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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on RuW by Materials Project

RuW crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. W is bonded to six equivalent W and six equivalent Ru atoms to form WRu6W6 cuboctahedra that share corners with eighteen equivalent WRu6W6 cuboctahedra, edges with six equivalent WRu6W6 cuboctahedra, edges with twelve equivalent RuRu6W6 cuboctahedra, faces with eight equivalent WRu6W6 cuboctahedra, and faces with twelve equivalent RuRu6W6 cuboctahedra. All W–W bond lengths are 2.79 Å. All W–Ru bond lengths are 2.76 Å. Ru is bonded to six equivalent W and six equivalent Ru atoms to form RuRu6W6 cuboctahedra that share corners with eighteen equivalent RuRu6W6 cuboctahedra, edges with six equivalent RuRu6W6 cuboctahedra, edges with twelve equivalent WRu6W6 cuboctahedra, faces with eight equivalent RuRu6W6 cuboctahedra, and faces with twelve equivalent WRu6W6 cuboctahedra. All Ru–Ru bond lengths are 2.79 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaRu3 by Materials Project

TaRu3 is Uranium Silicide-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ta is bonded to twelve equivalent Ru atoms to form TaRu12 cuboctahedra that share corners with six equivalent TaRu12 cuboctahedra, corners with twelve equivalent RuTa4Ru8 cuboctahedra, edges with eighteen equivalent RuTa4Ru8 cuboctahedra, faces with eight equivalent TaRu12 cuboctahedra, and faces with twelve equivalent RuTa4Ru8 cuboctahedra. There are six shorter (2.73 Å) and six longer (2.80 Å) Ta–Ru bond lengths. Ru is bonded to four equivalent Ta and eight equivalent Ru atoms to form distorted RuTa4Ru8 cuboctahedra that share corners with four equivalent TaRu12 cuboctahedra, corners with fourteen equivalent RuTa4Ru8 cuboctahedra, edges with six equivalent TaRu12 cuboctahedra, edges with twelve equivalent RuTa4Ru8 cuboctahedra, faces with four equivalent TaRu12 cuboctahedra, and faces with sixteen equivalent RuTa4Ru8 cuboctahedra. There are four shorter (2.73 Å) and four longer (2.80 Å) Ru–Ru bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NdRu3 by Materials Project

NdRu3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Nd is bonded to twelve equivalent Ru atoms to form a mixture of corner, edge, and face-sharing NdRu12 cuboctahedra. All Nd–Ru bond lengths are 3.05 Å. Ru is bonded in a 10-coordinate geometry to four equivalent Nd and six equivalent Ru atoms. There are four shorter (2.61 Å) and two longer (3.16 Å) Ru–Ru bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mo4Ru by Materials Project

Mo4Ru is Tungsten-derived structured and crystallizes in the orthorhombic Fmmm space group. The structure is three-dimensional. there are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a 8-coordinate geometry to six Mo and two equivalent Ru atoms. There are two shorter (2.73 Å) and four longer (2.74 Å) Mo–Mo bond lengths. Both Mo–Ru bond lengths are 2.68 Å. In the second Mo site, Mo is bonded in a distorted body-centered cubic geometry to eight Mo atoms. There are two shorter (2.73 Å) and four longer (2.74 Å) Mo–Mo bond lengths. Ru is bonded in a 8-coordinate geometry to four equivalent Mo and four equivalent Ru atoms. All Ru–Ru bond lengths are 2.74 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaGe3Ru by Materials Project

LaRuGe3 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. La is bonded in a 12-coordinate geometry to five equivalent Ru and twelve Ge atoms. There are one shorter (3.49 Å) and four longer (3.54 Å) La–Ru bond lengths. There are a spread of La–Ge bond distances ranging from 3.24–3.46 Å. Ru is bonded in a 5-coordinate geometry to five equivalent La and five Ge atoms. There are one shorter (2.39 Å) and four longer (2.46 Å) Ru–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 1-coordinate geometry to four equivalent La, one Ru, and four equivalent Ge atoms. All Ge–Ge bond lengths are 2.78 Å. In the second Ge site, Ge is bonded in a 2-coordinate geometry to four equivalent La, two equivalent Ru, and two equivalent Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ThSi3Ru by Materials Project

