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At least 253 records · Page 14
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DOE OSTI2020

Materials Data on Ag6Ge2O7 by Materials Project

Ag6Ge2O7 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are twelve inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to three O2- atoms. There are two shorter (2.16 Å) and one longer (2.82 Å) Ag–O bond lengths. In the second Ag1+ site, Ag1+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.20–2.60 Å. In the third Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.33–2.97 Å. In the fourth Ag1+ site, Ag1+ is bonded in a distorted linear geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.19–3.00 Å. In the fifth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.37–2.82 Å. In the sixth Ag1+ site, Ag1+ is bonded to four O2- atoms to form distorted AgO4 trigonal pyramids that share corners with five GeO4 tetrahedra. There are a spread of Ag–O bond distances ranging from 2.27–2.67 Å. In the seventh Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.22–2.82 Å. In the eighth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.32–2.90 Å. In the ninth Ag1+ site, Ag1+ is bonded in a distorted see-saw-like geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.25–2.67 Å. In the tenth Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.18–2.86 Å. In the eleventh Ag1+ site, Ag1+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.17–2.48 Å. In the twelfth Ag1+ site, Ag1+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.18–2.61 Å. There are four inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one GeO4 tetrahedra and corners with three equivalent AgO4 trigonal pyramids. There are a spread of Ge–O bond distances ranging from 1.76–1.82 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one GeO4 tetrahedra and corners with two equivalent AgO4 trigonal pyramids. There are a spread of Ge–O bond distances ranging from 1.76–1.80 Å. In the third Ge4+ site, Ge4+ is bonded to four O2- atoms to form corner-sharing GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.76–1.82 Å. In the fourth Ge4+ site, Ge4+ is bonded to four O2- atoms to form corner-sharing GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.76–1.81 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to four Ag1+ and one Ge4+ atom. In the second O2- site, O2- is bonded to three Ag1+ and one Ge4+ atom to form distorted corner-sharing OAg3Ge tetrahedra. In the third O2- site, O2- is bonded in a 5-coordinate geometry to four Ag1+ and one Ge4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ag1+ and two Ge4+ atoms. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to four Ag1+ and one Ge4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Ge4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Ge4+ atom. In the eighth O2- site, O2- is bonded to three Ag1+ and one Ge4+ atom to form distorted corner-sharing OAg3Ge tetrahedra. In the ninth O2- site, O2- is bonded to three Ag1+ and one Ge4+ atom to form distorted corner-sharing OAg3Ge tetrahedra. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to four Ag1+ and one Ge4+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ag1+ and two Ge4+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Ge4+ atom. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to four Ag1+ and one Ge4+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to four Ag1+ and one Ge4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(Ag2Sb)2 by Materials Project

EuAg4Sb2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Eu2+ is bonded to six equivalent Sb3- atoms to form edge-sharing EuSb6 octahedra. All Eu–Sb bond lengths are 3.31 Å. There are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 1-coordinate geometry to six Ag1+ and four equivalent Sb3- atoms. There are three shorter (2.95 Å) and three longer (3.02 Å) Ag–Ag bond lengths. There are one shorter (2.88 Å) and three longer (3.23 Å) Ag–Sb bond lengths. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent Ag1+ and three equivalent Sb3- atoms. All Ag–Sb bond lengths are 2.84 Å. Sb3- is bonded in a 10-coordinate geometry to three equivalent Eu2+ and seven Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(Ag2Sb)2 by Materials Project

SrAg4Sb2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Sr2+ is bonded to six equivalent Sb3- atoms to form edge-sharing SrSb6 octahedra. All Sr–Sb bond lengths are 3.44 Å. There are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 1-coordinate geometry to six Ag1+ and four equivalent Sb3- atoms. There are three shorter (2.97 Å) and three longer (3.05 Å) Ag–Ag bond lengths. There are one shorter (2.86 Å) and three longer (3.21 Å) Ag–Sb bond lengths. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent Ag1+ and three equivalent Sb3- atoms. All Ag–Sb bond lengths are 2.84 Å. Sb3- is bonded in a 10-coordinate geometry to three equivalent Sr2+ and seven Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaAg8S5 by Materials Project

