Search Results (17)

To investigate the application potential of amorphous transition metal chalcogenides in catalysis, this study successfully synthesized amorphous molybdenum telluride (MoTe_x) materials and systematically explored their structural characteristics, compositional modulation, and catalytic performance. Experimental results indicate that the synthesized amorphous system consists of particles of approximately 200–300 nm in size. This distinct microstructure facilitates the exposure of abundant active sites and enhances physical adsorption capacity. The amorphous MoTe₂/MoTe₃ catalysts achieve an approximately 30%/40% degradation of methylene blue (MB) within 90 min, demonstrating significantly enhanced photocatalytic efficiency compared to that of crystalline MoTe₂ (≈20% degradation under identical conditions). Furthermore, when integrated with titanium dioxide (TiO₂), the composite exhibits exceptional co-catalytic performance, achieving a 90% degradation of MB within 90 min under visible-light irradiation, representing a catalytic efficiency improvement exceeding 160% compared to the results for pristine TiO₂. Furthermore, through comparative analysis of the catalytic behavior and microstructural variations between amorphous MoTe₃ (a-MoTe₃) and MoTe₂ (a-MoTe₂), we observed that the catalytic activity of molybdenum tellurides exhibits a weak correlation with the tellurium content, with co-catalytic efficacy jointly governed by the density of the active sites and the physical adsorption properties. This research provides new methods and insights for the study and improvement of catalytic performance in chalcogenide materials. Full article

As a transition metal chalcogenide, molybdenum disulfide is an important two-dimensional material. Due to its structural anisotropy, its different morphological structures impact performance. Therefore, improving existing preparation methods enhances its applications. Single-layer molybdenum disulfide is a direct bandgap semiconductor with excellent mechanical properties and chemical stability. We chose ammonium molybdate as the molybdenum source and L-cysteine as the sulfur source. By changing the pH and the reaction time in the environment, the hydrothermal method is used to synthesize the precursor and molybdenum disulfide with different morphologies to control its morphology. Electrochemical test results showed that the specific capacity of molybdenum disulfide synthesized at a current density of 0.6 A reaches 187.79 F/g at a reaction time of 24 h and a pH of 0.6. Its microstructure is in the shape of a flower ball, with a single piece size of about 50 nm and a thickness of about 5 nm. Its specific surface area reaches 36.88 m²/g, which provides enough active sites. Full article

In the past few years, metal chalcogenides have received extensive consideration because of their excellent physicochemical belongings. Particularly, molybdenum selenide (MoSe₂) is a promising metal dichalcogenide which possesses decent optical, electrical, and chemical properties and can be explored for a variety of applications. MoSe₂ has been extensively used for several applications such as energy storage and sensing. Since the energy crisis is one of the major challenges of today’s world, super-capacitors and hydrogen evolution are promising energy technologies that may benefit the global world in the future. Thus, researchers have been motivated towards the strategy and fabrication of electrode materials for super-capacitors and hydrogen evolution applications. MoSe₂ is a multifunctional material, and previous years have witnessed the rapid growth in the publication of MoSe₂-based electrode materials for super-capacitors, hydrogen evolution, and electrochemical sensing applications. Thus, it is of great significance to merge the previous reports into a single review article on MoSe₂-based modified electrode materials for super-capacitors, hydrogen evolution, and electrochemical sensing applications. Therefore, we have compiled the previous reports on the design and fabrication of MoSe₂ and electrodes based on its composites for super-capacitors, hydrogen evolution, and electrochemical sensing applications. It is believed that this article may benefit the researchers working in the research field of super-capacitors, hydrogen evolution, and electrochemical sensing applications. Full article