ThRuSi3 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. Th is bonded in a 12-coordinate geometry to five equivalent Ru and twelve Si atoms. There are four shorter (3.38 Å) and one longer (3.39 Å) Th–Ru bond lengths. There are a spread of Th–Si bond distances ranging from 3.11–3.38 Å. Ru is bonded in a 5-coordinate geometry to five equivalent Th and five Si atoms. There are one shorter (2.36 Å) and four longer (2.38 Å) Ru–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded in a distorted single-bond geometry to four equivalent Th, one Ru, and four equivalent Si atoms. All Si–Si bond lengths are 2.61 Å. In the second Si site, Si is bonded in a distorted bent 120 degrees geometry to four equivalent Th, two equivalent Ru, and two equivalent Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ru3Rh by Materials Project

Ru3Rh is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ru is bonded to eight equivalent Ru and four equivalent Rh atoms to form RuRu8Rh4 cuboctahedra that share corners with four equivalent RhRu12 cuboctahedra, corners with fourteen equivalent RuRu8Rh4 cuboctahedra, edges with six equivalent RhRu12 cuboctahedra, edges with twelve equivalent RuRu8Rh4 cuboctahedra, faces with four equivalent RhRu12 cuboctahedra, and faces with sixteen equivalent RuRu8Rh4 cuboctahedra. There are a spread of Ru–Ru bond distances ranging from 2.68–2.74 Å. There are two shorter (2.68 Å) and two longer (2.74 Å) Ru–Rh bond lengths. Rh is bonded to twelve equivalent Ru atoms to form RhRu12 cuboctahedra that share corners with six equivalent RhRu12 cuboctahedra, corners with twelve equivalent RuRu8Rh4 cuboctahedra, edges with eighteen equivalent RuRu8Rh4 cuboctahedra, faces with eight equivalent RhRu12 cuboctahedra, and faces with twelve equivalent RuRu8Rh4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RuRh by Materials Project

RhRu crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Ru is bonded to six equivalent Ru and six equivalent Rh atoms to form RuRu6Rh6 cuboctahedra that share corners with eighteen equivalent RuRu6Rh6 cuboctahedra, edges with six equivalent RuRu6Rh6 cuboctahedra, edges with twelve equivalent RhRu6Rh6 cuboctahedra, faces with eight equivalent RuRu6Rh6 cuboctahedra, and faces with twelve equivalent RhRu6Rh6 cuboctahedra. All Ru–Ru bond lengths are 2.73 Å. All Ru–Rh bond lengths are 2.68 Å. Rh is bonded to six equivalent Ru and six equivalent Rh atoms to form RhRu6Rh6 cuboctahedra that share corners with eighteen equivalent RhRu6Rh6 cuboctahedra, edges with six equivalent RhRu6Rh6 cuboctahedra, edges with twelve equivalent RuRu6Rh6 cuboctahedra, faces with eight equivalent RhRu6Rh6 cuboctahedra, and faces with twelve equivalent RuRu6Rh6 cuboctahedra. All Rh–Rh bond lengths are 2.73 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ni4Ru by Materials Project

