Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Mo(CO)6”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CoMoP2 by Materials Project

MoCoP2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mo4+ is bonded to six equivalent P3- atoms to form edge-sharing MoP6 octahedra. All Mo–P bond lengths are 2.49 Å. Co2+ is bonded in a 6-coordinate geometry to six equivalent P3- atoms. All Co–P bond lengths are 2.27 Å. P3- is bonded in a 3-coordinate geometry to three equivalent Mo4+, three equivalent Co2+, and one P3- atom. The P–P bond length is 2.45 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Co(BMo)2 by Materials Project

CoMo2B2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Mo2+ is bonded in a 6-coordinate geometry to six equivalent B3- atoms. There are four shorter (2.33 Å) and two longer (2.53 Å) Mo–B bond lengths. Co2+ is bonded in a square co-planar geometry to four equivalent B3- atoms. All Co–B bond lengths are 2.08 Å. B3- is bonded in a 9-coordinate geometry to six equivalent Mo2+, two equivalent Co2+, and one B3- atom. The B–B bond length is 1.87 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoMoP2 by Materials Project

MoCoP2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mo4+ is bonded to six equivalent P3- atoms to form distorted MoP6 pentagonal pyramids that share corners with twelve equivalent CoP6 octahedra, edges with six equivalent MoP6 pentagonal pyramids, and faces with two equivalent CoP6 octahedra. The corner-sharing octahedral tilt angles are 48°. All Mo–P bond lengths are 2.48 Å. Co2+ is bonded to six equivalent P3- atoms to form CoP6 octahedra that share corners with twelve equivalent MoP6 pentagonal pyramids, edges with six equivalent CoP6 octahedra, and faces with two equivalent MoP6 pentagonal pyramids. All Co–P bond lengths are 2.26 Å. P3- is bonded in a 6-coordinate geometry to three equivalent Mo4+ and three equivalent Co2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Temperature-Dependent Mechanical Properties of Ni-Based Concentrated Alloys: Insights from First-Principles Calculations

The present work focuses on predicting temperature-dependent mechanical properties of Ni-based concentrated alloys Ni 18 Cr 10 Co 10 Fe 6 M 4 (abbreviated by X 44 M 4 , with M = Al, V, Mn, Fe, Nb, Mo, and W) using density functional theory (DFT). These predictions are based on shear (plastic) and elastic deformations, utilizing the special quasirandom structure (SQS), the phonon-based quasiharmonic approach (QHA), and the quasistatic approach. The resulting properties include coefficient of thermal expansion via QHA, ideal shear strength (τ IS ), and stable and unstable stacking fault energies (γ SF and γ US ) through pure alias shear deformation, and elastic constants (c ij ), bulk modulus (B 0 ), and shear modules (G 0 ) via elastic deformation. Notably, predicting accurate γ SF is challenging due to uncertainties that can exceed the γ SF values. τ IS and γ US exhibit a strong linear relationship, enabling the accurate prediction of γ US based on the precisely determined τ IS . All mechanical properties of X 44 M 4 decrease with increasing temperature, except for some γ SF cases such as X 44 M 4 with M = V, Mn, Fe, Mo, and W. Among the X 44 M 4 alloys, X 44 Nb 4 exhibits the lowest τ IS , γ US , and G 0 values, and the highest B 0 /G 0 ratio, while X 44 Mn 4 has the lowest B 0 and B 0 /G 0 ratio. We found that volume is a crucial descriptor for understanding and modeling mechanical properties (except B0 and maybe also γ SF ) affected by alloying elements and temperature. Ni-based dilute alloys (e.g., Ni 11 M 1 and Ni 31 M 1 ) and concentrated alloys (e.g., X 44 M 4 ) show similar trends in mechanical properties influenced by alloying elements and temperature, simplifying the analysis and design of Ni-based alloys.

