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At least 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Cu3Pd2 by Materials Project

Pd2Cu3 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a distorted body-centered cubic geometry to nine Cu atoms. There are eight shorter (2.62 Å) and one longer (2.89 Å) Pd–Cu bond lengths. In the second Pd site, Pd is bonded in a body-centered cubic geometry to eight Cu atoms. All Pd–Cu bond lengths are 2.59 Å. There are four inequivalent Cu sites. In the first Cu site, Cu is bonded in a 8-coordinate geometry to four equivalent Pd and four equivalent Cu atoms. All Cu–Cu bond lengths are 2.50 Å. In the second Cu site, Cu is bonded in a body-centered cubic geometry to eight Pd atoms. In the third Cu site, Cu is bonded in a body-centered cubic geometry to eight equivalent Pd atoms. In the fourth Cu site, Cu is bonded in a 10-coordinate geometry to two equivalent Pd and eight equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Efficient Screening of Bi–Metallic Electrocatalysts for Glycerol Valorization

Glycerol is a byproduct of biodiesel production and, as such, it is of limited economic value. By means of electrooxidation, glycerol can be used as a feedstock for scalable hydrogen production, in addition to conversion to value-added products. The development of novel and efficient catalytic electrode materials for the anodic side of the reaction is a key towards a hydrogen-based energy economy. In the present study, a computational screening protocol combining DFT, scaling relations, and microkinetic modeling allows for a rational selection of novel catalysts that can deliver efficient glycerol electrooxidation, low cost of production, and environmental sustainability. Activity and chemical selectivity towards hydrogen production on pure metal catalysts is discussed in terms of volcano-shaped plots. We find that the selectivity in the glycerol oxidation reaction is influenced by a different energy landscape when in the presence of water and best classified by a comparison of O—H and C—H bond-breaking barriers. In addition, we screened 3570 bi-metallic catalysts in the AB (L1 0 ) and A 3 B (L1 2 ) ordered structures for activity, stability, price, and toxicity. By filtering based on the criteria for toxicity, resistance to oxidation, miscibility, and price, we have identified 5 L1 0 structured catalysts (AgPd, AuPd, PtSb, CuPt, and AgPt) and 20 L1 2 catalysts (Ga 3 Ta, In 3 Ta, Ir 3 W, Ir 3 Mo, Cu 3 Pt, Ir 3 Ta, Ir 3 Re, Pd 3 Bi, Pd 3 Cu, Pd 3 W, Pd 3 Co, Pd 3 Sn, Pd 3 Mo, Pd 3 Ag, Pd 3 Ga, Pd 3 Ta, Au 3 Ru, Pd 3 In, Au 3 Ir, and Pd 3 Au) that are all predicted to show high activity. We also identify an additional 37 L1 0 and 92 L1 2 structured electrocatalysts with an anticipated medium-high activity.

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

AuPd Nanoicosahedra: Atomic-Level Surface Modulation for Optimization of Electrocatalytic and Photocatalytic Energy Conversion

Modulation of bimetallic nanocatalysts with atomic precision would allow for significant increases in catalyst activity through the optimization of heteroatomic interplay. In practice, this level of control over homogeneously turning the heteroatomic states in the surface regions of catalysts remains a great challenge for practical applications requiring mass production. In this work, a one-step aqueous strategy for preparation of AuPd nanoicosahedra core–shell structures has been developed. By turning the molar ratio of Au and Pd precursors, the nanoicosahedra could be made with uniform core composition (Pd ~20%) and largely flexible surface compositions (Pd: 20–70%). Under model reactions of electrochemical ethanol oxidation (EOR) and 4-nitrophenol (4-NP) reduction, the Au 55 Pd 45 surface displayed superior activities. Here, x-ray absorption spectroscopy revealed that AuPd nanoicosahedra with Pd-poor surfaces (Au 79 Pd 21 and Au 60 Pd 40 ) maintain Au-like electronic structures while those with Pd-rich surfaces are more Pd-like. The Au 55 Pd 45 surface struck a delicate balance between the two extremes, leading to the optimal Au–Pd interplay for catalytic performance. Overall, the development of a one-step aqueous strategy for atomic-level control over bimetallic nanoparticle surface states is an important milestone for future advances in catalysis. Our findings in atomic-scale catalyst design will bring deep insights into the fields of nanosynthesis and heterogeneous catalysis, which will be beneficial for further scientific breakthroughs.

