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26 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Pr4(MoO2)9 by Materials Project

Mo(Pr10Mo22O45)2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional and consists of two molybdenum molecules and one Pr10Mo22O45 framework. In the Pr10Mo22O45 framework, there are fourteen inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Pr–O bond distances ranging from 2.34–2.79 Å. In the second Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Pr–O bond distances ranging from 2.33–2.88 Å. In the third Pr3+ site, Pr3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Pr–O bond distances ranging from 2.30–2.49 Å. In the fourth Pr3+ site, Pr3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Pr–O bond distances ranging from 2.27–2.51 Å. In the fifth Pr3+ site, Pr3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Pr–O bond distances ranging from 2.34–3.01 Å. In the sixth Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.40–3.07 Å. In the seventh Pr3+ site, Pr3+ is bonded in a 5-coordinate geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.40–3.04 Å. In the eighth Pr3+ site, Pr3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Pr–O bond distances ranging from 2.33–3.01 Å. In the ninth Pr3+ site, Pr3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Pr–O bond distances ranging from 2.38–2.73 Å. In the tenth Pr3+ site, Pr3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Pr–O bond distances ranging from 2.37–2.96 Å. In the eleventh Pr3+ site, Pr3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Pr–O bond distances ranging from 2.39–2.95 Å. In the twelfth Pr3+ site, Pr3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Pr–O bond distances ranging from 2.42–3.00 Å. In the thirteenth Pr3+ site, Pr3+ is bonded in a 6-coordinate geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.30–2.88 Å. In the fourteenth Pr3+ site, Pr3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.34–2.91 Å. There are twenty-seven inequivalent Mo+2.67+ sites. In the first Mo+2.67+ site, Mo+2.67+ is bonded to five O2- atoms to form corner-sharing MoO5 square pyramids. The corner-sharing octahedra tilt angles range from 45–54°. There are a spread of Mo–O bond distances ranging from 2.13–2.20 Å. In the second Mo+2.67+ site, Mo+2.67+ is bonded to five O2- atoms to form corner-sharing MoO5 square pyramids. The corner-sharing octahedra tilt angles range from 48–51°. There are a spread of Mo–O bond distances ranging from 2.13–2.20 Å. In the third Mo+2.67+ site, Mo+2.67+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with two equivalent MoO6 octahedra and corners with two equivalent MoO5 square pyramids. The corner-sharing octahedral tilt angles are 51°. There are a spread of Mo–O bond distances ranging from 2.08–2.18 Å. In the fourth Mo+2.67+ site, Mo+2.67+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with two MoO6 octahedra and corners with two MoO5 square pyramids. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Mo–O bond distances ranging from 2.10–2.18 Å. In the fifth Mo+2.67+ site, Mo+2.67+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.05–2.15 Å. In the sixth Mo+2.67+ site, Mo+2.67+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.06–2.13 Å. In the seventh Mo+2.67+ site, Mo+2.67+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.15 Å) and two longer (2.16 Å) Mo–O bond lengths. In the eighth Mo+2.67+ site, Mo+2.67+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.10–2.17 Å. In the ninth Mo+2.67+ site, Mo+2.67+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with three MoO5 square pyramids, an edgeedge with one MoO6 octahedra, and an edgeedge with one MoO5 square pyramid. There are a spread of Mo–O bond distances ranging from 2.13–2.17 Å. In the tenth Mo+2.67+ site, Mo+2.67+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with three MoO5 square pyramids, an edgeedge with one MoO6 octahedra, and an edgeedge with one MoO5 square pyramid. There are a spread of Mo–O bond distances ranging from 2.09–2.19 Å. In the eleventh Mo+2.67+ site, Mo+2.67+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with three MoO5 square pyramids, an edgeedge with one MoO6 octahedra, and an edgeedge with one MoO5 square pyramid. There are a spread of Mo–O bond distances ranging from 2.11–2.21 Å. In the twelfth Mo+2.67+ site, Mo+2.67+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with two MoO5 square pyramids and an edgeedge with one MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.03–2.17 Å. In the thirteenth Mo+2.67+ site, Mo+2.67+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with two equivalent MoO5 square pyramids and an edgeedge with one MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.05–2.16 Å. In the fourteenth Mo+2.67+ site, Mo+2.67+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.11–2.15 Å. In the fifteenth Mo+2.67+ site, Mo+2.67+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.10–2.14 Å. In the sixteenth Mo+2.67+ site, Mo+2.67+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.10–2.15 Å. In the seventeenth Mo+2.67+ site, Mo+2.67+ is bonded to six O2- atoms to form MoO6 octahedra that share a cornercorner with one MoO5 square pyramid and edges with four MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.10–2.26 Å. In the eighteenth Mo+2.67+ site, Mo+2.67+ is bonded to six O2- atoms to form MoO6 octahedra that share a cornercorner with one MoO5 square pyramid and edges with four MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.06–2.24 Å. In the nineteenth Mo+2.67+ site, Mo+2.67+ is bonded to six O2- atoms to form MoO6 octahedra that share a cornercorner with one MoO5 square pyramid and edges with four MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.06–2.24 Å. In the twentieth Mo+2.67+ site, Mo+2.67+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two MoO5 square pyramids, edges with two MoO6 octahedra, and edges with three MoO5 square pyramids. There are a spread of Mo–O bond distances ranging from 2.05–2.17 Å. In the twenty-first Mo+2.67+ site, Mo+2.67+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two equivalent MoO5 square pyramids, edges with two equivalent MoO6 octahedra, and edges with three MoO5 square pyramids. There are a spread of Mo–O bond distances ranging from 2.10–2.17 Å. In the twenty-second Mo+2.67+ site, Mo+2.67+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are two shorter (2.09 Å) and one longer (2.15 Å) Mo–O bond lengths. In the twenty-third Mo+2.67+ site, Mo+2.67+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two MoO5 square pyramids and edges with four MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.09–2.15 Å. In the twenty-fourth Mo+2.67+ site, Mo+2.67+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two equivalent MoO5 square pyramids and edges with four MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.12–2.17 Å. In the twenty-fifth Mo+2.67+ site, Mo+2.67+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.06–2.21 Å. In the twenty-sixth Mo+2.67+ site, Mo+2.67+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.05–2.21 Å. In the twenty-seventh Mo+2.67+ site, Mo+2.67+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.14–2.18 Å. There are fifty-six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three Pr3+ and two Mo+2.67+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to three Pr3+ and two Mo+2.67+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to three Pr3+ and two Mo+2.67+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to three Mo+2.67+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Pr3+ and three Mo+2.67+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to three Mo+2.67+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to three Mo+2.67+ atoms. In the eighth O2- site, O2- is bonded to one Pr3+ and three Mo+2.67+ atoms to form distorted corner-sharing OPrMo3 tetrahedra. In the ninth O2- site, O2- is bonded to one Pr3+ and three Mo+2.67+ atoms to form distorted OPrMo3 tetrahedra that share corners with three OPr4 tetrahedra and edges with two equivalent OPr2Mo2 trigonal pyramids. In the tenth O2- site, O2- is bonded in a distorted see-saw-like geometry to two Pr3+ and two Mo+2.67+ atoms. In the eleventh O2- site, O2- is bonded to two Pr3+ and two Mo+2.67+ atoms to form distorted OPr2Mo2 tetrahedra that share corners with two equivalent OPr4 tetrahedra, corners with two OPrMo3 trigonal pyramids, and an edgeedge with one OPr2Mo2 tetrahedra. In the twelfth O2- site, O2- is bonded in a distorted see-saw-like geometry to two Pr3+ and two Mo+2.67+ atoms. In the thirteenth O2- site, O2- is bonded to four Pr3+ atoms to form corner-sharing OPr4 tetrahedra. In the fourteenth O2- site, O2- is bonded to four Pr3+ atoms to form OPr4 tetrahedra that share corners with four OPrMo3 tetrahedra and corners with two equivalent OPr2Mo2 trigonal pyramids. In the fifteenth O2- site, O2- is bonded in a trigonal planar geometry to three Pr3+ atoms. In the sixteenth O2- site, O2- is bonded to four Pr3+ atoms to form corner-sharing OPr4 tetrahedra. In the seventeenth O2- site, O2- is bonded in a distorted see-saw-like geometry to two Pr3+ and two Mo+2.67+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted see-saw-like geometry to two Pr3+ and two Mo+2.67+ atoms. In the nineteenth O2- site, O2- is bonded to two Pr3+ and two Mo+2.67+ atoms to form distorted OPr2Mo2 trigonal pyramids that share corners with four OPr2Mo2 tetrahedra, an edgeedge with one OPrMo3 tetrahedra, and an edgeedge with one OPr2Mo2 trigonal pyramid. In the twentieth O2- site, O2- is bonded in a 3-coordinate geometry to two Pr3+ and two Mo+2.67+ atoms. In the twenty-first O2- site, O2- is bonded in a 3-coordinate geometry to two Pr3+ and two Mo+2.67+ atoms. In the twenty-second O2- site, O2- is bonded in a 3-coordinate geometry to three Pr3+ and two Mo+2.67+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted T-shaped geometry to three Mo+2.67+ atoms. In the twenty-fourth O2- site, O2- is bonded in a 5-coordinate geometry to one Pr3+ and three Mo+2.67+ atoms. In the twenty-fifth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Pr3+ and three Mo+2.67+ atoms. In the twenty-sixth O2- si

