Preparation of In0.5Sc1.5Mo3O12 nanofibers and its negative thermal expansion property

Orthorhombic In_0.5Sc_1.5Mo₃O₁₂ nanofibers were prepared by electrospinning followed by a heat treatment. The effects of post-annealing temperatures on the phase composition, microstructure and morphology were investigated by XRD, SEM, HRTEM and XPS. Negative thermal expansion (NTE) behaviors of the In_0.5Sc_1.5Mo₃O₁₂ nanofibers were analyzed by high-temperature XRD. Results indicate that the as-prepared In_0.5Sc_1.5Mo₃O₁₂ nanofibers show an amorphous structure with smooth and homogeneous shape. The average diameter of the as-prepared In_0.5Sc_1.5Mo₃O₁₂ nanofibers is around 515 nm. Well crystallized orthorhombic In_0.5Sc_1.5Mo₃O₁₂ nanofibers could be prepared after post-annealing at 550 °C for 2 h with an average diameter of about 192 nm. The crystallinity of In_0.5Sc_1.5Mo₃O₁₂ nanofibers gradually improved with the increase of annealing temperature. However, too high post-annealing temperature leads to a damage of sample's fiber structure. The high-temperature XRD results reveal that In_0.5Sc_1.5Mo₃O₁₂ nanofibers show an anisotropic NTE, and the coefficients of thermal expansion (CTEs) along a-axis and c-axis were −5.95 × 10⁻⁶ °C⁻¹ and -3.54 × 10⁻⁶ °C⁻¹, while the one along b-axis is 5.61 × 10⁻⁶ °C⁻¹. The volumetric CTE of In_0.5Sc_1.5Mo₃O₁₂ nanofibers is −3.90 × 10⁻⁶ °C⁻¹ and the linear one is 1.3 × 10⁻⁶ °C⁻¹ in 25–700 °C.     

Synthesis and characterization of ternary layered i-MAX (Mo2/3Y1/3)2AlC ceramics fabricated by spark plasma sintering

In this paper, the i-MAX phase (Mo_2/3Y_1/3)₂AlC ceramic with high purity of 98.29 wt% (1.13 wt% Y₂O₃ and 0.58 wt% Mo₂C) and high relative density of 98.59% was successfully synthesized by spark plasma sintering (SPS) at 1500°C with the molar ratio of n(Mo):n(Y):n(Al):n(C) = 4:2:3.3:2.7. The positions of C atoms in the crystal of (Mo_2/3Y_1/3)₂AlC were determined. Microstructure and physical and mechanical properties of (Mo_2/3Y_1/3)₂AlC ceramic were systematically investigated. It was found that the obtained (Mo_2/3Y_1/3)₂AlC ceramic had an average grain size of 32.1 ± 3.1 μm in length and 14.2 ± 1.7 μm in width. In terms of physical properties, the measured thermal expansion coefficient (TEC) of (Mo_2/3Y_1/3)₂AlC was 8.99 × 10⁻⁶ K⁻¹, and the thermal capacity and thermal conductivity at room temperature were 0.43 J·g⁻¹·K⁻¹ and 13.75 W·m⁻¹·K⁻¹, respectively. The room temperature electrical conductivity of (Mo_2/3Y_1/3)₂AlC ceramic was measured to be 1.25 × 10⁶ Ω⁻¹·m⁻¹. In terms of mechanical properties, Vickers hardness under 10 N load was measured as 10.54 ± 0.29 GPa, while flexural strength, fracture toughness, and compressive strength were determined as 260.08 ± 14.18 MPa, 4.51 ± 0.70 MPa·m^1/2, and 855 ± 62 MPa, respectively, indicating the promising structural applications.     