BaAg8S5 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Ba–S bond distances ranging from 3.19–3.53 Å. In the second Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Ba–S bond distances ranging from 3.23–3.46 Å. There are nine inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.55–3.03 Å. In the second Ag1+ site, Ag1+ is bonded in a linear geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.44–3.53 Å. In the third Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.55–3.24 Å. In the fourth Ag1+ site, Ag1+ is bonded in a distorted bent 150 degrees geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.49–3.15 Å. In the fifth Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to six S2- atoms. There are a spread of Ag–S bond distances ranging from 2.58–3.13 Å. In the sixth Ag1+ site, Ag1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.57–2.92 Å. In the seventh Ag1+ site, Ag1+ is bonded in a bent 150 degrees geometry to two S2- atoms. There are one shorter (2.47 Å) and one longer (2.48 Å) Ag–S bond lengths. In the eighth Ag1+ site, Ag1+ is bonded in a linear geometry to two equivalent S2- atoms. Both Ag–S bond lengths are 2.49 Å. In the ninth Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.48–3.06 Å. There are six inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to two Ba2+ and six Ag1+ atoms. In the second S2- site, S2- is bonded in a 6-coordinate geometry to two Ba2+ and four Ag1+ atoms. In the third S2- site, S2- is bonded in a 8-coordinate geometry to two Ba2+ and six Ag1+ atoms. In the fourth S2- site, S2- is bonded in a 8-coordinate geometry to one Ba2+ and seven Ag1+ atoms. In the fifth S2- site, S2- is bonded in a distorted pentagonal pyramidal geometry to two Ba2+ and four Ag1+ atoms. In the sixth S2- site, S2- is bonded in a 7-coordinate geometry to one Ba2+ and six Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag15Bi7I40 by Materials Project

