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This study shows that the mechanical strength of the composite of Fe matrix and titanium carbide (TiC) ceramic particles is significantly enhanced with addition of molybdenum (Mo) atoms. TiC reinforced Fe (Fe-0.2C-7Mn) composites with and without Mo were fabricated by a liquid pressing infiltration (LPI) process and the effect of Mo on interfacial properties of TiC–Fe composite was investigated using atomic probe tomography (APT) analysis, molecular dynamics (MD) simulations, first-principle density functional theory (DFT), and thermodynamic calculations. First, DFT calculations showed that total energies of the Mo-doped TiC–Fe superlattices strongly depend on the position of Mo defects, and are minimized when the Mo atom is located at the TiC/Fe interface, supporting the probable formation of MoC-like interphase at the TiC/Fe interface region. Then, APT analysis confirmed the DFT predictions by finding that about 6.5 wt.% Mo is incorporated in the TiC–Fe(Mo) composite and that sub-micrometer thick (Ti,Mo)C interphase is indeed formed near the interface. The MD simulations show that Mo atoms migrate to the Mo-free TiC–Fe interface at elevated temperatures and the mechanical strength of the interface is considerably enhanced, which is in good agreement with experimental observations.

Two relatively simple synthetic procedures were developed for the synthesis of Pt–HxMoO3 composites. The obtained materials may be of interest as CO-tolerant catalysts for hydrogen-air fuel cells with proton-exchange membranes (PEMFCs). The first step of both syntheses was to prepare hydrogen molybdenum bronzes (HxMoO3) through the addition of Zn powder to acidic solutions containing Mo(VI) species. Two types of hydrogen-containing molybdenum bronzes were synthesized, namely, red bronze (x≈1.55) and green bronze (x≈2.0). The next step was the Pt deposition in a redox reaction between HxMoO3 and potassium tetrachloroplatinate (K2PtCl4) under open-circuit conditions that resulted in composite materials defined by aPt⋅b(HxMoO3). Numerous physical methods, including XRD, STEM, SEM, and XPS, were used to determine both the composition and structure of the catalysts. Platinum clusters were distributed over the surface of catalytically active support (HxMoO3) in both cases; however, the type of molybdenum bronze used for synthesis affects the size of Pt particles. Linear sweep voltammetry (LSV) was used to determine the regularities of both adsorbed carbon monoxide electrodesorption and dissolved CO electrooxidation. CO-tolerance of prepared composites was estimated using H2/100 ppm CO mixture under conditions of both an electrochemical cell and a membrane electrode assembly (MEA). The results of this work are promising, as they provide a relatively simple method for the synthesis of CO-tolerant catalysts. The understanding of the origin of the CO-tolerance is essential for the development of electrode materials that could be used in the real fuel cells.

To find a cocatalyst that can replace noble metals, fungal carbon dot (CD) modified molybdenum disulfide (MoS2) cocatalyst system was designed. The composites were prepared by hydrothermal and calcination methods with different ratios of CDs, MoS2 and nitrogen-rich carbon nitride (p-C3N5). p-C3N5 has excellent electronic properties, and MoS2 modified by CDs (D-MoS2) can significantly enhance the photocatalytic performance of p-C3N5 by improving the photogenerated electron migration efficiency. The experiments showed that the developed CDs/MoS2/C3N5 composites exhibited excellent performance in both photocatalytic hydrogen (H2) evolution and methylene blue (MB) degradation, with CMSCN5 (D-MoS2 with 5% mass fraction) showing the best photocatalytic activity. The corresponding H2 evolution rate of CMSCN5 was 444 μmol g-1 h-1 and 1.45 times higher than that of unmodified p-C3N5, by 120 min, the removal rate of MB was up to 93.51%. The 5 cycle tests showed that CMSCN5 had great stability. The high charge mobility and high density of H2 evolution active sites of MoS2 nanosheets, together with the electron storage and transfer properties of CDs can obviously improve electron migration and reduce the photogenerated carrier recombination on the p-C3N5 surface. The design and preparation of such composites offer broad prospects for the development of photocatalytic systems with noble metal-free cocatalysts.

Molybdenum silicides (Mo–Si) have attracted great interest owing to their good electrical conductivity, ultra-high melting point and well oxidation resistance. In this work, the controllable syntheses of Mo5Si3 and Mo3Si powders by silicothermic reduction of MoS2 in the presence of lime are studied for the first time. The internal mixture composed of MoS2 and Si is wrapped by sufficient CaO. After the reaction is finished, the synthesized molybdenum silicides can be easily separated from the desulfurization layer by peeling off the desulfurization product. The results show that Mo3Si and Mo5Si3 can be prepared at 1500 °C for the samples with the MoS2:Si molar ratio of 1:1.7 and 1:2.33, respectively. In addition, the results show that both SiS2 and SiS can be formed during the heating process. The thermodynamic analysis about the disproportionation reaction of SiS indicates that the existence of SiS2 depends on the partial pressure of SiS (PSiS) and temperature. Moreover, it is demonstrated that SiS2 is preferentially formed under low temperature conditions. As the temperature rises, it is much easier for SiS2 to react with Si to form SiS. Additionally, this work experimentally proves for the first time that SiS gas can directly reduce MoS2 to form MoSi2 and SiS2. Subsequently, the recovery of S in the desulfurization product was studied. S in MoS2 was first captured by CaO in the form of CaS (accompanied by Ca2SiO4 and Si). In order to solve this CaS containing desulfurization product which is detrimental to the environment, CaS in the desulfurization product is react with Fe2O3 and C to form FeS. This work provides new insights into the closed-loop capture and recovery of S in the process of extracting metals or metal compounds from sulfide ores.

