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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Cs2Np2PO4F7 by Materials Project

Cs2Np2PO4F7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 1-coordinate geometry to two O2- and six F1- atoms. There are one shorter (3.05 Å) and one longer (3.20 Å) Cs–O bond lengths. There are a spread of Cs–F bond distances ranging from 2.87–3.39 Å. In the second Cs1+ site, Cs1+ is bonded in a 2-coordinate geometry to two O2- and six F1- atoms. There are one shorter (3.10 Å) and one longer (3.12 Å) Cs–O bond lengths. There are a spread of Cs–F bond distances ranging from 2.88–3.50 Å. There are two inequivalent Np4+ sites. In the first Np4+ site, Np4+ is bonded in a 9-coordinate geometry to two O2- and seven F1- atoms. There are one shorter (2.28 Å) and one longer (2.33 Å) Np–O bond lengths. There are a spread of Np–F bond distances ranging from 2.25–2.49 Å. In the second Np4+ site, Np4+ is bonded in a 8-coordinate geometry to two O2- and six F1- atoms. There are one shorter (2.31 Å) and one longer (2.33 Å) Np–O bond lengths. There are a spread of Np–F bond distances ranging from 2.17–2.42 Å. P5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Cs1+, one Np4+, and one P5+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Cs1+, one Np4+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Cs1+, one Np4+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one Cs1+, one Np4+, and one P5+ atom. There are seven inequivalent F1- sites. In the first F1- site, F1- is bonded in a 2-coordinate geometry to two equivalent Cs1+ and two Np4+ atoms. In the second F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two Np4+ atoms. In the third F1- site, F1- is bonded in a 2-coordinate geometry to two Cs1+ and two equivalent Np4+ atoms. In the fourth F1- site, F1- is bonded in a 3-coordinate geometry to two equivalent Cs1+ and two Np4+ atoms. In the fifth F1- site, F1- is bonded in a 2-coordinate geometry to two Cs1+ and two equivalent Np4+ atoms. In the sixth F1- site, F1- is bonded in a 3-coordinate geometry to two Cs1+ and one Np4+ atom. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to two Cs1+ and two equivalent Np4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpPa3 by Materials Project

NpPa3 is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded to twelve Pa atoms to form NpPa12 cuboctahedra that share corners with four equivalent NpPa12 cuboctahedra, corners with eight equivalent PaNp4Pa8 cuboctahedra, edges with eight equivalent NpPa12 cuboctahedra, edges with sixteen equivalent PaNp4Pa8 cuboctahedra, faces with four equivalent NpPa12 cuboctahedra, and faces with fourteen PaNp4Pa8 cuboctahedra. There are four shorter (3.06 Å) and eight longer (3.29 Å) Np–Pa bond lengths. There are two inequivalent Pa sites. In the first Pa site, Pa is bonded to four equivalent Np and eight Pa atoms to form PaNp4Pa8 cuboctahedra that share corners with twelve equivalent PaNp4Pa8 cuboctahedra, edges with eight equivalent NpPa12 cuboctahedra, edges with sixteen PaNp4Pa8 cuboctahedra, faces with four equivalent NpPa12 cuboctahedra, and faces with fourteen PaNp4Pa8 cuboctahedra. There are four shorter (3.06 Å) and four longer (3.29 Å) Pa–Pa bond lengths. In the second Pa site, Pa is bonded to four equivalent Np and eight equivalent Pa atoms to form distorted PaNp4Pa8 cuboctahedra that share corners with four equivalent PaNp4Pa8 cuboctahedra, corners with eight equivalent NpPa12 cuboctahedra, edges with twenty-four PaNp4Pa8 cuboctahedra, faces with six equivalent NpPa12 cuboctahedra, and faces with twelve PaNp4Pa8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpFe3 by Materials Project