RuNi4 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ru is bonded to six equivalent Ru and six equivalent Ni atoms to form RuNi6Ru6 cuboctahedra that share corners with six equivalent RuNi6Ru6 cuboctahedra, corners with six NiNi12 cuboctahedra, edges with six equivalent RuNi6Ru6 cuboctahedra, edges with eighteen NiNi9Ru3 cuboctahedra, faces with six equivalent RuNi6Ru6 cuboctahedra, and faces with twelve equivalent NiNi9Ru3 cuboctahedra. All Ru–Ru bond lengths are 2.56 Å. All Ru–Ni bond lengths are 2.55 Å. There are five inequivalent Ni sites. In the first Ni site, Ni is bonded to three equivalent Ru and nine Ni atoms to form NiNi9Ru3 cuboctahedra that share corners with twelve NiNi9Ru3 cuboctahedra, edges with six equivalent RuNi6Ru6 cuboctahedra, edges with eighteen NiNi9Ru3 cuboctahedra, faces with six equivalent RuNi6Ru6 cuboctahedra, and faces with twelve NiNi9Ru3 cuboctahedra. There are three shorter (2.48 Å) and six longer (2.56 Å) Ni–Ni bond lengths. In the second Ni site, Ni is bonded to twelve Ni atoms to form NiNi12 cuboctahedra that share corners with three equivalent RuNi6Ru6 cuboctahedra, corners with nine NiNi9Ru3 cuboctahedra, edges with three equivalent RuNi6Ru6 cuboctahedra, edges with twenty-one NiNi9Ru3 cuboctahedra, and faces with eighteen NiNi9Ru3 cuboctahedra. There are three shorter (2.48 Å) and six longer (2.56 Å) Ni–Ni bond lengths. In the third Ni site, Ni is bonded to twelve Ni atoms to form NiNi12 cuboctahedra that share corners with three equivalent RuNi6Ru6 cuboctahedra, corners with nine NiNi9Ru3 cuboctahedra, edges with three equivalent RuNi6Ru6 cuboctahedra, edges with twenty-one NiNi9Ru3 cuboctahedra, and faces with eighteen NiNi9Ru3 cuboctahedra. There are three shorter (2.48 Å) and six longer (2.56 Å) Ni–Ni bond lengths. In the fourth Ni site, Ni is bonded to twelve Ni atoms to form NiNi12 cuboctahedra that share corners with three equivalent RuNi6Ru6 cuboctahedra, corners with nine NiNi9Ru3 cuboctahedra, edges with three equivalent RuNi6Ru6 cuboctahedra, edges with twenty-one NiNi9Ru3 cuboctahedra, and faces with eighteen NiNi9Ru3 cuboctahedra. There are six shorter (2.48 Å) and six longer (2.56 Å) Ni–Ni bond lengths. In the fifth Ni site, Ni is bonded to twelve Ni atoms to form NiNi12 cuboctahedra that share corners with three equivalent RuNi6Ru6 cuboctahedra, corners with nine NiNi9Ru3 cuboctahedra, edges with three equivalent RuNi6Ru6 cuboctahedra, edges with twenty-one NiNi9Ru3 cuboctahedra, and faces with eighteen NiNi9Ru3 cuboctahedra. There are three shorter (2.48 Å) and six longer (2.56 Å) Ni–Ni bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeRu by Materials Project

FeRu crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Ru is bonded to six equivalent Ru and six equivalent Fe atoms to form distorted RuFe6Ru6 cuboctahedra that share corners with eighteen equivalent RuFe6Ru6 cuboctahedra, edges with six equivalent RuFe6Ru6 cuboctahedra, edges with twelve equivalent FeFe6Ru6 cuboctahedra, faces with eight equivalent RuFe6Ru6 cuboctahedra, and faces with twelve equivalent FeFe6Ru6 cuboctahedra. All Ru–Ru bond lengths are 2.64 Å. All Ru–Fe bond lengths are 2.54 Å. Fe is bonded to six equivalent Ru and six equivalent Fe atoms to form distorted FeFe6Ru6 cuboctahedra that share corners with eighteen equivalent FeFe6Ru6 cuboctahedra, edges with six equivalent FeFe6Ru6 cuboctahedra, edges with twelve equivalent RuFe6Ru6 cuboctahedra, faces with eight equivalent FeFe6Ru6 cuboctahedra, and faces with twelve equivalent RuFe6Ru6 cuboctahedra. All Fe–Fe bond lengths are 2.64 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Activity and selectivity for CO 2 methanation of clusters and nanoplates of ruthenium dispersed on ceria: In-situ studies with XAFS and DRIFTS

The performance of Ru/CeO 2 catalysts under CO 2 hydrogenation conditions was studied using in situ X-ray absorption fine structure (XAFS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to understand the structural evolution and chemical nature of each component under reaction conditions. The catalysts were prepared using a reverse microemulsion method that maximized the dispersion of RuOx particles on ceria. A RuO x → Ru transformation was observed upon exposure of the RuO x /CeO 2 systems to H 2 at 250 °C. For a sample with 5% molar Ru, two-dimensional clusters (2-4 atoms) of Ru formed on top of the ceria support. An increase in the loading of ruthenium to 20% molar led to the formation of nanoplates of the metal 2-3 atomic layers thick. Both Ru structures were highly dispersed on ceria. They were oxidized after exposure to CO 2 at 250 °C. However, under CO 2 /H 2 mixture, they remained in a metallic state as two-dimensional clusters and nanoplates. In situ DRIFTS studies, the 5% and 20% Ru/CeO 2 catalysts showed distinct reaction intermediates when exposed to CO 2 or CO 2 /H 2 (1/4) reaction mixtures. Normalized to the Ru molar percentage, the 5% Ru/CeO 2 system was the most active catalyst exhibiting a selectivity of ~ 60% CH 4 and 40% CO at 250 °C. On the other hand, under the same reaction conditions, the 20% Ru/CeO 2 system was less active but had a CH 4 selectivity close to 80%. In conclusion, these results highlight the importance of the structure of the metallic Ru particles as a factor that determines the catalytic performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Support size regulated ruthenium-sulfoacid-nitrogen sites intensify cellulose hydrogenolysis to 1,2-propylene glycol

