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MoO2 nanoparticles (NPs) and reduced graphene oxide (rGO) nanocomposites (MoO2 NPs/rGO) with different rGO contents were prepared by a two-step hydrothermal process. When the content of rGO was 10 wt%, the MoO2 nanoparticles were uniformly deposited on the rGO nanosheets, and the corresponding MoO2 NPs/rGO nanocomposites also exhibited the highest...
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Citations
... MoO2/MoS2 composites show increased cyclic stability and storage of lithium ions [77]. Therefore, research on the production of various composites, including MoO2/carbon (MoO2/carbon nanotubes [78], hybrid MoO2/carbon nanowires [79] and MoO2/graphene [80]) is another effective route to improve electrochemical efficiency. ...
Hydrothermal crystallization was used to synthesize an advanced hybrid system containing titania and molybdenum disulfide (with a TiO2:MoS2 molar ratio of 1:1). The way in which the conditions of hydrothermal treatment (180 and 200 °C) and thermal treatment (500 °C) affect the physicochemical properties of the products was determined. A physicochemical analysis of the fabricated materials included the determination of the microstructure and morphology (scanning and transmission electron microscopy—SEM and TEM), crystalline structure (X-ray diffraction method—XRD), chemical surface composition (energy dispersive X-ray spectroscopy—EDS) and parameters of the porous structure (low-temperature N2 sorption), as well as the chemical surface concentration (X-ray photoelectron spectroscop—XPS). It is well known that lithium-ion batteries (LIBs) represent a renewable energy source and a type of energy storage device. The increased demand for energy means that new materials with higher energy and power densities continue to be the subject of investigation. The objective of this research was to obtain a new electrode (anode) component characterized by high work efficiency and good electrochemical properties. The synthesized TiO2-MoS2 material exhibited much better electrochemical stability than pure MoS2 (commercial), but with a specific capacity ca. 630 mAh/g at a current density of 100 mA/g.
... MoO2/MoS2 composites show increased cyclic stability and storage of lithium ions [77]. Therefore, research on the production of various composites, including MoO2/carbon (MoO2/carbon nanotubes [78], hybrid MoO2/carbon nanowires [79] and MoO2/graphene [80]) is another effective route to improve electrochemical efficiency. ...
TiO2-MoO3 composite systems were successfully prepared using a template-assisted microwave method at molar ratios TiO2:MoO3 = 8:2, 5:5 and 2:8. The synthesized material systems were comprehensively characterized, in terms of their crystalline structure (XRD and Raman spectroscopy), morphology (SEM, TEM and HRTEM analysis) and parameters of the porous structure (low-temperature N2 sorption). The materials exhibited highly crystalline phases: anatase and hexagonal molybdenum trioxide. Moreover, TEM analysis revealed hexagonal prism particles of MoO3 and nanocrystalline particles of TiO2. The proposed template-assisted microwave synthesis enabled the incorporation of TiO2 particles on the surface of hexagonal particles of MoO3, which resulted in a stable junction between titania and molybdenum trioxide. The values of BET surface area were 57, 29 and 11 m2/g for samples obtained at molar ratios TiO2:MoO3 = 8:2, 5:5 and 2:8 respectively. In electrochemical applications, titanium dioxide plays a crucial role as an intercalation intensifier, in which MoO3 is responsible for current conduction. Taking account of the potential electrochemical applications, the best system was obtained at the molar ratio TiO2:MoO3 = 5:5. The anode could maintain a capacity of 400 mAh/g at current densities in the range 100–1000 mA/g at potential values ranging from 1.00 to 3.30 V vs. Li/Li+. X-ray photoelectron spectroscopy (XPS) confirmed the effective intercalation of lithium ions into the TiO2-MoO3 composite materials.
... Among lots of carbon materials, graphene has widely used because of its large specific surface area, excellent electronic transport property and prominent flexibility. In recent years, different structure of MoO 2 -rGO hybrids have been designed and the experimental results show that the electrochemical performance can be effectively improved [11,12]. However, the aggregating of nanosheets just like graphene and MoO 2 is inescapable during the cycling process or even during the synthesis process, and it is still desirable to build multileveled/multiple structures to address this problem [13]. ...
... This unique 1D loosened structure with MoO 2 nanosheets anchored on rGO provides large area and short ion/electron paths, exhibiting enhanced rate performance and capacity as anode material of LIBs compared with MoO 3 @GO hybrid. [12]. In addition, intensity ratios of D (1347 cm −1 ) and G (1587 cm −1 ) bands (I D /I G ) increases from 0.917 for the MoO 3 @GO to 1.225 for MoO 2 -rGO, indicating the reduction of GO, which can be ascribed to the re-establishment of conjugated graphene networks decreased size of sp 2 domains and the GO sheets become more disordered, and the highly crystalline carbon facilitates rapid electron transfer during electrochemical process [16][17][18]. ...