A mixed-metal ternary chalcogenide, cobalt molybdenum telluride (CMT), has been identified as an efficient tri-functional electrocatalyst for seawater splitting, leading to enhanced oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR). The CMT was synthesized by a single step hydrothermal technique. Detailed electrochemical studies of the CMT-modified electrodes showed that CMT has a promising performance for OER in the simulated seawater solutions, exhibiting a small overpotential of 385 mV at 20 mA cm⁻², and superior catalyst durability for prolonged period of continuous oxygen evolution. Interestingly, while gas chromatography analysis confirmed the evolution of oxygen in an anodic chamber, it showed that there was no chlorine evolution from these electrodes in alkaline seawater, highlighting the novelty of this catalyst. CMT also displayed remarkable ORR activity in simulated seawater as indicated by its four-electron reduction pathway forming water as the dominant product. One of the primary challenges of seawater splitting is chlorine evolution from the oxidation of dissolved chloride salts. The CMT catalyst successfully and significantly lowers the water oxidation potential, thereby separating the chloride and water oxidation potentials by a larger margin. These results suggest that CMT can function as a highly active tri-functional electrocatalyst with significant stability, making it suitable for clean energy generation and environmental applications using seawater. Full article

A key research focus at present is the exploration and innovation of electrode materials suitable for energy storage and conversion. Molybdenum-based sulfides/selenides (primarily MoS₂ and MoSe₂) have garnered attention in recent years due to their intrinsic two-dimensional structures, which are conducive to ion/electron transfer or insertion/extraction, making them promising candidates in electrocatalytic hydrogen production and sodium-ion battery applications. However, their inherently poor electronic structures have led most research efforts to concentrate on modifications aimed at enhancing their performance in hydrogen evolution reactions (HERs) and sodium-ion batteries (SIBs). Owing to their remarkable chemical inertness, expansive specific surface areas, and tunable pore architectures, carbon-based materials have garnered significant attention in research. The utilization of biomass as a renewable and environmentally sustainable precursor offers considerable benefits, including abundant availability, ecological compatibility, and cost-effectiveness. Consequently, recent scholarly endeavors have concentrated intensively on the synthesis of valuable carbon materials derived from renewable biomass sources. This review addresses the scientific challenges related to the development of electrode materials for HERs and SIBs in electrochemical energy storage and conversion. It delves into the recent focus on the two-dimensional transition-metal chalcogenides, particularly MoS₂ and MoSe₂, and the difficulties encountered in modulating their electronic structures when applied to HERs and SIBs. The review proposes the use of eco-friendly and widely sourced biomass-derived carbon (BMC) as a supporting matrix combined with MoS₂ and MoSe₂ to regulate their structures and enhance their electrocatalytic activity and sodium storage performance. Additionally, it highlights the existing challenges faced by these BMC/MoS₂ and BMC/MoSe₂ composites and offers insights into future developments. Full article

This work presents a biological remediation process for molybdenum-bearing wastewater which may lead to the fabrication of biogenic Mo chalcogenide particles with (photo)catalytic properties. The process is based on dissimilatory sulphate reduction, utilising sulphate-reducing bacteria (SRB), and reductive precipitation of molybdate which is the predominant species of molybdenum in oxygenated water/wastewater. The SRB culture was established in a biofilm reactor which was fed with synthetic solutions containing sulphate (17.7 mM), molybdate molybdenum (2 mM), divalent iron (1.7 mM) and ethanol as the carbon/electron donor. The performance of the bioreactor was monitored in terms of pH, sulphate and molybdenum (Mo(VI) and total) content. The presence of thiomolybdate species was studied by scanning UV-Vis absorbance of samples from the reactor outflow while the reactor precipitates were studied via electron microscopy coupled with energy dispersive spectrometry, X-ray diffractometry and laser light scattering. A molar molybdate/sulphate ratio of 1:12.5 proved effective for molybdate reduction and recovery by 76% in 96 h, whereas sulphate was reduced by 57%. Molybdenum was immobilised in the sulphidic precipitates of the bioreactor, presumably via two principal mechanisms: (i) microbially mediated reduction and precipitation, and (ii) thiomolybdate formation and sorption/incorporation into iron sulphides. Full article