Developing durable and efficient non-precious-metal based catalysts for oxygen evolution reaction (OER) is highly desirable in the field of electrocatalysis. In this work, a series of novel Mo anchored N-doped carbon catalysts (denoted as Mo/NC-T) were prepared starting from the zeolitic imidazolate framework 8 (ZIF-8) precursor. Firstly, Mo doped ZIF-8 precursor (Mo/ZIF-8) with a regular polyhedron structure was formed through a simple ion-exchange method process between molybdenum pentachloride (MoCl5) and ZIF-8. Afterward, Mo/ZIF-8 was converted to Mo/NC-T through a two-step calcination process in nitrogen (N2) and ammonia (NH3). The as-synthesized Mo/NC-T samples exhibited superior electrocatalytic OER properties. The optimal sample at 650 °C (Mo/NC-650) presented a low overpotential of 320 mV at 10 mA cm-2, a Tafel slope of 71 mV dec-1, and an outstanding long-term stability for 30 h in 1 M KOH solution. The remarkable OER activity of Mo/NC-T could be ascribed to the structural stability of carbon matrix and the synergistic effect between Mo3+ (derived from Mo-C bonds) and pyridinic N. This work provides a novel perspective on the roles of Mo species in the N-doped carbon electrocatalysts for OER.

Graphical abstract A facile fabrication of MoOxSy-CoPI photocatalyst revealed a conformal growth of nanoflowers. The photoelectrochemical studies exhibited significantly enhanced photocurrents with a stable and repeatable photocurrent response under visible light (1SUN) simulated solar irradiation., Highlights • Facile synthesis of Molybdenum oxysulphide-cobalt phosphate (MoOxSy-CoPi) novel material for solar water splitting. • The MoOxSy-CoPI photocatalyst corresponded to the most stable oxidation states of Mo, Co, S, P, and O in the composite. • Nanoflowers of MoOxSy-CoPI showed controlled thickness up to ∼10 nm, and variable interspaces of 200-400 nm were produced. • Band-gap energy of 2.44 eV and significantly higher (7-8 folds) photocurrent density of MoOxSy-CoPI is recorded compared to MoOxSy and CoPI., Introduction Hydrogen is considered as a clean alternative green energy future fuel. Since the Honda-Fujishima effect for photoelectrochemical water splitting is known, there has been a substantial boost in this field. Numerous photocatalysts based on metals, semiconductors, and organic-inorganic hybrid-systems have been proposed. Several factors limit their efficiency, e.g., a stable PEC-WS setup, absorbing visible light, well-aligned band energy for charge transfer, electrons and holes, and their separation to avoid recombination and limited water redox reactions. Metallic doping and impregnation of stable and efficient co-catalysts such as Pt, Ag, and Au showed enhanced PEC-WS. We used Cobalt-based co-catalyst with molybdenum oxysulfide photocatalyst for effectual solar-driven water splitting. Objectives To develop photocatalysts for efficient PEC processes capable of absorbing sufficient visible light, good band energy for effective charge transfer, inexpensive, significant solar-to-chemical energy conversion efficiencies. Above all, it is developing such PEC-WS systems that will be commercially viable for renewable energy resources. Methods We prepared Molybdenum oxysulphide-cobalt phosphate photocatalyst for PEC-WS through a facile hydrothermal route using ammonium heptamolybdate, thiourea, and metallic Cobalt precursors. Results An effectual photocatalyst is produced for solar-driven water splitting. The conformal morphology of MoOxSy-CoPi nanoflowers is a significant feature, as observed under FE-SEM and HR-TEM. XRD confirmed the degree of purity and orthorhombic crystal structure of MoOxSy-CoPi. EDX and XPS identify the elemental compositions and corresponding oxidation states of each atom. A 2.44 eV band-gap energy is calculated for MoOxSy-CoPi from the diffused reflectance spectrum. Photo- Electrochemical Studies (PEC) under 1-SUN solar irradiation revealed 7-8 folds enhanced photocurrent (∼ 3.5 mA/cm2) generated from MoOxSy-CoPi/FTO in comparison to Co-PI/FTO (∼ 0.5 mA/cm2) and MoOxSy-/FTO respectively, within 0.5 M Na2SO4 electrolyte (@pH=7) and standard three electrodes electrochemical cell. Conclusion Our results showed MoOxSy-CoPi as promising photocatalyst material for improved solar-driven photoelectrochemical water splitting system.