Two-dimensional (2D) materials have been widely studied and used as anode materials for lithium ion batteries (LIBs) because of their high specific surface area and intrinsic mechanical flexibility which could offer numerous active sites and protect effect for LIBs. However, 2D nanosheets are easy to stack and partially lose surface area for Li-ion storage thus greatly affecting their electrochemical performance. Here, we develop a simple strategy to obtain a nanosheets-based one-dimensional structure hybrid by in situ reduction from MoO3 nanorods to MoO2 nanosheets and nanoparticles which are anchored on a 1D reduced graphene oxide skeleton (MoO2-rGO). It was demonstrated that the primary MoO2 nanosheets and nanoparticles are uniformly dispersed on the reduced graphene oxide nanosheets, which are further assembled into a 1D loosened nanostructure. The loosened nanosheets offer more accessible surface area and facilitate transport of electrons and Li-ions. Moreover, MoO2 nanoparticles effectively avoid agglomeration from nanosheets. Results show that MoO2-rGO hybrid demonstrates an enhanced cyclic life, high stability and prominent rate performance when evaluated as anode material for LIBs. The first discharge capacity can reach 1256.4 mAh g-1 and provide a highly reversible capacity of 1003.7 mA h g-1 after 100 cycles at 0.1 A g-1, which makes MoO2-rGO a promising candidate for LIBs. The excellent performance can be attributed to the unique 1D loosened structure consists of MoO2 and conducting rGO nanosheets, which facilitates fast transfer of Li-ion and electron, and the reduced graphene oxide nanosheets acting as a skeleton provide a continuous conductive network and simultaneously strengthen the structural stability.
... Although molybdenum has oxidation states ranging from +2 to +6, among them, two forms of oxides are existing mainly i.e., Mo(IV) and Mo(VI) oxide. The presence of free electrons in the valance band region enhances the catalytic activity of Mo 4+ in MoO2 unlike Mo 6+ in MoO3, where all the valence electrons of the metal are covalently bonded to neighbouring oxygen atoms [1][2][3][4][5]. MoO2 nanostructure has more advantages than bulk MoO2 because it exhibits high surface area leading to increasing the number of active sites available to the reaction and enhances the applications [6][7][8][9][10][11][12]. ...
... MoO2 nanostructure has more advantages than bulk MoO2 because it exhibits high surface area leading to increasing the number of active sites available to the reaction and enhances the applications [6][7][8][9][10][11][12]. To date, many morphologies of MoO2 nanostructures have been synthesized such as nanowires arrays, hollow fibres, hollow spherical and others morphologies [1,3,[7][8][9][10][12][13][14][15][16][17][18][19]. Among the different morphologies of MoO2 nanostructure, MoO2 nanohseets have significance chemical, physical, electronic and optical properties which make them favourable candidates for a wide range of application such as photocatalytic reactions [6,7,9,11,17,19,20]. ...
Monoclinic molybdenum dioxide (MoO2) nanosheets have been successfully synthesized by a simple electrochemical method. The as prepared MoO2 was used as a photocatalyst for the photocatalytic degradation of Indigo carmine dye under various experimental conditions and also as oxygen evaluation catalyst for the decomposition of potassium permanganate. Initially, as-prepared MoO2 was characterized by different techniques namely, X-ray diffraction, scanning electron microscopy FE-SEM, UV-visible and FT-IR techniques, so as to study and revealed the morphological, structural, functional and optical properties. The results revealed that photocatalyst has nanosheets morphology with thickness less than 10 nm and it has also monoclinic crystal structure with an average crystallite size of 27 nm. The optical properties studies showed that band gap (Eg) value of MoO2 (3.85 eV) lies in the UV region and can be a suitable candidate for UV light photocatalytic application. In addition, the experimental results revealed an excellent photocatalytic performance of MoO2 in the degradation of Indigo carmine under UV light irradiation and also for the decomposition of KMnO4 by oxygen evaluation reaction.
... This demonstrates the metamorphosis in its Li + ion storage mechanism i. e., from an insertion dominant reaction mechanism to conversion dominant reaction mechanism. [23][24][25][26][27] The representative charge-discharge profile of the MoO 2 -rGO nanocomposite at a current rate of 0.1 C in a potential window 0.01 to 3.00 V is shown in the Figure 9. For the first cycle, the charge and discharge capacities are found to be 1030 and 756 mA h g À 1 , respectively. ...