Electrochemical synthesis of bismuth molybdates with controllable composition and their photocatalytic performance

Bismuth molybdate photocatalysts were controllably prepared via an electrochemical approach at room temperature. The composition and optical property of each product were determined according to the NaOH and Na₂MoO₄ quantities in the electrolyte. Pure Bi_3.64Mo_0.36O_6.55 was prepared at a NaOH concentration range of 0.2‐0.8 mol L^?1, whereas the Bi_3.64Mo_0.36O_6.55/Bi₁₄MoO₂₄ composite was obtained in an electrolyte containing 0.4 mol L^?1 NaOH and 0.5 mol L^?1 Na₂MoO₄. The results of rhodamine B degradation under visible light indicated that Bi_3.64Mo_0.36O_6.55 nanoparticles with a size of 10‐50 nm displayed the best photocatalytic efficiency, which was considerably higher than that of composite one and bulk Bi_3.64Mo_0.36O_6.55.     

Study on the reduction of commercial MoO3 with carbon black to prepare MoO2 and Mo2C nanoparticles

A simple method was developed to synthesize MoO₂ and Mo₂C nanoparticles via controlling nucleation and growth in carbothermic reduction of commercial MoO₃ with carbon black. It was found that the appropriate C/MoO₃ molar ratio for preparation of Mo₂C was 2.8, and the carbothermic reduction process followed the sequence: MoO₃ → transport phase (TP) → MoO₂ → Mo₂C. It was revealed that the most crucial issues for controlling number of produced particles of product were migration of Mo source and aid of nucleating agent, which can be achieved by using MoO₃ and carbon black as starting materials. MoO₂ nanosheets with the thickness of 12 nm and lateral size of 60 nm, as well as Mo₂C nanoparticles with particle size of 30 nm were prepared via reduction of MoO₃ with carbon black. However, MoO₂ and Mo₂C produced via reducing MoO₃ by other kinds of carbon sources (activated carbon, graphite) or gas reductants (10% CH₄/H₂, CO) had much larger particle sizes of a few micrometers, which were tens of times than those using MoO₃ and carbon black, due to the too small amount of formed nuclei. The effects of C/MoO₃ molar ratio (0.5-2.8), molybdenum sources and carbon sources on the reaction mechanisms were investigated in detail.     

Electrospinning synthesis and negative thermal expansion of one-dimensional Sc2Mo3O12 nanofibers

Orthorhombic Sc₂(MoO₄)₃ nanofibers have been prepared by ethylene glycol assisted electrospinning method. The effects of annealing temperature, precursor concentration, spinning distance and solvent on the preparation of Sc₂(MoO₄)₃ nanofibers were characterized by XRD, SEM, HRTEM, EDX and high-temperature XRD. XRD analysis shows as-prepared nanofibers are amorphous. Orthorhombic Sc₂(MoO₄)₃ nanofibers can be fabricated after annealing at different temperatures in 500–800 °C for 2 h. The crystallinity of Sc₂(MoO₄)₃ nanofibers improves and the nanofiber diameter decreases gradually as the annealing temperature increases. However, the nanofiber structure was destroyed at the annealing temperature above 700 °C. Higher precursor concentration results in a slight increase of diameter and decrease in destroying temperature of Sc₂(MoO₄)₃ nanofibers. Spinning distance also affects the diameter of nanofibers, and the nanofiber diameter decreases as the distance increases. One-dimensional orthorhombic Sc₂(MoO₄)₃ nanofibers exhibit anisotropic negative thermal expansion. In 25–700 °C, the coefficients of thermal expansion (CTE) of α_a, α_b and α_c are ?5.81 × 10^?6 °C^?1, 4.80 × 10^?6 °C^?1 and -4.33 × 10^?6 °C^?1, and the α_l of Sc₂(MoO₄)₃ nanofibers is ?1.83 × 10^?6 °C^?1.     

