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Porous mullite ceramics were synthesized via ceramic processing using a local industrial kaolin, alumina, and with AlF3 and MoO3 precursor additives to catalyze the formation of pores and acicular mullite grains. The textural properties, crystalline phases, microstructures, and mechanical properties of the obtained samples were comprehensively analyzed and compared with a reference mullite formulated without additives. The obtained ceramics have a well‐defined porous microstructure, with a porosity of about 50%, and a pore size distribution in the 0.1–2 µm range. Ceramics that involve the addition of MoO3 present well‐defined acicular mullite grains, with slightly higher porosity, larger pores, and better mechanical resistance compared to those processed using AlF3.To correlate the ceramic porosity with its mechanical properties, a simple model of spherical pores was proposed to assess the flexural strength of the dense ceramic. It was found that the inclusion of additives promoting needle‐like microstructures increases the mechanical resistance up to four times the value determined for the ceramic without additives (flexural strength up to 390 MPa for zero‐porosity extrapolation). These results, together with the refractoriness of mullite, allow inferring the potential applications of the developed materials as structural ceramics with relatively low density and for filtering applications. [ABSTRACT FROM AUTHOR]

Bioresorbable electrochemical sensors remain mostly unexplored despite their ability to provide continuous in situ measurements of critical biomarkers. The primary challenge arises from the direct exposure of the electrodes' thin metal films to biofluids, which poses difficulties in ensuring both proper operational lifetimes and sensing performance. Molybdenum (Mo) presents itself as a promising biometal due to its uniquely gradual dissolution in biofluids, facilitated by the formation of a slower‐dissolving MoOx surface layer. Consequently, carefully engineered MoOx films can endow transient electrochemical sensors with unparalleled stability during extended operational lifetimes. Herein an unprecedented sensor architecture achieved via the unique pairing of sputtered Mo and MoOx thin films, probed as a pH and dissolved oxygen sensor is reported. Compared to a bare Mo electrode, a bilayer Mo+MoOx electrode subjected to post‐deposition annealing (400 °C, 60 min, N2 environment) displayed a largely improved stability (>24 h) in solution and demonstrated predictable functionality during ongoing film dissolution at 37 °C. Collectively, this work establishes a pioneering strategy for the fabrication of reliable and clinically relevant implantable electrochemical sensors. [ABSTRACT FROM AUTHOR]

The reduction of nitrogen oxides (NOx), critical pollutants from stationary to mobile sources, mainly relies on the selective catalytic reduction (NH3-SCR) method, employing ammonia to reduce NOx into nitrogen and water. However, conventional catalysts, while effective, pose both environmental and operational challenges. This study investigates ceria-zirconia-supported molybdenum-based catalysts, exploring the effects of zirconium doping and different catalyst synthesis techniques, i.e., co-precipitation and impregnation. The catalytic performance of the differently prepared samples was significantly influenced by the molybdenum incorporation method and the zirconium content within the ceria-zirconia support. Co-precipitation at higher temperatures resulted in catalysts with better structural attributes but slightly lower catalytic activity compared to those prepared via impregnation. Optimal NOx reduction (close to 100%) was observed at a 15 mol% zirconium doping level when using the impregnation method. [ABSTRACT FROM AUTHOR]

In this study, the hydrogen reduction mechanism of MoO3 was analyzed in detail using Ti–Mo core–shell powder manufactured through a milling and reduction process. MoO3 and Ti powders were ball-milled to refine the MoO3 powder and coat it onto the Ti powder to fabricated core-shell structure. Subsequently, the milled powder was heat-treated at 600°C in a hydrogen atmosphere to reduce MoO3 to nano-sized Mo. In addition, the reduction behavior of MoO3 was analyzed by varing the reduction times to 1, 10, 30 min and 1, 3, 5 h. Phase analysis was conducted using X-ray diffraction, and oxidation state analysis was conducted using X-ray photoelectron spectroscopy. Morphology analysis was performed using scanning electron microscopy, and elemental analysis was conducted using electron probe micro-analysis. It was confirmed that Mo9O26 and Mo4O11 intermediate phases were formed sequentially as MoO3 was reduced to MoO2, and Mo9O26 had a plate shape with a thickness of sub-70 nm, and Mo4O11 exhibited a thickness of sub-300 nm. Especially, the Mo2O3 intermediate phase, previously studied only theoretically, was experimentally confirmed for the first time in the reduction process from MoO2 to Mo. Furthermore, the analysis of Mo-oxide intermediate phases was explained by the structural characteristics of the core–shell. The shell of Mo oxide was thick and dense, making it difficult for the vapor phase necessary for CVT reduction to penetrate and diffuse into the shell. As a result, the rapid CVT reduction occurred outside the shell, while relatively slower reduction occurred inside the shell where intermediate phases were observed.

Abstract Bioresorbable electrochemical sensors remain mostly unexplored despite their ability to provide continuous in situ measurements of critical biomarkers. The primary challenge arises from the direct exposure of the electrodes’ thin metal films to biofluids, which poses difficulties in ensuring both proper operational lifetimes and sensing performance. Molybdenum (Mo) presents itself as a promising biometal due to its uniquely gradual dissolution in biofluids, facilitated by the formation of a slower‐dissolving MoOx surface layer. Consequently, carefully engineered MoOx films can endow transient electrochemical sensors with unparalleled stability during extended operational lifetimes. Herein an unprecedented sensor architecture achieved via the unique pairing of sputtered Mo and MoOx thin films, probed as a pH and dissolved oxygen sensor is reported. Compared to a bare Mo electrode, a bilayer Mo+MoOx electrode subjected to post‐deposition annealing (400 °C, 60 min, N2 environment) displayed a largely improved stability (>24 h) in solution and demonstrated predictable functionality during ongoing film dissolution at 37 °C. Collectively, this work establishes a pioneering strategy for the fabrication of reliable and clinically relevant implantable electrochemical sensors.

