259.0 m²/g. After calcination at 800 °C, the crystalline grain size maintained 16.2 nm and the surface area still remained 132.6 m²/g. The SnO₂/SiO₂ composite nanoparticles showed better photocatalytic activity than pure SnO₂ nanoparticles.     

Synthesis of 2D Molybdenum Disulfide (MoS2) for enhancement of mechanical and electrical properties of polystyrene (PS) polymer

In this research article, ultrasound assisted exfoliation in a liquid phase production process has been adopted for synthesis of 2D Molybdenum Disulfide (MoS₂). The energetic governing dispersion of Nano sheets in a wide range of solvents has been studied. Nano sheets dispersion in an aqueous media has been prepared with the help of high surface tension solvents like N-Methyl-1, 2-Pyyrolidone (NMP) and Tetrahydrofuran (THF). The dispersion was composed of layers of MoS₂ with some quantities of mono and bi-layer materials were observed. Scanning Electron Microscopy (SEM), X-Rays Diffractometry (XRD), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) were used to characterize the samples; SEM clearly evident the microstructure of samples while XRD shows the peaks of filler in the polystyrene composite membrane. AFM confirmed the presence of 2D MoS₂ with 0.9–7 nm thickness range of MoS₂ flake. In order to get the surfactant stabilized dispersed material, the processing was enhanced using prolonged sonication to yield maximized concentration. Liquid phase exfoliation allows dispersion to be cast into thin film by using vacuum filtration assembly. The obtained film is dispersed in solvent and is used in polymers. Two sets of concentrations (0.01, 0.03, 0.05 and 0.07% by wt. and 0.1, 0.3, 0.7 and 0.9% by wt.) were analyzed and it was observed during tensile testing that modulus of elasticity (E), percentage elongation and ultimate tensile strength (UTS) of composite material increases maximum up to 741times, 374 times and 200 times as compared to base polymer (PS), respectively. Furthermore, dielectric constant, dielectric loss and electrical conductivity of PS-MoS₂ were also evaluated and finding clearly pointed out that filler loading of MoS₂ has considerable effects on these properties and maximum value of dielectric constant is 3.6 at 0.9% loading as compared with of pure PS (polystyrene) matrix. On the other hand, variation in dielectric loss from lower to higher frequency is 2.5 × 10⁻² on average which is not so significant. Electrical conductivity was also accounted, and measurement results are indicating that conductivity was almost constant at lower frequency in range of 10⁻¹⁰ due to low field strength, but it increases to 10⁻⁹ value at higher frequency due to hoping mechanism and network formation of filler.     

Gold Nanoclusters Grown on MoS2 Nanosheets by Pulsed Laser Deposition: An Enhanced Hydrogen Evolution Reaction

Au nanoparticles were decorated on a 2H MoS₂ surface to form an Au/MoS₂ composite by pulse laser deposition. Improved HER activity of Au/MoS₂ is evidenced by a positively shifted overpotential (−77 mV) at a current density of −10 mA cm⁻² compared with pure MoS₂ nanosheets. Experimental evidence shows that the interface between Au and MoS₂ provides more sites to combine protons to form an active H atom. The density functional theory calculations found that new Au active sites on the Au and MoS₂ interface with improved conductivity of the whole system are essential for enhancing HER activity of Au/MoS₂.     

Successful location of tin dopant cations on surface sites of anatase-type TiO2 crystallites evidenced by 119Sn Mössbauer spectroscopic probe and XPS techniques

