Mo Precursor Research Articles

Facile Synthesis of Highly Supercapacitive Mo‐doped Titanium Nanotube Arrays and Effect of Anodization Voltage

AbstractDesigning potential architectures by the modification of conventional electrode materials is an effective approach in the development of high performance supercapacitor electrodes. The present study investigated the effect of varying anodization voltages (50, 75, and 100 V) on the morphology and electrochemical properties of titanium nanotubes (TNT). Molybdenum was doped onto TNT using a simple hydrothermal procedure, followed by thermal treatment at 450 °C. The study effectively demonstrated control over the dimensions of the nanotube structure by adjusting the anodization voltage. Additionally, it was found that the tube diameters were increased due to etching during the hydrothermal treatment with the Mo precursor, which potentially enhanced the supercapacitive performance of Mo‐doped TNT. Further, structural analysis revealed that Mo doping improved both crystallinity and electrode stability. With an optimal anodization voltage of 100 V, TNT and Molybdenum‐doped TNT could exhibit capacitance value of 13.34 and 326.54 mF cm−2 respectively, at a current density of 1 mA cm−2. Furthermore, the electrode demonstrated good cyclic stability with 88% capacitance retention and 97% coulombic efficiency after 5000 cycles. An impressive energy density of 87.03 µWh cm−2 and a power density of 799.99 µW cm−2 could be achieved with this sample in an asymmetrical device.

Multi-interface and rich-defects 1T phase MoS2 combine with FeS anchored on reduced graphene oxide for efficient alkaline hydrogen evolution

Exploring and fabricating noble-metal-free and cost-effective electrocatalysts to minimise the excessive potential required is of great significance for alkaline hydrogen evolution reaction (HER). Herein, we report FeS/1T-MP MoS2@rGO heterostructure with 1T and 2H mixed phase MoS2 (1T-MP MoS2) combining with FeS anchored on reduced graphene oxide (rGO) matrix, which is synthetized by utilizing Anderson polyoxometalate as Fe–Mo precursor by a facile hydrothermal method. The FeS/1T-MP MoS2@rGO heterostructure in the form of interconnected nanosheet arrays with multiple interfaces and rich-defects, which is in favor of the immersion of the electrolyte and exposing more active sites. Benefiting from the synergistic advantages of 1T-MoS2, FeS and rGO, FeS/1T-MP MoS2@rGO heterostructure delivers enhanced conductivity, enlarged electrochemical active surface area, and eventually promote the HER kinetics. As expected, FeS/1T-MP MoS2@rGO heterostructure emerges prominent HER activity with low overpotentials of 102 and 256 mV to achieve current density of 10 and 100 mA cm−2, outperforming vast majority of the advanced 1T MoS2-based alkaline HER electrocatalysts.

Interlayer Space Engineering-Induced Pseudocapacitive Zinc-Ion Storage in Holey Graphene Oxide-Bearing Vertically Oriented MoS2 Nano-Wall Array Cathode for Aqueous Rechargeable Zn Metal Batteries.

Transition metal dichalcogenides, particularly MoS2, are acknowledged as a promising cathode material for aqueous rechargeable zinc metal batteries (ARZMBs). Nevertheless, its lack of hydrophilicity, poor electrical conductivity, significant restacking, and restricted interlayer spacing translate into inadequate capacity and rate performance. Herein, the unique porous structure and additional functional groups present in holey graphene oxide (hGO) are taken advantage of to dictate the vertical growth pattern of oxygen-doped MoS2 nanowalls (O-MoS2/NW) over the hGO surface. Compared to conventional graphene oxide (GO), the presence of nano-pores in hGO facilitates the homogeneous dispersion of Mo precursors and provides stronger interaction sites, promoting the uniform vertical alignment of O-MoS2/NW. The synergistic interaction between O-MoS2-NW and hGO translates to enhanced electron conductivity, efficient electrolyte penetration, enhanced interlayer spacing, reduced restacking, and enhanced surface area. As a consequence of precise control of various factors that decide the overall battery performance, a high discharge capacity (227mAhg-1 at 100mAg-1) cathode material with significantly lower charge transfer resistance (66Ω) compared to pristine O-MoS2 (153Ω) is developed. These findings underscore the potential of hGO as a multifunctional platform for nanoengineering high-performance cathode materials for the next generation of efficient and durable ARZMBs.