Ag15Bi7I40 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are fifteen inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded to six I1- atoms to form AgI6 octahedra that share corners with three AgI6 octahedra, edges with two equivalent BiI6 octahedra, and edges with seven AgI6 octahedra. The corner-sharing octahedra tilt angles range from 3–10°. There are a spread of Ag–I bond distances ranging from 2.90–3.23 Å. In the second Ag1+ site, Ag1+ is bonded to six I1- atoms to form AgI6 octahedra that share edges with two equivalent AgI6 octahedra and edges with four BiI6 octahedra. There are a spread of Ag–I bond distances ranging from 2.98–3.26 Å. In the third Ag1+ site, Ag1+ is bonded to six I1- atoms to form AgI6 octahedra that share edges with two equivalent AgI6 octahedra and edges with four BiI6 octahedra. There are a spread of Ag–I bond distances ranging from 2.94–3.30 Å. In the fourth Ag1+ site, Ag1+ is bonded to six I1- atoms to form AgI6 octahedra that share edges with two equivalent AgI6 octahedra and edges with four BiI6 octahedra. There are a spread of Ag–I bond distances ranging from 2.97–3.26 Å. In the fifth Ag1+ site, Ag1+ is bonded to six I1- atoms to form AgI6 octahedra that share edges with two equivalent BiI6 octahedra and edges with four AgI6 octahedra. There are a spread of Ag–I bond distances ranging from 2.89–3.29 Å. In the sixth Ag1+ site, Ag1+ is bonded to six I1- atoms to form edge-sharing AgI6 octahedra. There are a spread of Ag–I bond distances ranging from 2.89–3.12 Å. In the seventh Ag1+ site, Ag1+ is bonded to six I1- atoms to form edge-sharing AgI6 octahedra. There are a spread of Ag–I bond distances ranging from 2.87–3.09 Å. In the eighth Ag1+ site, Ag1+ is bonded to six I1- atoms to form edge-sharing AgI6 octahedra. There are a spread of Ag–I bond distances ranging from 2.89–3.09 Å. In the ninth Ag1+ site, Ag1+ is bonded to six I1- atoms to form edge-sharing AgI6 octahedra. There are a spread of Ag–I bond distances ranging from 2.90–3.09 Å. In the tenth Ag1+ site, Ag1+ is bonded to six I1- atoms to form edge-sharing AgI6 octahedra. There are a spread of Ag–I bond distances ranging from 2.88–3.10 Å. In the eleventh Ag1+ site, Ag1+ is bonded to six I1- atoms to form a mixture of corner and edge-sharing AgI6 octahedra. The corner-sharing octahedra tilt angles range from 2–12°. There are a spread of Ag–I bond distances ranging from 2.89–3.32 Å. In the twelfth Ag1+ site, Ag1+ is bonded to six I1- atoms to form a mixture of corner and edge-sharing AgI6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are a spread of Ag–I bond distances ranging from 2.98–3.14 Å. In the thirteenth Ag1+ site, Ag1+ is bonded to six I1- atoms to form a mixture of corner and edge-sharing AgI6 octahedra. The corner-sharing octahedra tilt angles range from 4–7°. There are a spread of Ag–I bond distances ranging from 2.86–3.32 Å. In the fourteenth Ag1+ site, Ag1+ is bonded to six I1- atoms to form a mixture of corner and edge-sharing AgI6 octahedra. The corner-sharing octahedra tilt angles range from 4–12°. There are a spread of Ag–I bond distances ranging from 2.90–3.23 Å. In the fifteenth Ag1+ site, Ag1+ is bonded to six I1- atoms to form AgI6 octahedra that share a cornercorner with one BiI6 octahedra, corners with five AgI6 octahedra, and edges with ten AgI6 octahedra. The corner-sharing octahedra tilt angles range from 1–7°. There are a spread of Ag–I bond distances ranging from 2.92–3.19 Å. There are seven inequivalent Bi+3.57+ sites. In the first Bi+3.57+ site, Bi+3.57+ is bonded to six I1- atoms to form BiI6 octahedra that share a cornercorner with one AgI6 octahedra, edges with two equivalent BiI6 octahedra, and edges with four AgI6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are a spread of Bi–I bond distances ranging from 2.98–3.18 Å. In the second Bi+3.57+ site, Bi+3.57+ is bonded to six I1- atoms to form BiI6 octahedra that share edges with two equivalent AgI6 octahedra and edges with four BiI6 octahedra. There are a spread of Bi–I bond distances ranging from 2.88–3.28 Å. In the third Bi+3.57+ site, Bi+3.57+ is bonded to six I1- atoms to form edge-sharing BiI6 octahedra. There are a spread of Bi–I bond distances ranging from 3.02–3.27 Å. In the fourth Bi+3.57+ site, Bi+3.57+ is bonded to six I1- atoms to form BiI6 octahedra that share edges with two equivalent AgI6 octahedra and edges with four BiI6 octahedra. There are a spread of Bi–I bond distances ranging from 2.86–3.31 Å. In the fifth Bi+3.57+ site, Bi+3.57+ is bonded to six I1- atoms to form edge-sharing BiI6 octahedra. There are a spread of Bi–I bond distances ranging from 3.03–3.27 Å. In the sixth Bi+3.57+ site, Bi+3.57+ is bonded to six I1- atoms to form BiI6 octahedra that share edges with two equivalent BiI6 octahedra and edges with four AgI6 octahedra. There are a spread of Bi–I bond distances ranging from 2.93–3.23 Å. In the seventh Bi+3.57+ site, Bi+3.57+ is bonded to six I1- atoms to form BiI6 octahedra that share edges with two equivalent BiI6 octahedra and edges with four AgI6 octahedra. There are