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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on MoO3 by Materials Project

MoO3 crystallizes in the monoclinic Pc space group. The structure is two-dimensional and consists of two MoO3 sheets oriented in the (0, 0, 1) direction. Mo6+ is bonded to five O2- atoms to form distorted corner-sharing MoO5 trigonal bipyramids. There are a spread of Mo–O bond distances ranging from 1.71–1.99 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Mo6+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Mo6+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Mo6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO3 by Materials Project

MoO3 crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two MoO3 sheets oriented in the (0, 0, 1) direction. Mo6+ is bonded to five O2- atoms to form corner-sharing MoO5 trigonal bipyramids. There is two shorter (1.78 Å) and three longer (2.04 Å) Mo–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Mo6+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Mo6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Electronic structure modulation of MoS2 by substitutional Se incorporation and interfacial MoO3 hybridization: Implications of Fermi engineering for electrocatalytic hydrogen evolution and oxygen evolution

The design of earth-abundant electrocatalysts that can facilitate water splitting at low overpotentials, provide high current densities, and enable prolonged operational lifetimes is central to the production of sustainable fuels. The distinctive atomistic and electronic structure characteristics of the edges of MoS2 imbue high reactivity toward the hydrogen evolution reaction. MoS2 is nevertheless characterized by significantly high overpotentials as compared to platinum. Here, we demonstrate that modulation of the electronic structure of MoS2 through interfacial hybridization with MoO3 and alloying of selenium on the anion sublattice allows for systematic lowering of the conduction band edge and raising of the valence band edge, respectively. The former promotes enhanced electrocatalytic activity toward hydrogen evolution, whereas the latter promotes enhanced activity toward the oxygen evolution reaction. Such alloyed heterostructures prepared by sol-gel reactions and hydrothermal selenization expose a high density of edge sites. The alloyed heterostructures exhibit low overpotential, high current density, high turnover frequency, and prolonged operational lifetime. The mechanistic origins of catalytic activity have been established based on electronic structure calculations and x-ray absorption and emission spectroscopy probes of electronic structure, which suggest that interfacial hybridization at the MoO3 interface yields low-lying conduction band states that facilitate hydrogen adsorption. In contrast, shallow Se 4p-derived states give rise to a raised effective valence band maximum, which facilitates adsorption of oxygen intermediates and engenders a low overpotential for the oxygen evolution reaction. The findings illustrate the use of electronic structure modulation through interfacial hybridization and alloying to systematically improve electrocatalytic activity.

Parija, Abhishek↗
DOE OSTI2020

Materials Data on MoO3 by Materials Project

MoO3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to six O2- atoms to form distorted corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 11–17°. There are a spread of Mo–O bond distances ranging from 1.76–2.28 Å. In the second Mo6+ site, Mo6+ is bonded to six O2- atoms to form distorted corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 11–17°. There are a spread of Mo–O bond distances ranging from 1.76–2.28 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Mo6+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to two Mo6+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two Mo6+ atoms. In the fourth O2- site, O2- is bonded in a linear geometry to two Mo6+ atoms. In the fifth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Mo6+ atoms. In the sixth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Mo6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO3 by Materials Project

MoO3 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to six O2- atoms to form distorted corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 19–28°. There are a spread of Mo–O bond distances ranging from 1.77–2.26 Å. In the second Mo6+ site, Mo6+ is bonded to six O2- atoms to form distorted corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 20–26°. There are a spread of Mo–O bond distances ranging from 1.77–2.24 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Mo6+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Mo6+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two Mo6+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Mo6+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Mo6+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Mo6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO3 by Materials Project

MoO3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to six O2- atoms to form corner-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles are 23°. There is two shorter (1.92 Å) and four longer (1.93 Å) Mo–O bond length. In the second Mo6+ site, Mo6+ is bonded to six O2- atoms to form corner-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles are 23°. There is two shorter (1.92 Å) and four longer (1.93 Å) Mo–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Mo6+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Mo6+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two Mo6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2022

Surface plasmons induce topological transition in graphene/α-MoO3 heterostructures

Abstract Polaritons in hyperbolic van der Waals materials—where principal axes have permittivities of opposite signs—are light-matter modes with unique properties and promising applications. Isofrequency contours of hyperbolic polaritons may undergo topological transitions from open hyperbolas to closed ellipse-like curves, prompting an abrupt change in physical properties. Electronically-tunable topological transitions are especially desirable for future integrated technologies but have yet to be demonstrated. In this work, we present a doping-induced topological transition effected by plasmon-phonon hybridization in graphene/α-MoO 3 heterostructures. Scanning near-field optical microscopy was used to image hybrid polaritons in graphene/α-MoO 3 . We demonstrate the topological transition and characterize hybrid modes, which can be tuned from surface waves to bulk waveguide modes, traversing an exceptional point arising from the anisotropic plasmon-phonon coupling. Graphene/α-MoO 3 heterostructures offer the possibility to explore dynamical topological transitions and directional coupling that could inspire new nanophotonic and quantum devices.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Mitigating Iodine Diffusion by a MoO 3 –Organic Composite Hole Transport Layer for Stable Perovskite Solar Cells

