SEARCH · Search NASA

Results for “CE”

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

SourceResearch connectionFrom yearThrough year

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

At least 181 records · Page 10

All sources NASA NTRS DOE OSTI

DOE OSTI2020

Materials Data on Ce(PO3)4 by Materials Project

Ce(PO3)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are three inequivalent Ce4+ sites. In the first Ce4+ site, Ce4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.31–2.45 Å. In the second Ce4+ site, Ce4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.26–2.47 Å. In the third Ce4+ site, Ce4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.30–2.48 Å. There are eight inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. There are twenty-five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ce4+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ce4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ce4+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ce4+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ce4+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ce4+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ce4+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fourteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fifteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. In the sixteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. In the seventeenth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the eighteenth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the nineteenth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the twentieth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the twenty-first O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ce4+ and one P5+ atom. In the twenty-third O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a 1-coordinate geometry to one Ce4+ and one P5+ atom. In the twenty-fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ce4+ and one P5+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ce(N4O9)2 by Materials Project

Ce(NO3)6N2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four ammonia molecules and two Ce(NO3)6 clusters. In each Ce(NO3)6 cluster, Ce4+ is bonded in a cuboctahedral geometry to twelve O2- atoms. There are a spread of Ce–O bond distances ranging from 2.57–2.62 Å. There are three inequivalent N4+ sites. In the first N4+ site, N4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.23 Å) and two longer (1.28 Å) N–O bond length. In the second N4+ site, N4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.23 Å) and two longer (1.28 Å) N–O bond length. In the third N4+ site, N4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.24 Å) and two longer (1.27 Å) N–O bond length. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one N4+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one N4+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one N4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one N4+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one N4+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one N4+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one N4+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one N4+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to one Ce4+ and one N4+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ce(Ge3Pt)4 by Materials Project

Ce(PtGe3)4 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Ce is bonded to twelve equivalent Ge atoms to form CeGe12 cuboctahedra that share faces with eight equivalent PtGe6 octahedra. All Ce–Ge bond lengths are 3.36 Å. Pt is bonded to six equivalent Ge atoms to form PtGe6 octahedra that share corners with six equivalent PtGe6 octahedra and faces with two equivalent CeGe12 cuboctahedra. The corner-sharing octahedral tilt angles are 60°. All Pt–Ge bond lengths are 2.51 Å. Ge is bonded in a 2-coordinate geometry to one Ce, two equivalent Pt, and two equivalent Ge atoms. There are one shorter (2.55 Å) and one longer (2.64 Å) Ge–Ge bond lengths.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ce(PrS2)2 by Materials Project

Ce(PrS2)2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Pr is bonded to eight equivalent S atoms to form distorted PrS8 hexagonal bipyramids that share corners with four equivalent PrS8 hexagonal bipyramids, corners with four equivalent CeS8 hexagonal bipyramids, edges with four equivalent PrS8 hexagonal bipyramids, faces with four equivalent PrS8 hexagonal bipyramids, and faces with four equivalent CeS8 hexagonal bipyramids. There are a spread of Pr–S bond distances ranging from 2.92–3.10 Å. Ce is bonded to eight equivalent S atoms to form distorted CeS8 hexagonal bipyramids that share corners with eight equivalent PrS8 hexagonal bipyramids, edges with four equivalent CeS8 hexagonal bipyramids, and faces with eight equivalent PrS8 hexagonal bipyramids. There are four shorter (2.90 Å) and four longer (3.07 Å) Ce–S bond lengths. S is bonded to four equivalent Pr and two equivalent Ce atoms to form a mixture of distorted face, edge, and corner-sharing SCe2Pr4 octahedra. The corner-sharing octahedra tilt angles range from 16–51°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ce(Al10V)2 by Materials Project

