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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
Transition metal based materials containing Fe have drawn great attention as oxygen evolution reaction (OER) catalysts. The nature of the electrocatalytic active species remains under debate due to the ambiguous physicochemical properties of the catalyst materials, such as the oxidation states and crystal structures. Here, in order to address this issue, transition metal Prussian blue analogues (TM-PBA, Na(TM)(Fe)(CN) 6 , TM = V, Fe, Co, and Ni) with an isomorphous structure are investigated for OER catalysis. Our combined experimental measurements and density functional theory (DFT) calculations reveal that TM-PBAs exhibit volcano-like OER activity with Ni-PBA located near the top of the volcano. Such a volcano-like activity profile can be attributed to the distinctive binding energy difference between *O and *OH on different TM-PBAs surfaces. This research demonstrates that TM-PBAs can be used as platform materials for understanding structure-property-activity relationships in OER catalysts.
Plate impact experiments are conducted on cemented tungsten carbides (WC) with a 3.7 and 6.0 wt. % cobalt binder to better understand their dynamic, high-pressure response to 100 GPa. The measured wave profiles show propagation of steady structured waves. Standard impedance matching procedures are used to determine the Hugoniot relations in the shock velocity–particle velocity (U s –v p ) and Hugoniot stress–specific volume (P–V/V o ) planes. The Hugoniot elastic limit of the samples is controlled by ductility of the Co binder and is determined to be 4.45 ± 0.29 GPa for cemented WC with 3.7 wt. % cobalt and 3.72 ± 0.24 GPa for a 6.0 wt. % cobalt binder. Both grades show a non-linear U s –v p relationship depending on whether the particle velocity is in the strength dominated or hydrodynamic regime. In the strength dominated regime, a non-linear decrease in U s is observed as v p increases from ambient to the material’s hydrodynamic limit. In the hydrodynamic regime, the U s –v p Hugoniot is linear and is determined to be U s = 4.97(±0.006)+1.446(±0.018)v p km/s for WC with 3.7 wt. % Co and U s = 4.93(±0.006)+1.463(±0.017)v p km/s for 6 wt. % Co. Both WC grades indicate shear-stress hardening with mean stress immediately after yield, followed by pressure softening, and then a sharp fall in stress carrying capacity as the mean stress is increased to ≈70 GPa (hydrodynamic limit) and beyond. This behavior is in contrast to pure WC ceramics, which show continued shear-stress hardening with mean stress to ≈80 GPa.
V4Co2N crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. there are two inequivalent V sites. In the first V site, V is bonded in a 6-coordinate geometry to six equivalent Co atoms. All V–Co bond lengths are 2.35 Å. In the second V site, V is bonded in a distorted bent 150 degrees geometry to four equivalent Co and two equivalent N atoms. There are two shorter (2.54 Å) and two longer (2.82 Å) V–Co bond lengths. Both V–N bond lengths are 2.01 Å. Co is bonded in a 12-coordinate geometry to nine V and three equivalent Co atoms. All Co–Co bond lengths are 2.59 Å. N is bonded to six equivalent V atoms to form corner-sharing NV6 octahedra. The corner-sharing octahedral tilt angles are 37°.