We developed a high-performance CdSe/ZnS quantum-dot light-emitting diode (QLED) incorporating a hole injection layer (HIL) composed of a solution-processed vanadium oxide (VO) and molybdenum oxide (MoO) mixture. The QLED with a VO:MoO ratio of 1:1 in the HIL demonstrated a current efficiency of 62.0 cd/A, representing a 60% improvement over the QLED utilizing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the HIL. Besides improved performance, the substitution of the highly reactive PEDOT: PSS with chemically stable metal oxides in HIL fabrication is anticipated to enhance device reliability. The highest occupied molecular orbital level of the VO:MoO ratio of 1:1 HIL was higher than that of HILs with other mixing ratios. Additionally, the VO:MoO ratio of 1:1 HIL exhibited higher oxidation number states compared to HILs with other mixing ratios. These characteristics contributed to the superior performance of the QLED with the VO:MoO ratio of 1:1 HIL. Our approach, which employs chemically stable metal oxides as HIL materials for high-performance QLEDs, can advance future QLED technology.

In this work, a new MoO3@Mo2CT x nanocomposite was prepared from two–dimensional (2D) Mo2CT x MXene by in situ oxidization in air, which exhibited wonderful lithium-storage performance as anodes of lithium–ion batteries (LIBs). The precursor Mo2CT x was synthesized from Mo2Ga2C by selective etching of NH4F at 180 °C for 24 h. Thereafter, the Mo2CT x was oxidized in air at 450 °C for 30 min to obtain MoO3@Mo2CT x nanocomposite. In the composite, in situ generated MoO3 nanocrystals pillar the layer structure of Mo2CT x MXene, which increases the interlayer space of Mo2CT x for Li storage and enhances the structure stability of the composite. Mo2CT x 2D sheets provide a conductive substrate for MoO3 nanocrystals to enhance the Li+ accessibility. As anodes of LIBs, the final discharge specific capacity of the MoO3@Mo2CT x composite was 511.1 mAh g–1 at a current density of 500 mA g–1 after 100 cycles, which is about 36.7 times that of pure Mo2CT x MXene (13.9 mAh g–1) and 3.2 times that of pure MoO3 (159.9 mAh g–1). In the composites, both Mo2CT x and MoO3 provide high lithium storage capacity and can enhance the performance of each other. Moreover, this composite can be made by a facile method of in situ oxidation. Therefore, the MoO3@Mo2CT x MXene nanocomposite is a promising anode of LIB with high performance. [ABSTRACT FROM AUTHOR]

[Display omitted] Monkeypox is a zoonotic viral infection caused by the monkeypox virus (MPXV), which belongs to the Poxviridae family of the Orthopoxvirus (OPXV) genus. Monkeypox is transmitted from animals to humans and humans to humans; therefore, the accurate and early detection of MPXV is crucial for reducing mortality. A novel graphene-based material, graphene quantum rods (GQRs) was synthesized and confirmed using high-resolution transmission electron microscopy (HR-TEM) and atomic force microscopy (AFM). In this study, molybdenum oxide was electrodeposited and one-pot electrodeposition of MoO 3 -GQRs composite on carbon fiber paper (CFP) enabled by an antibody (Ab A29)/MoO 3 -GQRs immunoprobe was developed for the early diagnosis of MPXV protein (A29P). Several studies were conducted to analyze the MoO 3 -GQRs composite, and the prepared Ab A29/MoO 3 -GQRs immunoprobe selectively bound to the A29P antigen that was measured using differential pulse voltammetry (DPV) analysis and impedance spectroscopy. The antigen–antibody interaction was analyzed using X-ray photoelectron spectroscopy. DPV analysis showed a wide linear range of detection from 0.5 nM to 1000 nM, a detection limit of 0.52 nM, and a sensitivity of 4.51 µA in PBS. The prepared immunoprobe was used to analyze A29P in serum samples without reducing electrode sensitivity. This system is promising for the clinical analysis of A29P antigen and offers several advantages, including cost-effectiveness, ease of use, accuracy, and high sensitivity. [ABSTRACT FROM AUTHOR]

The adequate optical properties, low cost, and thermal stability of graphitic carbon nitride and molybdenum oxide make them both promising materials for photocatalytic applications. However, they both suffer from strong recombination of their photogenerated charge carriers. Therefore, searching for strategies that enable an efficient charge carrier separation is desirable for improving the photocatalytic performance of both semiconductors. In this work, we have synthesized a g-C3N4/MoO3 heterojunction by a facile solid dispersion approach to the pristine semiconductors that allows a uniform dispersion of the two phases in the heterojunction. The resulting hybrid photocatalyst exhibits light absorption features similar to pristine g-C3N4 and presents an improved separation of the photogenerated charge carriers, likely through a Z-scheme between both semiconductor phases, as inferred by photoelectrochemical measurements. As a result, the g-C3N4/MoO3 heterojunction showed better photocatalytic activity than the individual semiconductors and good cycling stability for the degradation of methylparaben and its reaction intermediates. We drew these conclusions based on total organic carbon (TOC) measurements. [ABSTRACT FROM AUTHOR]

Novel photochromic composites based on biopolymers (polyvinyl alcohol, starch) and Mo4O11 and W18O49 as the fillers were obtained and characterized. To improve the photochromic properties, molybdenum and tungsten oxide sols were treated by an underwater diaphragm discharge to obtain binary structures of the MoOx/WOx and WOx/MoOx (2 < x < 3) types. The formation of such oxides was confirmed by TEM, EDX, XRD analysis, and Raman spectroscopy data. Plasma treatment is increased the color intensity and reversibility. The modified sols were incorporated into polymer matrices. Spectral studies have shown that the color of photo‐colored composites depends on the chemical structure of the polymer matrix. Mechanical tests have shown the possibility of obtaining hardened or plastic composites depending on the concentration and nature of the filler. Highlights: Photochromic polymer composites with W18O49 and Mo4O11 as fillers were obtained.Diaphragm discharge used as a tool for sol modification.WOx/MoOx and MoOx/WOx structures have improved photochromic properties.Color of irradiated polymer composites depends on chemical structure of polymer.Mechanical properties are determined by the polymer filler concentration. [ABSTRACT FROM AUTHOR]