Elastic properties↗
DOE OSTI2020

New Synthesis Strategies to Improve Co-Free LiNi0.5Mn0.5O2 Cathodes: Early Transition Metal d0 Dopants and Manganese Pyrophosphate Coating

In this work, we report solution-based doping and coating strategies to improve the electrochemical performance of the Co-free layered oxide cathode LiNi0.5Mn0.5O2 (LNMO). Small amounts of d0 dopants (e.g., Mo6+and Ti4+, 0.5-1 at. %) increase the cathode’s specific capacity, cycling stability, and rate capability. More specifically, a Mo-doped cathode with the nominal composition LiNi0.495Mn0.495Mo0.01O2 achieves a high reversible capacity of 180 mAh/g at 20 mA/g with good retention at higher rates (e.g., 120 mAh/g at 100 mA/g). Effects of 1 at.% Mo dopant on the cathode structure were studied using a suite of characterization tools including X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). These measurements demonstrate that Mo6+ reduces Li+/Ni2+cation mixing and mitigates undesirable phase transformations near the cathode surface during cycling. This work also reports the use of an inorganic Mn2P2O7 coating which enhances cycling stability, presumably through formation of a stable cathode electrolyte interphase (CEI) layer. Overall, the synthesis approaches reported herein are quite general and can potentially be expanded to other high voltage LIB cathodes.

Co-free cathodes, d0 cation, pyrophosphate coating↗
DOE OSTI2020

Single crystal neutron and magnetic measurements of Rb 2 Mn 3 (VO 4 ) 2 CO 3 and K 2 Co 3 (VO 4 ) 2 CO 3 with mixed honeycomb and triangular magnetic lattices

Two new alkali vanadate carbonates with divalent transition metals have been synthesized as large single crystals via a high-temperature (600 °C) hydrothermal technique. Compound I, Rb 2 Mn 3 (VO 4 ) 2 CO 3 , crystallizes in the trigonal crystal system in the space group P[3 with combining macron]1c, and compound II, K 2 Co 3 (VO 4 ) 2 CO 3 , crystallizes in the hexagonal space group P6 3 /m. Both structures contain honeycomb layers and triangular lattices made from edge-sharing MO 6 octahedra and MO 5 trigonal bipyramids, respectively. The honeycomb and triangular layers are connected along the c-axis through tetrahedral [VO 4 ] groups. The MO 5 units are connected with each other by carbonate groups in the ab-plane by forming a triangular magnetic lattice. The difference in space groups between I and II was also investigated with Density Functional Theory (DFT) calculations. Single crystal magnetic characterization of I indicates three magnetic transitions at 77 K, 2.3 K, and 1.5 K. The corresponding magnetic structures for each magnetic transition of I were determined using single crystal neutron diffraction. At 77 K the compound orders in the MnO 6 -honeycomb layer in a Néel-type antiferromagnetic orientation while the MnO 5 triangular lattice ordered below 2.3 K in a colinear ‘up–up–down’ fashion, followed by a planar ‘Y’ type magnetic structure. K 2 Co 3 (VO 4 ) 2 CO 3 (II) exhibits a canted antiferromagnetic ordering below T N = 8 K. Here, the Curie–Weiss fit (200–350 K) gives a Curie–Weiss temperature of –42 K suggesting a dominant antiferromagnetic coupling in the Co 2+ magnetic sublattices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Mo5As4 by Materials Project

Mo5As4 is Titanium telluride structured and crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. there are two inequivalent Mo+2.40+ sites. In the first Mo+2.40+ site, Mo+2.40+ is bonded to five equivalent As3- atoms to form a mixture of distorted corner and edge-sharing MoAs5 square pyramids. There are a spread of Mo–As bond distances ranging from 2.51–2.69 Å. In the second Mo+2.40+ site, Mo+2.40+ is bonded in a square co-planar geometry to four equivalent As3- atoms. All Mo–As bond lengths are 2.82 Å. As3- is bonded in a 6-coordinate geometry to six Mo+2.40+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoMo4O15 by Materials Project