Ionic conductivities and phase transitions of lanthanide rare-earth substituted La2Mo2O9

The ion conductivities and phase transitions of lanthanum molybdate (La₂Mo₂O₉) substituted with lanthanide rare-earths are investigated using impedance spectroscopy, dilatometry, and X-ray powder diffraction. Among the substituted La₂Mo₂O₉ of 10 mol% Ce, Nd, Sm, Gd, Dy, Er, Yb, the specimens containing Er, and Dy exhibit depressed α–β phase transformation and high conductivities. Their 700 °C conductivities are approximately five to seven times that of La₂Mo₂O₉, around 0.26 S cm⁻¹, comparable with those of (LaSr)(GaMg)O₃ and Gd-substituted CeO₂. Among the three compositions of 10 mol% Gd, Dy, Er showing depressed phase transition, Er- and Dy-substituted La₂Mo₂O₉ possess relatively low thermal expansion coefficient 11×10⁻⁶ K⁻¹, compared with that of the Gd-substituted La₂Mo₂O₉, 18×10⁻⁶ K⁻¹, which is near that of La₂Mo₂O₉. Hence, Dy and Er are valuable dopants in improving the La₂Mo₂O₉ properties. Across the lanthanide series, 10 mol%-substituted La₂Mo₂O₉ demonstrates systematic variations in the conductivity–temperature relation. Hysteresis phenomena in both of conductivity and thermal expansion are also observed in those compositions which display phase transition.     

Electrospinning-derived ZnCo2O4@carbon nanofiber composite for high-performance lithium ion storage

The degradation of the cobalt-zinc oxide structure and its poor conductivity during the charge and discharge limit their further applications for lithium ion storage. Herein, ZnCo₂O₄@carbon nanofiber composite with nano-fibrous structure is obtained by electrospinning, annealing in argon and low-temperature oxidation to effectively overcome the above issue. The active sites of ZnCo₂O₄ are evenly dispersed inside the carbon nanofibers, which can effectively avoid its aggregation and improve electrical conductivity. Additionally, the stable nanofibrous structure can maintain structural stability. The composite exhibits superior lithium ion storage capacity when being served as anode electrode. The ZnCo₂O₄@carbon nanofiber electrode possesses a high capacity of 1071 mA h g⁻¹ at 0.1 A g⁻¹. Besides, the electrode shows an outstanding rate capability of 505 mA h g⁻¹ at 3 A g⁻¹ and maintain 714 mA h g⁻¹ after 250 cycles when current density is adjusted to 0.2 A g⁻¹ again. Additionally, the electrode has an outstanding long-cycle performance, which remains a capacity of 447.165 mA h g⁻¹ at 0.5 A g⁻¹ after 500 cycles and 421.477 mA h g⁻¹ at 1 A g⁻¹ after 518 cycles. This result demonstrates that ZnCo₂O₄@carbon nanofiber composite has potential application prospects in the fields of advanced energy storage.     

Synthesis,microstructure and properties of ternary layered i-MAX (Mo2/3M1/3)2AlC (M = Sc and Lu) ceramics fabricated by spark plasma sintering

Recently, a new i-MAX phase with in-plane chemical order has been discovered. In this study, the i-MAX phase (Mo_2/3Sc_1/3)₂AlC and (Mo_2/3Lu_1/3)₂AlC ceramics were synthesized by spark plasma sintering (SPS) with purity up to 96.45 wt% and 95.46 wt%, respectively. Relative densities were up to 98.29 % (M = Sc) and 98.23 % (M = Lu). Microstructure, physical and mechanical properties of (Mo_2/3M_1/3)₂AlC (M = Sc and Lu) ceramics were systematically investigated. Grain sizes of (Mo_2/3M_1/3)₂AlC (M = Sc and Lu) were also counted. The measured coefficients of thermal expansion (CTE) were 8.95 × 10⁻⁶ K⁻¹ (M = Sc) and 8.97 × 10⁻⁶ K⁻¹ (M = Lu), from 25 °C to 1200 °C. Regarding mechanical properties, the Vickers hardness of (Mo_2/3Lu_1/3)₂AlC was much higher than that of (Mo_2/3Sc_1/3)₂AlC, while the differences in flexural strength, fracture toughness and compressive strength were small. It indicates that both ceramics have good application prospects.     