The physicochemical and catalytic (CO2 hydrogenation) characteristics of Mo-containing catalysts were studied. The catalysts containing 8 and 15 wt % Mo oxide were prepared by impregnation of γ‑Al2O3 with ammonium paramolybdate, followed by drying and calcination at 500°C. The introduction of Mo oxide reduced the pore volume of the support and increased the average pore size, indicating that molybdenum oxide was distributed in the support pores. According to the X-ray diffraction analysis, the calcinated catalyst did not contain the crystalline MoO3 phase. According to the Raman spectra, oxygen-containing formations were present on the catalyst surface, with Mo atoms tetrahedrally and octahedrally coordinated to the oxygen atoms. The impregnated MoO3 was partially reduced with hydrogen during linear heating, starting from 320°C. The hydrogenation of CO2 (gas composition, vol %: 30.7 CO2, 68 H2, the rest was N2; 0.5 g sample) was studied under conditions of linear heating to 400°C. The main reaction was the reverse reaction of CO steam reforming. The contribution of methanation to CO2 hydrogenation was small. An increase in the temperature and pressure had a positive effect on CO2 conversion. When the pressure increased from 1 to 5 MPa, the CO content was approximately doubled. In the CO2 hydrogenation, appreciable activity (although significantly lower compared to that of Mo-containing catalysts) was also exhibited by γ-Al2O3, preliminarily heated to 400°C in an H2 flow. The activity of alumina also increased with pressure. [ABSTRACT FROM AUTHOR]

The cutting of difficult to machine materials such as titanium alloys is challenging for the machining industry. In case of the titanium alloy Ti6Al4V, the properties of the material cause high temperatures, mechanical loads as well as high frequency vibrations at the cutting edge, leading to premature tool failure. The use of uncoated carbide tools is very common for machining of Ti based alloys. However, temperature active, self-lubricating physical vapor deposition (PVD) coatings like CrAlMoN showed promising results to reduce friction and wear during turning of Ti6Al4V. In the present study, self-lubricating (Cr34Al41Mo25)N, (Cr29Al36Mo35)N and (Cr25Al31Mo44)N coatings were investigated on cemented carbide tools. These were deposited by a hybrid process combining direct current Magnetron Sputtering and High Power Pulsed Magnetron Sputtering. Coating morphology, thickness, chemical composition, indentation hardness and modulus at ϑ = 20 °C, ϑ = 200 °C, ϑ = 400 °C and ϑ = 600 °C as well as the oxidation behavior were analyzed. Moreover, wear development after cutting tests using a CNC-lathe was investigated. Independent of Mo-content, all coating variants possessed a dense morphology and a smooth surface topography, as well as a coating adhesion class of HF1 to the cemented carbide substrate in Rockwell indentation tests according to DIN 4856. With an increasing amount of Mo, heat treatment temperature and time, more self-lubricating molybdenum oxides such as MoO3 and Mo4O11 were detected by Raman spectroscopy. Therefore, the coating with the highest amount of Mo possessed the highest amount of molybdenum oxides. After cutting tests, molybdenum oxides were also found on the tool flank face by Raman spectroscopy. The level of flank wear land width decreased with increasing amount of Mo. [ABSTRACT FROM AUTHOR]

The physicochemical and catalytic (CO2 hydrogenation) characteristics of Mo-containing catalysts were studied. The catalysts containing 8 and 15 wt % Mo oxide were prepared by impregnation of γ‑Al2O3 with ammonium paramolybdate, followed by drying and calcination at 500°C. The introduction of Mo oxide reduced the pore volume of the support and increased the average pore size, indicating that molybdenum oxide was distributed in the support pores. According to the X-ray diffraction analysis, the calcinated catalyst did not contain the crystalline MoO3 phase. According to the Raman spectra, oxygen-containing formations were present on the catalyst surface, with Mo atoms tetrahedrally and octahedrally coordinated to the oxygen atoms. The impregnated MoO3 was partially reduced with hydrogen during linear heating, starting from 320°C. The hydrogenation of CO2 (gas composition, vol %: 30.7 CO2, 68 H2, the rest was N2; 0.5 g sample) was studied under conditions of linear heating to 400°C. The main reaction was the reverse reaction of CO steam reforming. The contribution of methanation to CO2 hydrogenation was small. An increase in the temperature and pressure had a positive effect on CO2 conversion. When the pressure increased from 1 to 5 MPa, the CO content was approximately doubled. In the CO2 hydrogenation, appreciable activity (although significantly lower compared to that of Mo-containing catalysts) was also exhibited by γ-Al2O3, preliminarily heated to 400°C in an H2 flow. The activity of alumina also increased with pressure. [ABSTRACT FROM AUTHOR]

Electrocatalytic glucose oxidation reaction (GOR) has attracted much attention owing to its crucial role in biofuel cell fabrication. Herein, we load MoO3 nanoparticles on carbon nanotubes (CNTs) and use a discharge process to prepare a noble-metal-free MC-60 catalyst containing MoO3, Mo2C, and a Mo2C–MoO3 interface. In the GOR, MC-60 shows activity as high as 745 µA/(mmol/L cm2), considerably higher than those of the Pt/CNT (270 µA/(mmol/L cm2)) and Au/CNT catalysts (110 µA/(mmol/L cm2)). In the GOR, the response minimum on MC-60 is as low as 8 µmol/L, with a steady-state response time of only 3 s. Moreover, MC-60 has superior stability and anti-interference ability to impurities in the GOR. The better performance of MC-60 in the GOR is attributed to the abundant Mo sites bonding to C and O atoms at the MoO3–Mo2C interface. These Mo sites create active sites for promoting glucose adsorption and oxidation, enhancing MC-60 performance in the GOR. Thus, these results help to fabricate more efficient noble-metal-free catalysts for the fabrication of glucose-based biofuel cells. [ABSTRACT FROM AUTHOR]