Metallic carbides demonstrated tremendous application potential in energy conversion field deriving from their distinctive electrochemical activity and chemical stability. Herein, a molybdenum-based hybrid self-template strategy was adopted to confine ultrafine molybdenum carbides and tungsten carbides nanoparticles in N, P-codoped carbon nanotubes (MoC/WC@N, P-CNTs) for enhanced lithium-ion storage. Specifically, hierarchical MoW-polydopamine nanotubes were prepared via a self-template strategy, which employed Mo3O10(C6H8N)2·2H2O nanowires as the template. Ultrafine MoC and WC nanoparticles embedded in ultrathin carbon nanosheets could be obtained rationally after carbonization treatment, which could not only prevent carbides nanoparticles from agglomeration and oxidation, but also endow the rapid electron transfer rate. Thus, MoC/WC@N, P-CNTs displayed outstanding lithium storage abilities with great rate property and long-term cycling durability. The stable specific capacity of 475.0 mAh g−1 could be preserved at high current intensity of 5.0 A g−1 after 1000 cycles, which was one of the best performances for metal carbides anodes. Furthermore, the successful fabrication of lithium-ion hybrid capacitors (LIHCs) delivered the maximum energy density of 117 Wh kg−1 and power density of 6571 W kg−1. Moreover, the superior capacity retention of 89.7 % after 2000 cycles also indicated the excellent cycling stability. The present work highlights a self-template strategy for designing nanostructures toward efficient energy storage and conversion fields.

Loss of fracture resistance due to thermal aging degradation is a potential limiting factor affecting the long-term (80+ year) viability of nuclear reactors. To evaluate the effects of decades of aging in a practical time frame, accelerated aging must be employed prior to mechanical characterization. In this study, a variety of chemically and microstructurally diverse austenitic stainless steels were aged between 0 and 30,000 h at 290–400 °C to simulate 0–80+ years of operation. Over 600 static fracture tests were carried out between room temperature and 400 °C. The results presented include selected J-R curves of each material as well as K0.2mm fracture toughness values mapped against aging condition and ferrite content in order to display any trends related to those variables. Results regarding differences in processing, optimal ferrite content under light aging, and the relationship between test temperature and Mo content were observed. Overall, it was found that both the ferrite volume fraction and molybdenum content had significant effects on thermal degradation susceptibility. It was determined that materials with >25 vol% ferrite are unlikely to be viable for 80 years, particularly if they have high Mo contents (>2 wt%), while materials less than 15 vol% ferrite are viable regardless of Mo content.

Refractory high-entropy alloy nanocomposites (HEA-NPs) are important class of materials with unique structure and potential applications. Although several synthetic methods have been reported, developing novel routes to prepare nanoscale HEA-based catalysts facilely is still urgently desired. This work takes advantage of confinement assisted arc and plasma shock (APS) to prepare a series of HEA-NPs by regulating the type and proportion of metal precursors. The phase constitutes and morphology of the HEA-NPs are fully characterized. The prepared refractory HEA-NPs possesses five highly dispersed metal components, including titanium (Ti), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo) and simultaneously exhibits an uniform hexagonal morphology of nanocrystals. By taking advantage of its unique corrosion resistance, TiNbTaCrMo HEA-NPs can function as a promising candidate for electrocatalytic hydrogen evolution reaction (HER) in natural seawater. And its catalytic performance after alloying is significantly enhanced compared with the elemental metal. Theoretically, the promoted HER activity can be attributed to the strong adsorption for the various metal components in HEA-NPs caused by the upshifting d-band center close to the Fermi level. Furthermore, this confinement strategy can be further extended to synthesize other HEA-NPs. Our strategy provides a novel method to synthesize various HEA-NPs for further catalytic application.

Herein, a simple and fast laser-assisted coupling method is used for preparation of rod-like carbon-coated Mo/MoO2 hybrids at room temperature and air environment. Under high energy of laser and reductive atmosphere caused by precursor decomposition, Mo-polydopamine complex-wrapped MoO3 rods are quickly converted into nitrogen-doped carbon-coated Mo/MoO2 rods. Carbon-coated Mo/MoO2 exhibits high surface area, uniform metal dispersion and appealing hydrogen evolution reaction (HER) catalytic performance in a wide pH range. Carbon-coated Mo/MoO2 shows overpotential of 134, 108 and 164 mV to deliver current density of 10 mA cm-2 under alkaline, acidic and neutral solution, respectively. Theoretical calculation demonstrates that combination of Mo and MoO2 into Mo/MoO2 composite favors the dissociation of water and adsorption of hydrogen. This study not only provides a high-efficiency strategy for preparation of electrocatalysts but also give guidance for development of hybrid electrocatalysts for HER.

Selective laser melting (SLM) is an additive manufacturing process in which layers of metallic powder are selectively melted and fused by a high-powered laser to form near-fully dense 3D components. The SS316L is an austenitic chromium-nickel stainless steel containing a deliberate amount of molybdenum which increases general corrosion resistance and especially improves its pitting resistance to chloride ion solutions. The importance of process parameter such as layer thickness and orientation of specimen on the hardness and microstructure are being explored. Hence, it is essential to carry out research in that direction. The aim of the study is to understand the effect of layer thickness and angle orientation on hardness of the material as it is one of the desirable properties for SS316 material. The excellent hardness (218.835 BHN) was attained at the angle orientation of 90° and layer thickness of 40 µm according to ANOVA analysis.

