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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Strong Electronic and Magnetic Coupling in M 4 (M = Ni, Cu) Clusters via Direct Orbital Interactions between Low-Coordinate Metal Centers

In this report we present an extensive study of tetranuclear transition-metal cluster compounds M 4 (NP t Bu 3 ) 4 and [M 4 (NP t Bu 3 ) 4 ][B(C 6 F 5 ) 4 ] (M = Ni, Cu; t Bu = tert -butyl), which feature low-coordinate metal centers and direct metal-metal orbital overlap. X-ray diffraction, electrochemical, magnetic, spectroscopic, and computational analysis elucidate the nature of the bonding interactions in these clusters and the impact of these interactions on the electronic and magnetic properties. Direct orbital overlap results in strongly coupled, large-spin ground states in the [Ni 4 (NP t Bu 3 ) 4 ] +/0 clusters and fully delocalized, spin-correlated electrons. Correlated electronic structure calculations confirm the presence of ferromagnetic ground states that arise from direct exchange between magnetic orbitals, and, in the case of the neutral cluster, itinerant electron magnetism similar to that in metallic ferromagnets. The cationic nickel cluster also possesses large magnetic anisotropy exemplified by a large, positive axial zero-field splitting parameter of D = +7.95 or +9.2 cm -1 , as determined by magnetometry or electron paramagnetic resonance spectroscopy, respectively. The [Ni 4 (NP t Bu 3 ) 4 ] + cluster is also the first molecule with easy-plane magnetic anisotropy to exhibit zero-field slow magnetic relaxation, and under a small applied field, it exhibits relaxation exclusively through an Orbach mechanism with a spin relaxation barrier of 16 cm -1 . The S = 1 / 2 complex [Cu 4 (NP t Bu 3 ) 4 ] + exhibits slow magnetic relaxation via a Raman process on the millisecond time scale, supporting the presence of slow relaxation via an Orbach process in the nickel analogue. Overall, this work highlights the unique electronic and magnetic properties that can be realized in metal clusters featuring direct metal-metal orbital interactions between low-coordinate metal centers.

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

Materials Data on Cu3(BiI4)4 by Materials Project

Cu3(BiI4)4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are three inequivalent Cu+1.33+ sites. In the first Cu+1.33+ site, Cu+1.33+ is bonded to four I1- atoms to form CuI4 tetrahedra that share corners with four BiI6 octahedra and corners with two equivalent CuI4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–62°. There are one shorter (2.57 Å) and three longer (2.66 Å) Cu–I bond lengths. In the second Cu+1.33+ site, Cu+1.33+ is bonded to four I1- atoms to form CuI4 tetrahedra that share corners with four equivalent BiI6 octahedra and a cornercorner with one CuI4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Cu–I bond distances ranging from 2.52–2.94 Å. In the third Cu+1.33+ site, Cu+1.33+ is bonded to four I1- atoms to form CuI4 tetrahedra that share corners with three CuI4 tetrahedra and a faceface with one BiI6 octahedra. There are a spread of Cu–I bond distances ranging from 2.55–2.67 Å. There are three inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded to six I1- atoms to form BiI6 octahedra that share corners with three equivalent CuI4 tetrahedra, an edgeedge with one BiI6 octahedra, and a faceface with one CuI4 tetrahedra. There are a spread of Bi–I bond distances ranging from 3.03–3.25 Å. In the second Bi3+ site, Bi3+ is bonded to six I1- atoms to form BiI6 octahedra that share a cornercorner with one CuI4 tetrahedra and edges with three BiI6 octahedra. There are a spread of Bi–I bond distances ranging from 2.95–3.40 Å. In the third Bi3+ site, Bi3+ is bonded to six I1- atoms to form BiI6 octahedra that share corners with two equivalent CuI4 tetrahedra and edges with three BiI6 octahedra. There are a spread of Bi–I bond distances ranging from 3.04–3.18 Å. There are twelve inequivalent I1- sites. In the first I1- site, I1- is bonded in a bent 120 degrees geometry to one Cu+1.33+ and one Bi3+ atom. In the second I1- site, I1- is bonded in an L-shaped geometry to two equivalent Bi3+ atoms. In the third I1- site, I1- is bonded in an L-shaped geometry to two Bi3+ atoms. In the fourth I1- site, I1- is bonded in an L-shaped geometry to two Bi3+ atoms. In the fifth I1- site, I1- is bonded in an L-shaped geometry to two equivalent Bi3+ atoms. In the sixth I1- site, I1- is bonded in a 1-coordinate geometry to one Cu+1.33+ and one Bi3+ atom. In the seventh I1- site, I1- is bonded in a bent 120 degrees geometry to one Cu+1.33+ and one Bi3+ atom. In the eighth I1- site, I1- is bonded in a bent 120 degrees geometry to one Cu+1.33+ and one Bi3+ atom. In the ninth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi3+ atoms. In the tenth I1- site, I1- is bonded in a 2-coordinate geometry to two Cu+1.33+ and one Bi3+ atom. In the eleventh I1- site, I1- is bonded in a 3-coordinate geometry to one Cu+1.33+ and two equivalent Bi3+ atoms. In the twelfth I1- site, I1- is bonded in a water-like geometry to two Cu+1.33+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2Cu3(WO4)6 by Materials Project