Preparation of Mo2C by the temperature-programmed reaction between h-MoO3 and CO

In the work, the temperature-programmed reaction (TPR) between hexagonal-shaped h-MoO₃ and high-purity CO under different heating rates was investigated in order to prepare Mo₂C. Various technologies such as TG-DTA-DTG, XRD, FESEM, FT-IR and Raman spectrum as well as the thermodynamic calculation were adopted to analyze the experimental data. The results showed that the physically adsorbed water on the sample surface, the residual ammonium and coordinated water in the internal structure of h-MoO₃ were successively released as the temperature increased, and then α-MoO₃ and Mo₄O₁₁ were formed when the temperature arrived at around 791 K. Upon further increasing the temperature, the reduction process occurred and MoO₂ will be generated. Thereafter, the carburization reaction was taken place and the subsequent reaction pathways were significantly different at lower and higher heating rates: at lower heating rates (8 and 12 K/min), the carburization process of MoO₂ to Mo₂C followed MoO₂→MoO₂+Mo₂C→Mo₂C + Mo→Mo₂C; while at higher heating rates (16 and 20 K/min), the reaction pathways followed MoO₂→MoO₂+Mo₂C→MoO₂+Mo₂C + Mo + MoO_xC_y→Mo→Mo₂C, single-phase metallic Mo can be generated. The work also discovered that the as-prepared Mo₂C always kept the same platelet-shaped morphology as that of the newly-formed MoO₂; while due to the removal of oxygen and the decrease of molar volume during the transformation process, the as-prepared Mo₂C exhibited a rougher and more porous morphological structure.     

Electrospinning combined with hydrothermal synthesis and lithium storage properties of ZnFe2O4-graphene composite nanofibers

ZnFe₂O₄-graphene composite nanofibers were prepared through electrospinning technique, then with graphene oxide by the facile solvothermal method to get the final products for the first time. The obtained ZnFe₂O₄ nanofibers composed of numerous same size nanoparticles wrapped by graphene sheets to form a unique nanostructure. When the ZnFe₂O₄-graphene electrode was evaluated as anode for lithium-ion batteries, good rate capability and long-term cycling stability could be achieved. The ZnFe₂O₄-graphene electrode exhibited a first discharge capacity of 2166 mAh g⁻¹ cycling at 0.05 C, remained an average reversible capacity of 1000 mAh g⁻¹ after 50 cycles, and kept the high rate capacities of 899, 822, 760 and 711 mAh g⁻¹ at the current rates of 0.5, 1, 2 and 5 C, respectively. The excellent electrochemical performance could be ascribed to the following reasons: the large electrochemical active surface area provided by the composite nanofibers; the graphene sheets decreased the internal resistance of the lithium-ion batteries, which resulted from the electrical conductivity of the graphene sheets; the graphene sheets as conductive network could effectively restrain the agglomeration of ZnFe₂O₄ nanopaiticals.     

Electrospun ZnO–SnO2 composite nanofibers with enhanced electrochemical performance as lithium-ion anodes

ZnO–SnO₂ composite nanofibers with different structures were synthesized by a simple electrospinning approach with subsequent calcination at three different temperatures using polyacrylonitrile as the polymer precursor. The electrochemical performance of the composites for use as anode materials in lithium-ion batteries were investigated. It was found that the ZnO–SnO₂ composite nanofibers calcined at 700 °C showed excellent lithium storage properties in terms of cycling stability and rate capability, compared to those calcined at 800 and 900 °C, respectively. ZnO–SnO₂ composite nanofibers calcined at 700 °C not only delivered high initial discharge and charge capacities of 1450 and 1101 mAh g⁻¹, respectively, with a 75.9% coulombic efficiency, but also maintained a high reversible capacity of 560 mAh g⁻¹ at a current density of 0.1 A g⁻¹ after 100 cycles. Additionally, a high reversible capacity of 591 mAh g⁻¹ was obtained when the current density returned to 0.1 A g⁻¹ after 50 cycling at a high current density of 2 A g⁻¹. The superior electrochemical performance of ZnO–SnO₂ composite nanofibers can be attributed to the unique nanofibrous structure, the smaller particle size and smaller fiber diameter as well as the porous structure and synergistic effect between ZnO and SnO₂.     