Searching for non-noble-metal cocatalyst for hydrogen evolution in photocatalytic water–splitting has attracted much attention. Herein, molybdenum phosphide (MoP) as an efficient and stable cocatalyst was prepared in a facile phosphorization process at relatively low temperatures under N2 atmosphere, and the effect of preparation temperature (300–500 °C) was studied. Using Eosin Y (EY) and the prepared sample as catalyst (sensitizer) and cocatalyst, respectively, the photocatalytic activity for hydrogen evolution was investigated in aqueous trimethylamine (TMA) solution under visible light irradiation (λ ≥ 420 nm). MoP prepared at 400 °C (MoP-400) exhibits the highest sensitization activity and superior stability, and the maximal apparent quantum yield (AQY) for hydrogen evolution is up to 48.0% at 420 nm, much higher than the most reported data for MoP-based photocatalysts. The highest activity can be attributed to the highest P content in MoP-400 and the rapidest electron transfer between photoexcited EY and MoP-400. The possible mechanism was discussed.

Monolayer molybdenum di-selenide (1L-MoSe2) stands out in the transition metal dichalcogenide family of materials as an outlier where optical generation of valley polarization is inefficient. Here we show that using charge doping in conjunction with an external magnetic field, the valley polarization of 1L-MoSe2 can be controlled effectively. Most remarkably, the valley polarization can be tuned to negative values, where the higher energy Zeeman mode emission is more intense than the lower energy one. Our experimental observations are interpreted with valley-selective exciton-charge dressing that manifests when gate induced doping populates predominantly one valley in the presence of Zeeman splitting.

Significant efforts have been directed towards the use of transition metal nitrides as electrocatalysts for hydrogen evolution reaction (HER). Molybdenum nitride, despite its promise for scalable production, suffers from the bottleneck of poor catalytic activity. Furthermore the kinetics of water dissociation process ought to be improved for enhancing its potential. Here, we report a facile method for the incorporation of trace amount of Pd nanoparticle into Mo3N2 nanobelts (0.75Pd/Mo3N2,) for enhanced HER in both acidic and alkaline solutions. When employed for HER, the 0.75 wt%Pd/Mo3N2 nanobelt delivers excellent catalytic activity with overpotentials of 45 and65 mV in 0.5 M H2SO4 and 1 M KOH at a current density of 10 mA cm-2. As-prepared 0.75 wt%Pd/Mo3N2 displays a smaller Tafel slope and offers substantial stability in both acidic and alkaline media under the same operating conditions. The improved performance of the as-prepared 0.75 wt%Pd/Mo3N2 points to fast charge transfer, higher electrical conductivity and synergistic effects between Pd and Mo. This work displays a direct method for reducing the use and cost associated with use of platinum-group metals while also delivering superior HER catalytic performance.

Role of specific catalysts system is still a thrust area for the synthesis of carbon nanotubes. Titania-supported Fe and Co catalysts were prepared using the sol-gel and wet-impregnation method. These catalysts were used for the deposition of multiwalled carbon nanotubes (MWNTs) from xylene by the catalytic chemical vapour deposition (CCVD) technique at 800 °C. In the present work, the effect of the addition of molybdenum with monometallic catalyst had been investigated from the viewpoint of the growth of the carbon nanotubes (CNTs). The results showed that the presence of molybdenum in minor amount with Fe/Co-based catalysts can increase the amount of deposition of CNTs. CNTs-Epoxy resin composites were fabricated using prepared carbon nanotubes with a CNTs loading of 0.2 wt% and performed flexural testing measurement. These multi-components systems of titania and carbon nanotubes have a capacity to enhance many properties significantly for specific applications.

In this paper, Inconel 600 alloy has been cut by water-mist wire-cut electrical discharge machining (WEDM) using a molybdenum wire tool. A little amount of tap water mixed with pressurized air (water-mist) was used to provide the dielectric insulation medium in the plasma zone. A new experimental arrangement has been made to conduct the near-dry WEDM using input parameters of the Current (K), Pulse-duration (PD), Pulse-pause time (PP), and flow rate (FR) of mixing tap water to predict the cutting speed (CS) and surface irregularity (SI). It was discovered that pulse-duration and current increase the CS and SI; conversely, the PT minimizes the CS and SI. The highest CS and SI are achieved by the highest flow rate of the tap water due to the quick flushing of debris. The percentage of contributions of K, PD, PP, and FR on CS is 20.94%, 22.22%, 47.86%, and 8.97% respectively and the percentage of contributions of K, PD, PP, and FR on SI is 17.06%, 39.1%, 26.50 %, and 17.34% respectively.

Aluminium matrix composites (AMCs) find a wide spectrum of application in various fields of engineering and technology. Owing to the below par inherent characteristics of unreinforced AMCs, reinforcements are used to improve the characteristics of AMCs. Reinforcing the self-lubricating graphite (Gr) and molybdenum disulphide (MoS2) in aluminium matrix was found to improve the machinability and surface finish of the composites which in turn enhances the application prospects. In the current investigation, aluminium alloy 2219 (AA2219) was reinforced with Gr and MoS2 and the composites were fabricated by conventional casting technique. Drilling behavior of the composites were investigated by conducting drilling experiments in CNC machining center and surface roughness of the holes were measured. Experiments were designed by full factorial method. Results of the experiments portrayed that the composites with Gr as reinforcement exhibited better drilling behavior when compared with MoS2 reinforced AA2219 composites.