Mo4CoO15 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Mo sites. In the first Mo site, Mo is bonded to six O atoms to form distorted MoO6 octahedra that share a cornercorner with one MoO6 octahedra and corners with two equivalent CoO6 octahedra. The corner-sharing octahedra tilt angles range from 0–11°. There are a spread of Mo–O bond distances ranging from 1.78–2.20 Å. In the second Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.79–2.23 Å. Co is bonded to six O atoms to form CoO6 octahedra that share corners with four equivalent MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–11°. There is two shorter (1.87 Å) and four longer (1.89 Å) Co–O bond length. There are eight inequivalent O sites. In the first O site, O is bonded in a linear geometry to one Mo and one Co atom. In the second O site, O is bonded in a linear geometry to one Mo and one Co atom. In the third O site, O is bonded in a linear geometry to two equivalent Mo atoms. In the fourth O site, O is bonded in a bent 120 degrees geometry to two Mo atoms. In the fifth O site, O is bonded in a distorted T-shaped geometry to three Mo atoms. In the sixth O site, O is bonded in a linear geometry to two Mo atoms. In the seventh O site, O is bonded in a linear geometry to one Mo and one Co atom. In the eighth O site, O is bonded in a single-bond geometry to one Mo atom.

36 MATERIALS SCIENCE↗
NASA NTRS1993

Co-transplantation of plasmid-transfected myoblasts and myotubes into rat brains enables high levels of gene expression long-term

We have previously proposed the use of primary muscle cells as a "platform," or "vehicle" for intracerebral transgene expression. Brain grafts of minced muscle, or cultured muscle cells persisted in rat brains for at least 6 mo without any decrease in graft size, or tumor formation. Stable, but moderate levels of intracerebral transgene expression were obtained by transplanting plasmid-transfected myotubes in culture. In the present study, high and stable levels of intracerebral transgene expression were achieved by the co-transplantation of plasmid-transfected myoblasts and myotubes in culture. Approximately 5 X 10(5) myoblasts and myotubes were transfected with 10 micrograms pRSVL plasmid DNA, and 30 micrograms Lipofectin (BRL), respectively. They were mixed together (total cell number was 1 million), and stereotactically injected into the caudate nucleus of an adult rat brain. The activity of luciferase, the product of transgene expression, was stable for at least 4 mo, and much higher than the levels in myotube grafts, or co-grafts of myoblasts and minced muscle. Presumably, the myotubes served as a framework on which the myoblasts can form myotubes. The sections of brains transplanted with co-graft of myoblasts, and myotubes transfected with pRSVLac-Z were stained immunofluorescently for beta-galactosidase activity. The muscle grafts contained beta-galactosidase positive myofibers 4 mo after transplantation. Such high and stable levels of in vivo expression after postnatal gene transfer have rarely been achieved. Primary muscle cells are useful vehicle for transgene expression in brains, and potentially valuable for gene therapy of degenerative neurological disorders.

NASA Program Space Biology↗
NASA NTRS2012

Siderophile Element Constraints on the Conditions of Core Formation in Mars

Siderophile element concentrations in planetary basalts and mantle samples have been used to estimate conditions of core formation for many years and have included applications to Earth, Moon, Mars and asteroid 4 Vesta [1]. For Earth, we have samples of mantle and a diverse collection of mantle melts which have provided a mature understanding of the how to reconstruct the concentration of siderophile elements in mantle materials, from only concentrations in surficial basalt (e.g., [2]). This approach has led to the consensus views that Earth underwent an early magma ocean stage to pressures of 40-50 GPa (e.g., [3,4]), Moon melted extensively and formed a small (approx. 2 mass %) metallic core [5], and 4 Vesta contains a metallic core that is approximately 18 mass % [6,7]. Based on new data from newly found meteorites, robotic spacecraft, and experimental partitioning studies, [8] showed that eight siderophile elements (Ni, Co, Mo, W, Ga, P, V and Cr) are consistent with equilibration of a 20 mass% S-rich metallic core with the mantle at pressures of 14 +/- 3 GPa. We aim to test this rather simple scenario with additional analyses of meteorites for a wide range of siderophile elements, and application of new experimental data for the volatile siderophile and highly siderophile elements.