Halide perovskite solar cells (PSCs) exhibit commercialization potential, but long-term stability still must be addressed. Among various products of perovskite decomposition, iodine species are of considerable concern due to their high vapor pressure and corrosive nature. To address this, a small-molecule hole transport layer (HTL), 4,4',4"-tris[(3-methylphenyl)phenylamino]triphenylamine (m-MTDATA), is used; mixing it with molybdenum trioxide (MoO3) p-dopes the layer and slows iodine permeation. Furthermore, we demonstrate that m-MTDATA:MoO3 HTLs employed in PSCs improve stability under both thermal and voltage bias stress compared to devices with a conventional doped 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-OMeTAD) HTL.

14 SOLAR ENERGY↗
DOE OSTI2020

Materials Data on AlMoO3 by Materials Project

MoO3Al is (Cubic) Perovskite structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional and consists of one aluminum molecule and one MoO3 framework. In the MoO3 framework, Mo3+ is bonded to six equivalent O2- atoms to form corner-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.00 Å) and two longer (2.01 Å) Mo–O bond lengths. O2- is bonded in a linear geometry to two equivalent Mo3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Evaluating the Role of Metastable Surfaces in Mechanochemical Reduction of Molybdenum Oxide

Mechanochemistry and mechanocatalysis are gaining increasing attention as environmentally friendly chemical processes because of their solvent-free nature and scalability. Significant effort has been devoted for studying continuum-scale phenomena in mechanochemistry, such as temperature and pressure gradients, but the atomic-scale mechanisms remain relatively unexplored. In this work, we focus on the mechanochemical reduction of MoO3 as a case study. We use experimental techniques to determine the mechanochemical reduction conditions and density functional theory (DFT) simulations to establish an atomistic framework for identifying the metastable surfaces that are most likely to enable this process. Our results show that metastable surfaces can significantly lower or remove thermodynamic barriers for surface reduction and that kinetic energy from milling can facilitate the formation of metastable surfaces that have high surface fracture energies and are not thermally accessible. These findings indicate that metastable surfaces are an important aspect of mechanochemistry along with hot spots and other continuum-scale phenomena.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Achieving Stable Molybdenum Oxide Cathodes for Aqueous Zinc-Ion Batteries in Water-in-Salt Electrolyte

A layered MoO 3 material with large interlayer spacing represents a promising cathode for aqueous rechargeable Zn-ion batteries (ARZIBs), but the implementation of this material is limited due to the intrinsically low conductivity and poor structural stability. A 30 m ZnCl 2 water-in-salt electrolyte (WISE) was introduced to a MoO 3 nanobelt cathode for the first time, significantly increasing the stability of MoO 3 cathodes compared to those in 3 M ZnSO 4 and 3 M ZnCl2 electrolyte. The Zn/MoO 3 cell in WISE unambiguously demonstrated significantly improved rate performance delivering 349, 253, and 222 mAh/g at 100, 500, and 1000 mA/g, denoting a 2×, and 12× capacity increase of those achieved in 3 M electrolytes at 500 and 1000 mA/g, respectively. A capacity retention rate of 73% was achieved after (dis)charging at 100 mA/g for 100 cycles, and no obvious capacity fading was observed at higher current densities of 500 mA/g and 2A/g. A compilation of structural and morphological characterization was systematically performed to provide insight into the mechanisms of the improved performance in ZnCl 2 WISE for the MoO3 cathode materials. Specifically, our data collectively suggested that the drastic fading in 3M electrolytes can be attributed to the parasitic surface deposits on Zn originated from Mo dissolution and H 2 formation due to Zn corrosion and hydrogen evolution reaction (HER), which were significantly suppressed in the ZnCl 2 WISE. The direct visualization of these side reactions was achieved for the first time in the Zn-MoO 3 system, using an in situ optoelectrochemical measurement.

25 ENERGY STORAGE↗
DOE OSTI2024

Solution-based electrical doping of organic photovoltaics with non-fullerene acceptors facilitated by solvent vapor pre-treatment

Solution-based electrical doping of organic semiconductors using 12-molybdophosphoric acid (PMA) hydrate has been shown to allow p-type doping of conjugated polymers over a limited depth from the surface, enabling the fabrication of organic solar cells with a simplified device architecture. However, the doping level of certain conjugated polymers using PMA was found to be limited by the polymer film volume. Here, we report a modified PMA doping technique based on film volume expansion that is applicable to device fabrication, leading to hole-collecting layer-free non-fullerene organic photovoltaic devices, which exhibit a comparable photovoltaic performance to those with a commonly evaporated MoO3 hole-collecting layer.