CeV2Al20 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Ce is bonded in a 4-coordinate geometry to sixteen Al atoms. There are four shorter (3.15 Å) and twelve longer (3.21 Å) Ce–Al bond lengths. V is bonded to twelve Al atoms to form VAl12 cuboctahedra that share corners with six equivalent VAl12 cuboctahedra, edges with eighteen equivalent AlCeAl10V cuboctahedra, and faces with six equivalent AlCeAl10V cuboctahedra. There are six shorter (2.58 Å) and six longer (2.82 Å) V–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to two equivalent V and ten Al atoms. There are a spread of Al–Al bond distances ranging from 2.72–2.86 Å. In the second Al site, Al is bonded in a distorted linear geometry to two equivalent Ce and twelve equivalent Al atoms. All Al–Al bond lengths are 3.10 Å. In the third Al site, Al is bonded to one Ce, one V, and ten Al atoms to form distorted AlCeAl10V cuboctahedra that share corners with fifteen equivalent AlCeAl10V cuboctahedra, edges with two equivalent AlCeAl10V cuboctahedra, edges with three equivalent VAl12 cuboctahedra, a faceface with one VAl12 cuboctahedra, and faces with fifteen equivalent AlCeAl10V cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.71–2.93 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Suppressing CO formation in low-temperature methanol steam reforming via Ce-modified CuZnGa layered oxide catalysts

Cu-based layered double hydroxides (LDHs) are widely recognized as effective catalysts for low-temperature methanol steam reforming, yet achieving high hydrogen productivity together with near-complete suppression of CO formation remains challenging. Here, we report the synthesis and evaluation of a series of CuZnGa LDH-derived catalysts and Ce-modified analogues prepared via an aqueous miscible organic method, which enables high metal dispersion and precise structural control. The optimized CuZnGa catalyst exhibits a hydrogen production rate of 16.9 µmol H 2 ·g cat −1 ·s −1 at 180 °C with an H 2 /CO ratio exceeding 3500, outperforming many state-of-the-art low-temperature systems. Importantly, the incorporation of small amounts of Ce further suppresses CO formation while maintaining high hydrogen productivity. Combined spectroscopic characterization and density functional theory calculations reveal that Ce is incorporated into the LDH lattice by substituting Ga 3+ sites up to a critical threshold, beyond which highly dispersed CeO x species are formed. These species provide mobile lattice oxygen that participates in a Mars-van Krevelen-type pathway, selectively oxidizing CO and suppressing the reverse water-gas shift reaction. This study establishes a clear relationship between Ce speciation, oxygen mobility, and catalytic selectivity in LDH-derived systems. The resulting catalysts demonstrate the potential of interface-engineered Cu-based materials for efficient low-temperature hydrogen production with minimal CO contamination.

09 BIOMASS FUELS↗

DOE OSTI2022

Ce post-treatment for increased corrosion resistance of AA2024-T3 anodized in tartaric-sulfuric acid

Here, the effect of a post-treatment for short time in 50 mM Ce(NO 3 ) 3 solution, with or without H 2 O 2 , on the corrosion of AA2024-T3 anodized in tartaric-sulfuric acid was investigated. Electrochemical (EIS, polarization curves) and corrosion (immersion) tests showed improved performance for samples post-treated at 50 °C in the H 2 O 2 containing solution. Microstructural characterization (SEM, STEM, GDOES) evidenced the presence of Ce oxyhydroxides both at the surface and within the pores of the anodized layer, and their preferential interaction with defective sites both at micro and nanoscale. Important amounts of Ce-species were found near corrosion products, indicating active corrosion protection by Ce ions.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Strength mechanisms and tunability in Al-Ce-Mg ternary alloys enabled by additive manufacturing

Al-Ce-based alloys are promising candidates for additive manufacturing (AM) due to their hot-cracking resistance and because they do not require heat treatment to obtain precipitation strengthening. Rapid solidification rates enabled by AM methods can lead to enhanced mechanical properties; however, the strengthening mechanisms over large composition ranges were unclear. Here, combinatorial synthesis by directed-energy deposition (DED) and hardness measurements were used to rapidly map the composition-dependent strength of the ternary Al-Ce-Mg system. Tensile testing and microstructure characterization of selected compositions were performed to elucidate the compositional dependence of the strengthening mechanisms. Al 11 Ce 3 precipitates were present in all cases, and the maximum hardness (1.25 GPa) was measured for the Al-8Ce-10Mg composition. A combination of (i) Hall-Petch strengthening, based on the FCC-matrix-phase cell size; (ii) particle strengthening, based on Al 11 Ce 3 volume fraction and size; and (iii) solid-solution strengthening, based on Mg composition of the matrix phase, were used to account for the measured strengths. Vickers hardness is shown to correlate well with ultimate tensile strength in these alloys, highlighting the value of surface-based techniques for rapid screening.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Al-Ce Alloy-Based Compact Heat Exchanger for Refrigerant Charge Reduction and Unprecedented Durability (CRADA NFE-21-08888 Final Report)

