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All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Activationof Oxygen Evolution Electrocatalysis viaReduced Ruthenium–Oxygen–Ruthenium Coordination

Noble metal oxides such as RuO2 are the state-of-the-art electrocatalysts for anodic reactions in acidic electrolytes, but their scarcity and moderate activity greatly limit emerging renewable energy technologies. Here, we show that oxidized overlayers of ruthenium on earth-abundant manganese oxide (MnO2/o-RuOx) nanocrystal supports exhibit Ru chemical states associated with reduced Ru–O–Ru coordination that enable dynamic switching of hydrogen bonding, with *OH intermediates hydrogen bonding to surface O and *OOH intermediates bonding to protruding RuOx clusters. The resulting electrocatalysts exhibit an overpotential of 218.9 ± 0.3 mV at 10 mA cm–2 for the oxygen evolution reaction in acid, corresponding to a 2425% increase in Ru mass activity compared to RuO2, enabling the construction of electrolyzers that achieved 3 A cm–2 at 1.646 V, 5.54 A cm–2 at 1.8 V, and exhibited over 3000-h stability at 100 mA cm–2. These findings motivate further efforts to develop nanomaterials that harness reduced Ru–O–Ru coordination to enable emerging renewable energy technologies.

58 GEOSCIENCES↗
DOE OSTI2020

Definition of Redox Centers in Reactions of Lithium Intercalation in Li 3 RuO 4 Polymorphs

Cathodes based on layered LiMO 2 are the limiting components in the path toward Li-ion batteries with energy densities suitable for electric vehicles. Introducing an over-stoichiometry of Li increases storage capacity beyond a conventional mechanism of formal transition metal redox. However, the role and fate of the oxide ligands in such intriguing additional capacity remain unclear. This reactivity was predicted in Li 3 RuO 4 , making it a valuable model system. For this study, a comprehensive analysis of the redox activity of both Ru and O under different electrochemical conditions was carried out, and the effect of Li/Ru ordering was evaluated. Li 3 RuO 4 displays highly reversible Li intercalation to Li 4 RuO 4 below 2.5 V vs Li + /Li 0 , with conventional reactivity through the formal Ru 5+ -Ru 4+ couple. In turn, it can also undergo anodic Li extraction at 3.9 V, which involves O states to a much greater extent than Ru. This reaction competes with side processes such as electrolyte decomposition and, to a much lesser extent, oxygen loss. Although the associated capacity is reversible, reintercalation unlocks a different, conventional pathway also involving the formal Ru 5+ -Ru 4+ couple despite operating above 2.5 V, leading to chemical hysteresis. This new pathway is both chemically and electrochemically reversible in subsequent cycles. This work exemplifies both the challenge of stabilizing highly depleted O states, even with 4d metals, and the ability of solids to access the same redox couple at two very different potential windows depending on the underlying structural changes. It highlights the importance of properly defining the covalency of oxides when defining charge compensation in view of the design of materials with high capacity for Li storage.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Isopotential Electron Titration of Ammonia Charge Transfer on Metal Catalysts

Electron transfer between adsorbates and surfaces determines the binding strength and reactivity of chemical moieties on materials designed for separations and catalysis. To quantify electron exchange, the extent of charge transfer resulting from ammonia adsorption on a Ru surface was measured by isopotential electron titration (IET) on a Ru catalytic condenser, where isopotential conditions were maintained between Ru and silicon separated by an insulating HfO 2 layer during gas phase ammonia adsorption. Charge transfer upon ammonia adsorption on a Ru catalytic condenser increased from 40 to 1200 nC/cm 2 at 75 and 225 °C, respectively. Charge transfer measurements provided a direct estimate of ammonia adsorption thermodynamics on Ru without knowing surface coverages a priori, revealing an adsorption enthalpy of −53 ± 10 kJ/mol and entropy of −61 ± 26 J/mol·K. Combining experimentally-measured charge transfer with kinetic Monte Carlo simulations informed adsorbate surface coverages determined that 0.058 electrons were transferred to the Ru surface for each molecular ammonia adsorption event (δ NH 3 = 0.058 ± 0.005 e – /NH 3 *), consistent with calculated Bader charges. The ability to measure the extent of charge transfer for adsorbed species provides a fundamental descriptor to understand existing and new chemically functional surfaces, providing a foundational method for the emerging field of thermochemical surface coulometry.