The present study provides the first experimental evidence for the stabilization of tin dopant cations immediately on the surface of an oxide having a tetragonal structure. ¹¹⁹Sn Mössbauer spectra of the dopant, introduced by air annealing into the bulk of anatase microcrystals, showed that it was located, in the tetravalent state, in somewhat distorted octahedral sites of a unique type. On the contrary, the reduced tin species, formed upon subsequent hydrogen annealing the Sn⁴⁺-doped samples, are found to occupy different sites being characterized by two sets of the isomer shift δ and quadrupole splitting ΔE_Q values (δ_I = 3.25 mm s⁻¹, ΔE_QI = 1.75 mm s⁻¹; and δ_II = 2.85 mm s⁻¹, ΔE_QII = 1.71 mm s⁻¹). Either of them implies both the divalent state of tin atoms and their presence at low-coordination sites that can be assigned to the surface of crystallites. Mössbauer spectra of Sn^4+←2+ daughter ions, formed upon contact with air of Sn²⁺, consist of a symmetrically broadened peak characterized by only slightly different average values of both the isomer shift (<δ> = 0.07 mm s⁻¹) and quadrupole splitting (<ΔE_Q> = 0.50 mm s⁻¹), as compared to the δ and ΔE_Q values for the bulk-located Sn⁴⁺. However, considerable broadening of Sn^4+←2+ doublet components (Γ = 0.97 mm s⁻¹) allows one to suggest that these secondary formed ions remain distributed over the non equivalent sites inherited from their Sn²⁺ precursors. The occurrence of Sn^4+←2+ at surface sites is independently proven by XPS measurements that revealed a greater than 10-fold enrichment with tin of 3–5 nm thick surface layers.     

Investigation of the LiCo1−xMgxPO4 (0 ≤ x ≤ 0.1)–graphitic carbon foam composites

LiCo_1−xMg_xPO₄–graphitic carbon foam (LCMP–GCF with 0 ≤ x ≤ 0.1) composites are prepared by Pechini-assisted sol-gel method and annealed with the 2-steps annealing process (T = 300 °C for 5 min in flowing air, then at T = 730 °C for t = 12 h in flowing nitrogen). The XRD analysis, performed on powders reveals LiCoPO₄ as major crystalline phase, Co₂P and Co₂P₂O₇ as secondary phases. The morphological investigation revealed the formation and growth of microcrystalline “islands” which consist of acicular crystallites with different dimensions (typically 5–50 μm). By addition of Mg-ions, CV-curves of LCMP–GCF composites show a decrease of the surface between anodic and cathodic sweeps by cycling and a stark contribution of faradaic processes due to the graphitic structured foam. The electrochemical measurements, at a discharge rate of C/10 at room temperature, show the decrease of the discharge specific capacity from 100 mAh g⁻¹ for x = 0.0 to ∼35 mAh g⁻¹ for 0.025 ≤ x ≤ 0.05, then an increase to 69 mAh g⁻¹ for x = 0.1. The electrochemical impedance spectroscopy data reveal a decrease of the electrical resistance and the improvement of the Li-ion conductivity at high Mg-ions content into the LiCoPO₄ phase (x ≥ 0.025).     

Electrolysis of solid MoS2 in molten CaCl2 for Mo extraction without CO2 emission

Sintered (300 °C) porous pellets of MoS₂ were electrolysed to elemental S and Mo in molten CaCl₂ (800–900 °C) under argon at 1.0–3.0 V for 1–20 h. On a graphite anode, the product was primarily S (but traces of CS₂ could not yet be excluded by this work) and evaporated from the molten salt, allowing the electrolysis to continue. It then condensed to solid at the lower temperature regions of the system. The anode remained intact after repeated uses. The MoS₂ pellet was highly conducting at high temperatures and could be fast electro-reduced to fine Mo powders (0.1–1.0 μm) in which the S content could be below 1000 ppm. No reduction occurred at voltages below 0.5 V. Partial reduction was seen at 0.5–0.7 V, and converted MoS₂ to a mixture of MoS₂ and Mo₃S₄, or Mo₃S₄ and Mo with the Mo content increasing with the voltage. Cyclic voltammetry of the MoS₂ powder in a Mo-cavity electrode, together with the electrolysis results, revealed the reduction mechanism to include two steps: MoS₂ to Mo₃S₄ at −0.28 V (potential vs. Ag/AgCl), and then to Mo at −0.43 V.