36 MATERIALS SCIENCE↗
DOE OSTI2021

High work function MoO2 back contacts for improved solar cell performance

Improved high work function back contacts for solar cells are provided. In one aspect, a method of forming a solar cell includes: forming a completed solar cell having a substrate coated with an electrically conductive material, an absorber disposed on the electrically conductive material, a buffer layer disposed on the absorber, a transparent front contact disposed on the buffer layer, and a metal grid disposed on the transparent front contact; removing the substrate and the electrically conductive material using exfoliation, exposing a backside surface of the solar cell; depositing a high work function material onto the back side surface of the solar cell; and depositing a back contact onto the high work function material. A solar cell formed by the present techniques is also provided. Yield of the exfoliated device can be improved by removing bubbles from adhesive used for exfoliation and/or forming contact pads to access the metal grid.

Antunez, Priscilla D.↗
DOE OSTI2020

Materials Data on Mo2P2O11 by Materials Project

(MoO2)2P2O7 crystallizes in the monoclinic Pm space group. The structure is two-dimensional and consists of one (MoO2)2P2O7 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two equivalent MoO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. There are a spread of Mo–O bond distances ranging from 1.70–2.15 Å. In the second Mo6+ site, Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.70–2.40 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MoO6 octahedra. The corner-sharing octahedral tilt angles are 16°. There are a spread of P–O bond distances ranging from 1.50–1.59 Å. In the second P5+ site, P5+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.46 Å) and two longer (1.48 Å) P–O bond length. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear 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 single-bond geometry to one Mo6+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Mo6+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Mo6+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one Mo6+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Mo6+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mo6+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A study of in situ reduction of MoO 3 to MoO 2 by X-ray Photoelectron Spectroscopy

Results from X-ray Photoelectron Spectroscopy (XPS) of molybdenum oxide samples are presented to elucidate how Mo (VI) oxide evolves to Mo (IV) oxide upon heating of a MoO 3 sample. XPS data analysis techniques based on manipulation of spectra treated as vectors are shown and allow insights into intermediate phases of Mo oxide which suggest how the original oxide changes under the influence of heat but also supports an interpretation of as-received tetravalent Mo powders as multivalent materials. In particular, several new spectral components were observed and assigned to the Magnéli phase as well as MoO 3 domains that have been modified by the presence of X-rays or temperature. Finally, these assignments comprise a new method of data processing where sample modification is used to inform XPS data interpretation and differ from previous work where the linear relationship of the binding energy of molybdenum oxides has been used.

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

Controlling MoO 2 and MoO 3 phases in MoO x /CNTs nanocomposites and their application to anode materials for lithium-ion batteries and capacitors