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

Palladium at high pressure and high temperature: A combined experimental and theoretical study

Palladium is one of the most important technological materials, yet its phase diagram remains poorly understood. At ambient conditions, its solid phase is face-centered cubic (fcc). However, another solid phase of Pd, body-centered cubic (bcc), was very recently predicted in two independent theoretical studies to occur at high pressures and temperatures. In this work, we report an experimental study on the room-temperature equation of state (EOS) of Pd to a pressure of 80 GPa, as well as a theoretical study on the phase diagram of Pd including both fcc-Pd and bcc-Pd. Our theoretical approach consists in ab initio quantum molecular dynamics (QMD) simulations based on the Z methodology which combines both direct Z method for the simulation of melting curves and inverse Z method for the calculation of solid–solid phase transition boundaries. We obtain the melting curves of both fcc-Pd and bcc-Pd and an equation for the fcc–bcc solid–solid phase transition boundary as well as the thermal EOS of Pd which is in agreement with experimental data and QMD simulations. We uncover the presence of another solid phase of Pd on its phase diagram, namely, random hexagonal close-packed (rhcp), and estimate the location of the rhcp-bcc solid–solid phase transition boundary and the rhcp–fcc–bcc triple point. We also discuss the topological similarity of the phase diagrams of palladium and silver, the neighbor of Pd in the periodic table. We argue that Pd is a reliable standard for shock-compression studies and present the analytic model of its principal Hugoniot in a wide pressure range.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Palladium at high pressure and high temperature: A combined experimental and theoretical study

Palladium is one of the most important technological materials, yet its phase diagram remains poorly understood. At ambient conditions, its solid phase is face-centered cubic (fcc). However, another solid phase of Pd, body-centered cubic (bcc), was very recently predicted in two independent theoretical studies to occur at high pressures and temperatures. In this work, we report an experimental study on the room-temperature equation of state (EOS) of Pd to a pressure of 80 GPa, as well as a theoretical study on the phase diagram of Pd including both fcc-Pd and bcc-Pd. Our theoretical approach consists in ab initio quantum molecular dynamics (QMD) simulations based on the Z methodology which combines both direct Z method for the simulation of melting curves and inverse Z method for the calculation of solid–solid phase transition boundaries. We obtain the melting curves of both fcc-Pd and bcc-Pd and an equation for the fcc–bcc solid– solid phase transition boundary as well as the thermal EOS of Pd which is in agreement with experimental data and QMD simulations. We uncover the presence of another solid phase of Pd on its phase diagram, namely, random hexagonal close-packed (rhcp), and estimate the location of the rhcp-bcc solid–solid phase transition boundary and the rhcp–fcc–bcc triple point. We also discuss the topological similarity of the phase diagrams of palladium and silver, the neighbor of Pd in the periodic table. We argue that Pd is a reliable standard for shock-compression studies and present the analytic model of its principal Hugoniot in a wide pressure range.

36 MATERIALS SCIENCE↗
NASA NTRS1985

The interaction of small metal particles with refractory oxide supports

Islands and continuous layers of Pd were grown in UHV on Mo and MoO subtrates. As-deposited Pd islands and layers exhibited bulk Pd adsorption properties for CO when the Pd had been deposited at RT and at thicknesses exceeding 3 ML. However, CO adsorption was drastically reduced upon annealing. This deactivation was interpreted in terms of substrate/support interaction involving the diffusion of substrate species toward the Pd surface, using AES, TPD, and work function measurement techniques. A study of the growth and annealing behavior of Pd on Mo(110) was made for thicknesses up to 12 monolayers and substrate temperatures up to 1300K, using AES, XPS, LEED, and work function measurements. At low tempertures Pd formed a monolayer without alloying. In thick layers (12 ML) annealed about 700 K, Mo diffusion into the Pd layer and alloying were noted. Such layers remained continuous up to 1100 K. Thinner Pd layers were less stable and started coalescing upon annealing to as little as 550 K. Significant changes in Pd Auger peak shape, as well as shifts of Pd core levels, were observed during layer growth and annealing.

Park, C.↗
DOE OSTI2020

Materials Data on DyTlPd by Materials Project

DyPdTl crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Dy is bonded in a 11-coordinate geometry to five Pd and six equivalent Tl atoms. There are four shorter (3.06 Å) and one longer (3.16 Å) Dy–Pd bond lengths. There are two shorter (3.22 Å) and four longer (3.37 Å) Dy–Tl bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Dy and six equivalent Tl atoms. All Pd–Tl bond lengths are 2.84 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Dy and three equivalent Tl atoms. All Pd–Tl bond lengths are 2.92 Å. Tl is bonded in a 10-coordinate geometry to six equivalent Dy and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YTlPd by Materials Project

YPdTl crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Y is bonded in a 11-coordinate geometry to five Pd and six equivalent Tl atoms. There are four shorter (3.07 Å) and one longer (3.17 Å) Y–Pd bond lengths. There are two shorter (3.23 Å) and four longer (3.38 Å) Y–Tl bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Y and three equivalent Tl atoms. All Pd–Tl bond lengths are 2.92 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Y and six equivalent Tl atoms. All Pd–Tl bond lengths are 2.84 Å. Tl is bonded in a 10-coordinate geometry to six equivalent Y and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbTlPd by Materials Project