a spread of Bi–I bond distances ranging from 2.95–3.21 Å. There are forty inequivalent I1- sites. In the first I1- site, I1- is bonded in a rectangular see-saw-like geometry to three Ag1+ and one Bi+3.57+ atom. In the second I1- site, I1- is bonded in a 3-coordinate geometry to one Ag1+ and two equivalent Bi+3.57+ atoms. In the third I1- site, I1- is bonded in a 3-coordinate geometry to one Ag1+ and two equivalent Bi+3.57+ atoms. In the fourth I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Ag1+ and one Bi+3.57+ atom. In the fifth I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Ag1+ and one Bi+3.57+ atom. In the sixth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+3.57+ atoms. In the seventh I1- site, I1- is bonded in a 3-coordinate geometry to one Ag1+ and two equivalent Bi+3.57+ atoms. In the eighth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+3.57+ atoms. In the ninth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+3.57+ atoms. In the tenth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+3.57+ atoms. In the eleventh I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+3.57+ atoms. In the twelfth I1- site, I1- is bonded in a 3-coordinate geometry to one Ag1+ and two equivalent Bi+3.57+ atoms. In the thirteenth I1- site, I1- is bonded in a 3-coordinate geometry to three Bi+3.57+ atoms. In the fourteenth I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Ag1+ and one Bi+3.57+ atom. In the fifteenth I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Ag1+ and one Bi+3.57+ atom. In the sixteenth I1- site, I1- is bonded in a 3-coordinate geometry to one Ag1+ and two equivalent Bi+3.57+ atoms. In the seventeenth I1- site, I1- is bonded in a 3-coordinate geometry to one Ag1+ and two equivalent Bi+3.57+ atoms. In the eighteenth I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Ag1+ and one Bi+3.57+ atom. In the nineteenth I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Ag1+ and one Bi+3.57+ atom. In the twentieth I1- site, I1- is bonded in a 3-coordinate geometry to one Ag1+ and two equivalent Bi+3.57+ atoms. In the twenty-first I1- site, I1- is bonded in a 3-coordinate geometry to one Ag1+ and two equivalent Bi+3.57+ atoms. In the twenty-second I1- site, I1- is bonded in a distorted T-shaped geometry to three Ag1+ atoms. In the twenty-third I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Ag1+ and one Bi+3.57+ atom. In the twenty-fourth I1- site, I1- is bonded in a 3-coordinate geometry to three Ag1+ atoms. In the twenty-fifth I1- site, I1- is bonded in a distorted T-shaped geometry to three Ag1+ atoms. In the twenty-sixth I1- site, I1- is bonded in a 3-coordinate geometry to three Ag1+ atoms. In the twenty-seventh I1- site, I1- is bonded in a 3-coordinate geometry to three Ag1+ atoms. In the twenty-eighth I1- site, I1- is bonded in a 3-coordinate geometry to three Ag1+ atoms. In the twenty-ninth I1- site, I1- is bonded in a 3-coordinate geometry to three Ag1+ atoms. In the thirtieth I1- site, I1- is bonded in a 3-coordinate geometry to three Ag1+ atoms. In the thirty-first I1- site, I1- is bonded in a 3-coordinate geometry to three Ag1+ atoms. In the thirty-second I1- site, I1- is bonded in a distorted T-shaped geometry to three Ag1+ atoms. In the thirty-third I1- site, I1- is bonded in a 3-coordinate geometry to three Ag1+ atoms. In the thirty-fourth I1- site, I1- is bonded in a distorted T-shaped geometry to three Ag1+ atoms. In the thirty-fifth I1- site, I1- is bonded in a 3-coordinate geometry to three Ag1+ atoms. In the thirty-sixth I1- site, I1- is bonded to five Ag1+ atoms to form IAg5 square pyramids that share corners with two equivalent IAg6 octahedra, a cornercorner with one IAg5 square pyramid, edges with five IAg6 octahedra, and edges with two equivalent IAg5 square pyramids. The corner-sharing octahedral tilt angles are 9°. In the thirty-seventh I1- site, I1- is bonded in a rectangular see-saw-like geometry to four Ag1+ atoms. In the thirty-eighth I1- site, I1- is bonded to six Ag1+ atoms to form IAg6 octahedra that share corners with two equivalent IAg6 octahedra, corners with two equivalent IAg5 square pyramids, edges with five IAg6 octahedra, and edges with five IAg5 square pyramids. The corner-sharing octahedral tilt angles are 4°. In the thirty-ninth I1- site, I1- is bonded to six Ag1+ atoms to form IAg6 octahedra that share corners with two equivalent IAg6 octahedra, corners with two equivalent IAg5 square pyramids, edges with five IAg6 octahedra, and edges with five IAg5 square pyramids. The corner-sharing octahedral tilt angles are 4°. In the fortieth I1- site, I1- is bonded to five Ag1+ atoms to form IAg5 square pyramids that share corners with two equivalent IAg6 octahedra, a cornercorner with one IAg5 square pyramid, edges with five IAg6 octahedra, and edges with two equivalent IAg5 square pyramids. The corner-sharing octahedral tilt angles are 5°.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Discovery of Stable Surfaces with Extreme Work Functions by High‐Throughput Density Functional Theory and Machine Learning