Y2Cu3(WO4)6 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to six O2- atoms to form YO6 octahedra that share corners with five WO6 octahedra. The corner-sharing octahedra tilt angles range from 36–53°. There are a spread of Y–O bond distances ranging from 2.22–2.39 Å. In the second Y3+ site, Y3+ is bonded to six O2- atoms to form YO6 octahedra that share corners with five WO6 octahedra. The corner-sharing octahedra tilt angles range from 37–53°. There are a spread of Y–O bond distances ranging from 2.21–2.38 Å. There are six inequivalent W6+ sites. In the first W6+ site, W6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of W–O bond distances ranging from 1.74–2.32 Å. In the second W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share a cornercorner with one YO6 octahedra and an edgeedge with one WO6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are a spread of W–O bond distances ranging from 1.82–2.19 Å. In the third W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with four YO6 octahedra and an edgeedge with one WO6 octahedra. The corner-sharing octahedra tilt angles range from 37–53°. There are a spread of W–O bond distances ranging from 1.82–2.18 Å. In the fourth W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with four YO6 octahedra and an edgeedge with one WO6 octahedra. The corner-sharing octahedra tilt angles range from 36–53°. There are a spread of W–O bond distances ranging from 1.82–2.18 Å. In the fifth W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share a cornercorner with one YO6 octahedra and an edgeedge with one WO6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of W–O bond distances ranging from 1.82–2.19 Å. In the sixth W6+ site, W6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of W–O bond distances ranging from 1.74–2.32 Å. There are three inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Cu–O bond distances ranging from 1.86–2.73 Å. In the second Cu2+ site, Cu2+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.86–2.61 Å. In the third Cu2+ site, Cu2+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.86–2.60 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Y3+ and one W6+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one W6+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Y3+ and one W6+ atom. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to one Y3+, one W6+, and one Cu2+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one W6+ and one Cu2+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one W6+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two W6+ and one Cu2+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two W6+ and one Cu2+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to two W6+ and one Cu2+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to one Y3+, two W6+, and one Cu2+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to two W6+ and one Cu2+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Y3+ and two W6+ atoms. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one W6+ atom. In the fourteenth O2- site, O2- is bonded in a bent 120 degrees geometry to one W6+ and one Cu2+ atom. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Y3+, one W6+, and one Cu2+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Y3+ and one W6+ atom. In the seventeenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one W6+ atom. In the eighteenth O2- site, O2- is bonded in a single-bond geometry to one W6+ atom. In the nineteenth O2- site, O2- is bonded in a 3-coordinate geometry to two W6+ and one Cu2+ atom. In the twentieth O2- site, O2- is bonded in a 3-coordinate geometry to two W6+ and one Cu2+ atom. In the twenty-first O2- site, O2- is bonded in a distorted trigonal planar geometry to two W6+ and one Cu2+ atom. In the twenty-second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Y3+ and two W6+ atoms. In the twenty-third O2- site, O2- is bonded in a 2-coordinate geometry to two W6+ and one Cu2+ atom. In the twenty-fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Y3+, two W6+, and one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlCu7S4 by Materials Project