We describe the design of a new ion source that combines a hot filament hollow cathode source with a sputtering source. This combination makes it possible to provide ion beams of a wider range that previously could not be used due to respective high melting points and low vapor pressure of the needed elements. We demonstrate the sources viability for molybdenum, cobalt, niobium and the rare-earth element gadolinium. An implantation current of 20–900 nA on the sample, depending on the element, could be achieved. Moreover, we experimentally prove that these ion beams are suitable for ultra-low energy implantation into 2D materials like graphene and transition metal dichalcogenides (TMDs). Furthermore, computational studies were conducted to investigate the ion trajectories within the source and ion implantation into 2D materials. RBS and PIXE measurements were performed to quantitative investigate the implanted samples.

The formation of substitutional and interstitial diluted defects of tantalum, niobium and molybdenum in a tetragonal zirconia (T-ZrO2) crystal was studied with Density Functional Theory calculations. Bader charge analysis was used to select the oxidation states (OS) which reached electronic localization around the substitutional ion. Oxidation states from +5 to +3 for Nb, +6 to +2 for Mo and +5 to +3 for Ta substitution ions were selected and formation energies were calculated. The work is focused on substitutional defects, after confirmation that substitutional defects produce higher stability than interstitial ones. Comparing the whole calculation set, it was found that Ta charge defects with oxidation state +5 ( T a Z r ∗ ) exhibiting less available electrons than the replaced Zr ion, presented the minimum formation energy. Kroger-Vink diagrams evidence that T a Z r ∗ has indeed the lowest formation energy values over the entire range of electron chemical potential. Electronic redistribution due to the substitution of Zr by a charged Ta ion results in an enhanced covalent bond between Ta and nearest O ions and charge polarization between Ta ion and the next nearest O ions along 〈111〉 and 1 - 1> directions. The results are of great technological incidence, asserting that Ta addition to zirconium nuclear alloys could improve its corrosion resistance properties.

Molybdenum disulphide (MoS2) filled polypropylene (PP) composites were prepared using the horizontal ball milling machine followed by injection moulding. The content of MoS2 was varied from 0 to 7.12 vol.%. Scanning electron microscopy showed good dispersion and adhesion of MoS2 with the PP matrix. Experimental density of the composites prepared by horizontal ball milling was close to the theoretical density. Impact energy and Impact toughness were increased by 62.50% to pure PP matrix up to 4.28 vol% MoS2, and then it decreases as it reaches to 7.12 vol% of MoS2. It was found that the addition of 4.28 vol% MoS2 into PP matrix could improve the tensile strength by 11%. Limiting oxygen Index value increases up to 21.3% from 18% (pure PP) which indicates that, composites are fire resistant for their application.

In the interesting class of transition metal oxides, molybdenum oxides and its derivatives are exceptionally anticipated because of their particular optical and structural properties. At room temperature, molybdenum trioxide is a wide band gap semiconductor with enhanced exciton binding energy. In nature, MoO3 in three forms which are α, β and h-forms (α-orthorhombic, β-monoclinic, h- hexagonal phase). The synthesis and material properties of α-MoO3 nano crystals are reported under this study. Localized surface Plasmon resonance is a resonance with incident light of co-operative oscillations of free charge carriers in nano range material (LSPR). Such kind of plasmonic interactions exhibit by MoO3 nanoparticles due to movement of electron at different defect states. This concept has been used in to several functional materials and devices. We efficaciously synthesised α-MoO3 by one-pot hydrothermal route. Arranged nano sheet like structure was found as assured by FESEM. The synthesised nanostructure revealed noble optical and structural properties which was confirmed by X-ray diffraction (XRD), Field emission Scanning electron microscopy (FESEM), Ultra violet-Visible technique (UV–VIS), Fourier transform Infra-red (FT-IR) data. Energy dispersive X-ray spectrum (EDS) showed elemental composition present in synthesized material with no contaminants.

During the past decades, lithium-sulfur batteries have obtained great attention due to their advantages as energy storage systems, which have high specific capacity and energy density. However, the real applications were hindered by many challenges, especially the shuttle effect of the polysulfide from the cathode to the anode side. This is attributed that the traditional PP films could not prevent the polysulfide migration from the cathode to the anode side. Therefore, it is an efficient method to develop a modified film, which could inhibit the polysulfide shuttle effect. Based on this idea, we prepared molybdenum sulfide–modified (MS modified) film as separators in the lithium-sulfur batteries, which were obtained by coating the molybdenum sulfide on the surface of the traditional PP films. The electrochemical results indicate that the Li–S battery by using MS–modified films exhibits excellent electrochemical performance.

Although 2H molybdenum disulfide (MoS2) layers are highly desirable for hydrogen evolution reaction (HER) owing to their high chemical stabilities and low cost, the inert basal plane and semiconducting nature severely hinder their practical applications. Here, the catalytic activities of 2H phase molybdenum-based compounds are unlocked via topological conversion reaction from Mo2GeC MAX phase to accordion-like molybdenum phosphosulphide. During the conversion reaction, phosphorus atoms can be implanted into the sandwich-like S-Mo-S planes and gradually substitute sulfur atoms, which are beneficial to optimize the electronic configuration and facilitate to absorb water molecules, unlocking the inert basal planes of 2H phase molybdenum-based compounds. The accordion-like molybdenum phosphosulphide exhibits high hydrogen production rates up to 288 mmol g−1 h−1 cm−2 at a high loading of 3 mg cm−2 and ultralong durability up to 35,000 cycles, satisfying the practical application for HER.