Abstract The work function is the key surface property that determines the energy required to extract an electron from the surface of a material. This property is crucial for thermionic energy conversion, band alignment in heterostructures, and electron emission devices. This work presents a high‐throughput workflow using density functional theory (DFT) to calculate the work function and cleavage energy of 33,631 slabs (58,332 work functions) that are created from 3,716 bulk materials. The number of calculated surface properties surpasses the previously largest database by a factor of ≈27. Several surfaces with an ultra‐low (<2 eV) and ultra‐high (>7 eV) work function are identified. Specifically, the (100)‐Ba‐O surface of BaMoO 3 and the (001)‐F surface of Ag 2 F have record‐low (1.25 eV) and record‐high (9.06 eV) steady‐state work functions. Based on this database a physics‐based approach to featurize surfaces is utilized to predict the work function. The random forest model achieves a test mean absolute error (MAE) of 0.09 eV, comparable to the accuracy of DFT. This surrogate model enables rapid predictions of the work function (≈ 10 5 faster than DFT) across a vast chemical space and facilitates the discovery of material surfaces with extreme work functions for energy conversion and electronic device applications.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

Uncovering fast solid-acid proton conductors based on dynamics of polyanion groups and proton bonding strength

Achieving high proton conductivity in inorganic solids is key for advancing many electrochemical technologies, including low-energy nano-electronics and energy-efficient fuel cells and electrolyzers. A quantitative understanding of the physical traits of a material that regulate proton diffusion is necessary for accelerating the discovery of fast proton conductors. In this work, we have mapped the structural, chemical and dynamic properties of solid acids to the elementary steps of the Grotthuss mechanism of proton diffusion. Our approach combines ab initio molecular dynamics simulations, analysis of phonon spectra and atomic structure calculations. We have identified the donor–hydrogen bond lengths and the acidity of polyanion groups as key descriptors of local proton transfer and the vibrational frequencies of the cation framework as the key descriptor of lattice flexibility. The latter facilitates rotations of polyanion groups and long-range proton migration in solid acid proton conductors. The calculated lattice flexibility also correlates with the experimentally reported superprotonic transition temperatures. Using these descriptors, we have screened the Materials Project database and identified potential solid acid proton conductors with monovalent, divalent and trivalent cations, including Ag + , Sr 2+ , Ba 2+ and Er 3+ cations, which go beyond the traditionally considered monovalent alkali cations (Cs + , Rb + , K + , and NH 4 + ) in solid acids.

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

Growth of Well-Defined Model Catalysts for Electrochemistry: From Surface Science Studies to Electrocatalytic CO2 Conversion

We combined ultrahigh vacuum (UHV) surface science techniques, electrochemical measurements, and computational modeling to investigate electrocatalytic systems that are crucial components of the carbon management effort, including oxygen evolution reactions (OER) and CO2 reduction reactions (CO2RR). Well-defined Model catalysts were grown on substrates in the UHV chamber and characterized with X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Selected model electrocatalysts were then tested in electrochemical cells to establish the structure-property relationships in OER and CO2RR. Our results showed that the edge sites of Fe2O3 grown on Au(111) were the most active toward OER and incorporation of Ni at the edge sites (NiFeOx) further boosted their OER activity. We also resolved the size-dependent electrocatalytic CO2-to-CO conversion of the Ag nanoparticle electrocatalysts with average particle diameter between 2 to 6 nm: smaller diameter (< 3 nm) particles favored H2 evolution reaction (HER) due to a high population of Ag edge sites, whereas larger diameter particles favored CO2RR as the population of Ag(100) surface sites grew. We further discovered that electronic interactions between small diameter Ag particles and highly defective carbon supports could break the size-dependent CO2RR selectivity, resulting in highly selective (CO Faradaic Efficiency > 90%) and active Ag nanoparticle electrocatalysts with sizes < 2 nm diameter.