TlCu7S4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are seven inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a trigonal planar geometry to three S2- atoms. There are a spread of Cu–S bond distances ranging from 2.26–2.38 Å. In the second Cu1+ site, Cu1+ is bonded in a trigonal planar geometry to three S2- atoms. There are a spread of Cu–S bond distances ranging from 2.32–2.37 Å. In the third Cu1+ site, Cu1+ is bonded in a trigonal non-coplanar geometry to three S2- atoms. There are a spread of Cu–S bond distances ranging from 2.29–2.36 Å. In the fourth Cu1+ site, Cu1+ is bonded in a distorted trigonal non-coplanar geometry to three S2- atoms. There are a spread of Cu–S bond distances ranging from 2.34–2.43 Å. In the fifth Cu1+ site, Cu1+ is bonded in a 2-coordinate geometry to four S2- atoms. There are a spread of Cu–S bond distances ranging from 2.21–2.90 Å. In the sixth Cu1+ site, Cu1+ is bonded in a 3-coordinate geometry to four S2- atoms. There are a spread of Cu–S bond distances ranging from 2.25–2.92 Å. In the seventh Cu1+ site, Cu1+ is bonded in a 3-coordinate geometry to four S2- atoms. There are a spread of Cu–S bond distances ranging from 2.30–2.93 Å. Tl1+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are a spread of Tl–S bond distances ranging from 3.25–3.46 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to six Cu1+ and two equivalent Tl1+ atoms. In the second S2- site, S2- is bonded in a 7-coordinate geometry to five Cu1+ and two equivalent Tl1+ atoms. In the third S2- site, S2- is bonded in a 5-coordinate geometry to six Cu1+ and two equivalent Tl1+ atoms. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to seven Cu1+ and two equivalent Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2Cu(SiO3)2 by Materials Project

Li2Cu(SiO3)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There are a spread of Li–O bond distances ranging from 1.76–1.99 Å. In the second Li1+ site, Li1+ is bonded in a 1-coordinate geometry to three O2- atoms. There are a spread of Li–O bond distances ranging from 1.65–2.13 Å. In the third Li1+ site, Li1+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There are a spread of Li–O bond distances ranging from 1.76–2.00 Å. In the fourth Li1+ site, Li1+ is bonded in a 1-coordinate geometry to three O2- atoms. There are a spread of Li–O bond distances ranging from 1.66–2.13 Å. There are two inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Cu–O bond distances ranging from 1.65–1.94 Å. In the second Cu2+ site, Cu2+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Cu–O bond distances ranging from 1.65–1.94 Å. There are four inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of Si–O bond distances ranging from 1.59–2.24 Å. In the second Si4+ site, Si4+ is bonded in a 1-coordinate geometry to four O2- atoms. There are a spread of Si–O bond distances ranging from 1.20–2.24 Å. In the third Si4+ site, Si4+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of Si–O bond distances ranging from 1.60–2.26 Å. In the fourth Si4+ site, Si4+ is bonded in a 1-coordinate geometry to four O2- atoms. There are a spread of Si–O bond distances ranging from 1.20–2.25 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Cu2+ and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to two Li1+ and one Si4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two Si4+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Cu2+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Cu2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Cu2+ and one Si4+ atom. In the eighth O2- site, O2- is bonded in a distorted T-shaped geometry to two Li1+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Si4+ atoms. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two Si4+ atoms. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Cu2+, and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Cu2+, and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Ultrasmall Cu Nanoparticles Supported on Crystalline, Mesoporous ZnO for Selective CO 2 Hydrogenation