Effect of active site size in dispersed MoS2 nanocatalysts on slurry-phase hydrocracking of residue

This work investigates the influence of active site size in dispersed MoS2 on the slurry-phase hydrocracking of Merey residue (MRR). MoS2 nanocatalysts with varying morphologies were synthesized using the ligand sulfurization method, employing molybdenum oleate as the Mo precursor. The results demonstrate that mono-layered or double-layered MoS2 plates with slab sizes of 3 ∼ 10 nm can be synthesized at a sulfurization temperature of 400 °C and a sulfurization time of 0.5 h. Prolonged sulfurization time results in the growth and agglomeration of MoS2 plates, leading to multi-layered slabs with increased length and larger particle size, as well as a wider distribution range. The MoS2-0.5 (prepared with a sulfurization time of 0.5 h) exhibits superior hydrocracking activity, effectively converting resin and asphaltene into light fractions and significantly suppressing coke formation. Specifically, the conversion rates of resin and asphaltene are 51.3 wt% and 92.1 wt%, respectively, with the minimal coke yield of 0.6 wt% under conditions of 430 °C, 1 h, 7 MPa initial H2, and a catalyst dosage of 500 μg/g. The catalytic activity of the MoS2 nanocatalysts exhibits a strong correlation with their size and morphology obtained at different sulfurization times. Density functional theory (DFT) calculations reveal that MoS2 with smaller slab sizes are more beneficial for the adsorption and dissociation of H2, due to higher adsorption energy (Eads) and lower activation barrier (Ea). This facilitates the generation of sufficient active hydrogen to encourage the hydrocracking of residue and suppress coke formation.

Hybrid Molecular Layer Deposition of Molybdenum-Aminates as Hydrogen Evolution Reaction Electrocatalysts

The development of high-performance hydrogen evolution reaction (HER) electrocatalysts from noble metal-free materials is critical to achieving cost-effective water splitting and ultimately realizing affordable hydrogen based on renewable energy. Compounds based on earth-abundant transition metals have been the subject of great research interest for this purpose, with metal nitrides gaining recent attention due to their high conductivity and corrosion resistance. Molybdenum nitride-based electrocatalysts have shown particular promise, with many of the best reported activities occurring in composite systems wherein crystalline MoNx domains are embedded in an amorphous N-doped carbon matrix. The present work demonstrates the formation of such uniquely active morphologies in films deposited by organic-inorganic hybrid molecular layer deposition (MLD).Hybrid MLD is a hybridization of other well-established layer-by-layer deposition techniques – namely atomic layer deposition (used to deposit inorganic films) and purely organic MLD. This family of techniques involves the cyclical exposure of a growth surface to alternating vapor-phase chemical precursors which react in a self-limiting fashion to saturate available surface sites, offering atomic- and molecular-level control over the resulting films. This presentation will introduce the successful development of hybrid MLD deposition procedures for new Mo-aminate materials using Mo(CO)6 as a Mo precursor and various amine precursors, including ethylenediamine, p-phenylenediamine, and tris(2-aminoethyl)amine.We will describe how the molecular level of control offered by this technique enables tunable variations in film composition and structure, lending unique insights into how the local bonding environment of Mo active sites affects their catalytic properties towards HER. Increased nitrogen loading in the MLD films was shown to decrease the overpotentials required to drive HER in acidic media (0.5 M H2SO4) and improve film stability. Catalysts with N/Mo ratios above 2 demonstrated the best performance, with overpotentials lower than 400 mV at -10 mA/cm2. By incorporating organic components in the MLD films, it was possible to induce desirable morphological changes in the catalytic material – notably including the development of increased active site density – simply through initial exposure to HER testing conditions. The choice of organic precursor affected the rate and extent of these changes through structural effects like crosslinking and crystallinity, which led to more stable catalysts, slowed the rate of morphological changes, and impacted final film structure.

Boosting Monolayer Transition Metal Dichalcogenides Growth by Hydrogen-Free Ramping during Chemical Vapor Deposition.