Phosphomolybdate-based nanoparticles (PMo12-based NPs) have been commonly applied in nanomedicine. However, upon contact with biofluids, proteins are quickly adsorbed onto the NPs surface to form a protein corona, which induces the opsonization and facilitates the rapid clearance of the NPs by macrophage uptake. Herein, we introduce a family of structurally homologous PMo12-based NPs (CDS-PMo12@PVPx(x = 0 ~ 1) NPs) capping diverse content of zwitterionic polymer poly (N-vinylpyrrolidone) (PVP) to regulate the protein corona formation on PMo12-based NPs. The fluorescence quenching data indicate that the introduction of PVP effectively reduces the number of binding sites of proteins on PMo12-based NPs. Molecular docking simulations results show that the contact surface area and binding energy of proteins to CDS-PMo12@PVP1 NPs are smaller than the CDS-PMo12@PVP0 NPs. The liquid chromatography-tandem mass spectrometry (LC–MS/MS) is further applied to analyze and quantify the compositions of the human plasma corona formation on CDS-PMo12@PVPx(x = 0 ~ 1) NPs. The number of plasma protein groups adsorption on CDS-PMo12@PVP1 NPs, compared to CDS-PMo12@PVP0 NPs, decreases from 372 to 271. In addition, 76 differentially adsorption proteins are identified between CDS-PMo12@PVP0 and CDS-PMo12@PVP1 NPs, in which apolipoprotein is up-regulated in CDS-PMo12@PVP1 NPs. The apolipoprotein adsorption onto the NPs is proposed to have dysoponic activity and enhance the circulation time of NPs. Our findings demonstrate that PVP grafting on PMo12-based NPs is a promising strategy to improve the anti-biofouling property for PMo12-based nanodrug design. Graphical Abstract

The mixed powders of TiH2, molybdenum, aluminum and graphite with molar ratios of 2/2/n/2.85 (n ranges from 1.0 to 1.4 mol with an interval of 0.1 mol) were used as raw material powders for this work, and a novel porous Mo2Ti2AlC3 was synthesized via reactive synthesis. Through systematic research on the pore structure parameters of porous Mo2Ti2AlC3 prepared with different aluminum content, the results show that there is a clear correlation between the aluminum content and the pore structure parameters. With the aluminum content rising from 1.0 to 1.2 mol, the viscous permeability coefficient and pore size decreased, while the porosity increased; When the aluminum content increased from 1.2 to 1.4 mol, the pore structure parameters of porous Mo2Ti2AlC3 displayed an opposite trend. The reasons for the evolution laws of these pore structure parameters were also discussed in depth. In addition, the pore structure forming mechanism of porous Mo2Ti2AlC3 ceramics during the activation reaction sintering process has been explored. This work can provide an important reference for the subsequent preparation of quaternary porous MAX phase ceramics.

The results of studies of the thermal stability of materials operating in a plasma jet at high temperatures and a sharp change in thermal loads are presented. It has been proven that the use of plasma generators with the introduction of various powder materials makes it possible to simulate the operating conditions of parts in high-temperature gas flows with heated particles. The effect of the introduced powder materials on the thermal stability of samples prepared by plasma spraying from molybdenum, as well as tungsten and tungsten-based compositions is investigated. An installation is proposed for assessing the thermal stability of composite materials and protective hardening coatings operating under high-temperature gas flows, which makes it possible to determine their erosion resistance.

Two-phase titanium-based alloys are widely used in aerospace and biomedical applications, and they are obtained through phase transformations between a low-temperature hexagonal closed-packed α-phase and a high-temperature body-centred cubic β-phase. Understanding how a new phase evolves from its parent phase is critical to controlling the transforming microstructures and thus material properties. Here, we report time-resolved experimental evidence, at sub-angstrom resolution, of a non-classically nucleated metastable phase that bridges the α-phase and the β-phase, in a technologically important titanium–molybdenum alloy. We observed a nanosized and chemically ordered superstructure in the α-phase matrix; its composition, chemical order and crystal structure are all found to be different from both the parent and the product phases, but instigating a vanishingly low energy barrier for the transformation into the β-phase. This latter phase transition can proceed instantly via vibrational switching when the molybdenum concentration in the superstructure exceeds a critical value. We expect that such a non-classical phase evolution mechanism is much more common than previously believed for solid-state transformations. A full kinetic pathway of a non-classical nucleation-induced phase transformation through metastable states is elucidated at sub-angstrom resolution in a technologically important titanium alloy.

The Mo6 cluster which has the great optical properties and chemical activity because of their unique electronic structure have been attracted attention in many fields such as phosphor and photocatalyst. However, the Mo6 cluster it’s hard to recycling which limited its industry application because of its such small nanoscale. Immobilizing the Mo6 cluster on 2-D material has a great value to challenge it. In this research, we study on the sulfurization process of Mo6Br12 cluster to investigate the more possibility of the immobilization of Mo6 cluster.