The chemistry of transition metal clusters has been intensively developed in the last decades, leading to the preparation of a number of compounds with promising and practically useful properties. In this context, the present work demonstrates the preparation and study of the reactivity, i.e., the possibility of varying the ligand environment, of new square pyramidal molybdenum chalcogenide clusters [{Mo₅(μ₃-S)ⁱ₄(μ₄-S)ⁱ(μ-pz)ⁱ₄}(pzH)^t₅]^1+/2+ (pzH = pyrazole, i = inner, t = terminal). The one-step synthesis starting from the octahedral Mo₆Br₁₂ cluster as well as the substitution of the apical pyrazole ligand or the selective bromination of the inner pyrazolate ligands were demonstrated. All the obtained compounds were characterized in detail using a series of physicochemical methods both in solid state (X-ray diffraction analysis, etc.) and in solution (nuclear magnetic resonance spectroscopy, mass spectrometry, etc.). In this work, redox properties and absorption in the ultraviolet-visible and near-infrared region of the obtained compounds were studied. Full article

Spin-polarized density-functional theory (DFT) has been employed to study the effects of atmospheric gases on the electronic and magnetic properties of a defective transition-metal dichalcogenide (TMD) monolayer, MoX₂ with X = S or Se. This study focuses on three single vacancies: (i) molybdenum “V_Mo”; (ii) chalcogenide “V_X”; and (iii) di-chalcogenide “V_X2”. Five different samples of sizes ranging from 4 × 4 to 8 × 8 primitive cells (PCs) were considered in order to assess the effect of vacancy–vacancy interaction. The results showed that all defected samples were paramagnetic semiconductors, except in the case of V_Mo in MoSe₂, which yielded a magnetic moment of 3.99 μ_B that was independent of the sample size. Moreover, the samples of MoSe₂ with V_Mo and sizes of 4 × 4 and 5 × 5 PCs exhibited half-metallicity, where the spin-up state becomes conductive and is predominantly composed of $d_{xy}$ and $d_{{\mathrm{z}}^2}$ orbital mixing attributed to Mo atoms located in the neighborhood of V_Mo. The requirement for the establishment of half-metallicity is confirmed to be the provision of ferromagnetic-coupling (FMC) interactions between localized magnetic moments (such as V_Mo). The critical distance for the existence of FMC is estimated to be $d_c\cong$ 16 Å, which allows small sample sizes in MoSe₂ to exhibit half-metallicity while the FMC represents the ground state. The adsorption of atmospheric gases (H₂O, O₂, O₃) can drastically change the electronic and magnetic properties, for instance, it can demolish the half-metallicity characteristics. Hence, the maintenance of half-metallicity requires keeping the samples isolated from the atmosphere. We benchmarked our theoretical results with the available data in the literature throughout our study. The conditions that govern the appearance/disappearance of half-metallicity are of great relevance for spintronic device applications. Full article

The family of chalcogenide molybdenum clusters is well presented in the literature by a series of compounds of nuclearity ranging from binuclear to multinuclear articulating octahedral fragments. Clusters actively studied in the last decades were shown to be promising as components of superconducting, magnetic, and catalytic systems. Here, we report the synthesis and detailed characterization of new and unusual representatives of chalcogenide clusters: square pyramidal complexes [{Mo₅(μ₃-Se)ⁱ₄(μ₄-Se)ⁱ(μ-pz)ⁱ₄}(pzH)^t₅]^1+/2+ (pzH = pyrazole, i = inner, t = terminal). Individually obtained oxidized (2+) and reduced (1+) forms have very close geometry (proven by single-crystal X-ray diffraction analysis) and are able to reversibly transform into each other, which was confirmed by cyclic voltammetry. Comprehensive characterization of the complexes, both in solid and in solution, confirms the different charge state of molybdenum in clusters (XPS), magnetic properties (EPR), and so on. DFT calculations complement the diverse study of new complexes, expanding the chemistry of molybdenum chalcogenide clusters. Full article