The controlled vapor-phase synthesis of two-dimensional (2D) transition metal dichalcogenides (TMDs) is essential for functional applications. While chemical vapor deposition (CVD) techniques have been successful for transition metal sulfides, extending these methods to selenides and tellurides often faces challenges due to uncertain roles of hydrogen (H2) in their synthesis. Using CVD growth of MoSe2 as an example, this study illustrates the role of a H2-free environment during temperature ramping in suppressing the reduction of MoO3, which promotes effective vaporization and selenization of the Mo precursor to form MoSe2 monolayers with excellent crystal quality. As-synthesized MoSe2 monolayer-based field-effect transistors show excellent carrier mobility of up to 20.9 cm2/(V·s) with an on-off ratio of 7 × 107. This approach can be extended to other TMDs, such as WSe2, MoTe2, and MoSe2/WSe2 in-plane heterostructures. Our work provides a rational and facile approach to reproducibly synthesize high-quality TMD monolayers, facilitating their translation from laboratory to manufacturing.

Low-resistivity molybdenum-carbide thin films formed by thermal atomic layer deposition with pressure-assisted decomposition reaction

The rapid increase in the resistivity of thin metal films as their thickness decreases to sub-10 nm, known as the resistivity size effect, is an important issue that must be addressed to ensure device performance in ultraminiaturized semiconductor devices. Molybdenum carbide (MoCx) has been studied as a candidate for emerging interconnection materials because it can maintain a low resistivity even at a low thickness. However, reports on stable precursors with guaranteed reactivity for atomic layer deposition (ALD) remain limited; moreover, the process of forming low-resistance MoCx thin films must be studied. In this study, we propose a new route to form low-resistivity MoCx thin films by thermal ALD with partial ligand dissociation by controlling the process pressure to enhance the reactivity of the Mo precursor with reactants. Following the proposed deposition process and subsequent annealing, uniform and continuous thin films were formed (even at a sub-5 nm thickness), with an extremely low resistivity of approximately 130 μΩ cm. Therefore, the proposed method can be applied as a next-generation interconnect process; notably, high-quality thin films can be formed through pressure-assisted decomposition, even with a lack of thermal energy during the ALD process.

Polymer Supported Nitrogen-Bridged Symmetrical Binuclear Dioxidomolybdenum(VI) Complexes and Their Homogeneous Analogues as Potential Catalysts for Efficient Synthesis of 2-Amino-3-Cyano-4H-Chromenes/Pyrans.

Reaction of 2-chloromethyl-1H-benzimidazole with known intermediates (i-iii), prepared from diaminoguanidine hydrochloride with salicylaldehyde, 5-bromosalicylaldehyde or 3,5-di-tert-butylsalicylaldehyde, in the presence of triethylamine (NEt3) led to the formation of benzimidazole appended new ligands, H4L1-H4L3 (I-III). The homogeneous nitrogen-bridged symmetrical binuclear complexes, [(MoVIO2)2(L1)(H2O)2] (1), [(MoVIO2)2(L2)(H2O)2] (2) and [(MoVIO2)2(L3)(MeOH)2] (3) have been isolated by reacting these ligands with [MoVIO2(acac)2] in a 1 : 2 molar ratio in refluxing methanol. Using 1 : 1 (ligand to Mo precursor) molar ratio under above reaction conditions resulted in the corresponding mononuclear complexes, [MoVIO2(H2L1)(MeOH)] (4), [MoVIO2(H2L2)(H2O)] (5) and [MoVIO2(H2L3)(MeOH)] (6). The binuclear heterogeneous compounds [(MoVIO2)2(L1)(DMF)2]@PS (PS-1), [(MoVIO2)2(L2)(DMF)2]@PS (PS-2) and [(MoVIO2)2(L3)(DMF)2]@PS (PS-3) have been obtained by immobilization of 1-3 onto chloromethylated polystyrene (PS) beads. All synthesized ligands, homogeneous as well as supported compounds have been characterized by elemental analyses and various spectroscopic methods. Single crystal X-ray diffraction study of complexes 1 and 3 confirms their nitrogen-bridged symmetrical binuclear structures while 4 is mononuclear. Heterogeneous compounds (PS-1-PS-3) have further been studied by microwave plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy along with energy dispersive spectroscopy. These compounds (homogeneous and heterogeneous) were explored for catalytic applications to one-pot multicomponent reactions (MCRs) for efficient synthesis of biologically active 2-amino-3-cyano-4H-chromenes/pyrans (21 examples). Optimising various reaction parameters helped in achieving as high as 97 % yields of products. Though, only half equivalent of the binuclear complexes (1-3) was required compared to mononuclear analogues (4-6) to achieve comparable yields, heterogeneous catalysts have an added advantage due to their stability and recyclability. Suitable reaction mechanism has also been proposed based on isolated intermediates.