Converting CO 2 to value-added chemicals, e. g., CH 3 OH, is highly desirable in terms of the carbon cycling while reducing CO 2 emission from fossil fuel combustion. Cu-based nanocatalysts are among the most efficient for selective CO 2 -to-CH 3 OH transformation; this conversion, however, suffers from low reactivity especially in the thermodynamically favored low temperature range. We herein report ultrasmall copper (Cu) nanocatalysts supported on crystalline, mesoporous zinc oxide nanoplate (Cu@mZnO) with notable activity and selectivity of CO 2 -to-CH 3 OH in the low temperature range of 200–250 °C. Cu@mZnO nanoplates are prepared based on the crystal-crystal transition of mixed Cu and Zn basic carbonates to mesoporous metal oxides and subsequent hydrogen reduction. Under the nanoconfinement of mesopores in crystalline ZnO frameworks, ultrasmall Cu nanoparticles with an average diameter of 2.5 nm are produced. Cu@mZnO catalysts have a peak CH 3 OH formation rate of 1.13 mol h −1 per 1 kg under ambient pressure at 246 °C, about 25 °C lower as compared to that of the benchmark catalyst of Cu−Zn−Al oxides. In conclusion, our new synthetic strategy sheds some valuable insights into the design of porous catalysts for the important conversion of CO 2 -to-CH 3 OH.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Current‐Dependent Lithium Metal Growth Modes in “Anode‐Free” Solid‐State Batteries at the Cu|LLZO Interface

Abstract Controlling the lithium growth morphology in lithium reservoir‐free cells (RFCs), so‐called “anode‐free” solid‐state batteries, is of key interest to ensure stable battery operation. Despite several benefits of RFCs like improved energy density and easier fabrication, issues during the charging of the cell hinder the transition from lithium metal batteries with a lithium reservoir layer to RFCs. In RFCs, the lithium metal anode is plated during the first charging step at the interface between a metal current collector and the solid electrolyte, which is prone to highly heterogeneous growth instead of the desired homogeneous film‐like growth. Herein, the lithium morphology during the first charging step in RFCs is explored as a function of current density and current collector thickness. Using operando scanning electron microscopy, an increase in the lithium particle density is observed with increasing current density at the Cu|Li 6.25 Al 0.25 La 3 Zr 2 O 12 interface. This observation is then applied to improve the area coverage of lithium by pulsed plating. It is also shown that thin current collectors ( d = 100 nm) are unsuited for RFCs, as lithium whiskers penetrate them, resulting in highly heterogeneous interfaces. This suggests the use of thicker metal layers (several µm) to mitigate whisker penetration and facilitate homogeneous lithium plating.

25 ENERGY STORAGE↗
DOE OSTI2020

Atomically Precise Crystalline Materials Based on Kinetically Inert Metal Ions via Reticular Mechanopolymerization

Abstract Atomistic control of the coordination environment of lattice ions and the distribution of metal sites within crystalline mixed‐metal coordination polymers remain significant synthetic challenges. Herein is reported the mechanochemical synthesis of a reticular family of crystalline heterobimetallic metal–organic frameworks (MOFs) is now achieved by polymerization of molecular Ru 2 [II,III] complexes, featuring unprotected carboxylic acid substituents, with Cu(OAc) 2 . The resulting crystalline heterobimetallic MOFs are solid solutions of Ru 2 and Cu 2 sites housed within [M 3 L 2 ] phases. The developed mechanochemical strategy is modular and allows for systematic control of the primary coordination sphere of the Ru 2 sites within an isoreticular family of materials. This strategy is anticipated to provide a rational approach to atomically precise mixed‐metal materials.

Gao, Wen‐Yang↗
DOE OSTI2023

Effect of exposure temperature on the corrosion behavior of a FeNiCrCuAl high entropy alloy in supercritical water

The corrosion behavior of a FeNiCrCuAl high entropy alloy exposed to supercritical water at 380–650 °C and 25 MPa was investigated. The weight gain exhibited a nearly parabolic kinetics. At 380 °C, Al 2 O 3 precipitated on Fe 3 O 4 particles in FeCr-rich regions and intensified as the temperature increased to 650 °C, eventually resulting in an Al 2 O 3 particle. A mixed Fe 3 O 4 and NiAl 2 O 4 outer layer developed on NiAl-rich regions at 380 °C, whereas an Al 2 O 3 layer formed at 650 °C. Cu 2 O formed along the boundaries of NiAl-rich regions, regardless of exposure temperatures. In conclusion, the corrosion mechanism at different temperatures was elucidated.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Highly reversible Zn anode with a practical areal capacity enabled by a sustainable electrolyte and superacid interfacial chemistry