Superconducting polycrystalline composites YBa2Cu3O7–x + MoO3 with MoO3 nanofiber content of 1, 5, 10, and 15 wt % have been studied in the work. The temperature and width of transition into the superconducting state of samples with description of possible mechanisms for observable changes have been determined from measurements of electrical resistance. The elastic modulus, yield strength, fracture toughness, and fragility index have been determined from measurements of the Vickers microhardness. Five different models have been used during studies on the physical and mechanical properties of the MoO3-containing bulk HTSC samples to interpret microindentation data and explain the results with consideration of the indentation size effect. [ABSTRACT FROM AUTHOR]

The title compound, (C2H10N2)2[(C10H12N2O8)(MoO3)2]·4H2O, which crystallizes in the monoclinic C2/c space group, was obtained by mixing molybdenum oxide, ethylenediamine and ethylenediaminetetraacetic acid (H4edta) in a 2:4:1 ratio. The complex anion contains two MoO3 units bridged by an edta4− anion. The midpoint of the central C—C bond of the edta4− anion is located on a crystallographic inversion centre. The independent Mo atom is tridentately coordinated by a nitrogen atom and two carboxylate groups of the edta4− ligand, together with the three oxo ligands, producing a distorted octahedral coordination environment. In the three-dimensional supramolecular crystal structure, the dinuclear anions, the organoammonium counter-ions and the solvent water molecules are linked by N—H...Ow, N—H...Oedta and O—H...O hydrogen bonds.

In recent years, various transition metal dichalcogenides have been widely investigated, which are of interest for many applications, including gas sensors. In this work, some gas-sensitive nanostructures based on molybdenum disulfide and molybdenum oxide were synthesized by hydrothermal method. The surface chemical composition of the samples was studied by X-ray photoelectron spectroscopy. The gas-sensitive properties of the synthesized structures to isopropyl alcohol and acetone vapors at different working temperatures were analyzed. It was shown that as a result of heat treatment at 150°C, partial oxidation of molybdenum disulfide occured. Annealing of MoS2 samples at 400°C led to complete oxidation to MoO3. Analysis of the gas-sensitive properties of the structures showed that molybdenum oxide has the maximum response to isopropyl alcohol and acetone vapors in the entire temperature range under study. Both molybdenum disulfide and molybdenum oxide show a better response to isopropyl alcohol vapors compared to acetone vapors.

The reduction of nitrogen oxides (NOx), critical pollutants from stationary to mobile sources, mainly relies on the selective catalytic reduction (NH3-SCR) method, employing ammonia to reduce NOx into nitrogen and water. However, conventional catalysts, while effective, pose both environmental and operational challenges. This study investigates ceria-zirconia-supported molybdenum-based catalysts, exploring the effects of zirconium doping and different catalyst synthesis techniques, i.e., co-precipitation and impregnation. The catalytic performance of the differently prepared samples was significantly influenced by the molybdenum incorporation method and the zirconium content within the ceria-zirconia support. Co-precipitation at higher temperatures resulted in catalysts with better structural attributes but slightly lower catalytic activity compared to those prepared via impregnation. Optimal NOx reduction (close to 100%) was observed at a 15 mol% zirconium doping level when using the impregnation method.

Platinum alloys are highly efficient electrocatalysts for the oxygen reduction reaction (ORR) in acidic conditions. However, these alloys are susceptible to metal loss through leaching and degradation, leading to reduced catalyst stability and activity. Recently, it has been shown that doping with oxophilic elements can significantly alleviate these problems, with a prominent example being Mo‐doped Pt alloys. Here, to achieve atomic scale understanding of the exceptional activity and stability of these alloys, we present a detailed density functional theory description of the dopants' structures and impact on electrocatalyst properties. Beginning with the Mo/Pt system, we demonstrate that Mo can be stabilized in the form of low‐dimensional oxyhydroxide moieties on Pt defects. The resulting structures enhance stability and activity via distinct physical processes, with the Mo moieties both directly inhibiting Pt dissolution at defects and indirectly enhancing ORR activity by generation of strain fields on surrounding Pt terraces. We then generalize these analyses to other metal dopant elements, and we demonstrate that similar low‐dimensional oxyhydroxide structures control the electrocatalytic properties through an intricate interplay of the structures' acid stability, intrinsic activity for the ORR, and ability to induce ORR‐promoting strain fields on Pt. [ABSTRACT FROM AUTHOR]

Interfacial engineering is an effective approach for regulating the electronic structure of molybdenum carbides and promoting the hydrogen evolution reaction (HER). However, the development of a facile, cost-effective, and scalable synthesis method is crucial for industrial applications. In this work, we developed a mechanochemical method for the preparation of a composite of MoO 2 /MoC with superior HER electrocatalytic performance in alkaline solutions. The MoO 2 /MoC composite can be easily formed by ball milling for 1 h at ambient conditions, and this process can be scaled up for large-scale industrialization. The composite construction leads to a redistribution of electrons around the interface, optimizing the adsorption energy and enhancing the HER performance beyond that of Pt/C catalysts. This strategy provides a new route for the simple and efficient preparation of high-activity electrocatalysts. [Display omitted] • MoO 2 /MoC composite was obtained via ball milling without external heat input. • MoO 2 /MoC composite enables excellent hydrogen evolution reactions. • MoO 2 /MoC interface tunes electronic structure and favors hydrogen adsorption. • The synthetic route is conducive for industrial manufacturing. [ABSTRACT FROM AUTHOR]

In the present study, a new magnetic acid solid catalyst composed of an agro-industrial waste (rice husk ash-RHA) magnetized with cobalt ferrite (CoFe2O4) and impregnated with MoO3 was synthesized and applied in the methyl transesterification reaction of waste frying oil (WFO) for biodiesel production. The catalyst was synthesized by wet impregnation method and characterized by the following techniques: surface acidity, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy (EDS), and vibrating sample magnetometer (VSM). The one variable at time (OVAT) technique was used to optimize the variables of the transesterification reaction in the following ranges: temperature (130.0–170.0 °C), methanol:oil molar ratio (10:1–50:1), catalyst amount (2.0–10.0 wt%), and reaction time (1.0–5.0 h). The results demonstrate that the application of the MoO3/RHA-CoFe2O4 synthesized catalyst resulted in the attainment a biodiesel with ester content of 94.6 % under the optimized reaction conditions: temperature of 160.0 °C, methanol:oil molar ratio of 20:1, catalyst amount of 6.0 wt%, and reaction time of 3.0 h. The biodiesel produced was characterized and presented physicochemical properties in accordance with the limits established by the international standards ASTM D6751 and EN 14214. The kinetic study of the transesterification process revealed that the pseudo-first order model is the most suitable with an activation energy of 27.3 kJ mol−1. In addition, the catalyst showed bifunctional character (catalytic and magnetic), as well as high catalytic stability after ten reaction cycles, maintaining the production of biodiesel with ester content above 70.0 %, indicating its high potential for development and application.