Molybdenum oxides (MoO 2 and MoO 3 ) are attractive anode materials for Li- and Na- ion batteries. Although there have been extensive studies on them individually, systematic and comparative studies are still lacking. Here, we demonstrate a facile and straightforward synthesis method to control the phase and oxidation state in the MoO x /CNTs nanocomposites via hydrothermal reaction followed by heat-treatment. By changing the gas atmosphere during the annealing process, well-dispersed MoO 2 /CNTs and MoO 3 /CNTs nanocomposites are formed without altering their overall morphology. This strategy enables us to investigate the true structure-property correlation of MoO x /CNTs nanocomposites by comparing the structure and electrochemical properties of MoO 2 /CNTs and MoO 3 /CNTs. When tested as anode materials for lithium-ion batteries, both HT-MoO 2&3 /CNTs electrodes show much-improved cycling stability and rate performance compared to the rod-shaped bulk MoO 3 electrode. In situ Mo K-edge x-ray absorption spectroscopy (XAS) has been further employed to compare and elucidate Li + storage mechanisms of both electrodes. When employed to the negative electrode of a high-power lithium-ion capacitor (LIC), the LIC full-cell composed of HT-MoO 3 /CNTs negative and activated carbon positive electrodes demonstrates impressive energy and power densities (~ 90 Wh kg –1 with 2000 W kg –1 ) and excellent cycling stability (96.8 % capacity retention after 300 cycles), revealing the versatility of the MoO x /CNTs electrodes in energy applications.

25 ENERGY STORAGE↗
DOE OSTI2022

Hierarchically structured MoO 2 /dopamine-derived carbon spheres as intercalation electrodes for lithium-ion batteries

A hydrogen peroxide initiated sol-gel process involving molybdenum transformation in the presence of dopamine (Dopa) hydrochloride excess produced the metastable precipitate composed of polydopamine (PDopa) spheres coated with Dopa preintercalated molybdenum oxide, (Dopa) x MoO y @PDopa. The hydrothermal treatment (HT) of the (Dopa) x MoO y @PDopa precursor resulted in the simultaneous carbonization of Dopa and molybdenum reduction generating MoO 2 nanoplatelets distributed and confined on the surface of the Dopa-derived carbon matrix (HT-MoO 2 /C). The consecutive annealing (An) of the HT-MoO 2 /C sample at 600 °C under Ar atmosphere led to the formation of MoO 2 with increased Mo oxidation state and improved structural stability (AnHT-MoO 2 /C). Annealing had also further facilitated interaction between the molybdenum-derived and Dopa-derived components resulting in the modification of the carbon matrix confirmed by Raman spectroscopy. Morphology of both materials is best described as Dopa-derived carbon spheres decorated with MoO 2 nanoplatelets. These integrated metal oxide and carbon structures were tested as electrodes for lithium-ion batteries in the potential window that corresponds to the intercalation mechanism of charge storage. The AnHT-MoO 2 /C electrode showed enhanced electrochemical activity, with an initial specific discharge capacity of 260 mAh/g and capacity retention of 67% after 50 cycles, compared to the HT-MoO 2 /C electrode which exhibited an initial specific discharge capacity of 235 mAh g –1 and capacity retention of 47% after 50 cycles. The rate capability experiments revealed that the capacity of 93 mAh/g and 120 mAh/g was delivered by the HT-MoO 2 /C and AnHT-MoO 2 /C electrodes, respectively, when the current density was increased to 100 mA/g. Here, the improved specific capacity, electrochemical stability, and rate capability achieved after annealing were attributed to higher crystallinity of MoO 2 , increased oxidation state of Mo, and formation of the tighter MoO 2 /carbon contact accompanied by the annealing assisted interaction between MoO 2 and Dopa-derived carbon.

25 ENERGY STORAGE↗
DOE OSTI2022

Mesoporous MoO 2 thin films for high rate Li + storage: Effect of crystallinity and porous structure

MoO 2 has attracted much recent attention as a high capacity energy storage material. While much of the current work on MoO 2 has been focused on the high capacity four-electron reduction, this reaction is limited to slow charging process due to the large volume change and phase transitions involved. In this study we focus on one-electron insertion reactions and demonstrate that ordered mesoporous thin films of MoO 2 can show signatures of pseudocapacitive charge storage. Mesoporous MoO 2 (mp-MoO 2 ) thin films were treated at different temperatures between 350 and 700 °C to explore the role of crystallinity and nanoscale structure on charging dynamics. The porosity and pore size decreased while the crystallinity and grain size increased as the calcination temperature increased. Materials processed at 600 °C showed the best electrochemical performance due to an optimized combination of high crystallinity and small grain size. These materials could be charged and discharged in 24 s while still achieving a Li + storage capacity of 158 mAh/g. While such thin film systems do not constitute a practical energy storage device, the work here provides structural design parameters for the production of future bulk nanoporous materials.

25 ENERGY STORAGE↗