Righter, K.↗
DOE OSTI2025

Collaborative or competitive phase transformation processes in an additively manufactured-maraging steel M300

Although retained austenite is present in minor amounts in as-built additively manufactured-maraging steels, its evolution during ageing is key to controlling the final microstructure. This study investigates the relationship between austenite reversion and precipitation evolution during ageing, particularly whether these processes compete or cooperate. Using Scanning/Transmission Electron Microscopy, Atom Probe Tomography and Thermo-Calc® PRISMA simulations, the presence and evolution of retained austenite, Ni 3 Ti and Fe 7 Mo 6 intermetallic phases was characterised across different ageing conditions. Experimental results revealed the presence of non-enriched austenite in the as-built condition. Nevertheless, with increasing ageing temperature, Ni and Mo segregation became evident. High-Resolution Transmission Electron Microscopy revealed that Ni 3 Ti precipitation primarily occurred within the martensitic matrix, while Fe 7 Mo 6 nucleated preferentially at the austenite-martensite interface. PRISMA simulations indicated early and rapid precipitation in solute-enriched areas (i.e., intercellular regions), with Ni 3 Ti forming prior to Fe 7 Mo 6 . Both experimental and simulation results suggested Ni diffusion controls retained austenite growth, while Ti and Mo drive Ni 3 Ti and Fe 7 Mo 6 precipitation, respectively. The evidence reported in this work supports a both collaborative and independent phase transformation mechanism, where austenite reversion and precipitation co-evolve.

42 ENGINEERING↗
DOE OSTI2020

Materials Data on Co(Mo3Se4)4 by Materials Project

Co(Mo3Se4)4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twelve inequivalent Mo+2.50+ sites. In the first Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form a mixture of edge and corner-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.53–2.64 Å. In the second Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, a cornercorner with one CoSe4 tetrahedra, and edges with five MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.65 Å. In the third Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, a cornercorner with one CoSe4 tetrahedra, and edges with five MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.56–2.67 Å. In the fourth Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, a cornercorner with one CoSe4 tetrahedra, and edges with five MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.56–2.66 Å. In the fifth Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form distorted MoSe5 square pyramids that share corners with four MoSe5 square pyramids, edges with five MoSe5 square pyramids, and a faceface with one CoSe4 tetrahedra. There are a spread of Mo–Se bond distances ranging from 2.53–2.77 Å. In the sixth Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, edges with five MoSe5 square pyramids, and an edgeedge with one CoSe4 tetrahedra. There are a spread of Mo–Se bond distances ranging from 2.56–2.66 Å. In the seventh Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, edges with five MoSe5 square pyramids, and an edgeedge with one CoSe4 tetrahedra. There are a spread of Mo–Se bond distances ranging from 2.55–2.65 Å. In the eighth Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, a cornercorner with one CoSe4 tetrahedra, and edges with five MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.67 Å. In the ninth Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, a cornercorner with one CoSe4 tetrahedra, and edges with five MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.56–2.68 Å. In the tenth Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, a cornercorner with one CoSe4 tetrahedra, and edges with five MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.67 Å. In the eleventh Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, a cornercorner with one CoSe4 tetrahedra, and edges with five MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.56–2.65 Å. In the twelfth Mo+2.50+ site, Mo+2.50+ is bonded to five Se2- atoms to form MoSe5 square pyramids that share corners with four MoSe5 square pyramids, a cornercorner with one CoSe4 tetrahedra, and edges with five MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.68 Å. Co2+ is bonded to four Se2- atoms to form CoSe4 tetrahedra that share corners with eight MoSe5 square pyramids, edges with two MoSe5 square pyramids, and a faceface with one MoSe5 square pyramid. There are a spread of Co–Se bond distances ranging from 2.32–2.44 Å. There are sixteen inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to four Mo+2.50+ and one Co2+ atom. In the second Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.50+ atoms. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to three Mo+2.50+ atoms. In the fourth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.50+ atoms. In the fifth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.50+ atoms. In the sixth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.50+ atoms. In the seventh Se2- site, Se2- is bonded in a 1-coordinate geometry to three Mo+2.50+ and one Co2+ atom. In the eighth Se2- site, Se2- is bonded in a 1-coordinate geometry to four Mo+2.50+ and one Co2+ atom. In the ninth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.50+ atoms. In the tenth Se2- site, Se2- is bonded in a 6-coordinate geometry to three Mo+2.50+ atoms. In the eleventh Se2- site, Se2- is bonded in a 5-coordinate geometry to four Mo+2.50+ and one Co2+ atom. In the twelfth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.50+ atoms. In the thirteenth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.50+ atoms. In the fourteenth Se2- site, Se2- is bonded in a 6-coordinate geometry to three Mo+2.50+ atoms. In the fifteenth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.50+ atoms. In the sixteenth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ni(BMo)2 by Materials Project