Rational design of metal-acid-base multifunctional catalysts for upgrading cellulose to 1,2-propylene glycol (1,2-PG) is of great significance for building a sustainable world. However, it is time-consuming and tedious to regulate metal-acid-base sites to balance major reactions to render a high 1,2-PG yield. We herein report support size simultaneously regulated ruthenium-sulfoacid-nitrogen (Ru–SO 3 H–N) sites for cellulose hydrogenolysis to high yield 1,2-PG. Originated from the depolymerization and reassembly of zinc-1,3,5-benzenetricarboxylic acid (ZnBTC) fiber with zeolitic imidazolate framework (ZIF-8) in water, 2-methylimidazole infiltrated nanorod (ZnBTC(mIM)) with a varied aspect ratio was fabricated by varying the feed ratio of ZIF-8/ZnBTC. Upon being pyrolyzed, sulfonated and impregnated with Ru ions, the supported sites were tailored in terms of Ru single-atom/nanocluster ratio, SO 3 H acidity and N basicity. Further, the elaborately fabricated catalyst delivers 32.3% yield of 1,2-PG, corresponding to a high productivity of 67.71 mol h -1 g Ru -1 and a large turnover number of 34193, two and three orders of magnitude higher than those by using other Ru-containing catalytic systems for cellulose hydrogenolysis. The excellent performance can be attributed to optimized electronic and molecular structure of Ru–SO 3 H–N sites that can improve rate-determining cellulose hydrolysis/fructose hydrogenolysis, pivotal glucose isomerization with others to proceed at a matched rate. This study opens a new avenue to facilely tailor the metal-acid-base sites by rational design of size controlled supporting matrix.

1,2-Propylene glycol↗
DOE OSTI2024

Reductive Dynamic and Static Excited State Quenching of a Homoleptic Ruthenium Complex Bearing Aldehyde Groups

A new homoleptic Ru polypyridyl complex bearing two aldehyde groups on each bipyridine ligand, [Ru(dab) 3 ](PF 6 ) 2 , where dab is 4,4′-dicarbaldehyde-2,2′-bipyridine, was synthesized, characterized, and utilized for iodide photo-oxidation studies. In acetonitrile (CH 3 CN) solution, the complex displayed an intense metal-to-ligand charge transfer (MLCT) absorbance maximum at 475 nm (ε = 22,000 M –1 cm –1 ) and an infrared (IR) band at 1712 cm –1 assigned to the pendent aldehyde groups. Visible light excitation in air-saturated solution resulted in room temperature photoluminescence (PL) with a maximum at 675 nm, a quantum yield, ϕ PL = 0.048, and an excited state lifetime, τ ο = 440 ns, from which radiative and nonradiative relaxation rate constants were extracted, k r = 9.1 × 10 4 s –1 and knr = 1.8 × 10 6 s –1 . Pulsed visible light excitation yielded transient UV–vis and IR absorption spectra consistent with an MLCT excited state; relaxation occurred with the maintenance of two isosbestic points in the visible region, and a lifetime that agreed with that measured by time-resolved PL. Cyclic voltammetry studies in a CH 3 CN solution with 0.1 M TBAPF 6 electrolyte revealed a quasi-reversible oxidation, E°(Ru III/II ) = +1.25 V vs. Fc +/0 , and three sequential one-electron reductions at −1.10, −1.25, and −1.54 V vs. Fc +/0 . Here, an excited state reduction potential of E°(Ru *2+/+ ) = +0.89 V vs. Fc +/0 was estimated with the Rehm–Weller expression. Titration of tetrabutylammonium iodide, TBAI, into a CD 3 CN solution of [Ru(dab) 3 ](PF 6 ) 2 resulted in significant shifts in the aldehyde H atom and 3,3′-biypridyl resonances that were analyzed with a 1:1 equilibrium model, from which K eq = 460 M –1 was extracted, increasing to 5800 M –1 when the solvent was changed to acetone-d 6 . Iodide titrations resulted in a significant quenching of the [Ru(dab) 3 ] *2+ lifetime and quantum yield in both CH 3 CN and acetone solvents. In CH 3 CN, the quenching was mainly dynamic and well described by the Stern–Volmer model, from which a quenching rate constant, k q , of 4.5 × 10 10 M –1 s –1 and an equilibrium constant, K eq , of 8.3 × 10 3 M –1 were obtained. In acetone, the static quenching pathway by iodide was greatly enhanced, with a K eq of 1.2 × 10 4 M –1 and a higher k q of 9.2 × 10 10 M –1 s –1 .