Materials Science↗
DOE OSTI2022

Synthesis and Ultrahigh Pressure Compression of High-Entropy Boride (Hf0.2Mo0.2Nb0.2Ta0.2Zr0.2)B2 to 220 GPa

The high-entropy boride (Hf0.2Mo0.2Nb0.2Ta0.2Zr0.2)B2 material was synthesized under high-pressures and high-temperatures in a large-volume Paris-Edinburgh (PE) press from a ball-milled powder mix of HfO2, MoO3, Nb2O5, Ta2O5, ZrO2, carbon black, and boron carbide. The transformation process was monitored in situ by energy-dispersive x-ray diffraction with conversion starting at 1100 °C and completed by 2000 °C with the formation of a single hexagonal AlB2-type phase. The synthesized sample was recovered, powdered, and mixed with platinum pressure marker and studied under high pressure by angle-dispersive x-ray diffraction in a diamond anvil cell. The hexagonal AlB2-type phase of (Hf0.2Mo0.2Nb0.2Ta0.2Zr0.2)B2 was found to be stable up to the highest pressure of 220 GPa reached in this study (volume compression V/V0 = 0.70). The third order Birch-Murnaghan equation of state fit to the high-pressure data up to 220 GPa results in an ambient pressure unit cell volume V0=28.16±0.04 Å3, bulk modulusKo = 407 ± 6 GPa, pressure derivative of bulk-modulus K0′ = 2.73 ± 0.045 GPa. Our study indicates that this high-entropy boride (Hf0.2Mo0.2Nb0.2Ta0.2Zr0.2)B2 material is stable to ultrahigh pressures and temperatures and exhibit high bulk modulus similar to other incompressible transition metal borides like ReB2 and Os2B3.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Steam-Assisted Ammonolysis of MoO2 as a Synthetic Pathway to Oxygenated δ-MoN

A common route for the synthesis of molybdenum nitrides is through the temperature-programmed reaction of molybdenum oxides with NH3, or ammonolysis. In this work, the role of precursor phase, gas phase chemistry (impact of H2O), and temperature profile on the reaction outcome (700 °C) was examined, which resulted in varying amounts of MoO2, H2MoO5, and the nitride phases—cubic γ (nominally Mo2N) and hexagonal δ (nominally MoN). The phase fraction of the δ phase increased with precursor in the sequence MoO2 > MoO3 > H2MoO5. Steam in the reaction gas also favored the production of δ over γ, but with too much steam, MoO2 was obtained in the product. Synthesis conditions for obtaining nearly phase-pure δ were identified: MoO2 as the precursor, 2% H2O in the gas stream, and a moderate heating rate (3 °C/min). In situ X-ray diffraction provided insights into the reaction pathway. Extensive physico-chemical analysis of the δ phase, including synchrotron X-ray and neutron diffraction, electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and prompt gamma activation analysis, revealed its stoichiometry to be MoO0.108(8)N0.892(8)H0.012(5), indicating non-trivial oxygen incorporation. The presence of N/O ordering and an impurity phase Mo5N6 were also revealed, detectable only by neutron diffraction. Notably, a computationally predicted MoON phase (doi: 10.1103/PhysRevLett.123.236402), of interest due to its potential to display a metal-insulator transition, did not appear under any reaction condition examined.

Pandey, Shobhit↗
DOE OSTI2024

Selective CW Laser Synthesis of MoS2 and Mixture of MoS2 and MoO2 from (NH4)2MoS4 Film

Very recently, the synthesis of 2D MoS2 and WS2 through pulsed laser-directed thermolysis can achieve wafer-scale and large-area structures, in ambient conditions. In this paper, we report the synthesis of MoS2 and MoS2 oxides from (NH4)2MoS4 film using a visible continuous-wave (CW) laser at 532 nm, instead of the infrared pulsed laser for the laser-directed thermolysis. The (NH4)2MoS4 film is prepared by dissolving its crystal powder in DI water, sonicating the solution, and dip-coating onto a glass slide. We observed a laser intensity threshold for the laser synthesis of MoS2, however, it occurred in a narrow laser intensity range. Above that range, a mixture of MoS2 and MoO2 is formed, which can be used for a memristor device, as demonstrated by other research groups. We did not observe a mixture of MoS2 and MoO3 in the laser thermolysis of (NH4)2MoS4. The laser synthesis of MoS2 in a line pattern is also achieved through laser scanning. Due to of the ease of CW beam steering and the fine control of laser intensities, this study can lead toward the CW laser-directed thermolysis of (NH4)2MoS4 film for the fast, non-vacuum, patternable, and wafer-scale synthesis of 2D MoS2.

(NH4)2MoS4↗