Oak Ridge National Laboratory and Eck Industries produced and characterized durable and corrosion resistant Al-Ce-Mg alloy-based heat exchanger. Eck Industries successfully casted Al-Ce-Mg heat exchanger. ORNL characterized reaction bonding between Al-2Ce-6Mg alloy and stainless-steel tube in a heat exchanger header. Metallurgical bonds were achieved between stainless steel tubes and Al-Ce-Mg alloy cast headers. ORNL performed corrosion testing on Al-Ce-Mg alloy/stainless steel tube reactive bond interface. In most cases no significant changes to the reactive bond morphology or compositional distribution were observed in the samples after exposure to acid for 267h acid.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Additively-manufactured Al-0.3Zr-0.2Ce-0.2Cu alloy with high creep resistance and electrical conductivity

Here, a new, solute-lean Al-0.3Zr-0.2Ce-0.2Cu (wt.%) alloy is developed for additive manufacturing that overcomes the classical tradeoff between conductivity and creep resistance. The rapid-cooling-enabled supersaturation of Zr, and its uniform distribution in α-Al matrix, along with formation of submicron (Ce,Cu)-rich intermetallic particles on solidification lead to unusually high creep resistance at 200 °C. Near-zero secondary creep rates are achieved up to the alloy yield stress (YS) of 65 MPa at 200 °C in as-fabricated state. The Zr-solute-induced dislocation-climb suppression mechanism underlying this improvement also restricts dynamic recovery above YS, as noted from appreciable primary creep and its transitioning to near-zero secondary creep rates. A combination of relatively coarse, epitaxially-grown α-Al grains, low Zr concentration in α-Al, and the impurity-scavenging effect of Ce to purify α-Al matrix produces high electrical conductivity of ∼48 %IACS. Aging precipitation of L1 2 -Al 3 Zr nanoprecipitates doubles the YS (to ∼150 MPa) at room temperature and increases alloy conductivity to ∼58 %IACS, but loss of solid-solution Zr out of α-Al matrix leads to activation of dislocation climb, degrading the creep properties as compared to the supersaturated Al-Zr solid solution in the as-fabricated state. Compared to L1 2 -Al 3 Zr nanoprecipitates, submicron (Ce,Cu)-rich particles formed on solidification are more effective at impeding dislocation climb, producing a threshold stress for dislocation creep of ∼ 50 MPa at 200 °C. The new alloy design concepts, especially solute-induced dislocation-climb suppression for creep resistance, explored here may pave way for the design of new metallic alloys for thermal/electrical conductors and other high-temperature applications.

Additive Manufacturing↗

DOE OSTI2020

Structural, magnetic, and magnetocaloric properties of (Nd 0.7 Ce 0.3 )YFe 17

Structural, magnetic, and magnetocaloric properties of iron-deficient (Nd 1-x Ce x )YFe 17 alloys in the rhombohedral Th 2 Zn 17 –type crystal structure prepared by arc-melting and vacuum annealing have been investigated. Among the investigated alloys, (Nd 0.7 Ce 0.3 )YFe 17 shows the highest values of magnetic entropy change and relative cooling power, namely 5.45 J kg -1 K -1 and 504 J kg -1 for a magnetic field change of 5 T. The Curie temperature and saturation magnetization of the (Nd 0.7 Ce 0.3 )YFe 17 alloy are 301 K and 162 emu/g, respectively. The absence of thermal and magnetic hysteresis with relatively high cooling capacity near room temperature suggests that Fe-deficient (Nd 0.7 Ce 0.3 )YFe 17 carries significant potential for room-temperature magnetic refrigeration.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Evaluation of 134 Ce as a PET imaging surrogate for antibody drug conjugates incorporating 225 Ac

The in vivo generator 134 Ce/ 134 La has the potential to serve as a PET imaging surrogate for both alpha-emitting 225 Ac and 227 Th radionuclides due to the unique Ce III /Ce IV redox couple and the relatively long half-life of 134 Ce. Furthermore, the purpose of this study was to demonstrate the compatibility of 134 Ce with DOTA-based antibody drug conjugates, which would act as therapeutic agents when incorporating 225 Ac.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2026