Deng, Xingyi↗
DOE OSTI2025

Understanding of Ag Nanocatalysts for Electrocatalytic CO2 Conversion: Effects of Particle Size and Carbon Support

In this talk, we combined ultrahigh vacuum (UHV) surface science techniques, electrochemical measurements, and computational modeling to investigate Ag based electrocatalysts for CO2 reduction reaction (CO2RR). Our goal is to understand the critical characteristics governing the activity and selectivity of Ag electrocatalysts. Ag electrocatalysts were grown on highly oriented pyrolytic graphite (HOPG) in the UHV chamber, characterized with X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM), and then tested in a custom-built gastight H-cell. Supported by computational modeling based on density functional theory (DFT) calculations and microkinetic modeling (MKM), our studies revealed a strong size-dependent electrocatalytic CO2-to-CO conversion of the Ag nanoparticle electrocatalysts with average particle diameter between 2 to 6 nm. Smaller diameter (< 3 nm) particles favored H2 evolution reaction (HER) due to a high population of Ag edge sites, whereas larger diameter particles favored CO2RR as the population of Ag(100) surface sites grew. We further discovered that electronic interactions between small diameter Ag particles and highly defective carbon supports could break the size-dependent CO2RR reactivity, resulting in highly selective (CO Faradaic Efficiency > 90%) and active Ag nanoparticle electrocatalysts with sizes < 2 nm diameter. This knowledge is key to understand electrocatalysts performance and to ultimately guide electrocatalyst design

Ag nanoparticles↗
DOE OSTI2021

Sodium, Silver and Lithium-Ion Conducting β''-Alumina + YSZ Composites, Ionic Conductivity and Stability

Na-β''-alumina (Na 2 O.~6Al 2 O 3 ) is known to be an excellent sodium ion conductor in battery and sensor applications. In this study we report fabrication of Na- β''-alumina + YSZ dual phase composite to mitigate moisture and CO 2 corrosion that otherwise can lead to degradation in pure Na-β''-alumina conductor. Subsequently, we heat-treated the samples in molten AgNO 3 and LiNO3 to respectively form Ag-β''-alumina + YSZ and Li-β''-alumina + YSZ to investigate their potential applications in silver- and lithium-ion solid state batteries. Ion exchange fronts were captured via SEM and EDS techniques. Their ionic conductivities were measured using electrochemical impedance spectroscopy. Both ion exchange rates and ionic conductivities of these composite ionic conductors were firstly reported here and measured as a function of ion exchange time and temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2S by Materials Project

Ag2S crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are four inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a linear geometry to two S2- atoms. Both Ag–S bond lengths are 2.44 Å. In the second Ag1+ site, Ag1+ is bonded in a linear geometry to two S2- atoms. Both Ag–S bond lengths are 2.44 Å. In the third Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent S2- atoms. There are two shorter (2.51 Å) and one longer (2.75 Å) Ag–S bond lengths. In the fourth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent S2- atoms. There are two shorter (2.52 Å) and one longer (2.74 Å) Ag–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms. In the second S2- site, S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si2Ag9NO11 by Materials Project

Ag9Si2NO11 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are nine inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.31–2.85 Å. In the second Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.34–2.71 Å. In the third Ag1+ site, Ag1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.19–2.65 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three O2- atoms. There are two shorter (2.20 Å) and one longer (2.60 Å) Ag–O bond lengths. In the fifth Ag1+ site, Ag1+ is bonded in a distorted linear geometry to two O2- atoms. Both Ag–O bond lengths are 2.14 Å. In the sixth Ag1+ site, Ag1+ is bonded to four O2- atoms to form distorted AgO4 trigonal pyramids that share corners with three SiO4 tetrahedra. There are a spread of Ag–O bond distances ranging from 2.33–2.66 Å. In the seventh Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.32–2.84 Å. In the eighth Ag1+ site, Ag1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.21–2.81 Å. In the ninth Ag1+ site, Ag1+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.21–2.46 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent AgO4 trigonal pyramids. There is three shorter (1.66 Å) and one longer (1.67 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one AgO4 trigonal pyramid. All Si–O bond lengths are 1.66 Å. N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.27 Å) and one longer (1.28 Å) N–O bond length. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Si4+ atom. In the second O2- site, O2- is bonded to three Ag1+ and one Si4+ atom to form distorted corner-sharing OSiAg3 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Si4+ atom. In the fourth O2- site, O2- is bonded to three Ag1+ and one Si4+ atom to form distorted corner-sharing OSiAg3 tetrahedra. In the fifth O2- site, O2- is bonded to three Ag1+ and one Si4+ atom to form distorted corner-sharing OSiAg3 tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Si4+ atom. In the seventh O2- site, O2- is bonded to three Ag1+ and one Si4+ atom to form distorted corner-sharing OSiAg3 tetrahedra. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to three Ag1+ and one N5+ atom. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to three Ag1+ and one N5+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to two Ag1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SiAg8(SO2)2 by Materials Project