Aqueous zinc-metal batteries are plagued by poor Zn reversibility owing to zinc dendrite and layered double hydroxide (LDH) formation. Here, we introduce a novel additive—N,N-dimethylformamidium trifluoromethanesulfonate (DOTf)—in a low-cost aqueous electrolyte that can very effectively address these issues. The initial water-assisted dissociation of DOTf into triflic superacid creates a robust nanostructured solid-electrolyte interface (SEI)—revealed by operando spectroscopy and cryomicroscopy—which excludes water and enables dense Zn deposition. We demonstrate excellent Zn plating/stripping in a Zn||Cu asymmetric cell for more than 3,500 cycles. Furthermore, near 100% CE is realized at a combined high current density of 4 mA cm -2 and an areal capacity of 4 mAh cm -2 over long-term cycling. Zn||Zn 0.25 V 2 O 5 ·nH 2 O full cells retain ~83% of their capacity after 1,000 cycles with mass-limited Zn anodes. By restricting the depth of discharge, the cathodes exhibit less proton intercalation and LDH formation with an extended lifetime of 2,000 cycles.

25 ENERGY STORAGE↗
DOE OSTI2023

N-induced soil acidification triggers metal stimulation of soil methane oxidation in a temperate steppe ecosystem

Methane (CH 4 ) is a potent greenhouse gas, and it is well established that low nitrogen (N) stimulates- and high N suppresses CH 4 oxidation in grassland ecosystems. Here, in this study, we examined the response of CH 4 uptake to long-term (>10 years) multi-level N additions in a temperate steppe of northern China. The N impacts on CH 4 uptake transitioned from positive to negative at the N addition rate of 4 g N m -2 y -1 . However, the high-N suppression on CH 4 uptake was partially relieved when the continuous (>10 years) high N inputs (16 g N m -2 y -1 to 64 g N m -2 y -1 ) caused soil pH drop to < 5.7. Further experiments revealed that continuous high-N inputs acidified soil to pH < 5.7 that released metal ions to stimulate monooxygenase enzyme activity; therefore, the CH 4 oxidation suppression was partially relieved under continuous N loading. Structural equation model results confirmed that metal ions, such as Iron (Fe 3+ ), Manganese (Mn 4+ ), and Copper (Cu) desorbed by soil particles, were negatively correlated with soil pH while positively correlated with CH 4 oxidation under high N inputs. These analyses suggested that continuous high N inputs-induced soil acidification can release previously bounded metal elements that partially alleviated the N suppression on CH 4 uptake. The N-induced soil acidification impacts on CH 4 uptake might play a critical role in global CH 4 cycling and deserve further investigation as external N inputs continue climbing.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Trends in Formic Acid Electro-Oxidation on Transition Metals Alloyed with Platinum and Palladium

Direct formic acid fuel cells (DFAFCs) have emerged as a promising power source to meet increased demands for alternative energy sources in the transportation and portable energy storage sectors. Furthermore, these fuel cells utilize formic acid (FA), a nontoxic and carbon-neutral fuel when produced from biomass or via CO 2 reduction. Despite the promise of DFAFCs, the best monometallic catalysts, platinum and palladium, are poisoned by CO through the indirect oxidation pathway and require large overpotentials. By alloying Pt and Pd with other metals, we aim to improve both the activity and selectivity of these catalysts. Here, we present a systematic density functional theory (GGA-PW91) study of FA electro-oxidation (FAO) on the (111) facet of bimetallic Pt (Pt 3 M) or Pd (Pd 3 M) catalysts (M = Au, Ag, Cu, Pt, Pd, Ir, Rh, Ru, or Re) to evaluate the catalytic performance of these surfaces. For each surface, we calculate free energy diagrams and onset potentials of three key reaction mechanisms: direct oxidation of FA via carboxyl (COOH), direct oxidation of FA via formate (HCOO), and the indirect oxidation of FA that first forms CO en route to full oxidation to CO 2 . We then display the trends in the form of phase diagrams that compare the activity of the calculated surfaces against regions of high activity using the free energies of adsorbed CO and OH as descriptors, enabling high-throughput screening and design of improved catalysts, particularly those alloying Pt or Pd with Ir, Ru, or Re.