Crystal Growth of Quaternary RE 2 EuSi 2 S 8 ( RE = Ce–Nd, Sm, Gd, Tb) Using Flux-Assisted Boron Chalcogen Mixture (BCM) Method: Investigation of Magnetic and Luminescence Properties

A series of quaternary rare-earth containing thiosilicates with the general formula RE 2 EuSi 2 S 8 (RE = Ce–Nd, Sm, Gd, Tb) has been synthesized via the flux-assisted boron chalcogen mixture (BCM) crystal growth method. High-quality single crystals were obtained, and their crystal structures were determined by single-crystal X-ray diffraction. The RE 2 EuSi 2 S 8 series crystallizes in the trigonal system, adopting the space group R-3c. Polycrystalline samples were employed for physical property measurements, including magnetic susceptibility measurements, UV–visible diffuse reflectance, and photoluminescent response. Magnetic data of RE 2 EuSi 2 S 8 ( RE = Ce, Nd, and Gd) were collected over the 2–300 K temperature range. The samples were paramagnetic behavior with negative Weiss constants (θ W = −11.05, −10.55, and −1.35 K respectively). Their thermal stability was investigated using thermogravimetric analysis (TGA). Optical band gaps, estimated from diffuse reflectance spectra, were determined to be 2.2(1) eV for Ce 2 EuSi 2 S 8 , 1.8(1) eV for Nd 2 EuSi 2 S 8 , and 1.7(1) eV for Gd 2 EuSi 2 S 8 respectively. Finally, photoluminescence measurements were collected on Ce 2 EuSi 2 S 8 and Tb 2 EuSi 2 S 8 single crystals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Role of CeNiSi 2 and BaNiSn 3 Structure Types in the Emergent Magnetism of the Homologous Series Ln n +1 M n X 3 n +1 :Ce 4 Fe 3 Ge 10

The synthesis and characterization of Ce 4 Fe 3 Ge 10 , n =3 member of the homologous series Ln n+1 M n X 3n+1 (Ln = lanthanides, M = transition metal, X = tetrel), is reported. The structure can be modelled with the Cmcm space group adopting the Eu 2 Ni 2-x Sn 5 structure type, with lattice parameters of a = 4.3323 (15) Å, b = 35.507 (9) Å, and c = 4.3069 (12) Å. Members of the series for n > 2 consist of stacking of ordered (CeNiSi 2 type) and disordered (BaNiSn 3 / AuCu 3 type) subunits with the acting as a “spacer” between CeNiSi 2 subunits. Although neither CeFeGe 3 nor CeFe 0.63 Ge 2 order magnetically down to 2 K, Ce 4 Fe 3 Ge 10 is an antiferromagnet below 3.6 K. To rationalize the emergent magnetism: (i) we established the Kondo and RKKY interaction dominant regions for the Ce analogues adopting the BaNiSn 3 and CeNiSi 2 by creating an electronic landscape for each, (ii) mapped the strained subunits, due to stacking, within the series. Here, we established the CeFeGe 3 subunit within Ce 4 Fe 3 Ge 10 contracts and is located within the Kondo-interaction dominant region, while the CeFe 0.63 Ge 2 subunit expands and is in the RKKY-interaction dominant region.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Single-Determinant Ground State in Ce 4+ Imidophosphorane Complexes

X-ray spectroscopy techniques are critical in the electronic structure analysis of high-valent lanthanides. The interpretation of multipeaked features at the lanthanide L 3 -edge has remained a challenging question, as it is observed across a range of material classes. A series of structurally related Ce 4+ complexes were prepared to probe the potential ligand field perturbation of the ground state within the series. The tuning of relative 4f and ligand orbital energies in homoleptic and heteroleptic tetravalent Ce imidophosphorane complexes is achieved through ligand derivatization and is clearly demonstrated by UV−vis spectroscopy and electrochemically measured redox potentials. However, Ce L 3 - edge high-energy resolution fluorescence-detected (HERFD) X-ray absorption near-edge structure (XANES) spectra present features at consistent numbers and energies across the range of complexes. Resonant inelastic X-ray scattering (RIXS) is employed to visualize the observed features in the HERFD-XANES spectra. Large complete active space configuration interaction singles and doubles (CASCISD) calculations demonstrate that the ground-state wave function of all complexes can be described employing a single determinant. As a result, the multielectron feature at the L 3 -edge observed in this study for the Ce 4+ imidophosphorane complexes is described as excited-state multiconfigurational behavior that is independent of ligand variation, in systems where the ground state is described using the simple single determinant wave function.