Controlled lattice deformation for high-mobility two-dimensional MoTe2 growth

Two-dimensional (2D) MoTe2 shows great potential for future semiconductor devices, but the lab-to-fab transition is still in its preliminary stage due to the constraints in the crystal growth level. Currently, the chemical vapor deposition growth of 2D MoTe2 primarily relies on the tellurization process of Mo-source precursor (MSP). However, the target product 2H-MoTe2 from Mo precursor suffers from long growth time and suboptimal crystal quality, and MoOx precursor confronts the dilemma of unclear growth mechanism and inconsistent growth products. Here, we developed magnetron-sputtered MoO3 film for fast and high-mobility 2H-MoTe2 growth. The solid-to-solid phase transition growth mechanism of 2D MoTe2 from Mo and MoOx precursor was first experimentally unified, and the effect mechanism of MSPs on 2D MoTe2 growth was systematically elucidated. Compared with Mo and MoO2, the MoO3 precursor has the least Mo-unit lattice deformation and exhibits the optimal crystal quality of growth products. Meanwhile, the lowest Gibbs free energy change of the chemical reaction results in an impressive 2H-MoTe2 growth rate of 8.07 μm/min. The constructed 2H-MoTe2 field-effect transistor array from MoO3 precursor showcases record-high hole mobility of 85 cm2/(V·s), competitive on-off ratio of 3×104, and outstanding uniformity. This scalable method not only offers efficiency but also aligns with industry standards, making it a promising guideline for diverse 2D material preparation towards real-world applications.

Facile fabrication of confined spaces with molybdenum atoms for fast oxidative desulfurization of fuel oil

Molybdenum-based heterogeneous catalysts are promising for oxidative desulfurization (ODS) of fuel oil. However, the catalytic activity is linked with the dispersibility of Mo atoms on appropriate carriers. Here, Mo-based mesoporous silica was constructed by using confined spaces of as-synthesized SBA-15 (AS), where Mo atoms are homogeneously dispersed. By utilizing facile solid phase grinding followed by calcination, the Mo precursor was introduced into the confined spaces between template and silica walls to form Mo-O-Si structure during which the template P123 was also released. Characterization results revealed that up to 5 wt% of Mo can be well dispersed while sever aggregation takes place in the catalysts derived from template free SBA-15(CS) at similar loading. Confined spaces and abundant hydroxyl groups played a significant role for Mo dispersion. The catalysts derived from AS showed superior ODS activity to their counterparts derived from CS and converted 100 % of DBT in 25 min at T = 30 °C, O/S = 5 and a catalyst dose of 0.1 g. The kinetic studies revealed that the DBT oxidation follow pseudo-first-order kinetic and the activation energy of DBT calculated via Arrhenius equation is 36.97 kJ/mol and 33.88 kJ/mol over Mo-AS and Mo-CS, respectively. The thermodynamic studies demonstrated that DBT oxidation is endothermic with positive Gibbs free energy, suggesting the non-spontaneity of ODS of DBT over Mo based catalysts. Furthermore, the stability and regeneration capability of Mo-AS made it promising for ODS technology for fuel oil.

Bifunctional phosphorus-doped NiMo oxide/Ni–Fe hydroxide composite for overall water electrolysis: optimized performance with exceptional stability

The achievement of outstanding catalytic activity in water electrolysis is contingent upon the presence of abundant active sites with enhanced kinetics in electrocatalysts. This study focuses on enhancing the catalytic activity of water electrolysis under alkaline conditions by designing P-doped NiMo oxide/Ni–Fe hydroxide composite on Ni foam through a straightforward hydrothermal process. The composite is further annealed with NaH2PO4 and subjected to induced growth via in situ precipitation in an oxalic acid solution containing Fe precursors. The resulting bifunctional catalysts exhibit notable catalytic performance, manifesting overpotentials of 20.5 mV and 69.4 mV for the hydrogen evolution reaction (HER) and 225.9 mV and 271.8 mV for the oxygen evolution reaction (OER) to drive 10 and 100 mA/cm2, respectively. The improved kinetics, attributed to P doping, play a pivotal role in reducing the overpotential of HER. Meanwhile, the homogeneous mixing of Ni and Fe, coupled with the large active surface area, enhances the catalytic performance of OER. The investigation of Mo precursors reveals their significant contribution to structurally shaping the catalysts, thereby influencing excellent OER performance. Collectively, these factors enable overall water electrolysis with low potentials of 1.82 V at 100 mA/cm2, underscoring the efficacy of the developed bifunctional catalysts.