Two-dimensional (2D) materials with binary compounds, such as transition-metal chalcogenides, have emerged as complementary materials due to their tunable band gap and modulated electrical properties via the layer number. Ternary 2D materials are promising in nanoelectronics and optoelectronics. According to the calculation of density functional theory, in this work, we study the electronic structures of ternary 2D materials: monolayer Mo_1−xCr_xS₂ and W_1−xCr_xS₂. They are mainly based on monolayer molybdenum disulfide and tungsten disulfide and have tunable direct band gaps and work functions via the different mole fractions of chromium (Cr). Meanwhile, the Cr atoms deform the monolayer structures and increase their thicknesses. Induced by different mole fractions of Cr material, energy band diagrams, the projected density of states, and charge transfers are further discussed. Full article

Two-dimensional (2D) molybdenum telluride (MoTe₂) is attracting increasing attention for its potential applications in electronic, optoelectronic, photonic and catalytic fields, owing to the unique band structures of both stable 2H phase and 1T′ phase. However, the direct growth of high-quality atomically thin MoTe₂ with the controllable proportion of 2H and 1T′ phase seems hard due to easy phase transformation since the potential barrier between the two phases is extremely small. Herein, we report a strategy of the phase-controllable chemical vapor deposition (CVD) synthesis for few-layer (<3 layer) MoTe₂. Besides, a new understanding of the phase-controllable growth mechanism is presented based on a combination of experimental results and DFT calculations. The lattice distortion caused by Te vacancies or structural strain might make 1T′-MoTe₂ more stable. The conditions for 2H to 1T′ phase conversion are determined to be the following: Te monovacancies exceeding 4% or Te divacancies exceeding 8%, or lattice strain beyond 6%. In contrast, sufficient Te supply and appropriate tellurization velocity are essential to obtaining the prevailing 2H-MoTe₂. Our work provides a novel perspective on the preparation of 2D transition metal chalcogenides (TMDs) with the controllable proportion of 2H and 1T′ phase and paves the way to their subsequent potential application of these hybrid phases. Full article

Molybdenum disulfide (MoS₂) is the most well-known transition metal chalcogenide for lithium storage applications because of its simple preparation process, superior optical, physical, and electrical properties, and high stability. However, recent research has shown that bare MoS₂ nanosheet (NS) can be reformed to the bulk structure, and sulfur atoms can be dissolved in electrolytes or form polymeric structures, thereby preventing lithium insertion/desertion and reducing cycling performance. To enhance the electrochemical performance of the MoS₂ NSs, B₂O₃ nanoparticles were decorated on the surface of MoS₂ NSs via a sintering technique. The structure of B₂O₃ decorated MoS₂ changed slightly with the formation of a lattice spacing of ~7.37 Å. The characterization of materials confirmed the formation of B₂O₃ crystals at 30% weight percentage of H₃BO₃ starting materials. In particular, the MoS₂_B3 sample showed a stable capacity of ~500 mAh·g⁻¹ after the first cycle. The cycling test delivered a high reversible specific capacity of ~82% of the second cycle after 100 cycles. Furthermore, the rate performance also showed a remarkable recovery capacity of ~98%. These results suggest that the use of B₂O₃ decorations could be a viable method for improving the stability of anode materials in lithium storage applications. Full article