Mo2NiB2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Mo2+ is bonded in a 6-coordinate geometry to six equivalent B3- atoms. There are four shorter (2.33 Å) and two longer (2.54 Å) Mo–B bond lengths. Ni2+ is bonded in a square co-planar geometry to four equivalent B3- atoms. All Ni–B bond lengths are 2.10 Å. B3- is bonded in a 9-coordinate geometry to six equivalent Mo2+, two equivalent Ni2+, and one B3- atom. The B–B bond length is 1.84 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSiMo by Materials Project

CoMoSi crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent Mo2+ sites. In the first Mo2+ site, Mo2+ is bonded in a 7-coordinate geometry to seven Si4- atoms. There are a spread of Mo–Si bond distances ranging from 2.74–2.78 Å. In the second Mo2+ site, Mo2+ is bonded in a 5-coordinate geometry to five Si4- atoms. There are a spread of Mo–Si bond distances ranging from 2.68–2.80 Å. There are two inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded in a 6-coordinate geometry to two equivalent Co2+ and four Si4- atoms. Both Co–Co bond lengths are 2.45 Å. There are a spread of Co–Si bond distances ranging from 2.25–2.35 Å. In the second Co2+ site, Co2+ is bonded in a 6-coordinate geometry to four Co2+ and two equivalent Si4- atoms. There are one shorter (2.36 Å) and one longer (2.49 Å) Co–Co bond lengths. There are one shorter (2.33 Å) and one longer (2.44 Å) Co–Si bond lengths. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded to six Mo2+ and six Co2+ atoms to form SiCo6Mo6 cuboctahedra that share corners with fourteen SiCo6Mo6 cuboctahedra, edges with six SiCo6Mo6 cuboctahedra, and faces with four equivalent SiCo2Si4Mo6 cuboctahedra. In the second Si4- site, Si4- is bonded to six Mo2+, two equivalent Co2+, and four Si4- atoms to form SiCo2Si4Mo6 cuboctahedra that share corners with eight SiCo6Mo6 cuboctahedra, edges with two equivalent SiCo2Si4Mo6 cuboctahedra, and faces with ten SiCo6Mo6 cuboctahedra. There are a spread of Si–Si bond distances ranging from 2.34–2.46 Å. In the third Si4- site, Si4- is bonded to six Mo2+, two equivalent Co2+, and four equivalent Si4- atoms to form SiCo2Si4Mo6 cuboctahedra that share corners with six SiCo6Mo6 cuboctahedra, edges with six SiCo6Mo6 cuboctahedra, and faces with eight equivalent SiCo2Si4Mo6 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Co(Mo3O17)2 by Materials Project

Co(Mo3O11)2(O2)6 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of twelve oxygen molecules and two Co(Mo3O11)2 clusters. In each Co(Mo3O11)2 cluster, there are three inequivalent Mo sites. In the first Mo site, Mo is bonded in a 5-coordinate geometry to five O atoms. There are a spread of Mo–O bond distances ranging from 1.72–2.19 Å. In the second Mo site, Mo is bonded in a 4-coordinate geometry to five O atoms. There are a spread of Mo–O bond distances ranging from 1.72–2.32 Å. In the third Mo site, Mo is bonded in a 5-coordinate geometry to five O atoms. There are a spread of Mo–O bond distances ranging from 1.72–2.22 Å. Co is bonded in a square co-planar geometry to four O atoms. There is two shorter (1.74 Å) and two longer (1.86 Å) Co–O bond length. There are eleven inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to two Mo atoms. In the second O site, O is bonded in a single-bond geometry to one Mo atom. In the third O site, O is bonded in a single-bond geometry to one Mo atom. In the fourth O site, O is bonded in a single-bond geometry to one Mo atom. In the fifth O site, O is bonded in a 2-coordinate geometry to one Mo and one Co atom. In the sixth O site, O is bonded in a single-bond geometry to one Mo atom. In the seventh O site, O is bonded in a 3-coordinate geometry to two Mo and one Co atom. In the eighth O site, O is bonded in a single-bond geometry to one Mo atom. In the ninth O site, O is bonded in a single-bond geometry to one Mo atom. In the tenth O site, O is bonded in a bent 120 degrees geometry to two Mo atoms. In the eleventh O site, O is bonded in a bent 120 degrees geometry to two Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(MoO2)6 by Materials Project