In this research, the reduction mechanism of Nb(V) under various [F−]/[Nbn+] ratios (α) was investigated by a series of electrochemical techniques, such as square wave voltammetry (SWV) and chronopotentiometry (CP). We previously studied the electrode reduction process of Nb(V) and revealed that was Nb(V) → Nb(III) → Nb(I) → Nb in NaCl-KCl molten salt. It was found in this research that the electrode reduction process of Nb(V) ion was shortened to Nb(V) → Nb(III) → Nb when α was equal to 1.0; furthermore, the electrode reduction process of Nb(V) ion transforms to Nb(V) → Nb(IV) → Nb when α was greater than or equal to 5.0. Moreover, the reaction mechanism was also discussed in this work. Metallic niobium was collected on a molybdenum electrode under the condition of higher fluoride content after electrolysis in the melt.

Benefiting from the low cost and excellent stability, transition metal dichalcogenides (TMDs) have been widely applied in electrocatalysis for hydrogen evolution. As a member of TMDs, molybdenum di...

Scalable synthesis of one-dimensional molybdenum chalcogenides with tunable electronic properties may be critical for the development of nanoscale electronic device components as well as functional...

Pure niobium substrates were coated using laser cladding method. Pure molybdenum, Yttria Stabilized Zirkonia (YSZ) and corundum (Al2O3) powders were used as coating materials. Coatings were deposited on specimens as seperate paths with 3÷10mm width and 40mm of length. Two different laser power 3kW and 4kW were tested during deposition. In order to assess the quality of the Mo-YSZ and Mo-Al2O3 coatings, the light microscopy, Scanning Electron Microscopy (SEM), chemical analysis (EDS) and Vickers hardness test investigation were performed. The surface roughness and wear volume were also measured. As a result of YSZ-Mo powder cladding on the Nb substrate the composite layers were obtained without cracks and porosity not exceeding 1 μm. In addition, an increase in hardness of about 450 HV0.5 was revealed. As a result of Al2O3-Mo powder cladding on the Nb substrate the composite layers with many voids and cracks were obtained for each of the cladding variants.

Developing new low-cost and efficient proton-conducting materials remains an attractive and challenging task. Herein, sodium molybdate dihydrate is used as the source of molybdenum, mixed with transition metal chloride and 2-methylimidazole (2-MI), using the "one-pot method" to synthesize two crystalline proton conducting materials based on {P4Mo6} units: H14[C4H6N2]2[M(H2O)5] [M(H2O)2]2{M[(PO3)3(PO4)Mo6O15]2}·4H2O (M=Co and Fe) (1–2). Different from the common {P4Mo6}, we use H3PO3 to adjust the pH value, resulting in two different coordination modes of P atoms in the crystal structure. The structure is expanded into three-dimensional network by metal ions. At 75 °C and 98% relative humidity, the proton conductivity of compounds 1 and 2 are 1.33 × 10–2 S·cm−1 and 1.03 × 10–2 S·cm−1, respectively. The high proton conductivity is mainly attributed to the free state of 2-methylimidazole as the proton carrier, which has a fast migration rate. At the same time, 2-methylimidazole, coordination water, and {P4Mo6} anion form a hydrogen bond network to provide multiple pathways for the transmission of protons.

Reversing the thermal induced sintering phenomenon and forming high temperature stable fine dispersed metallic centers with unique structural and electronic properties is one of the ever-lasting targets of heterogeneous catalysis. Here we report that the dispersion of metallic Ni particles into under-coordinated two-dimensional Ni clusters over γ-Mo2N is a thermodynamically favorable process based on the AIMD simulation. A Ni-4nm/γ-Mo2N model catalyst is synthesized and used to further study the reverse sintering effect by the combination of multiple in-situ characterization methods, including in-situ quick XANES and EXAFS, ambient pressure XPS and environmental SE/STEM etc. The under-coordinated two-dimensional layered Ni clusters on molybdenum nitride support generated from the Ni-4nm/γ-Mo2N has been demonstrated to be a thermally stable catalyst in 50 h stability test in CO2 hydrogenation, and exhibits a remarkable catalytic selectivity reverse compared with traditional Ni particles-based catalyst, leading to a chemo-specific CO2 hydrogenation to CO., Reversing the thermal induced sintering phenomenon and forming high temperature stable fine dispersed metallic centers is one of the ever-lasting targets in heterogeneous catalysis. Here the authors report the dispersion of metallic Ni particles into under-coordinated two-dimensional Ni clusters over γ-Mo2N.

The synthesis of two-dimensional molybdenum disulfide (MoS2) has invoked much research interest in recent years. In this work, chemical vapor deposition (CVD) was employed to grow a novel molybdenum disulfide. The synthesis reaction was operated in an inert gas environment, with the sulfur precursor placed in the upstream zone of a double zone tube furnace, and the molybdenum trioxide (MoO3) precursor placed in a small tube in the downstream zone. A piece of glass was used as the substrate, which was placed beside the small tube. We intentionally built a high concentration of molybdenum precursor above the substrate. The specific morphology hinged highly on the concentration of molybdenum. Abundant molybdenum atoms adsorbed on the edges of the bottom MoS2 and formed defects, which promoted the nucleation of the top layer MoS2 and preferentially grew from the edges. This result provides an innovative method to controllably synthesize novel bilayer molybdenum disulfide by a one-step method of chemical vapor deposition.