An attempt was made, using computational methods, to understand whether the intermolecular interactions in the dimers of molybdenum dichalcogenides MoCh₂ (Ch = chalcogen, element of group 16, especially S, Se and Te) and similar mixed-chalcogenide derivatives resemble the room temperature experimentally observed interactions in the interfacial regions of molybdenites and their other mixed-chalcogen derivatives. To this end, MP2(Full)/def2-TVZPPD level electronic structure calculations on nine dimer systems, including (MoCh₂)₂ and (MoChCh′₂)₂ (Ch, Ch′ = S, Se and Te), were carried out not only to demonstrate the energetic stability of these systems in the gas phase, but also to reproduce the intermolecular geometrical properties that resemble the interfacial geometries of 2D layered MoCh₂ systems reported in the crystalline phase. Among the six DFT functionals (single and double hybrids) benchmarked against MP2(full), it was found that the double hybrid functional B2PLYPD3 has some ability to reproduce the intermolecular geometries and binding energies. The intermolecular geometries and binding energies of all nine dimers are discussed, together with the charge density topological aspects of the chemical bonding interactions that emerge from the application of the quantum theory of atoms in molecules (QTAIM), the isosurface topology of the reduced density gradient noncovalent index, interaction region indicator and independent gradient model (IGM) approaches. While the electrostatic surface potential model fails to explain the origin of the S···S interaction in the (MoS₂)₂ dimer, we show that the intermolecular bonding interactions in all nine dimers examined are a result of hyperconjugative charge transfer delocalizations between the lone-pair on (Ch/Ch′) and/or the π-orbitals of a Mo–Ch/Ch′ bond of one monomer and the d_π* anti-bonding orbitals of the same Mo–Ch/Ch′ bond in the second monomer during dimer formation, and vice versa. The HOMO–LUMO gaps calculated with the MN12-L functional were 0.9, 1.0, and 1.1 eV for MoTe₂, MoSe₂ and MoS₂, respectively, which match very well with the solid-state theoretical (SCAN-rVV10)/experimental band gaps of 0.75/0.88, 0.90/1.09 and 0.93/1.23 eV of the corresponding systems, respectively. We observed that the gas phase dimers examined are perhaps prototypical for a basic understanding of the interfacial/inter-layer interactions in molybdenum-based dichalcogenides and their derivatives. Full article

The drawbacks of utilizing nonrenewable energy have quickened innovative work on practical sustainable power sources (photovoltaics) because of their provision of a better-preserved decent environment which is free from natural contamination and commotion. Herein, the synthesis, characterization, and application of Mo chalcogenide nanoparticles (NP) as alternative sources in the absorber layer of QDSSCs is discussed. The successful synthesis of the NP was confirmed as the results from the diffractive peaks obtained from XRD which were positive and agreed in comparison with the standard. The diffractive peaks were shown in the planes (100), (002), (100), and (105) for the MoS₂ nanoparticles; (002), (100), (103), and (110) for the MoSe₂ nanoparticles; and (0002), (0004), (103), as well as (0006) for the MoTe₂ nanoparticles. MoSe₂ presented the smallest size of the nanoparticles, followed by MoTe₂ and, lastly, by MoS₂. These results agreed with the results obtained using SEM analysis. For the optical properties of the nanoparticles, UV–Vis and PL were used. The shift of the peaks from the red shift (600 nm) to the blue shift (270–275 nm and 287–289 nm (UV–Vis)) confirmed that the nanoparticles were quantum-confined. The application of the MoX₂ NPs in QDSSCs was performed, with MoSe₂ presenting the greatest PCE of 7.86%, followed by MoTe₂ (6.93%) and, lastly, by MoS₂, with the PCE of 6.05%. Full article

Hydrogen peroxide (H₂O₂) as a crucial signal molecule plays a vital part in the growth and development of various cells under normal physiological conditions. The development of H₂O₂ sensors has received great research interest because of the importance of H₂O₂ in biological systems and its practical applications in other fields. In this study, a H₂O₂ electrochemical sensor was constructed based on chalcogenide molybdenum disulfide–gold–silver nanocomposite (MoS₂-Au-Ag). Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) were utilized to characterize the nanocomposites, and the electrochemical performances of the obtained sensor were assessed by two electrochemical detection methods: cyclic voltammetry and chronoamperometry. The results showed that the MoS₂-Au-Ag-modified glassy carbon electrode (GCE) has higher sensitivity (405.24 µA mM⁻¹ cm⁻²), wider linear detection range (0.05–20 mM) and satisfactory repeatability and stability. Moreover, the prepared sensor was able to detect the H₂O₂ discharge from living tumor cells. Therefore, this study offers a platform for the early diagnosis of cancer and other applications in the fields of biology and biomedicine. Full article