The effect of sulfuration reaction rates with sulphur concentration gradient dependence on the growth pattern and morphological evolution of MoS2 in laminar flow.

Sulfuration reactions dominate the synthesis of transition-metal dichalcogenides via chemical vapor deposition. A neglected critical issue is the evolution of crystal domain morphology and growth models caused by boundary layer development. In this study, we propose two growth models within a laminar flow field to investigate the kinetic mechanism of uniformly grown MoS2. We used supercritical fluid pre-deposition to obtain a well-distributed and low-crystallinity Mo precursor on the surface of a substrate to avoid non-stoichiometric supply in sulfuration. The development of the boundary layer was suppressed through mainstream force by adjusting the substrate slope angle. For growth within the underdeveloped laminar boundary layer, monolayer MoS2 with a size of 50 μm uniformly distributed on the full substrate with R = 85% (relative change in boundary layer thickness). Moreover, the growth constrained by surface chemical reactions tended to promote spatially uniform growth. However, within the fully developed laminar flow, the crystal domains preferentially grew vertically, which was attributed to the excessive crystal growth rate (g). Our results provide new insights into the controllable preparation of two-dimensional materials.

Sulfur- and Nitrogen- Containing Molybdenum Films with a Thermally Stable Precursor

As devices become more and more complex with each generation, process requirements become more stringent and new materials are necessary. This also translates to the need of new precursors, in particular halide free organometallic precursors with high thermal stability. This combination prevents halide contamination/corrosion of the deposited and neighboring films, and expands the ALD window for processes. However, higher thermal stability should not compromise the reactivity of the precursors in the desired processes.We designed and successfully synthesized a new halide-free Mo precursor. It was characterized by 1H-, and 13C- NMR spectroscopy, and its molecular structure have been confirmed by x-ray crystallography. We studied its thermal stability, volatility, and chemical properties. Thermogravimetric analysis shows good volatility, with T½ of 230 oC and residual mass below 1%.Isothermal TGA at 130 °C indicates that the chemical is volatile and deliverable to the reaction chamber. Its thermal stress analysis showed that it is stable at 200 oC for more than 1 day, with ~1% residue mass. Pyrolysis experiments showed little decomposition at 475 °C.We used this precursor to attempt to deposit MoO, MoN and MoS based materials in mild conditions. ALD with NH3 afforded non uniform films with C contamination, and very low gpc. Similar results were obtained with H2O. On the other hand, films deposited with H2S were of uniform thickness with good gpc and selectivity for W over Si. The S content on the Mo-rich films was dependent on the deposition conditions and values as low as 6% could be obtained. Figure 1

Production of spherical Mo and Mo-Si powders by spray drying of Si suspension in a water-soluble Mo precursor

The study focuses on the production of molybdenum (Mo) and molybdenum-silicon (Mo-Si) powders using the spray drying method, followed by calcination and reduction steps. Mo powder was produced from an aqueous solution of ammonium hexamolybdate (AHM), while composite Mo-Si powders were produced from the same solution with suspended submicrometric Si particles. The as-sprayed powders were amorphous and had spherical hollow-shell morphology. In the case of Mo-Si composite powders, the powders had uniformly embedded Si aggregates on the surface. The spherical hollow-shell morphology of the powders was retained after calcination and reduction treatments. The observed chemical transition was AHM → MoO3 → Mo for Mo powders and AHM-Si → MoO3-Si → Mo-Si for composite powders. Extrusion tests demonstrated the suitability of the produced powders for extrusion-based additive manufacturing. The powders were extrudable at low load, resulting in stable filaments that stack layer by layer without deformation. The extruded filaments were then subjected to debinding and sintering processes, reaching an intermediate state of densification. Filaments fabricated from composite Mo-Si powders confirmed the alloying of Mo grains with Si during the sintering process.