Aldehydes↗
DOE OSTI2020

Air-Stable Calcium Cyanamide-Supported Ruthenium Catalyst for Ammonia Synthesis and Decomposition

Efficient ammonia synthesis and decomposition processes under mild conditions are important to meet the expanding demand in major applications of ammonia as the energy carrier and to provide feedstock for chemical industry. In this study, we report that air-stable calcium cyanamide-supported ruthenium (Ru/CaCN 2 ) works as an efficient and stable catalyst for ammonia synthesis and decomposition. Ru/CaCN 2 exhibits greater catalytic performances for both reactions than Ru/Ca 2 N electride and Ru–Cs/MgO. The kinetic analysis for ammonia synthesis suggests that Ru/CaCN 2 exhibits low apparent activation energy and high resistance to hydrogen poisoning, which has characteristics similar to the kinetic parameters of Ru-supported electride catalyst. H 2 -temperature programmed reaction and temperature programmed desorption revealed that Ru promoted the formation of CN 2 vacancies on the CaCN 2 surface which in turn capture hydrogen as H – ions during the reaction. Density functional theory calculations provide insights into how the formation of CN 2 vacancies is promoted by Ru, which leads to the decrease in the work function of the CaCN 2 surface and the hydrogen capture at the Ru-support interface. These results suggest that the high catalytic performance of Ru/CaCN 2 can be attributed to the formation of a quasi-electride structure at the Ru–CaCN 2 interface.

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

Unusual Magnetic Hysteresis and Transition between Vortex and Double Pole States Arising from Interlayer Coupling in Diamond-Shaped Nanostructures

Controlling the magnetic ground states at the nanoscale is a long-standing basic research problem and an important issue in magnetic storage technologies. Here, we designed a nanostructured material that exhibits very unusual hysteresis loops due to a transition between vortex and double pole states. Arrays of 700 nm diamond-shaped nanodots consisting of Py(30 nm)/Ru(t Ru )/Py(30 nm) (Py, permalloy (Ni 80 Fe 20 )) trilayers were fabricated by interference lithography and e-beam evaporation. We show that varying the Ru interlayer spacer thickness (t Ru ) governs the interaction between the Py layers. We found this interaction mainly mediated by two mechanisms: magnetostatic interaction that favors antiparallel (antiferromagnetic, AFM) alignment of the Py layers and exchange interaction that oscillates between ferromagnetic (FM) and AFM couplings. For a certain range of Ru thicknesses, FM coupling dominates and forms magnetic vortices in the upper and lower Py layers. For Ru thicknesses at which AFM coupling dominates, the magnetic state in remanence is a double pole structure. Our results showed that the interlayer exchange coupling interaction remains finite even at 4 nm Ru thickness. Furthermore, the magnetic states in remanence, observed by magnetic force microscopy (MFM), are in good agreement with corresponding hysteresis loops obtained by the magneto-optic Kerr effect (MOKE) and micromagnetic simulations.

interlayer exchange interaction↗
DOE OSTI2020

Excited Carrier Dynamics in a Dye-Sensitized Niobate Nanosheet Photocatalyst for Visible-Light Hydrogen Evolution