Crystal structure,infrared-reflectivity spectra,and microwave dielectric properties of novel Ce2(MoO4)2(Mo2O7) ceramics

Novel Ce₂(MoO₄)₂(Mo₂O₇) (CMO) ceramics were prepared by a conventional solid-state method, and the microwave dielectric properties were investigated. X-ray diffraction results illustrated that pure Ce₂(MoO₄)₂(Mo₂O₇) structure formed upon sintering at 600 °C-725 °C. [CeO₇], [CeO₈], [MoO₄], and [MoO₆] polyhedra were connected to form a three-dimensional structure of CMO ceramics. Analysis based on chemical bond theory indicated that the Mo–O bond critically affected the ceramics’ performance. Furthermore, infrared-reflectivity spectra analysis revealed that the primary polarisation contribution was from ionic polarisation. Notably, the optimum microwave dielectric properties of ε_r = 10.69, Q·f = 49,440 GHz (@ 9.29 GHz), and τ_f = −30.4 ppm/°C were obtained in CMO ceramics sintered at 700 °C.     

Flame-made MoO3/SiO2–Al2O3 metathesis catalysts with highly dispersed and highly active molybdate species

MoO₃/SiO₂–Al₂O₃ catalysts are prepared via flame spray pyrolysis and evaluated in the self-metathesis of propene to ethene and butene. Their specific surface area ranges between 100 and 170 m² g^?1 depending on the MoO₃ loading (1–15 wt.%, corresponding to Mo surface density between 0.3 and 6.1 Mo atoms per nm²). The catalysts were characterized by N₂-physisorption, X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToF-SIMS). The silica–alumina matrix condenses first in the flame and forms non-porous spherical particles of 5–20 nm, followed by the dispersion of Mo oxide at their surface. Depending on the MoO₃ loading, different MoO_x species are stabilized: dispersed and amorphous molybdates (mono- and oligomeric) at low loadings (<5 wt.%, <1.5 Mo nm^?2) and crystalline MoO₃ species at higher loadings. Raman spectroscopy suggests the presence of monomeric species for surface densities of 0.3, 0.5 and 0.8 Mo nm^?2. The formation of MoOMo bonds is, however, clearly established by ToF-SIMS from surface densities as low as 0.5 Mo nm^?2. At 1.5 Mo nm^?2, crystallites of β-MoO₃ (2–3 nm) are detected and further increasing the loading induces the formation of bigger α- and β-MoO₃ crystals (around 20 nm). The speciation of Mo proves to have a marked impact on the metathesis activity of the catalysts. Catalysts with high Mo loading and exhibiting MoO₃ crystals are poorly active, whereas catalysts with low Mo loading (<5 wt.%) perform well in the reaction. The catalyst loaded with only 1 wt.% of MoO₃ (0.3 Mo nm^?2) is the most active, reaching turn over frequencies seven times higher than reference catalysts reported in the literature. Moreover, the specific metathesis activity is clearly inversely correlated to the degree of condensation of the molybdenum oxide phase (as evaluated by ToF-SIMS). The latter finding indicates that monomeric MoO_x species are the main active centres in the olefin metathesis.     