VCoAl is Frank-Kasper $\mu$ Phase-derived structured and crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are four inequivalent V sites. In the first V site, V is bonded in a 6-coordinate geometry to six Co and six Al atoms. There are a spread of V–Co bond distances ranging from 2.25–2.40 Å. There are a spread of V–Al bond distances ranging from 2.74–2.83 Å. In the second V site, V is bonded in a 12-coordinate geometry to four V, two equivalent Co, and six Al atoms. There are a spread of V–V bond distances ranging from 2.29–2.52 Å. Both V–Co bond lengths are 2.48 Å. There are a spread of V–Al bond distances ranging from 2.81–2.93 Å. In the third V site, V is bonded in a 12-coordinate geometry to four V, two equivalent Co, and six Al atoms. There are one shorter (2.28 Å) and one longer (2.36 Å) V–V bond lengths. Both V–Co bond lengths are 2.47 Å. There are a spread of V–Al bond distances ranging from 2.82–2.93 Å. In the fourth V site, V is bonded in a 12-coordinate geometry to four V, two equivalent Co, and six Al atoms. Both V–Co bond lengths are 2.48 Å. There are two shorter (2.88 Å) and four longer (2.95 Å) V–Al bond lengths. There are three inequivalent Co sites. In the first Co site, Co is bonded to four V, two Co, and six Al atoms to form distorted CoAl6V4Co2 cuboctahedra that share corners with four CoAl6V2Co4 cuboctahedra, edges with six equivalent CoAl6V4Co2 cuboctahedra, and faces with eight CoAl6V4Co2 cuboctahedra. There are one shorter (2.47 Å) and one longer (2.48 Å) Co–Co bond lengths. There are a spread of Co–Al bond distances ranging from 2.65–2.82 Å. In the second Co site, Co is bonded to two equivalent V, four Co, and six Al atoms to form distorted CoAl6V2Co4 cuboctahedra that share corners with eight CoAl6V4Co2 cuboctahedra, edges with two equivalent CoAl6V2Co4 cuboctahedra, and faces with ten CoAl6V4Co2 cuboctahedra. There are one shorter (2.37 Å) and one longer (2.51 Å) Co–Co bond lengths. There are a spread of Co–Al bond distances ranging from 2.63–2.82 Å. In the third Co site, Co is bonded to two equivalent V, four Co, and six Al atoms to form distorted CoAl6V2Co4 cuboctahedra that share corners with eight CoAl6V4Co2 cuboctahedra, edges with two equivalent CoAl6V2Co4 cuboctahedra, and faces with ten CoAl6V4Co2 cuboctahedra. There are a spread of Co–Al bond distances ranging from 2.64–2.83 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 7-coordinate geometry to five V, seven Co, and four Al atoms. There are a spread of Al–Al bond distances ranging from 2.81–2.93 Å. In the second Al site, Al is bonded in a 5-coordinate geometry to seven V, five Co, and three equivalent Al atoms.
Gemini NIFS K-band spectra and Atacama Large Millimeter/submillimeter Array {sup 12}CO J=1→0, HCO{sup +}, and 100 GHz continuum observations are used to study a bright starburst clump on an outer arm of the interacting galaxy NGC 2207. This clump emits 23% of the total 24 μm flux of the galaxy pair and has an optically opaque dust cone extending out of its 170 pc core. The measured CO accounts for the dark cone extinction if almost all the gas and dust there are in front of the star clusters. An associated approaching CO outflow has v {sub z} ~ 16 km s{sup -1}, an estimated molecular mass 8 × 10{sup 6} M {sub ⊙}, and rises to heights ~0.9 kpc. A receding CO outflow on the far side with v {sub z} ~ 28 km s{sup -1} is less extensive. The observed star formation in the core over 10 Myr can supply the dark cone kinetic energy of roughly 2 × 10{sup 52} erg via supernovae and stellar winds. Other signs of intense activity are a variable radio continuum, suggesting an embedded supernova or other outburst; X-ray emission possibly from an X-ray binary or intermediate-mass black hole, depending on the extinction; and Brγ and He i lines with 82 km s{sup -1} line widths and fluxes consistent with excitation by embedded O-type stars. According to previous models, the retrograde encounter suffered by NGC 2207 caused the loss of angular momentum. This compressed its outer disk. We suggest that the resulting inward crashing stream hit a massive H i clump on the preexisting spiral arm and triggered the observed starburst.
A precipitation method involving a deep eutectic solvent (DES)–a mixture of hydrogen bond donor and acceptor–is used to synthesize a ternary metal oxide. Without toxic reagents, precipitates consisting of Zn 3 (OH) 2 V 2 O 7 ·nH 2 O and Zn 5 (OH) 6 (CO 3 ) 2 are obtained by simply introducing deionized H 2 O to the DES solution containing dissolved ZnO and V 2 O 5 . Manipulation of the synthetic conditions demonstrates high tunability in the size/morphology of the two-dimensional nanosheets precipitated during the dynamic equilibrium process. According to differential scanning calorimetry and high-temperature powder X-ray diffraction, Zn 3 V 2 O 8 and ZnO obtained by the annealing of the precipitate are intermediates in the reaction pathway toward metastable Zn 4 V 2 O 9 . Intimate mixing of the metal precursors achieved by the precipitation method allows access to the metastable zinc-rich vanadate with unusually rapid heat treatment. Furthermore, the UV–vis and surface photovoltage spectra reveal the presence of sub-band gap states, stemming from the reduced vanadium (V 4+ ) center. Photoelectrochemical measurements confirm weak photoanodic currents for water and methanol oxidation. For the first time, this work shows the synthesis of a metastable oxide with the DES-precipitation route and provides insight into the structure–property relationship of the zinc-rich vanadate.