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

Influence of the neutron-skin effect on nuclear isobar collisions at energies available at the BNL Relativistic Heavy Ion Collider

The unambiguous observation of a Chiral Magnetic Effect (CME)-driven charge separation is the core aim of the isobar program at RHIC consisting of $96\atop{40}$Zr+$96\atop{40}$Zr and $96\atop{44}$Ru+$96\atop{44}$Ru collisions at √s NN = 200 GeV. We quantify the role of the spatial distributions of the nucleons in the isobars on both eccentricity and magnetic field strength within a relativistic hadronic transport approach (SMASH, Simulating Many Accelerated Strongly-interacting Hadrons). In particular, we introduce isospin-dependent nucleon-nucleon spatial correlations in the geometric description of both nuclei, deformation for $96\atop{44}$Ru and the so-called neutron skin effect for the neutron-rich isobar i.e. $96\atop{40}$Zr. The main result of this study is a reduction of the magnetic field strength difference between $96\atop{44}$Ru+$96\atop{44}$Ru and $96\atop{40}$Zr+$96\atop{40}$Zr by a factor of 2, from 10% to 5% in peripheral collisions when the neutron-skin effect is included. Further, we find an increase of the eccentricity ratio between the isobars by up to 10% in ultra-central collisions as due to the deformation of $96\atop{44}$Ru while neither the neutron skin effect nor the nucleon-nucleon correlations result into a significant modification of this observable with respect to the traditional Woods-Saxon modeling. Our results suggest a significantly smaller CME signal to background ratio for the experimental charge separation measurement in peripheral collisions with the isobar systems than previously expected.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Estimate of background baseline and upper limit on the chiral magnetic effect in isobar collisions at $\sqrt{S_{NN}}$=200 GeV at the BNL Relativistic Heavy Ion Collider

For the search of the chiral magnetic effect (CME), STAR previously presented the results from isobar collisions ($^{96}_{44}$Ru + $^{96}_{44}$Ru, $^{96}_{40}$Zr + $^{96}_{40}$Zr) obtained through a blind analysis. The ratio of results in Ru+Ru to Zr+Zr collisions for the CME-sensitive charge-dependent azimuthal correlator (Δ⁢𝛾), normalized by elliptic anisotropy (𝑣2), was observed to be close to but systematically larger than the inverse multiplicity ratio. The background baseline for the isobar ratio, 𝑌= (Δ⁢𝛾/𝑣2) Ru /(Δ⁢𝛾/𝑣2) Zr , is naively expected to be (1/𝑁) Ru /(1/𝑁) Zr ; however, genuine two- and three-particle correlations are expected to alter it. We estimate the contributions to 𝑌 from those correlations, utilizing both the isobar data and hijing simulations. After including those contributions, we arrive at a final background baseline for 𝑌, which is consistent with the isobar data. Here, we extract an upper limit for the CME fraction in the Δ⁢𝛾 measurement of approximately 10% at a 95% confidence level on in isobar collisions at $\sqrt{S_{NN}}$=200 GeV, with an expected 15% difference in their squared magnetic fields.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Ruthenium speciation and distribution in the environment: A review

Here, the review focuses on speciation and migration of anthropogenic ruthenium (Ru) originated from nuclear industry releases and presents updated information regarding Ru in the environment. It provides analysis of the main pathways of Ru species distribution in the aqueous and terrestrial environment, starting from its natural occurrence, generation and release from anthropogenic sources, predominant speciation, and ending with bioaccumulation, which can be directly or indirectly related to human health. Literature sources belonging to the post-Chernobyl time frame were preferentially considered, in which Ru-103 and Ru-106 are the major fission isotopes studied due to their traceability in the environment and their relatively long half-lives.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
DOE OSTI2023

Reconstructing Oxygen-Deficient Zirconia with Ruthenium Catalyst on Atomic-Scale Interfaces toward Hydrogen Production

Downsizing a catalyst nanoparticle (NP) to a single atom (SA) has proven to be highly effective in increasing catalytic activity and decreasing the amount of catalyst required for various electrochemical reactions. However, insufficient stability of the single-atom site catalysts (SACs) is still a significant challenge for their practical application. Here, SACs firmly bound to stable metal oxide NPs are proposed to dramatically increase the electrochemical activity and stability of SA-based catalysts for hydrogen evolution reaction (HER). Starting from a Ru-infiltrated, Zr-based metal-organic framework (MOF), the tetragonal zirconium oxide (ZrO 2-x ) NPs-embedded carbon matrix is fabricated as support through facile pyrolysis. Simultaneously, Ru SAs as active sites are well dispersed on the surface of ZrO 2-x NPs due to the generation of oxygen vacancies in the tetragonal ZrO 2-x . Finally, the Ru-ZrO 2-x SAC exhibits a 4–5 times higher mass activity than commercial Pt and Ru catalysts and superior durability due to strong metal-support interaction (SMSI) between Ru atoms and ZrO 2-x substrate.