MoO3/reduced graphene oxide composites as anode material for sodium ion batteries

MoO₃/reduced graphene oxide (MoO₃/RGO) composites were successfully prepared via a facile one-step hydrothermal method, and evaluated as anode materials for sodium ion batteries (SIBs). The crystal structures, morphologies and electrochemical properties of the as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge tests, respectively. The results show that the introduction of RGO can enhance the electrochemical performances of MoO₃/RGO composites. MoO₃/RGO composite with 6 wt% RGO delivers the highest reversible capacity of ~208 mA h g⁻¹ at 50 mA g⁻¹ after 50 cycles with good cycling stability and excellent rate performance for SIBs. The excellent sodium storage performance of MoO₃/RGO should be attributed to the synergistic effect between MoO₃ and RGO, which offers the increased electrical conductivity, the facilitated electron transfer ability and the buffering of volume expansion.     

Sr2Fe1.5Mo0.5O6–δ – Zr0.84Y0.16O2–δ Materials as Oxygen Electrodes for Solid Oxide Electrolysis Cells

The high‐temperature solid oxide electrolysis cell (SOEC) is one of the most promising devices for hydrogen mass production. To make SOEC suitable from an economical point of view, each component of the SOEC has to be optimized. At this level, the optimization of the oxygen electrode is of particular interest since it contributes to a large extent to the cell polarization resistance. The present paper is focused on an alternative oxygen electrode of Zr_0.84Y_0.16O_2–δ‐Sr₂Fe_1.5Mo_0.5O_6–δ (YSZ‐SFM). YSZ‐SFM composite oxygen electrodes were fabricated by impregnating the YSZ matrix with SFM, and the ion‐impregnated YSZ‐SFM composite oxygen electrodes showed excellent performance. For a voltage of 1.2 V, the electrolysis current was 223 mA cm⁻², 327 mA cm⁻² and 310 mA cm⁻² at 750 °C for the YSZ‐SFM10, YSZ‐SFM20, and YSZ‐SFM30 oxygen electrode, respectively. A hydrogen production rate as high as 11.46 NL h⁻¹ has been achieved for the SOEC with the YSZ‐SFM20 electrode at 750 °C. The results demonstrate that YSZ‐SFM fabricated by impregnating the YSZ matrix with SFM is a promising composite electrode for the SOEC.     

Mo2C intermediate layers for the wetting and infiltration of graphite foams by liquid copper

Since copper does not wet graphite foams (GFs), a method for the synthesis of Mo₂C coatings throughout the GFs was developed for improving the wetting between GFs and copper and for the preparation of GF/copper composites. The coatings were formed on the GFs in a reaction medium consisting of ammonium paramolybdate, which decomposed to fine MoO₃, in a mixture of molten NaCl–KCl salts. The formation mechanism and microstructure of the Mo₂C coatings on GFs were investigated. Then the microstructure, thermal conductivity and thermal expansion behavior of the obtained GF/copper composites were studied. Results indicated the formation of Mo₂C coatings occurred in two steps, namely, the reduction of MoO₃ to MoO₂ and the reduction of MoO₂ to Mo₂C. Copper was infiltrated into the Mo₂C-coated GFs without external pressure and the nearly pore-free GF/copper composites were obtained. The thermal conductivity of the composite with a density of 5.76 g/cm³ reached 268.4 W/mK. Significant reduction in coefficient of thermal expansion of the composite compared with that of copper (8.91 versus 18.59 ppm/K) was obtained.     

Magnetoelectric coupling in CoFe2O4-Pb(Zr0.2Ti0.8)O3 coaxial nanofibers

In this work, we reported the fabrication and magnetoelectric coupling properties of the multiferroic CoFe₂O₄-PbZr_0.2Ti_0.8O₃ (CFO-PZT) coaxial nanofibers synthesized by electrospinning technique. The coaxial structure of nanofibers was demonstrated by magnetic force microscope and transmission electron microscope. The multiferroic properties of coaxial nanofibers have been revealed by magnetic hysteresis loops and piezoresponse amplitude butterfly curves and phase hysteresis loops. The as-prepared coaxial nanofibers show an effective piezoelectric coefficient d₃₃ of 30 pm/V and a saturated magnetization of 12 emu/g. Their magnetoelectric response has been probed by means of the localized changes in magnetization after poling the domains of the composite system. A static, large converse magnetoelectric coupling coefficient of 1.2 × 10⁻⁸ s/m was obtained in a single CFO-PZT nanofiber.     