Though molybdenum dioxide (MoO2) has attractive properties, conductivity is still threat to its implementation as it is very low compared to graphite. Herein, we have come up with MoO2‐rGO nanocomposite to mitigate this drawback, where nano sized MoO2 particles have been synthesised and supported with graphene sheets. Several physicochemical characterization techniques have been used to confirm the desired state of the obtained material. In this report, rGO supported MoO2 nanoparticles have been investigated as an anode for lithium ion battery and its electrochemical properties have been extensively studied. The new architecture exhibits excellent electrochemical performance by delivering a high discharge capacity of 1205 mA h g⁻¹ even after 100 cycles. It also exhibits good rate capability by delivering discharge capacities of 809, 753, 675 mA h g⁻¹ at current rates of 1 C, 3 C and 5 C, respectively.
... The first peak is assigned to the C-C bonds of rGO, whereas the second peak is corresponded to C-O bonds, [47] respectively. Figure 4e 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A c c e p t e d M a n u s c r i p t assigned to Mo IV 3d 3/2 and 3d 5/2 which are at +4 oxidation state of MoO 2 , respectively. ...
In this manuscript, we synthesize a porous three-dimensional anode material consists of molybdenum dioxide nanodots anchored on the nitrogen/sulfur co-doped reduced graphene oxide (3D MoO2/NP-NSG) through hydrothermal, lyophilization and thermal treatment. First, the NP-NSG is formed via hydrothermal treatment using graphene oxide (GO), hydrogen peroxide (H2O2), and thiourea as the co-dopant for N and S followed by calcination the N/S co-doped GO in the presence of ammonium molybdate tetrahydrate to obtain the 3D MoO2/NP-NSG product. This novel material exhibits a series of out-bound electrochemical performances, such as superior conductivity, high specific capacity, and splendid stability. As an anode for lithium-ion batteries (LIBs), MoO2/NP-NSG electrode has a high initial specific capacity (1376 mAh g-1), good cycling performance (1250 mAh g-1 after 100 cycles at a current density of 0.2 A g-1), and glorious coulombic efficiency (99% after 450 cycles at a current density of 1 A g-1). Remarkably, the MoO2/NP-NSG battery exhibits exceedingly good rate capacities of 1021, 965, 891, 760, 649, 500 and 425 mAh g-1 at different current densities of 200, 500, 1000, 2000, 3000, 4000 and 5000 mA g-1, respectively. The wally electrochemical performance is owing to the high porosity of 3D architecture, the synergistic effect contributes from N and S co-doped in the reduced graphene oxide (rGO), and the uniform distribution of MoO2 nanodots on rGO surface.
Binary metal oxides with superior charge capacity and electrochemical activity have gained great interests. In this work, monodispersed CoMoO4 nanoclusters on the ordered mesoporous carbons were fabricated by a facile self-developed impregnation method. The synthesized hybrids possess improved wettability, high specific surface area (>700 m²/g) and regular mesoporous channels (∼4 nm), resulting in improved electrochemical performance for supercapacitors. These well-dispersed CoMoO4 nanoclusters exhibit a significant specific capacitance up to 367 F/g in the aqueous KNO3 electrolyte and good reversibility with a cycling efficiency of 99.8%. It is proposed that the mesoporous structure can facilitate the diffusion of electrolyte ions and then accelerate the electrochemical utilization of CoMoO4 nanoclusters. The results demonstrate that the produced binary metal oxide nanoclusters with excellent capacitance and good retention can be used as promising electrodes for the environment-friendly supercapacitors.
Developing the high-performance anode with high capacity, excellent rate capability and cycling stability for sodium ion batteries is still a great challenge. MoS2 has been extensively investigated as anode for sodium ion batteries. Herein, the vertically oxygen-incorporated MoS2 nanosheets/carbon fibers are synthesized through a hydrothermal process followed by calcination in air. Oxygen incorporation in MoS2 can increase defect degree and expand interlayer spacing. Vertical MoS2 nanosheets array coated on carbon fibers not only can provide more active sites and shorten Na+ diffusion distance, but also improve the electronic conductivity and enhance the structural stability. Meanwhile, interlayer expanded MoS2 can decrease Na+ diffusion resistance and increase accessible active sites for Na+. This work demonstrates that electrode combining the oxygen-incorporated strategy with vertical MoS2 nanosheets integrated carbon fibers displays high reversible capacities of 330 mAh g-1 at 0.1 A g-1 after 100 cycles together with excellent rate capability as anode for sodium ion batteries. This strategy offers a helpful way for improving the electrochemical performance.