V6CoNi crystallizes in the cubic Pm-3 space group. The structure is three-dimensional. V is bonded in a 6-coordinate geometry to two equivalent V, two equivalent Co, and two equivalent Ni atoms. There are one shorter (2.32 Å) and one longer (2.33 Å) V–V bond lengths. Both V–Co bond lengths are 2.60 Å. Both V–Ni bond lengths are 2.60 Å. Co is bonded to twelve equivalent V atoms to form CoV12 cuboctahedra that share edges with six equivalent CoV12 cuboctahedra and faces with eight equivalent NiV12 cuboctahedra. Ni is bonded to twelve equivalent V atoms to form NiV12 cuboctahedra that share edges with six equivalent NiV12 cuboctahedra and faces with eight equivalent CoV12 cuboctahedra.
V3Co crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. V is bonded in a 6-coordinate geometry to two equivalent V and four equivalent Co atoms. Both V–V bond lengths are 2.33 Å. All V–Co bond lengths are 2.60 Å. Co is bonded to twelve equivalent V atoms to form a mixture of edge and face-sharing CoV12 cuboctahedra.
A CO survey of 342 Infrared Excess Clouds (IRECs) distributed uniformly across the sky is presented. Following comparison of the integrated CO brightness with the 100 micron infrared brightness B(sub 4) obtained from the IRAS data, evidence was found for a threshold in B(sub 4) of 4-5 MJy sr(exp -1) below which CO does not form. Evidence is also presented that the threshold effect can be seen within an individual cloud, providing evidence for a phase transition between atomic and molecular gas. While the main thrust was to examine the CO content of the IRECs, it was also attempted to detect CO toward a number of UV stars so that CO brightness could be correlated with direct measurements of H2 column density and E(B-V). Of the 26 observed stars CO was detected toward 6. It is consistent with the results obtained using infrared data.
A low-spin and mononuclear vanadium complex, ( Me nacnac)V(CO)(η 2 -P≡C t Bu) ( 2 ) ( Me nacnac - =[ArNC(CH 3 )] 2 CH, Ar=2,6- i Pr 2 C 6 H 3 ), was prepared upon treatment of the vanadium neopentylidyne complex ( Me nacnac)V≡C t Bu(OTf) ( 1 ) with Na(OCP)(diox) 2.5 (diox=1,4-dioxane), while the isoelectronic ate-complex [Na(15-crown-5)]{([ArNC(CH 2 )]CH[C(CH 3 )NAr])V(CO)(η 2 -P≡C t Bu)} ( 4 ), was obtained via the reaction of Na(OCP)(diox) 2.5 and ([ArNC(CH 2 )]CH[C(CH 3 )NAr])V≡C t Bu(OEt 2 ) ( 3 ) in the presence of crown-ether. Computational studies suggest that the P-atom transfer proceeds by [2+2]-cycloaddition of the P≡C bond across the V≡C t Bu moiety, followed by a reductive decarbonylation to form the V-C≡O linkage. Additionally, the nature of the electronic ground state in diamagnetic complexes, 2 and 4 , was further investigated both theoretically and experimentally, using a combination of density functional theory (DFT) calculations, UV/Vis and NMR spectroscopies, cyclic voltammetry, X-ray absorption spectroscopy (XAS) measurements, and comparison of salient bond metrics derived from X-ray single-crystal structural characterization. In combination, these data are consistent with a low-valent vanadium ion in complexes 2 and 4 . This study represents the first example of a metathesis reaction between the P-atom of [PCO] - and an alkylidyne ligand.