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

Spectral Addressability in a Modular Two Qubit System

The combination of structural precision and reproducibility of synthetic chemistry is perfectly suited for the creation of chemical qubits, the core units of a quantum information science (QIS) system. By exploiting the atomistic control inherent to synthetic chemistry, we address a fundamental question of how the spin–spin distance between two qubits impacts electronic spin coherence. To achieve this goal, in this study we designed a series of molecules featuring two spectrally distinct qubits, an early transition metal, Ti 3+ , and a late transition metal, Cu 2+ with increasing separation between the two metals. The spectral separation between the two metals enables us to probe each metal individually in the bimetallic species and compare it with monometallic control samples. Coherence times found to be governed by the distance to nuclear spins on the other qubit’s ligand framework. This finding offers guidance for the design of spectrally addressable molecular qubits.

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

Materials Data on Ca2Cu by Materials Project

Ca2Cu crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two Ca2Cu sheets oriented in the (0, 0, 1) direction. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a 3-coordinate geometry to three equivalent Cu atoms. There are two shorter (3.00 Å) and one longer (3.02 Å) Ca–Cu bond lengths. In the second Ca site, Ca is bonded in a 4-coordinate geometry to four equivalent Cu atoms. There are a spread of Ca–Cu bond distances ranging from 3.03–3.33 Å. Cu is bonded in a 9-coordinate geometry to seven Ca and two equivalent Cu atoms. Both Cu–Cu bond lengths are 2.52 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr2La6TiCu3O16 by Materials Project

Sr2La6TiCu3O16 is (La,Ba)CuO4-derived structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Sr2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.58–2.91 Å. There are three inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.26–2.83 Å. In the second La3+ site, La3+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.26–2.80 Å. In the third La3+ site, La3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.32–2.79 Å. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four equivalent CuO6 octahedra. The corner-sharing octahedra tilt angles range from 2–3°. There are four shorter (1.92 Å) and two longer (2.08 Å) Ti–O bond lengths. There are two inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded to six O2- atoms to form CuO6 octahedra that share corners with two equivalent TiO6 octahedra and corners with two equivalent CuO6 octahedra. The corner-sharing octahedra tilt angles range from 1–3°. There are a spread of Cu–O bond distances ranging from 1.92–2.46 Å. In the second Cu2+ site, Cu2+ is bonded to six O2- atoms to form corner-sharing CuO6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are four shorter (1.93 Å) and two longer (2.41 Å) Cu–O bond lengths. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to one Sr2+, four La3+, and one Cu2+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to two equivalent Sr2+, two La3+, one Ti4+, and one Cu2+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to two equivalent Sr2+, two La3+, one Ti4+, and one Cu2+ atom. In the fourth O2- site, O2- is bonded to three equivalent Sr2+, two La3+, and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OSr3La2Ti octahedra. The corner-sharing octahedra tilt angles range from 0–57°. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to one Sr2+, four La3+, and one Cu2+ atom. In the sixth O2- site, O2- is bonded to four La3+ and two Cu2+ atoms to form distorted OLa4Cu2 octahedra that share corners with three OSr3La2Ti octahedra, an edgeedge with one OLa4Cu2 octahedra, and faces with three equivalent OLa4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–57°. In the seventh O2- site, O2- is bonded to four La3+ and two Cu2+ atoms to form distorted OLa4Cu2 octahedra that share corners with three OSr3La2Ti octahedra, an edgeedge with one OLa4Cu2 octahedra, and faces with three equivalent OLa4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–57°. In the eighth O2- site, O2- is bonded in a 6-coordinate geometry to five La3+ and one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba2La2Fe2Cu2O11 by Materials Project