In situ X-ray diffraction indicates that the structural phase transition from h-MoO3 to α-MoO3 is a first-order transition with a phase transition temperature range of 378.5–443.1 °C. The linear coefficients of thermal expansion of h-MoO3 are strongly anisotropic, that is, αa=b = 72.87 × 10−6 K−1 and αc = −19.44 × 10−6 K−1. In the h-MoO3 phase, water molecules are located at the (0 0 0.25) site inside the MoO6 octahedra tunnel that is formed by six MoO6 corner-sharing octahedron zigzag chains. With increasing temperature, the release of water molecules from the octahedra tunnel causes the octahedra chains to shrink and the octahedra tunnel to expand. When the phase transition occurs, the anomalous expansion of the MoO6 octahedra tunnel ruptures the Mo–O2 bonds, forming individual MoO6 octahedron zigzag chains that then share corners to generate octahedron layers in the ⟨100⟩α direction. The octahedron layers are bonded by van der Waals interactions in the ⟨010⟩α direction, crystalizing into the α-MoO3 structure.

Potentiometric sensing of oxyanions such as arsenate over self-assembly engineered and chemically responsive molybdenum dioxide grafted polyaniline (PANI/MoO3) plated ITO glass electrode has been reported. FT-IR, XRD, SEM, EDX, STEM-mapping, Raman spectroscopy, and N2 adsorption-desorption measurements were used to determine the impact of molecular architecture on the structure, morphology, and physical characteristics of PANI/MoO3. The obtained result implies the synthesis of a porous hybrid nanostructured material with enhanced orientated crystallinity, enhanced adsorption capacity, and responsiveness because of an optimized molecular structure and crystallinity alignment. The limit of detection (LOD) for detecting As(V) ions by using PANI/MoO3 composite/ITO electrodes based on the differential pulse voltammetry technique (DPV) was found to be around 0.15 ppb. The interaction between arsenate and molybdate oxyanions led to the development of an induced potential, which helped to clarify the sensing mechanism, charge transfer, and shifting characteristics. For the on-site detection of residual arsenate in diverse environmental samples, the analytical performance of the produced electrode in a genuine sample was also investigated.

Research on hybrid nanofluid flow around spinning discs has potential uses in cooling technology, microfluidics, and energy systems, among other areas. Furthermore, in recent scientific and engineering endeavors, it is becoming more crucial to take sustainability and environmental impact into account when conducting nanofluid research. Heat transfer and heat generation/absorption has been examined due to activation energy and binary chemical reaction for the magnetohydrodynamic flow of hybrid nanofluid owing to rotating disk. Also, the introduction of Casson nanofluid has been made in this analysis. Temperature and concentration both show a rising tendency for rising Ha. Stronger temperature is correlated with higher Pr, while the opposite is true. With Nb and Nt, a stronger temperature distribution is observed. The concentration field for Higher γ shows a decreasing trend. The results show the rapid change for aggregated nanoparticles as compared to non-aggregated nanoparticles. The inclusion of hybrid nanofluid improves the temperature and thermal layers heat transfer in concerning nanofluid.

It is well known that electrocatalytic oxygen evolution reaction (OER) activities primarily depend on the active centers of electrocatalysts. In some oxide electrocatalysts, high‐valence metal sites (e.g., molybdenum oxide) are generally not the real active centers for electrocatalytic reactions, which is largely due to their undesired intermediate adsorption behaviors. As a proof‐of‐concept, molybdenum oxide catalysts are selected as a representative model, in which the intrinsic molybdenum sites are not the favorable active sites. Via phosphorus‐modulated defective engineering, the inactive molybdenum sites can be regenerated as synergistic active centers for promoting OER. By virtue of comprehensive comparison , it is revealed that the OER performance of oxide catalysts is highly associated with the phosphorus sites and the molybdenum/oxygen defects. Specifically, the optimal catalyst delivers an overpotential of 287 mV to achieve the current density of 10 mA cm−2, accompanied by only 2% performance decay for continuous operation up to 50 h. It is expected that this work sheds light on the enrichment of metal active sites via activating inert metal sites on oxide catalysts for boosting electrocatalytic properties. [ABSTRACT FROM AUTHOR]

In the present work, MoO3 - MoO2 nanocomposite is synthesised via hydrothermal method and is characterised using various state-of-the-art techniques. The high crystallinity of the sample is observed from XRD and FESEM reveals the 2D plate like layered structures with hexagonal facets. The prepared composite is subjected to ethanol sensing at room temperature and it is observed that the material exhibits 4.5% for 25 ppm ethanol with response time as 98 s and recovery time as 219 s. The observed small response of the composite material MoO3 - MoO2 with longer response-recovery time might be due to the large sized fibrils observed. [ABSTRACT FROM AUTHOR]