Introduction COVID-19 vaccines may be administered with other vaccines during the same healthcare visit. COVID-19 monovalent (Fall 2021) and bivalent (Fall 2022) vaccine recommendations coincided with annual seasonal influenza vaccination. Data describing the frequency of the co-administration of COVID-19 vaccines with other vaccines are limited. Methods We used V-safe, a voluntary smartphone-based U.S. safety surveillance system established by the CDC, to describe trends in the administration of COVID-19 vaccines with other vaccines reported to V-safe during December 14, 2020 – May 19, 2023. Results Of the 21 million COVID-19 vaccinations reported to V-safe, 2.2% (459,817) were administered with at least 1 other vaccine. Co-administration most frequently occurred during the first week of October 2023 (27,092; 44.1%). Most reports of co-administration included influenza vaccine (393,003; 85.5%). Co-administration was most frequently reported for registrants aged 6 months-6 years (4,872; 4.4%). Conclusion Reports of co-administration to V-safe peaked during October 2023, when influenza vaccination most often occurs, possibly reflecting increased opportunities for multiple vaccinations and greater acceptability of the co-administration of COVID-19 vaccine with other vaccines, especially influenza vaccine.
Geometries, vibrational frequencies, spin states, H2 binding energies, and Delta(S) values have been determined for V(H2)n(+), for n = 1-6, using the B3LYP hybrid functional. The binding energies and Delta(S) values are in good agreement with experiment, thus showing that the B3LYP functional offers a reliable approach for optimizing the geometry and determining the H2 binding energies for this system. The calculations show that the increase in the binding energy and entropy associated with the addition of the sixth H2 to V(+) is due to a change in spin state from quintet for the smaller clusters to triplet for V(H2)6(+). The results for V(H2)n(+) are compared with those for CO(H2)n(+).
Molecular “Chevrel-type” clusters of the formula Co 6 Se 8 L 6 (L = neutral ligand) are a well-studied class of clusters due to their utility as molecular analogues to the Chevrel extended solid phase and their application as subunits in hierarchical materials. However, their solution and optical properties remain relatively underexplored. Aiming to develop the fundamental relationships between the molecular and electronic structures of these clusters and their electrochemical and photophysical properties, this work reports the preparation of a series of Co 6 Se 8 (P(C 6 H 4 R) 3 ) 6 -type clusters with R = Cl (1), F (2), H (3), CH 3 (4), and OCH 3 (5) via a stepwise synthetic approach. Solution and solid-state experimental characterization and density functional theory calculations reveal that the Co 6 Se 8 cores of 1–5 maintain consistent electronic and structural properties despite the variation of the triarylphosphine ligand para-substituent Hammett parameters (σ p ). However, cyclic voltammetry measurements indicate that the electron transfer energetics of 1–5 are strongly influenced by ligand substitution, with the E 1/2 of a given redox event spanning ∼0.5 V depending on the triarylphosphine ligand’s σ p . In conclusion, these findings support the characterization of Co 6 Se 8 clusters as atomically precise nanoclusters with both the structural robustness and the electrochemical tunability needed to act as components in larger charge transfer assemblies.
V3CoSb2(PO4)6 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are three inequivalent V5+ sites. In the first V5+ site, V5+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There is three shorter (1.91 Å) and three longer (2.06 Å) V–O bond length. In the second V5+ site, V5+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are three shorter (1.98 Å) and three longer (2.07 Å) V–O bond lengths. In the third V5+ site, V5+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are three shorter (1.96 Å) and three longer (2.09 Å) V–O bond lengths. Co2+ is bonded to six O2- atoms to form distorted CoO6 octahedra that share corners with six PO4 tetrahedra. There are three shorter (1.96 Å) and three longer (2.25 Å) Co–O bond lengths. There are two inequivalent Sb+0.50+ sites. In the first Sb+0.50+ site, Sb+0.50+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.19 Å) and three longer (2.51 Å) Sb–O bond lengths. In the second Sb+0.50+ site, Sb+0.50+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are three shorter (2.30 Å) and three longer (2.46 Å) Sb–O bond lengths. 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 CoO6 octahedra and corners with three VO6 octahedra. The corner-sharing octahedra tilt angles range from 27–44°. There are a spread of P–O bond distances ranging from 1.50–1.60 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CoO6 octahedra and corners with three VO6 octahedra. The corner-sharing octahedra tilt angles range from 26–49°. There are a spread of P–O bond distances ranging from 1.53–1.57 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one V5+ and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one V5+, one Sb+0.50+, and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Co2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one V5+, one Sb+0.50+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one V5+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one Co2+, one Sb+0.50+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one V5+, one Sb+0.50+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one V5+ and one P5+ atom.