Dye-sensitized photocatalysts that consist of a light-absorbing dye and a wide gap oxide semiconductor have been studied extensively as components of solar energy conversion systems. Although surface modification by a metal and/or metal oxide has a significant impact on the photocatalytic efficiency, the mechanism by which these modifications increase the activity has not been fully understood. Here a dye-sensitized H 2 evolution system was constructed by using Pt-intercalated HCa 2 Nb 3 O 10 nanosheets, Ru(II) complex photosensitizers ([Ru(4,4’-(CH 3 ) 2- bpy) 2 (4,4’-(PO 3 H 2 ) 2- bpy)] 2+ and [Ru(4,4’-(CH 3 ) 2- bpy) 2 (4,4’-(CH 2 PO 3 H 2 ) 2- bpy)] 2+ , abbreviated as RuP 2+ and RuCP 2+ ; bpy = 2,2'-bipyridine), and amorphous Al 2 O 3 as building blocks. In the presence of iodide as the electron donor, the H 2 evolution rate from Pt/HCa 2 Nb 3 O 10 nanosheets sensitized by RuP 2+ was increased by modification of the nanosheets with Al 2 O 3 . On the other hand, Al 2 O 3 had a negative impact on the H 2 evolution rate when RuCP 2+ was employed. These hybrid materials were studied by transient diffuse reflectance spectroscopy and steady-state emission spectroscopy. A detailed analysis of the transient absorption profiles of the adsorbed Ru(II) complexes revealed that there are at least three states of the complexes on the nanosheet surface. The transient bleaching of the ground state absorbance had different lifetime components ranging from a few μs to several hundred μs, which mainly reflect back electron transfer rates from HCa 2 Nb 3 O 10 to the oxidized Ru(II) complexes. Here, the Al 2 O 3 modifier could inhibit not only the back electron transfer events but also electron injection from the excited state photosensitizer. Interestingly, the negative effect of Al 2 O 3 on the electron injection rate was negligible in the case of RuP 2+ , which also had a higher H 2 evolution rate. This work highlights that suppressing fast back electron transfer from Pt/HCa 2 Nb 3 O 10 to the oxidized Ru(II) complex, which occurs on a time scale of a few μs, and maximizing the electron injection efficiency are both necessary for improving dye-sensitized H 2 evolution.

14 SOLAR ENERGY↗
DOE OSTI2025

Exploring Atomic-Scale Interactions at the Interface of Reducible Oxide and Ruthenium Nanocatalyst for Ammonia Decomposition

Restructuring atomic-scale interfaces between noble metal nanoparticles and metal oxides provides a promising approach to enhancing catalytic properties. In this study, Ru nanoparticles were supported on CeO 2 , ZrO 2 , and HfO 2 via pyrolysis of MOFs under oxygen-suppressed high-temperature conditions. Despite its nearly ideal particle size (∼2.3 nm), the Ru–CeO 2 /C catalyst exhibited the lowest ammonia decomposition activity. X-ray absorption spectroscopy and DFT calculations revealed that electron transfer from Ru to CeO 2 formed positively charged Ru and partially reduced Ce 4+ , weakening the catalytic performance. In contrast, oxygen-deficient ZrO 2 and HfO 2 support donated electrons to Ru, preserving its metallic state. These findings demonstrate that the reducibility of oxide supports governs the direction and magnitude of interfacial charge transfer, directly tuning catalytic behavior. This study provides insights into the design of oxide-supported Ru catalysts for ammonia decomposition.

Catalysts↗
DOE OSTI2025

Long-Range Metal–Sorbent Interactions Determine CO 2 Capture and Conversion in Dual-Function Materials

Carbon capture and utilization involve multiple energy- and cost-intensive steps. Dual-function materials (DFMs) can reduce these demands by coupling CO 2 adsorption and conversion into a single material with two functionalities: a sorbent phase and a metal for catalytic CO 2 conversion. The role of metal catalysts in the conversion process seems salient from previous work, but the underlying mechanisms remain elusive and deserve deeper investigation to achieve maximum utilization of the two phases. Here, for this work, preformed colloidal Ru nanoparticles were deposited onto a “NaOx”/Al 2 O 3 sorbent to prepare prototypical DFMs with controlled phases for CO 2 capture and hydrogenation to CH 4 . Ru addition was found to double the high-temperature CO 2 adsorption capacity by activating the “NaOx”/Al 2 O 3 sorbent phase during a reductive pretreatment step. Most importantly, low Ru loadings were sufficient to ensure maximum CO 2 adsorption and conversion. This was attributed to the key role of the metal–sorbent interactions, wherein Ru was required to hydrogenate strongly bound CO 2 on the “NaO x ”/Al 2 O 3 sorbent to CH 4 via the H 2 activated on Ru. This interaction facilitated rate-determining carbonate migration and subsequent hydrogenation at the metal–sorbent interface. Overall, Ru controlled the CO 2 hydrogenation reaction rate, while the “NaO x ”/Al 2 O 3 sorbent dictated the CO 2 uptake capacity. By controlling metal–sorbent interactions at the molecular level, we demonstrate the critical role of the two phases and their synergy, facilitating the design of DFMs with maximum CO 2 capture and conversion efficiency.

carbon capture↗