Effects of inorganic seed promoters on MoS2 few-layers grown via chemical vapor deposition

In the last years, transition metal dichalcogenides (TMDs), especially at the two-dimensional (2D) limit, gained a large interest due to their unique optical and electronic properties. Among them, MoS2 received great attention from the scientific community due to its versatility, workability, and applicability in a large number of fields such as electronics, optoelectronics and electrocatalysis. To open the possibility of 2D-MoS2 exploitation, its synthesis over large macroscopic areas using cost-effective methods is fundamental. In this study, we report a method for the synthesis of large-area (∼cm2) few-layers MoS2 via liquid precursor CVD (L-CVD), where the Mo precursor (i.e. ammonium heptamolybdate AHM) is provided via a solution that is spin-coated over the substrate. Given the capability of organic and inorganic molecules, such as alkaline salts, to enhance MoS2 growth, we investigated the action of different inorganic salts as seed promoters. In particular, by using visible Raman spectroscopy, we focused on the effect of Na(OH), KCl, KI, and Li(OH) on the thickness, morphology, uniformity and degree of coverage of the grown MoS2. We optimized the process tuning parameters such as the volume of spin-coated solution, the growth temperature, and the seed promoter concentration, to synthesise the lowest possible thickness which resulted to be 2 layers (2L) of the highest quality. We witnessed that the addition of an inorganic seed promoter in the solution improves the extension of the grown MoS2 promoting lateral growth front, and therefore the degree of coverage. From this study, we conclude that, amongst the investigated seed promoters, K-based salts proved to grant the growth of high-quality two-layer MoS2 with optimal and uniform coverage of the SiO2/Si substrate surface.

Deposition and in-situ formation of nanostructured Mo2C nanoparticles on graphene nanowalls support for efficient electrocatalytic hydrogen evolution

To accelerate the transition to a green economy based on hydrogen, more efficient and cost-effective electrocatalysts should be adapted. Among them, transition metal carbides, particularly Mo2C, have gained significant attention within the scientific community due to their abundance and potential for high performance in the hydrogen evolution reaction (HER). This study introduces a bottom-up approach involving chemical vapor deposition, impregnation in solvent containing the Mo precursor and thermal annealing processes to carburize the Mo nanostructures anchored on vertical graphene nanowalls supports (GNWs). The role of GNWs is highlighted in the above processes. First, they provide abundant defective sites on their edges, which facilitate the binding of the metal compound molecules. Second, they provide C species during the annealing process which migrate and react with the transition metal to carburize it. Thus, they act as both C precursor and support system. Electrochemical characterization shows that the hybrids can be very efficient electrocatalysts towards hydrogen evolution reaction in acid electrolyte. When used as a cathode in a cell, it requires only − 141 mV to generate 10 mA/cm2 and shows excellent stability after hours of operation, making them highly promising for practical applications. This study paves the way for the design of hybrid nanostructures, utilizing nanocatalyst deposition on three-dimensional graphene supports. Such advancements hold great potential for driving the development of sustainable and efficient hydrogen production systems.

Plasma-enhanced atomic layer deposition of molybdenum carbide and carbonitride films using bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride and an H2/N2/Ar plasma

Molybdenum carbide (MoC) and molybdenum carbonitride (MoCN) films were successfully deposited by plasma-enhanced atomic layer deposition (PEALD) using bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride [(iPrCp)2MoH2] as the Mo precursor at temperatures of 200−400 °C. To obtain the MoC and MoCN films, 4%H2/96%Ar (H2/Ar) and 4%H2/96%N2 (H2/N2) plasmas were selectively used as co-reactants, respectively. PEALD MoC and MoCN exhibited atomic layer deposition temperature windows of 200−400 and 250−300 °C with growth per cycle of 0.012 and 0.047 nm/cycle, respectively. X-ray photoelectron spectroscopy revealed that the 300 °C-grown MoC film prepared using an H2/Ar plasma contained Mo–C bonds and an atomic composition of MoC0.77. In contrast, the 300 °C-grown MoCN film prepared using an H2/N2 plasma exhibited Mo–C and Mo–N bonds, with an atomic composition of MoC0.31N0.23. The atomic composition of the PEALD MoCN films varied depending on the deposition temperature; at 200 °C, the carbon-rich MoC0.52N0.16 film was obtained, whereas the MoC0.23N0.23 film with a carbon-to-nitrogen ratio of 1 was grown at a higher temperature of 400 °C. The 300 °C-grown MoC film was crystallized into a cubic δ-MoC phase, whereas the PEALD MoCN film showed diffraction peaks corresponding to the hexagonal MoC and molybdenum nitride (MoN) structures. The as-deposited PEALD MoC and MoCN films at 300 °C exhibited resistivities of 600 and 3038 μΩ cm, respectively, and post-deposition annealing at 700−800 °C resulted in significantly low resistivities of 37−203 μΩ cm due to the formation of metallic Mo films.