Chalcogenide-based aerogels, known as chalcogels, represent a novel class of nanoparticle-based porous amorphous materials characterized by high surface polarizability and Lewis base properties, exhibiting promising applications in clean energy and separation science. This work presents a K–Co–Mo–S x (KCMS) chalcogel as a highly efficient sorbent for heavy metal ions and details its sorption mechanisms. Its incoherent structure comprises Mo 2 V (S 2 ) 6 and Mo 3 IV S(S 6 ) 2 anion-like clusters with four- and six-coordinated Co–S polyhedra, forming a Co–Mo–S covalent network that hosts K + ions through electrostatic attraction. The interactions of KCMS with heavy metal ions, particularly Pb 2+ and Ag + , reveal that KCMS is exceptionally effective in removing these ions from ppm concentrations down to trace levels (≤5 ppb). KCMS rapidly removes Ag + (≈81.7%) and Pb 2+ (≈99.5%) within five minutes, achieving >99.9% removal within an hour, with a distribution constant K d ≥10 8 mL g -1 . KCMS exhibits an impressive removal capacity of 1378 mg g -1 for Ag + and 1146 mg g -1 for Pb 2+ , establishing it as one of the most effective materials known to date for heavy metal removal. This material is also effective for the removal of Ag + and Pb 2+ along with Hg 2+ , Ni 2+ , Cu 2+ , and Cd 2+ from various water sources even in the presence of highly concentrated and chemically diverse cations, anions, and organic species. Analysis of the post-interacted KCMS by synchrotron X-ray pair distribution function (PDF), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) revealed that the sorption of Pb 2+ , Ag + , and Hg 2+ mainly occurs by the exchange of K + and Co 2+ . Despite being amorphous, this material exhibits unprecedented ion-exchange mechanisms both for the ionically and covalently bound K + and Co 2+ , respectively. In conclusion, this discovery advances our knowledge of amorphous gels and guides material synthesis principles for the highly selective and efficient removal of heavy metal ions from water.
Electrodeposited dendritic copper foams have been extensively studied as an electrocatalyst for CO 2 reduction reaction (CO 2 RR). Many parameters, such as dendrite size, porosity, pore size, and crystal faceting, define the hierarchical properties of these structures and their subsequent bubble evolution and CO 2 RR capabilities. Herein, the effects the electrodeposition conditions (potential, pH) have on the resulting crystallinity, microstructure, and macroporosity of the copper foam are studied. These morphological differences and the corresponding effects on electrocatalytic activity are characterized. It is shown that the composition of the electrodeposition bath can have significant effects on the mechanics of bubble formation and detachment at the surface during hydrogen evolution reaction in acidic solutions. Similarly, the electrodeposition conditions for the synthesis of the foam affect the product selectivity during CO 2 RR electrocatalysis. As a result, foams deposited in alkaline electrodeposition solutions show high faradaic efficiency and specificity toward C 2 H 6 , an uncommon product of CO 2 RR, at modest applied potentials (−0.8 V versus reversible hydrogen electrode.
V6IrCo crystallizes in the cubic Pm-3 space group. The structure is three-dimensional. V is bonded in a 6-coordinate geometry to two equivalent V, two equivalent Ir, and two equivalent Co atoms. There are one shorter (2.32 Å) and one longer (2.40 Å) V–V bond lengths. Both V–Ir bond lengths are 2.65 Å. Both V–Co bond lengths are 2.63 Å. Ir is bonded to twelve equivalent V atoms to form IrV12 cuboctahedra that share edges with six equivalent IrV12 cuboctahedra and faces with eight equivalent CoV12 cuboctahedra. Co is bonded to twelve equivalent V atoms to form CoV12 cuboctahedra that share edges with six equivalent CoV12 cuboctahedra and faces with eight equivalent IrV12 cuboctahedra.