Ag8Si(SO2)2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. there are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 1-coordinate geometry to one S2- and two equivalent O2- atoms. The Ag–S bond length is 2.54 Å. Both Ag–O bond lengths are 3.06 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to one S2- and two equivalent O2- atoms. The Ag–S bond length is 2.34 Å. Both Ag–O bond lengths are 2.25 Å. In the third Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to two equivalent S2- and two equivalent O2- atoms. Both Ag–S bond lengths are 2.71 Å. Both Ag–O bond lengths are 2.68 Å. Si4+ is bonded to four equivalent O2- atoms to form SiO4 tetrahedra that share corners with four equivalent SAg6O2 hexagonal bipyramids. All Si–O bond lengths are 1.66 Å. S2- is bonded to six Ag1+ and two equivalent O2- atoms to form distorted SAg6O2 hexagonal bipyramids that share corners with four equivalent SAg6O2 hexagonal bipyramids and corners with two equivalent SiO4 tetrahedra. Both S–O bond lengths are 2.56 Å. O2- is bonded in a 1-coordinate geometry to four Ag1+, one Si4+, and one S2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs3Ag9(SbS3)4 by Materials Project

Cs3Ag9(SbS3)4 crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are four shorter (3.61 Å) and four longer (3.70 Å) Cs–S bond lengths. In the second Cs1+ site, Cs1+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Cs–S bond distances ranging from 3.58–3.75 Å. There are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four equivalent S2- atoms. All Ag–S bond lengths are 2.82 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.52–3.19 Å. In the third Ag1+ site, Ag1+ is bonded in a distorted trigonal planar geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.54–3.35 Å. Sb3+ is bonded in a distorted trigonal non-coplanar geometry to three S2- atoms. There are two shorter (2.47 Å) and one longer (2.50 Å) Sb–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Cs1+, two Ag1+, and one Sb3+ atom. In the second S2- site, S2- is bonded in a 6-coordinate geometry to two Cs1+, three Ag1+, and one Sb3+ atom. In the third S2- site, S2- is bonded in a 7-coordinate geometry to two Cs1+, four Ag1+, and one Sb3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb3Ag9(SbS3)4 by Materials Project

Rb3Ag9(SbS3)4 crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. there are two inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are four shorter (3.49 Å) and four longer (3.61 Å) Rb–S bond lengths. In the second Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Rb–S bond distances ranging from 3.45–3.67 Å. There are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four equivalent S2- atoms. All Ag–S bond lengths are 2.83 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.52–3.17 Å. In the third Ag1+ site, Ag1+ is bonded in a distorted trigonal planar geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.54–3.34 Å. Sb3+ is bonded in a distorted trigonal non-coplanar geometry to three S2- atoms. There are a spread of Sb–S bond distances ranging from 2.45–2.49 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 7-coordinate geometry to two Rb1+, four Ag1+, and one Sb3+ atom. In the second S2- site, S2- is bonded in a 6-coordinate geometry to two Rb1+, three Ag1+, and one Sb3+ atom. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Rb1+, two Ag1+, and one Sb3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Oxidative Self-Assembly of Au/Ag/Pt Alloy Nanoparticles into High-Surface Area, Mesoporous, and Conductive Aerogels for Methanol Electro-oxidation