Effect of Mo Oxides on the Phase Composition and Characteristics of Mo-10Re Pre-Alloyed Powders Co-Reduced with NH4ReO4.

Mo-Re pre-alloyed powders are crucial raw materials in fabricating Mo-Re alloys, and their properties can significantly impact the properties of the resulting alloys. The powders are usually produced by the co-reduction of a mixture of Mo and Re oxides. However, it remains unclear if the overall characteristics of the produced Mo-Re powders rely on the different combinations of the Mo and Re oxide precursors. Therefore, in this work, a comparative study is conducted on the co-reduction processes of different Mo oxides together with NH4ReO4, along with its influence on the size distribution and phase composition of the resulting Mo-10Re pre-alloyed powders. The results show that MoO3 is more promising than MoO2 as a precursor material. The powders fabricated using MoO3, when compared to MoO2, have a much more uniform size distribution, with a primary particle size ranging from 0.5-4 μm. In addition, it is also beneficial to achieve atomic-scale homogeneous mixing with Mo and Re elements and the formation of a solely Mo(Re) solid solution if MoO3 is used as a precursor oxide. In contrast, such desirable features were not identified when using the MoO2 route. The reason for this discrepancy may relate to whether Mo-O-Re metallurgical bonding has formed during the co-reduction process.

Study on the Construction of Interlayer Adjustable C@MoS2 Fiber Anode by Biomass Confining and its Lithium/Sodium Storage Mechanism.

Building a stable and controllable interlayer structure is the key to improving the sodium storage cycling stability and rate performance of two-dimensional anode materials. This study explored the rich functional groups in bacterial cellulose culture medium in the way of biological self-assembly. Mo precursors were used to produce chemical bond in bacterial cellulose culture medium, and intercalation groups are introduced to achieve MoS2 localized nucleation and in situ localized construction of carbon intercalation stable interlaminar structure, thus improving ion transport dynamics and cycle stability. In order to avoid structural irreversibility of MoS2 at low potential, an extended voltage window of 1.5-4 V was selected for lithium/sodium intercalation testing. It was found that there was a significant improvement in sodium storage capacity and stability. During the electrochemical cycling process, in-situ Raman testing revealed that the structure of MoS2 was completely reversible, and the intensity changes of MoS2 characteristic peaks showed in-plane vibration without involving interlayer bonding fracture. Moreover, after the lithium sodium was removed from the intercalation C@MoS2 all structures have good retention.

Synthesis and characterization of volatile liquid Mo precursors for vapor phase deposition of thin films containing molybdenum

Volatile molybdenum precursors in liquid phase for vapor phase deposition of thin films containing molybdenum have been successfully synthesized. Heteroleptic liquid molybdenum precursors were prepared by treating MoCl5 with bidentate β-ketonate ligands such as 2,2,6,6-Tetramethyl-3,5-heptanedione (thdH) at different stoichiometric ratios (1:1 and 1:2). Molybdenum precursors in liquid phases also have been obtained via simple ligand-exchange reactions of Mo(thd)xCl4-x (x = 1 or 2) with LiNR2 (R = Et(C2H5), iPr(C3H7), SiMe3(Si(CH3)3)). The newly synthesized molybdenum precursors are readily miscible (soluble) in most organic solvents, such as acetonitrile, diethyl ether, and hexane. The chemical composition of these precursors has been characterized using Fourier-transform infrared analysis and nuclear magnetic resonance spectroscopy. The volatility and thermal stability of precursor compounds have also been investigated using thermogravimetric analysis and vapor pressure measurement. The strategy used in this experiment, which introduces bidentate ligands to the coordination sphere of the central molybdenum atom in MoCl5, improves the volatility and transferability of molybdenum precursors in gas-phase deposition processes by making them in a liquid phase.