Ba2La2Fe2Cu2O11 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a distorted q6 geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.80–2.89 Å. In the second Ba2+ site, Ba2+ is bonded in a distorted q6 geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.78–2.99 Å. There are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded to twelve O2- atoms to form LaO12 cuboctahedra that share corners with eight LaO12 cuboctahedra, faces with five LaO12 cuboctahedra, faces with two equivalent CuO6 octahedra, faces with four FeO6 octahedra, and faces with two equivalent CuO5 square pyramids. There are a spread of La–O bond distances ranging from 2.65–2.87 Å. In the second La3+ site, La3+ is bonded to twelve O2- atoms to form LaO12 cuboctahedra that share corners with eight LaO12 cuboctahedra, faces with five LaO12 cuboctahedra, faces with two equivalent FeO6 octahedra, faces with four CuO6 octahedra, and faces with two equivalent FeO5 square pyramids. There are a spread of La–O bond distances ranging from 2.74–2.80 Å. There are four inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with five CuO6 octahedra, a cornercorner with one CuO5 square pyramid, and faces with eight LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Fe–O bond distances ranging from 1.86–1.96 Å. In the second Fe3+ site, Fe3+ is bonded to five O2- atoms to form FeO5 square pyramids that share corners with five CuO6 octahedra and faces with four equivalent LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°. There is one shorter (1.85 Å) and four longer (1.92 Å) Fe–O bond length. In the third Fe3+ site, Fe3+ is bonded to five O2- atoms to form FeO5 square pyramids that share a cornercorner with one CuO6 octahedra and corners with four equivalent CuO5 square pyramids. The corner-sharing octahedral tilt angles are 0°. There is one shorter (1.86 Å) and four longer (1.98 Å) Fe–O bond length. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one CuO6 octahedra, corners with five CuO5 square pyramids, and faces with four equivalent LaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Fe–O bond distances ranging from 1.87–2.02 Å. There are four inequivalent Cu3+ sites. In the first Cu3+ site, Cu3+ is bonded to six O2- atoms to form CuO6 octahedra that share corners with five FeO6 octahedra, a cornercorner with one FeO5 square pyramid, and faces with eight LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Cu–O bond distances ranging from 1.90–2.00 Å. In the second Cu3+ site, Cu3+ is bonded to six O2- atoms to form CuO6 octahedra that share a cornercorner with one FeO6 octahedra, corners with five FeO5 square pyramids, and faces with four equivalent LaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Cu–O bond distances ranging from 1.96–2.05 Å. In the third Cu3+ site, Cu3+ is bonded to five O2- atoms to form CuO5 square pyramids that share a cornercorner with one FeO6 octahedra and corners with four equivalent FeO5 square pyramids. The corner-sharing octahedral tilt angles are 0°. All Cu–O bond lengths are 2.01 Å. In the fourth Cu3+ site, Cu3+ is bonded to five O2- atoms to form CuO5 square pyramids that share corners with five FeO6 octahedra and faces with four equivalent LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–6°. There is four shorter (1.94 Å) and one longer (2.00 Å) Cu–O bond length. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four equivalent La3+, one Fe3+, and one Cu3+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to four La3+, one Fe3+, and one Cu3+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to four equivalent La3+, one Fe3+, and one Cu3+ atom. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four equivalent La3+, one Fe3+, and one Cu3+ atom. In the fifth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Ba2+, two equivalent La3+, one Fe3+, and one Cu3+ atom. In the sixth O2- site, O2- is bonded in a distorted linear geometry to four equivalent La3+, one Fe3+, and one Cu3+ atom. In the seventh O2- site, O2- is bonded to four Ba2+, one Fe3+, and one Cu3+ atom to form a mixture of distorted edge, corner, and face-sharing OBa4FeCu octahedra. The corner-sharing octahedra tilt angles range from 9–17°. In the eighth O2- site, O2- is bonded in a distorted linear geometry to four equivalent Ba2+, one Fe3+, and one Cu3+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, two equivalent La3+, one Fe3+, and one Cu3+ atom. In the tenth O2- site, O2- is bonded in a distorted linear geometry to four equivalent Ba2+, one Fe3+, and one Cu3+ atom.

36 MATERIALS SCIENCE↗