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

Materials Data on UB2Ru3 by Materials Project

URu3B2 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to two equivalent U, twelve equivalent Ru, and six equivalent B atoms. Both U–U bond lengths are 2.97 Å. All U–Ru bond lengths are 3.13 Å. All U–B bond lengths are 3.19 Å. Ru is bonded in a distorted square co-planar geometry to four equivalent U and four equivalent B atoms. All Ru–B bond lengths are 2.18 Å. B is bonded in a 6-coordinate geometry to three equivalent U and six equivalent Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrRu3C by Materials Project

ZrRu3C is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Zr is bonded to twelve equivalent Ru atoms to form ZrRu12 cuboctahedra that share corners with twelve equivalent ZrRu12 cuboctahedra, faces with six equivalent ZrRu12 cuboctahedra, and faces with eight equivalent CRu6 octahedra. All Zr–Ru bond lengths are 2.90 Å. Ru is bonded to four equivalent Zr and two equivalent C atoms to form a mixture of distorted edge, face, and corner-sharing RuZr4C2 octahedra. The corner-sharing octahedra tilt angles range from 0–60°. Both Ru–C bond lengths are 2.05 Å. C is bonded to six equivalent Ru atoms to form CRu6 octahedra that share corners with six equivalent CRu6 octahedra and faces with eight equivalent ZrRu12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc2Al3Ru by Materials Project

Sc2RuAl3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sc is bonded in a 12-coordinate geometry to four equivalent Sc, three equivalent Ru, and nine equivalent Al atoms. There are three shorter (3.20 Å) and one longer (3.33 Å) Sc–Sc bond lengths. All Sc–Ru bond lengths are 3.10 Å. There are three shorter (3.03 Å) and six longer (3.13 Å) Sc–Al bond lengths. Ru is bonded to six equivalent Sc and six equivalent Al atoms to form RuSc6Al6 cuboctahedra that share corners with twelve equivalent AlSc6Al4Ru2 cuboctahedra, edges with six equivalent RuSc6Al6 cuboctahedra, faces with two equivalent RuSc6Al6 cuboctahedra, and faces with eighteen equivalent AlSc6Al4Ru2 cuboctahedra. All Ru–Al bond lengths are 2.62 Å. Al is bonded to six equivalent Sc, two equivalent Ru, and four equivalent Al atoms to form distorted AlSc6Al4Ru2 cuboctahedra that share corners with four equivalent RuSc6Al6 cuboctahedra, corners with fourteen equivalent AlSc6Al4Ru2 cuboctahedra, edges with six equivalent AlSc6Al4Ru2 cuboctahedra, faces with six equivalent RuSc6Al6 cuboctahedra, and faces with twelve equivalent AlSc6Al4Ru2 cuboctahedra. There are two shorter (2.63 Å) and two longer (2.68 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbAlRu2 by Materials Project

NbRu2Al is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Nb is bonded in a body-centered cubic geometry to eight equivalent Ru atoms. All Nb–Ru bond lengths are 2.69 Å. Ru is bonded in a body-centered cubic geometry to four equivalent Nb and four equivalent Al atoms. All Ru–Al bond lengths are 2.69 Å. Al is bonded in a body-centered cubic geometry to eight equivalent Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(PRu)2 by Materials Project

ErRu2P2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Er is bonded in a 8-coordinate geometry to eight equivalent Ru and eight equivalent P atoms. All Er–Ru bond lengths are 3.12 Å. All Er–P bond lengths are 3.10 Å. Ru is bonded in a 12-coordinate geometry to four equivalent Er and four equivalent P atoms. All Ru–P bond lengths are 2.35 Å. P is bonded in a 9-coordinate geometry to four equivalent Er, four equivalent Ru, and one P atom. The P–P bond length is 2.36 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn3Ru by Materials Project