In this study, MoO 2 -Cu-C composite anode is synthesized using element transfer method via mechanochemical reaction. Cu-C hybrid matrix induces fast Li+ and electron transport during cycling process. The MoO 2 -Cu-C electrode deliveres promising electrochemical performance (674 and 520 mAh g−1 at 100 and 500 mA g−1, respectively, after 100 cycles) and high rate retention (476 mAh g−1 and 73% capacity retention at 5 A g−1 compared to 100 mA g−1), which outperforms most of the recently reported MoO 2 -based anode for Lithium-ion batteries. [Display omitted] • MoO 2 -Cu-C composite anode is synthesized using element transfer method. • MoO 2 is well-surrounded by electron-rich Cu-C hybrid matrix. • Cu-C hybrid matrix induce fast Li+ and electron transport during cycling process. • MoO 2 -Cu-C shows high reversible capacity and rate performance after activation. • MoO 2 -Cu-C anode is a promising anode for Lithium-ion batteries. Although MoO 2 -based electrodes have been intensively studied as potential candidate anodes for lithium-ion batteries (LIBs) based on their high theoretical capacity (840 mAh g−1 and 5447 mAh cm−3), common issues such as severe volume variation, electrical conductivity loss, and low ionic conductivity, are prevalent. In this study, we demonstrate enhanced Li-ion kinetics and electrical conductivity of MoO 2 -based anodes with ternary MoO 2 -Cu-C composite materials. The MoO 2 -Cu-C was synthesized via two-step high energy ball milling where Mo and CuO are milled, followed by the secondary milling with C. With the introduction of the Cu-C hybrid matrix in MoO 2 nanoparticles via the element transfer method using mechanochemical reactions, the sluggish Li-ion diffusion and unstable cycling behavior were significantly improved. The inactive Cu-C matrix contributes to the increase in electrical and ionic conductivity and mechanical stability of active MoO 2 during cycling, as characterized by various electrochemical analyses and ex situ analysis techniques. Hence, the MoO 2 -Cu-C anode delivered promising cycling performance (674 mAh g−1 (at 0.1 A g−1) and 520 mAh g−1 (at 0.5 A g−1), respectively, after 100 cycles) and high-rate property (73% retention at 5 A g−1 as comparison with the specific capacity at 0.1 A g−1). The MoO 2 -Cu-C electrode is a propitious next-generation anode for LIBs. [ABSTRACT FROM AUTHOR]

In this study, we delved into the influence of Ir nanofilm coating thickness on the optical and optoelectronic behavior of ultrathin MoO3 wafer-scale devices. Notably, the 4 nm Ir coating showed a negative Hall voltage and high carrier concentration of 1.524 × 1019 cm−3 with 0.19 nm roughness. Using the Kubelka–Munk model, we found that the bandgap decreased with increasing Ir thickness, consistent with Urbach tail energy suggesting a lower level of disorder. Regarding transient photocurrent behavior, all samples exhibited high stability under both dark and UV conditions. We also observed a positive photoconductivity at bias voltages of >0.5 V, while at 0 V bias voltage, the samples displayed a negative photoconductivity behavior. This unique aspect allowed us to explore self-powered negative photodetectors, showcasing fast response and recovery times of 0.36/0.42 s at 0 V. The intriguing negative photoresponse that we observed is linked to hole self-trapping/charge exciton and Joule heating effects. [ABSTRACT FROM AUTHOR]

Unexpected benefits to the catalytic performance of materials often originate from the presence of surface defects. Here, novel D-penicillamine modified molybdenum oxide nanodots, with abundant oxygen vacancy defects, were fabrication by a mild, simple, and cost-effective method. Ultraviolet—visible (UV—Vis) absorption spectra analysis showed that the nanodots had peroxidase-like and catalase-like activities. The reactive oxygen species were probed by electronic paramagnetic resonance technique and spectroscopic methods, demonstrating that the nanodots also had oxidase-like activity. Interestingly, the peroxidase-like activity of nanodots was synergistically enhanced in the presence of ferrous ions or ferric ions. Remarkably, less than nanomolar levels of ferrous ions were required to display this phenomenon, meaning Fenton reagent acted as leverage. Based on this, a sensitive colorimetric and fluorescent dual-mode sensor for alendronate sodium was developed. The linear ranges for colorimetric and fluorescence analysis were 0.2–2.5 and 0.2–2.0 µM, with detection limits of 31.21 and 71.84 nM, correspondingly. The method has a simple large-scale material preparation process with higher sensitivity and shorter reaction time, which can inspire and enlighten the design of nanozyme sensors. [ABSTRACT FROM AUTHOR]

Herein, we report the effect of different reducing agents on Ag-MoO3/polyacrylonitrile nanofibers for their promising potential as advanced wound dressings. The nanofibers were treated with NaOH, NaBH4, sodium citrate, and UV light, and their properties were evaluated. Water contact angle measurements revealed that NaOH treatment resulted in a less wettable surface, while NaBH4 and sodium citrate treatments led to more wettable surfaces. UV light treatment induced a slight increase in the surface wettability. Antibacterial inhibition zone tests showed that NaOH and UV treatments exhibited significant inhibitory effects against both Escherichia coli and Bacillus subtilis, while NaBH4 and sodium citrate treatments displayed moderate inhibitory effects. Moreover, silver release profiles demonstrated a sustained release of silver ions over time, with sodium citrate treatment exhibiting a higher release rate. MoO3/polyacrylonitrile displayed a substantially lower stress value, 73% less than that of the blank polyacrylonitrile (PAN) nanofiber. This decrease in the stress value is advantageous for wound dressings, as it allows for improved flexibility and conformability to the wound site. Overall, these findings provide insights into the surface wettability, antimicrobial properties, and silver ion release capabilities of Ag-MoO3/polyacrylonitrile nanofibers under different treatments, highlighting their potential for wound dressing applications. [ABSTRACT FROM AUTHOR]