YbPdTl crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Yb is bonded in a 11-coordinate geometry to five Pd and six equivalent Tl atoms. All Yb–Pd bond lengths are 3.10 Å. There are two shorter (3.27 Å) and four longer (3.39 Å) Yb–Tl bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Yb and six equivalent Tl atoms. All Pd–Tl bond lengths are 2.88 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Yb and three equivalent Tl atoms. All Pd–Tl bond lengths are 2.88 Å. Tl is bonded in a 10-coordinate geometry to six equivalent Yb and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlAsPd5 by Materials Project

Pd5TlAs crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a distorted square co-planar geometry to four equivalent Tl atoms. All Pd–Tl bond lengths are 2.89 Å. In the second Pd site, Pd is bonded in a 4-coordinate geometry to two equivalent Tl and two equivalent As atoms. Both Pd–Tl bond lengths are 2.93 Å. Both Pd–As bond lengths are 2.52 Å. Tl is bonded to twelve Pd atoms to form a mixture of corner and face-sharing TlPd12 cuboctahedra. As is bonded in a body-centered cubic geometry to eight equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaSnPd by Materials Project

LaPdSn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. La is bonded in a 11-coordinate geometry to five Pd and six equivalent Sn atoms. There are four shorter (3.15 Å) and one longer (3.21 Å) La–Pd bond lengths. There are two shorter (3.36 Å) and four longer (3.50 Å) La–Sn bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent La and three equivalent Sn atoms. All Pd–Sn bond lengths are 2.97 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent La and six equivalent Sn atoms. All Pd–Sn bond lengths are 2.85 Å. Sn is bonded in a 12-coordinate geometry to six equivalent La and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrZnPd by Materials Project

PrPdZn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Pr is bonded in a 11-coordinate geometry to five Pd and six equivalent Zn atoms. There are four shorter (3.03 Å) and one longer (3.06 Å) Pr–Pd bond lengths. There are two shorter (3.30 Å) and four longer (3.34 Å) Pr–Zn bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Pr and six equivalent Zn atoms. All Pd–Zn bond lengths are 2.71 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Pr and three equivalent Zn atoms. All Pd–Zn bond lengths are 2.90 Å. Zn is bonded in a 4-coordinate geometry to six equivalent Pr and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YAlPd by Materials Project

YPdAl crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Y is bonded in a 5-coordinate geometry to five Pd and six equivalent Al atoms. There are four shorter (2.97 Å) and one longer (2.98 Å) Y–Pd bond lengths. There are two shorter (3.22 Å) and four longer (3.30 Å) Y–Al bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Y and three equivalent Al atoms. All Pd–Al bond lengths are 2.80 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Y and six equivalent Al atoms. All Pd–Al bond lengths are 2.66 Å. Al is bonded in a 4-coordinate geometry to six equivalent Y and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeZnPd by Materials Project

CePdZn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to five Pd and six equivalent Zn atoms. There are four shorter (2.99 Å) and one longer (3.02 Å) Ce–Pd bond lengths. There are two shorter (3.23 Å) and four longer (3.30 Å) Ce–Zn bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent Zn atoms. All Pd–Zn bond lengths are 2.68 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent Zn atoms. All Pd–Zn bond lengths are 2.84 Å. Zn is bonded in a 4-coordinate geometry to six equivalent Ce and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ScSnPd by Materials Project

ScPdSn crystallizes in the hexagonal P-62c space group. The structure is three-dimensional. Sc is bonded in a 11-coordinate geometry to five Pd and six equivalent Sn atoms. There are a spread of Sc–Pd bond distances ranging from 2.88–3.03 Å. There are a spread of Sc–Sn bond distances ranging from 3.09–3.26 Å. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Sc and six equivalent Sn atoms. All Pd–Sn bond lengths are 2.75 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Sc and three equivalent Sn atoms. All Pd–Sn bond lengths are 2.77 Å. Sn is bonded in a 10-coordinate geometry to six equivalent Sc and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeSnPd by Materials Project

CePdSn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to five Pd and six equivalent Sn atoms. There are four shorter (3.11 Å) and one longer (3.15 Å) Ce–Pd bond lengths. There are two shorter (3.30 Å) and four longer (3.45 Å) Ce–Sn bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent Sn atoms. All Pd–Sn bond lengths are 2.90 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent Sn atoms. All Pd–Sn bond lengths are 2.84 Å. Sn is bonded in a 10-coordinate geometry to six equivalent Ce and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdAlPd by Materials Project

GdPdAl crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Gd is bonded in a 5-coordinate geometry to five Pd and six equivalent Al atoms. All Gd–Pd bond lengths are 2.99 Å. There are two shorter (3.24 Å) and four longer (3.33 Å) Gd–Al bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Gd and six equivalent Al atoms. All Pd–Al bond lengths are 2.67 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Gd and three equivalent Al atoms. All Pd–Al bond lengths are 2.81 Å. Al is bonded in a 4-coordinate geometry to six equivalent Gd and four Pd atoms.

36 MATERIALS SCIENCE↗