The α phase Mo carbide has been widely investigated recently for its high activity in hydrogen production from water gas shift (WGS) reaction. However, high loading of noble metals as well as high economic and environmental cost derived from high-temperature ammonification and carbonization process will lead to high cost of hydrogen production. Thus, the efficient controlling of phase transfer is promising. Herein, metals (Au, Pt, Rh, Cu) with a wide range of loadings were impregnated on flame spray pyrolysis (FSP) made MoO3 to produce Mo carbides by one-step carbonization. A breakthrough high metal-normalized hydrogen production rate of 213 mmol H2·gmetal−1·s−1 was achieved on 0.025 wt% Rh/MoCx, which was much higher than Pt and Au based Mo carbides ever reported. The addition of trace Rh induced direct MoO3 transformation to high purity α-MoC1-x in one-step carbonization instead of two-steps ammonification and carbonization process. In comparison to Rh, the addition of Pt, Au and Cu tend to transfer MoO3 into β-Mo2C at the same conditions. Besides, the one with 2 wt% Rh exhibited high stability in WGS reaction even at high temperature (300 °C) due to its inhibition on carbides oxidation induced by H2O. We demonstrate that it is feasible to control phase transfer of Mo carbides even by trace amount of metals to simplify the production process of catalysts. The catalytic performance improved by Rh in aspects of both activity and stability provides a guide for producing more stable Mo carbides catalysts.

There is a challenge to increase the application range of chalcogenide materials due to the fixed photoelectric properties and complex preparation process. To solves the problem, bulk ceramics with different doping ratios should be investigated. Here, the influence of the doping ratio of molybdenum MO and Ga oxide on the composition, structure, morphology and luminescence properties of bulk ceramics is studied, the optimal doping ratio in this range is determined by analysis of mass loss and volume shrinkage. The cubic crystal structure is confirmed by X-ray diffraction results. The results showed that molybdenum was successfully doped Mo into the matrix material is revealed by Raman spectroscopy. The X-ray fluorescence is used to study the composition ratio changes of bulk ceramics before and after sintering. The molecular structure model of Mo–ZnSe/ZnS with different concentration is constructed. The X-ray photoelectron spectroscopy shows the spin orbits of Zn 2p and S 2p, as well as the +3 valences in terms of Mo and Ga. The optical performance is enhanced the light-emitting band is enlarged to the near infrared region. All the work suggest that this new compound has an improved micro-structural, optical and electrical properties. This research can provide theoretical and experimental reference for the doping research of chalcogenide materials and new optoelectronic devices.

To overcome the absence of sodium (Na) and to prevent undesired impurity diffusion from stainless steel (STS) substrates, a bi-layer molybdenum (Mo) structure consisting of a 1- μ m-thick Mo and Na-doped Mo (Mo:Na) with variable thickness was utilized as the back contact layer in copper–indium–gallium–selenide (CIGS) solar cells. Na ions were supplied to the CIGS absorber layer from the Mo:Na layer, and the amount of Na ions was controlled by changing the thickness of Mo:Na layer. The Na doping to the CIGS layer is verified by the X-ray photoelectron spectroscopy (XPS) and the dynamic secondary ion mass spectroscopy (D-SIMS). The recombination process in the bulk CIGS and the CdS/CIGS junction has been analyzed by temperature dependent current density–voltage (J–V–T) measurement. The D-SIMS showed that the amount of Na ions in the CIGS layer grown on Mo/Mo:Na/STS is comparable with that in the conventional CIGS film deposited on Mo coated soda-lime glass. Moreover, the bi-layer Mo also acts as a diffusion barrier layer against the Fe atoms, which deteriorate the quality of CIGS. The higher content of Na ions and the lower content of Fe ions in the CIGS layer lowered the recombination activation energy, series resistance and ideality factor, leading to improved junction quality. As a result, the short circuit current density and power conversion efficiency of the CIGS on the Mo and 600-nm-thick Mo:Na were improved by 8.1 and 69.4%, respectively, compared with those of CIGS solar cells fabricated without a Mo:Na layer.

Molybdenum plays a role in solid solution strengthening in Ni-based superalloys by sitting in the sublattice of L12 structure γ′-Ni3(Al,Mo) precipitates and dissolving in γ matrix. By coupling the sublattice free energy with a phase-field model, the precipitation kinetics and composition distribution of the γ′ phase in the Ni-x Al-(17−x) Mo (at.%) alloys were investigated, and the influences of Mo on the precipitation and growth of the γ′ phases was revealed by the element diffusion potential. Mo gathers firstly inside of γ′ phase at nucleation and growth stage, then Mo diffuses into the γ matrix and accumulates around the γ′ phase, for the slower diffusion of Mo than that of Al. This inequality diffusion supports Mo to hinder the element diffusion between the γ/γ′ phases and reduces the interconnection and the coarsening rate of γ′ phase. As the Mo content increases from 2 at.% to 4 at.%, the diffusion potential of Al and Mo in γ′ phases raises and the coarsening rate of γ′ phase decreases.