Growth and Magneto-Optical Properties of Li2MoO4·1.8Tb2(MoO4)3 Crystal

Li₂MoO₄·1.8Tb₂(MoO₄)₃ crystal, a kind of solid solution crystal, was grown in air by the top seeded solvent growth method in a Li₂Mo₂O₇ flux. The lattice parameters of the crystal were determined by X-ray diffraction analysis. The absorption coefficient of the crystal was investigated at wavelengths from 400 to 1500 nm at room temperature. Valence states of Tb ions in Li₂MoO₄·1.8Tb₂(MoO₄)₃ crystal were analyzed by X-ray photoelectron spectroscopy measurement. Verdet constants for the Li₂MoO₄·1.8Tb₂(MoO₄)₃ crystal at 532, 633 and 1064 nm wavelengths were measured by the extinction method. They are −341, −239 and −75 rad m⁻¹ T⁻¹, respectively. The results show that the crystal has a larger magneto-optical figure of merit than terbium gallium garnet at wavelength of 633 nm.     

Tailoring carboxyl tubular carbon nanofibers/MnO2 composites for high-performance lithium-ion battery anodes

Three kinds of novel carboxyl modification tubular carbon nanofibers (CMTCFs) and MnO₂ composites materials (CMTCFs/MnO₂) are prepared by combining hyper-crosslinking, liquid phase oxidation and hydrothermal technology. The complex morphology and crystal phase of MnO₂ in CMTCFs/MnO₂ are effectively regulated by adjusting the hydrothermal reaction time. The δ-MnO₂ nanosheet-wrapped CMTCFs (CMTCFs@MNS) are used as anode and compared with the other two CMTCFs/MnO₂. Electrochemical analysis shows that CMTCFs@MNS electrode exhibits a large reversible capacity of 1497.1 mAh g⁻¹ after 300 cycles at 1000 mA g⁻¹ and a long cycling reversible capacity of 400.8 mAh g⁻¹ can be maintained after 1000 cycles at 10 000 mA g⁻¹. CMTCFs@MNS manifests an average reversible capacity of 256.32 mAh g⁻¹ at 10 000 mA g⁻¹ after twelve changes in current density. In addition, the structural superiority of CMTCFs@MNS electrode is clarified by characterizing the microscopic morphology and crystal phase of the electrode after electrochemical performance test.     

One-pot solution combustion synthesis of crystalline and amorphous molybdenum trioxide as anode for lithium-ion battery

In this study, crystalline MoO₃ rods and amorphous MoO₃ microsheets were synthesized using a one-step, large-scale, and time- and energy-efficient solution combustion synthesis method. When urea was used as a fuel, ultralong rod-like crystalline MoO₃ with a length over 50 μm was synthesized. In the case of citric acid, an amorphous MoO₃ product with a porous microsheet structure was obtained. As anode materials for lithium-ion batteries, the unique structure of amorphous MoO₃ sample has significant advantages including fast diffusion of lithium ion, providing a lot of active sites for lithium ion storage and stable structure. Thus, the amorphous MoO₃ sample exhibits greater electrochemical performance, a high capacity of 818 mAh g⁻¹ at 0.1 A g⁻¹ in the 100th cycle and 510 mAh g⁻¹ at 1 A g⁻¹ in the 300th cycle, than that of crystalline MoO₃ product. Moreover, this study provides guide for preparing other amorphous and crystalline transition-metal oxides with a pure phase.