The discharge characteristics of cells of a heat activated battery (HAB) containing NiCl2–CoF2–MoO3 mixtures as a positive electrode are studied. Molybdenum oxide is found to stabilize the discharge plateau and to increase the discharge voltage at temperatures above 530°C. The discharge curve has a steplike character. The number of steps of the discharge curve is determined by the operating conditions of the HAB. The low-voltage step (lower than 0.4 V) corresponds to the reduction of lithium molybdates, which are formed during the interaction of molybdenum oxide with the reduction products of transition metal halides. The reduction products of the cathodic mixture are studied by X-ray diffraction (XRD), synchronous thermal analysis (STA), and scanning electron microscopy (SEM). During the discharge of the HAB cell, the initial components of the cathodic mixture are found to be reduced to metals, which form a dendritic matrix. The differential thermal calorimetry (DSC) curves of the salt fraction having formed during electrochemical reactions have a number of thermal effects corresponding to the temperatures of joint melting of a ternary LiF–LiCl–LiBr lithium halide mixture and the eutectics of the binary LiF–LiCl and LiCl–Li2O systems, in which transition metal halides and lithium molybdates are dissolved. [ABSTRACT FROM AUTHOR]

The adequate optical properties, low cost, and thermal stability of graphitic carbon nitride and molybdenum oxide make them both promising materials for photocatalytic applications. However, they both suffer from strong recombination of their photogenerated charge carriers. Therefore, searching for strategies that enable an efficient charge carrier separation is desirable for improving the photocatalytic performance of both semiconductors. In this work, we have synthesized a g-C3N4/MoO3 heterojunction by a facile solid dispersion approach to the pristine semiconductors that allows a uniform dispersion of the two phases in the heterojunction. The resulting hybrid photocatalyst exhibits light absorption features similar to pristine g-C3N4 and presents an improved separation of the photogenerated charge carriers, likely through a Z-scheme between both semiconductor phases, as inferred by photoelectrochemical measurements. As a result, the g-C3N4/MoO3 heterojunction showed better photocatalytic activity than the individual semiconductors and good cycling stability for the degradation of methylparaben and its reaction intermediates. We drew these conclusions based on total organic carbon (TOC) measurements.

In this study, a new catalyst for heterogeneous acid based on molybdenum oxide (MoO 3) supported over graphene oxide (GO) was synthesized and applied in simultaneous esterification-transesterification reactions using waste cooking oil (WCO) to obtain biodiesel. In the catalyst synthesis, the GO support was synthesized from graphite oxidation, followed by wet MoO 3 impregnation. The MoO 3 /GO catalyst was characterized by Surface Acidity, Thermogravimetric Analysis (TG/DTG), X-ray Diffraction (XRD), Fourier Transformation Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) and Energy Dispersion X-ray Spectroscopy (EDS). The application of the catalyst in the conversion of WCO into biodiesel had as parameters reaction temperature (120.0–160.0 °C), reaction time (1.0–5.0 h), catalyst loading of (2.0–10.0%) and methanol:oil molar ratio of (25:1–45:1). The results of the catalytic tests showed the best condition of biodiesel synthesis was 140.0 °C reaction temperature, 5.0 h of reaction time, 6.0% catalyst loading and 35:1 methanol:oil molar ratio, leading to a biodiesel with ester content of 95.6%. The catalyst showed good recovery and excellent catalytic performance in the reuse study, producing biodiesel with ester content above 70.0% after 5 reaction cycles. Thus, this study shows a promising new catalyst of heterogeneous acid with high catalytic activity and applicability in the biodiesel synthesis process. [Display omitted] [ABSTRACT FROM AUTHOR]

The present work reports the photoelectrocatalytic properties of pyrolyzed molybdenum oxide thin film. Microstructural analysis revealed clustered nanoaggregates. Structural analysis showed a polycrystalline α -MoO3 phase. The crystallite size, dislocation density, microstrain, and stacking faults were found to be 41.27 nm, 5.87 × 10−4 lines/cm2, 8.41 × 10−4 and 1.78, respectively. The optical bandgap was found to be 3.20 eV. Linear sweep voltammetry measurement in 1 M KOH electrolyte revealed a significant photocurrent density of 992.39 μA/cm2 at a bias of 1.2 V versus Ag/AgCl (1.4 V vs. RHE). The reasonable performance of the device suggests that the rarely deployed spray pyrolysis method is promising for preparing photoactive α -MoO3 films for photoelectrochemical measurement. [ABSTRACT FROM AUTHOR]

MoO 3 is a kind of promising cathode material for lithium-ion batteries (LIBs), owing to its high specific capacity (279 mA h g−1) and layered structure. However, low electrical conductivity and sluggish reaction kinetics results in poor rate and Li-ions storage capability. The introduction of oxygen vacancies (OVs) can promote Li+ diffusion, and produce great electrical conductivity. Here, we report a strategy to synergize the merits of OVs by pulsed laser deposition (PLD) by adjusting oxygen partial pressures (2～20 Pa). The appropriate OVs concentration not only significantly approves electrochemical performance but also increases pseudocapacitance contribution. The Li-ion diffusion coefficient of MoO 3−x is remarkably improved by one or two orders of magnitude compared with that of MoO 3. Therefore, this facile and efficient strategy on OVs could afford a reference for other metal oxides for high-performance electrode materials. [ABSTRACT FROM AUTHOR]

Molybdenum oxide (MoO3) electrochromic (EC) materials have not been widely used at present due to relatively poor performance and inadequate research. In order to enhance the EC properties of the MoO3 to achieve the purpose of practical use, the modified nanocrystalline MoO3 films were fabricated by a cheap and simple complexation-assisted sol–gel method followed by annealing at 300 °C. In this method, dopamine (DA) is used as a structure-directing agent and the added amount of DA has a great influence on the structure and morphology and, thus, electrochemical and EC properties of the MoO3 films. Different from the pure MoO3 polycrystalline film, the film modified with a suitable amount of DA possesses a distinctive nanocrystal-embedded amorphous structure, and, thus, can achieve synergy effects of EC properties through combining the advantages of both amorphous phases and nanocrystalline. Therefore, compared with the pure MoO3 film, the modified MoO3 film shows much higher EC properties in terms of optical contrast, coloration efficiency, switching speed, and cycling stability. Moreover, a complementary type EC device with dual active layers (the modified MoO3 film and polyaniline) was fabricated and tested, and the results demonstrate the potential application of the modified MoO3 film. [ABSTRACT FROM AUTHOR]