Pr(MoO2)6 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Pr3+ is bonded in a distorted square co-planar geometry to four equivalent O2- atoms. All Pr–O bond lengths are 2.45 Å. There are two inequivalent Mo+3.50+ sites. In the first Mo+3.50+ site, Mo+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Mo–O bond distances ranging from 2.06–2.23 Å. In the second Mo+3.50+ site, Mo+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 49–52°. There are a spread of Mo–O bond distances ranging from 1.95–2.23 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Pr3+ and three Mo+3.50+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Mo+3.50+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to three Mo+3.50+ atoms. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to three Mo+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Co(MoO6)3 by Materials Project

(MoO4)3CoO6 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of four cobalt;hexahydrate molecules and two MoO4 ribbons oriented in the (1, 0, 0) direction. In each MoO4 ribbon, there are three inequivalent Mo sites. In the first Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.69–2.45 Å. In the second Mo site, Mo is bonded in a 4-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.71–2.50 Å. In the third Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.70–2.47 Å. There are twelve inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Mo atom. In the second O site, O is bonded in a bent 120 degrees geometry to one Mo and one O atom. The O–O bond length is 1.26 Å. In the third O site, O is bonded in a 3-coordinate geometry to three Mo atoms. In the fourth O site, O is bonded in a single-bond geometry to one Mo atom. In the fifth O site, O is bonded in a distorted T-shaped geometry to three Mo atoms. In the sixth O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.29 Å. In the seventh O site, O is bonded in a single-bond geometry to one Mo atom. In the eighth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Mo atoms. In the ninth O site, O is bonded in a bent 120 degrees geometry to one Mo and one O atom. In the tenth O site, O is bonded in a single-bond geometry to one O atom. In the eleventh O site, O is bonded in a single-bond geometry to one Mo atom. In the twelfth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Presentation of gas-phase-reactant-accessible single-rhodium-atom catalysts for CO oxidation, via MOF confinement of an Anderson polyoxometalate

Geometric or electronic confinement of guests within nanoporous hosts holds promise for imparting catalytic functionality, including single-metal-atom catalytic functionality, to existing materials. When the nanoporous host is a metal–organic framework (MOF), single-metal-ion catalysts have typically been installed by grafting to an open site on an inorganic node, with the node effectively becoming the support for the catalyst. This approach, however, imposes compositional constraints, as the node not only needs to be receptive to grafting, but also must be capable of stabilizing the framework against solvent evacuation, chemical exposure, and heating. Here, we show that disk-like, Anderson polyoxometalate clusters (RhMo 6 O 24 n- and Mo 7 O 24 m- ; POMs) can be confined in pore-specific and orientation-specific fashion within the hierarchically porous, Zr(IV)-based MOF, NU1K. Self-limiting loading of one cluster per pore, and associated nano-confinement, serve to isolate each POM and prevent consolidation caused by sintering. Additionally, the oriented confinement serves to expose individual rhodium atoms to candidate gas-phase reactants, while enabling the rhodium atom to employ a well-defined oxy-molybdenum cluster, rather than a MOF node, as a support. Synchrotron-based difference-electron-density maps and differential pair-distribution-function analyses of scattered X-rays establish cluster siting and orientation and confirm isolation. Nanoconfined (i.e., MOF- and POM-confined) single-rhodium(III)-atoms are catalytically competent for an illustrative gas-phase reaction, CO oxidation by O 2 , with the MOF-isolated POM enormously outperforming nonporous, MOF-free, solid (NH 4 ) 3 [H 6 RhMo 6 O 24 ]·6H 2 O. This paper highlights the value of MOF-based nano-confinement and oriented isolation of planar POMs as a means of uniformly presenting and stabilizing potent single-metal-atom catalysts, in reactant-accessible form, on well-defined supports.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