The ability to assemble nanoparticles (NPs) into functional nanostructures is critical for the advancement of nanoscience. However, common assembling techniques utilize organic ligands or biomolecules, which are detrimental for charge transport and interparticle coupling, which impede the efficient integration of low-dimensional properties. Herein, we report a methodology for the self-supported assembly of ultra-small (3-6 nm) Au/Ag/Pt alloy NPs into large, free-standing alloy superstructures (aerogels) that exhibit direct NP connectivity, high surface area (125 ± 0.43 to142 ± 0.93 m 2 /g) and mesoporosity (21.6 ± 2.2 nm), and superior electrocatalytic activity for methanol oxidation reaction (MOR). Precursor Au/Ag/Pt alloy NPs and hydrogels were synthesized via stepwise galvanic replacement reaction (GRR) of the glutathione (GSH)-coated Ag NPs, followed by oxidative removal of the surfactant ligands. The composition of alloy aerogels was tuned by varying the oxidant/GSH molar ratio, which governs the extent of Ag dealloying with in-situ generated HNO 3 and increases the exposure of Au and Pt on the aerogel surface. The alloy aerogels exhibit superior MOR mass activity, which is 21.4 and 2.5 times higher than those of the precursor NPs and commercial Pt (40 wt.%)/C electrocatalysts, respectively. The MOR surface-specific activity (MOR-SSA) of the aerogels was improved by >17% when the Pt content was increased from 22.4% to 31.2%. The aerogels exhibit improved electronic conductivity, enhanced tolerance for carbonaceous byproducts, and maintained ~94% of the initial MOR activity at -0.3 V for 24 h in an alkaline medium. In conclusion, the interconnected porous superstructure of the aerogel provides a facile conduit for molecules to reach the pristine active surface whereas the presence of oxophilic Au promotes the dissociative adsorption of methanol, enabling the Au/Ag/Pt alloy aerogel a high efficiency, durable electrocatalyst for next generation of energy conversion studies.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaNb(AgO3)2 by Materials Project

TaNb(AgO3)2 is Orthorhombic Perovskite-derived structured and crystallizes in the orthorhombic P2_12_12 space group. The structure is three-dimensional. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share a cornercorner with one TaO6 octahedra and corners with five equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 16–24°. There are a spread of Ta–O bond distances ranging from 1.92–2.12 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share a cornercorner with one NbO6 octahedra and corners with five equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 16–24°. There are a spread of Nb–O bond distances ranging from 1.94–2.14 Å. There are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three O2- atoms. There are two shorter (2.45 Å) and one longer (2.50 Å) Ag–O bond lengths. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three O2- atoms. There are two shorter (2.46 Å) and one longer (2.48 Å) Ag–O bond lengths. In the third Ag1+ site, Ag1+ is bonded in a 12-coordinate geometry to eight O2- atoms. There are a spread of Ag–O bond distances ranging from 2.50–2.79 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Ta5+, one Nb5+, and two equivalent Ag1+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Ta5+, one Nb5+, and two equivalent Ag1+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Ta5+, one Nb5+, and two Ag1+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ta5+, one Nb5+, and two Ag1+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and one Ag1+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ta5+ and one Ag1+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ta5+, one Nb5+, and two equivalent Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UAg2(SeO4)2 by Materials Project

UAg2(SeO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. U6+ is bonded in a distorted pentagonal bipyramidal geometry to seven O2- atoms. There are a spread of U–O bond distances ranging from 1.82–2.46 Å. There are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ag–O bond distances ranging from 2.34–3.14 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to six O2- atoms. There are a spread of Ag–O bond distances ranging from 2.31–3.08 Å. There are two inequivalent Se4+ sites. In the first Se4+ site, Se4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of Se–O bond distances ranging from 1.73–1.77 Å. In the second Se4+ site, Se4+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.72 Å) and two longer (1.74 Å) Se–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one U6+, two equivalent Ag1+, and one Se4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one U6+ and one Ag1+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one U6+, one Ag1+, and one Se4+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one U6+, one Ag1+, and one Se4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one U6+, one Ag1+, and one Se4+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one U6+, two Ag1+, and one Se4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Se4+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one U6+ and one Ag1+ atom.

36 MATERIALS SCIENCE↗