RuZn3 is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ru is bonded to twelve Zn atoms to form RuZn12 cuboctahedra that share corners with four equivalent ZnZn8Ru4 cuboctahedra, corners with eight equivalent RuZn12 cuboctahedra, edges with four equivalent RuZn12 cuboctahedra, edges with twelve ZnZn8Ru4 cuboctahedra, faces with five equivalent RuZn12 cuboctahedra, and faces with nine ZnZn8Ru4 cuboctahedra. There are a spread of Ru–Zn bond distances ranging from 2.63–2.81 Å. There are three inequivalent Zn sites. In the first Zn site, Zn is bonded to four equivalent Ru and eight Zn atoms to form distorted ZnZn8Ru4 cuboctahedra that share corners with four equivalent RuZn12 cuboctahedra, corners with eight equivalent ZnZn8Ru4 cuboctahedra, edges with four equivalent RuZn12 cuboctahedra, edges with twelve ZnZn8Ru4 cuboctahedra, faces with five equivalent RuZn12 cuboctahedra, and faces with nine ZnZn8Ru4 cuboctahedra. There are four shorter (2.68 Å) and four longer (2.76 Å) Zn–Zn bond lengths. In the second Zn site, Zn is bonded in a distorted square co-planar geometry to four equivalent Ru and four equivalent Zn atoms. In the third Zn site, Zn is bonded to four equivalent Ru and eight Zn atoms to form ZnZn8Ru4 cuboctahedra that share corners with four equivalent ZnZn8Ru4 cuboctahedra, edges with eight equivalent RuZn12 cuboctahedra, edges with eight equivalent ZnZn8Ru4 cuboctahedra, faces with four equivalent RuZn12 cuboctahedra, and faces with twelve ZnZn8Ru4 cuboctahedra. All Zn–Zn bond lengths are 2.68 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(BRu)2 by Materials Project

CeRu2B2 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. Ce is bonded in a 10-coordinate geometry to four equivalent Ru and six equivalent B atoms. All Ce–Ru bond lengths are 3.00 Å. There are two shorter (2.84 Å) and four longer (3.05 Å) Ce–B bond lengths. Ru is bonded in a 4-coordinate geometry to two equivalent Ce and four equivalent B atoms. There are two shorter (2.08 Å) and two longer (2.15 Å) Ru–B bond lengths. B is bonded in a 7-coordinate geometry to three equivalent Ce and four equivalent Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al6Ru by Materials Project

Al6Ru crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ru is bonded in a distorted q6 geometry to ten Al atoms. There are a spread of Ru–Al bond distances ranging from 2.52–2.65 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a distorted bent 120 degrees geometry to two equivalent Ru atoms. In the second Al site, Al is bonded in a distorted bent 150 degrees geometry to two equivalent Ru atoms. In the third Al site, Al is bonded in a distorted single-bond geometry to one Ru atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TmGa3Ru by Materials Project

TmRuGa3 crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Tm is bonded in a 8-coordinate geometry to four equivalent Ru and ten Ga atoms. All Tm–Ru bond lengths are 3.20 Å. There are eight shorter (2.93 Å) and two longer (3.20 Å) Tm–Ga bond lengths. Ru is bonded to four equivalent Tm and eight equivalent Ga atoms to form distorted RuTm4Ga8 cuboctahedra that share corners with four equivalent RuTm4Ga8 cuboctahedra, edges with four equivalent GaTm6 octahedra, and faces with eight equivalent RuTm4Ga8 cuboctahedra. All Ru–Ga bond lengths are 2.66 Å. There are two inequivalent Ga sites. In the first Ga site, Ga is bonded to six equivalent Tm atoms to form GaTm6 octahedra that share corners with six equivalent GaTm6 octahedra and edges with twelve equivalent RuTm4Ga8 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. In the second Ga site, Ga is bonded in a 6-coordinate geometry to three equivalent Tm and three equivalent Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdGeRu by Materials Project

GdRuGe crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Gd is bonded in a 9-coordinate geometry to four equivalent Ru and six equivalent Ge atoms. There are a spread of Gd–Ru bond distances ranging from 2.96–3.01 Å. There are a spread of Gd–Ge bond distances ranging from 3.07–3.26 Å. Ru is bonded in a 8-coordinate geometry to four equivalent Gd and four equivalent Ge atoms. There are a spread of Ru–Ge bond distances ranging from 2.54–2.59 Å. Ge is bonded in a 10-coordinate geometry to six equivalent Gd and four equivalent Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(GeRu)2 by Materials Project

Sr(RuGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Ru and eight equivalent Ge atoms. All Sr–Ru bond lengths are 3.39 Å. All Sr–Ge bond lengths are 3.40 Å. Ru is bonded in a 4-coordinate geometry to four equivalent Sr and four equivalent Ge atoms. All Ru–Ge bond lengths are 2.45 Å. Ge is bonded in a 4-coordinate geometry to four equivalent Sr and four equivalent Ru atoms.

36 MATERIALS SCIENCE↗