Molybdenum carbide is one of non‐precious metal materials and it is a promising electrocatalyst for hydrogen production. Synthesis and improvement of molybdenum carbide's catalytic performance is of great significance. Herein, carbon‐based Mo2C with hybrid phase of MoO2 was fabricated by matching the composition of Mo and C derived from pomelo peel and optimizing raw carbon amount and prolysis temperature. The resulting MoO2/Mo2C@C is composed of loose microspheres with mesoporous microstructure and is self‐assembled from nanoparticles. The results show that MoO2/Mo2C@C2 material exhibits excellent HER performance and only a low overpotentials of 143 mV is needed to drive the current density of 10 mA cm−2 in alkaline solution, and Tafel slopes are only 63.4 mV dec−1, respectively. Notably, it has potential application at low overpotentials to drive large current density and this strategy also provides a universal route to prepare non‐noble metal catalyst with hybrid phase of oxide/carbide. [ABSTRACT FROM AUTHOR]

The electrochemical sensing of biomarkers has attracted more and more attention due to the advantages of electrochemical biosensors, including their ease of use, excellent accuracy, and small analyte volumes. Thus, the electrochemical sensing of biomarkers has a potential application in early disease diagnosis diagnosis. Dopamine neurotransmitters have a vital role in the transmission of nerve impulses. Here, the fabrication of a polypyrrole/molybdenum dioxide nanoparticle (MoO3 NP)-modified ITO electrode based on a hydrothermal technique followed by electrochemical polymerization is reported. Several techniques were used to investigate the developed electrode's structure, morphology, and physical characteristics, including SEM, FTIR, EDX, N2 adsorption, and Raman spectroscopy. The results imply the formation of tiny MoO3 NPs with an average diameter of 29.01 nm. The developed electrode was used to determine low concentrations of dopamine neurotransmitters based on cyclic voltammetry and square wave voltammetry techniques. Furthermore, the developed electrode was used for monitoring dopamine in a human serum sample. The LOD for detecting dopamine by using MoO3 NPs/ITO electrodes based on the SWV technique was around 2.2 nmol L−1. [ABSTRACT FROM AUTHOR]

Hexagonal molybdenum oxide (h-MoO3) micro-rods were synthesized through a facile hydrothermal method. Thermogravimetric and differential thermal analysis (TGA-DTA) of the sample, over temperatures ranging from 30°C to 700°C, was carried out to analyze the phase transition characteristics and thermal stability. The effect of post-thermal treatment on the structural, morphological, and optical characteristics of as-prepared samples were investigated in detail. X-ray diffraction (XRD) patterns of the sample confirmed the formation of h-MoO3, and the presence of hexagonal-shaped micro-rods were observed through scanning electron microscopy (SEM). The crystalline phase was transformed to a thermodynamically stable orthorhombic structure (α-MoO3) on thermal treatment, with the micro-rods transformed to flake-like morphology. Elemental composition was confirmed through energy dispersive x-ray spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS). Band gap energy estimated from the absorption spectra lies in the range 2.70–2.94 eV. The material exhibited a superior irreversible thermochromic property, which has been observed as color bands, in the visible to NIR region of the absorption spectra. The phenomenon was well explained with the support of the XPS scan for the Mo-3d and O-1 s states. Furthermore, the photoluminescence (PL) spectra, at an excitation of 330 nm (3.76 eV), showed five emission peaks centered between 360 nm and 550 nm, with enhanced intensity on thermal treatment. The physico-chemical characteristics revealed that the material can be applicable in thermo-chromic smart windows and as host material in light-emitting diodes. [ABSTRACT FROM AUTHOR]

Molybdenum oxide (MoO3−x, x < 3) has been successfully used as an efficient hole‐selective contact material for crystalline silicon heterojunction solar cells. The carrier transport capability strongly depends on its work function, that is, oxygen vacancies; however, there are lack of effective methods to modulate the multiple oxidation states. Herein, the oxidation states of solution‐processed MoO3−x by doping Nb5+ to improve its hole‐selective contact performance with silicon are tuned. With the optimum doping concentration of 5%, both the reduced Mo5+ and oxygen vacancies increase, resulting in a decrease in the contact resistivity between the MoO3−x film and p‐type silicon from 161.1 to 62.9 mΩ·cm2 and an increase of the effective carrier lifetime from 165.4 to 391.0 μs simultaneously. Similarly, the doping of Ta5+ or V5+ in MoO3−x improves the passivated contact performance with silicon, while the former increases the concentration of oxygen vacancies and the latter reduces it. The solar cell with the structure of Ag/MoO3−x:Nb/p‐Si exhibits a conversion efficiency of 18.37%, which is the highest so far reported for the solution‐processed MoO3−x/silicon heterojunction. This work demonstrates a feasible strategy of tuning hole selectivity in MoO3−x by doping for high‐efficiency solar cells and other optoelectronic device applications. [ABSTRACT FROM AUTHOR]

Molybdenum oxides (MoO3 − x, x = 1, 2, and 3) with three types of morphologies were prepared and applied to the reaction of benzyl alcohol with dimethylformamide (DMF) for synthesis of tertiary amines. The MoO3 − 1 catalyst prepared by direct calcination exhibited high activity and tertiary amines selectivity in the N,N‐dimethylamination of benzyl alcohol under the reaction conditions at 150°C for 12 h using DMF as a methylating agent and solvent, as compared to MoO3 − 2 and MoO3 − 3 catalysts. This feature was ascribed to the high proportion of surface chemisorbed oxygen for MoO3 − 1 sample, which can promote the adsorbed benzyl alcohol transformation into benzaldehyde. The MoO3 − 1 catalyst was also found to be reusable in five consecutive runs without a significant decrease in catalytic activity. In addition, control experiments showed two parallel reaction routes in this catalytic system. One route is the reaction of benzaldehyde intermediate and DMF to form tertiary amines (Route I); the other route is that benzyl formate intermediate reacted with DMF (Route II), which has not been reported before and specifically involves the esterification of benzyl alcohol with formic acid from DMF decomposition to form benzyl formate. [ABSTRACT FROM AUTHOR]