Lanthanides↗

DOE OSTI2020

Morphology and Transport of Multivalent Cation-Exchanged Ionomer Membranes Using Perfluorosulfonic Acid–Ce Z+ as a Model System

Perfluorosulfonic acids (PFSAs) are commonly used as solid polymer electrolyte membranes (PEMs) in electrochemical energy devices, where they are vulnerable to attack by radical species during operation. A popular strategy to combat this problem is to introduce radical scavengers like cerium (Ce) ions that neutralize these species before they attack the PFSA. Such cation doping creates a multi-ion system, in which understanding the mechanisms of cation solvation and transport becomes important for the effective design and utilization of PFSA–cation systems. Ce ions also provide a representative model system for multication-exchanged ionomers in electrochemical systems. In this study, hydration and conductivity measurements, along with X-ray fluorescence and scattering, are employed to elucidate how Ce ion exchange alters PFSA’s ionic solvation, as well as nano- and mesoscale morphologies, which ultimately control its ion transport properties. A molecular transport model is used to deconvolute the impact of Ce ions on the local solvation structure of water in the membrane from mesoscale changes of the transport pathways. The combined experimental and theoretical analysis reveals a nonlinear decrease in conductivity driven by cation solvation at the molecular level and morphological changes at longer length scales. Migration–diffusion coupling, its nonlinear dependence on ion exchange and hydration, and its overall implications for ionomer performance are also discussed. Finally, these findings have the potential to be translated into other mixed cation–ionomer systems for a wide range of energy and environmental devices.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Double-Site Substitution of Ce into (Ba, Sr)MnO 3 Perovskites for Solar Thermochemical Hydrogen Production

Solar thermochemical hydrogen production (STCH) is a renewable alternative to hydrogen production using fossil fuels. While serial bulk experimental methods can accurately measure STCH performance, screening chemically complex materials systems for new promising candidates is more challenging. Here we identify double-site Ce-substituted (Ba,Sr)MnO 3 oxide perovskites as promising STCH candidates using a combination of bulk synthesis and high-throughput thin-film experiments. The Ce substitution on the B-site in 10H-BaMnO 3 and on the A-site in -SrMnO 3 leads to 2–3 times higher hydrogen production compared to CeO 2 , but these bulk single-site substituted perovskites suffer from incomplete reoxidation. Double-site Ce substitution on both A- and B-sites in (Ba,Sr)MnO 3 thin films increases Ce solubility and extends the stability of 10H and 3C structures, which is promising for their thermochemical reversibility. This study demonstrates a high-throughput experimental method for screening complex oxide materials for STCH applications.

08 HYDROGEN↗

DOE OSTI2024

A Ce-CuZn catalyst with abundant Cu/Zn-OV-Ce active sites for CO 2 hydrogenation to methanol

CO 2 hydrogenation to chemicals and fuels is a significant approach for achieving carbon neutrality. It is essential to rationally design the chemical structure and catalytic active sites towards the development of efficient catalysts. Here we show a Ce-CuZn catalyst with enriched Cu/Zn-OV-Ce active sites fabricated through the atomic-level substitution of Cu and Zn into Ce-MOF precursor. The Ce-CuZn catalyst exhibits a high methanol selectivity of 71.1% and a space-time yield of methanol up to 400.3 g·kg cat -1 ·h -1 with excellent stability for 170 h at 260°C, comparable to that of the state-of-the-art CuZnAl catalysts. Controlled experiments and DFT calculations confirm that the incorporation of Cu and Zn into CeO 2 with abundant oxygen vacancies can facilitate H 2 dissociation energetically and thus improve CO 2 hydrogenation over the Ce-CuZn catalyst via formate intermediates. This work offers an atomic-level design strategy for constructing efficient multi-metal catalysts for methanol synthesis through precise control of active sites.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