NpFe3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded to twelve Fe atoms to form NpFe12 cuboctahedra that share corners with four equivalent NpFe12 cuboctahedra, corners with eight equivalent FeNp4Fe8 cuboctahedra, edges with eight equivalent NpFe12 cuboctahedra, edges with sixteen equivalent FeNp4Fe8 cuboctahedra, faces with four equivalent NpFe12 cuboctahedra, and faces with fourteen FeNp4Fe8 cuboctahedra. There are eight shorter (2.62 Å) and four longer (2.63 Å) Np–Fe bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to four equivalent Np and eight Fe atoms to form distorted FeNp4Fe8 cuboctahedra that share corners with twelve equivalent FeNp4Fe8 cuboctahedra, edges with eight equivalent NpFe12 cuboctahedra, edges with sixteen FeNp4Fe8 cuboctahedra, faces with four equivalent NpFe12 cuboctahedra, and faces with fourteen FeNp4Fe8 cuboctahedra. There are four shorter (2.62 Å) and four longer (2.63 Å) Fe–Fe bond lengths. In the second Fe site, Fe is bonded to four equivalent Np and eight equivalent Fe atoms to form distorted FeNp4Fe8 cuboctahedra that share corners with four equivalent FeNp4Fe8 cuboctahedra, corners with eight equivalent NpFe12 cuboctahedra, edges with twenty-four FeNp4Fe8 cuboctahedra, faces with six equivalent NpFe12 cuboctahedra, and faces with twelve FeNp4Fe8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpNi5 by Materials Project

NpNi5 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Np is bonded in a distorted hexagonal planar geometry to eighteen Ni atoms. There are six shorter (2.79 Å) and twelve longer (3.12 Å) Np–Ni bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded to four equivalent Np and eight Ni atoms to form a mixture of edge, face, and corner-sharing NiNp4Ni8 cuboctahedra. There are four shorter (2.41 Å) and four longer (2.42 Å) Ni–Ni bond lengths. In the second Ni site, Ni is bonded to three equivalent Np and nine Ni atoms to form distorted NiNp3Ni9 cuboctahedra that share corners with twenty-one NiNp4Ni8 cuboctahedra, edges with six equivalent NiNp3Ni9 cuboctahedra, and faces with twenty-three NiNp4Ni8 cuboctahedra. All Ni–Ni bond lengths are 2.79 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpMn(OF2)3 by Materials Project

NpMn2O5F8NpOF4 crystallizes in the monoclinic C2 space group. The structure is zero-dimensional and consists of two NpMn2O5F8 clusters and two NpOF4 clusters. In each NpMn2O5F8 cluster, Np5+ is bonded in a 7-coordinate geometry to one O2- and six F1- atoms. The Np–O bond length is 1.80 Å. There are four shorter (2.03 Å) and two longer (2.51 Å) Np–F bond lengths. Mn7+ is bonded in a tetrahedral geometry to two O2- and two F1- atoms. There is one shorter (1.59 Å) and one longer (1.60 Å) Mn–O bond length. Both Mn–F bond lengths are 1.80 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Np5+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Mn7+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one Mn7+ atom. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to one Mn7+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Np5+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Np5+ atom. In the fourth F1- site, F1- is bonded in a distorted single-bond geometry to one Np5+ and one Mn7+ atom. In each NpOF4 cluster, Np5+ is bonded in a distorted square pyramidal geometry to one O2- and four F1- atoms. The Np–O bond length is 1.83 Å. There are two shorter (2.03 Å) and two longer (2.04 Å) Np–F bond lengths. O2- is bonded in a single-bond geometry to one Np5+ atom. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Np5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Np5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs(NpSe3)2 by Materials Project

Cs(NpSe3)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Cs1+ is bonded to eight equivalent Se2- atoms to form face-sharing CsSe8 hexagonal bipyramids. All Cs–Se bond lengths are 3.77 Å. Np+5.50+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Np–Se bond distances ranging from 2.89–2.96 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to four equivalent Np+5.50+ atoms to form a mixture of distorted corner and edge-sharing SeNp4 trigonal pyramids. In the second Se2- site, Se2- is bonded in a 2-coordinate geometry to two equivalent Cs1+, two equivalent Np+5.50+, and two equivalent Se2- atoms. There are one shorter (2.68 Å) and one longer (2.81 Å) Se–Se bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpAg3 by Materials Project

NpAg3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded to twelve Ag atoms to form NpAg12 cuboctahedra that share corners with four equivalent NpAg12 cuboctahedra, corners with eight equivalent AgNp4Ag8 cuboctahedra, edges with eight equivalent NpAg12 cuboctahedra, edges with sixteen equivalent AgNp4Ag8 cuboctahedra, faces with four equivalent NpAg12 cuboctahedra, and faces with fourteen AgNp4Ag8 cuboctahedra. There are eight shorter (3.11 Å) and four longer (3.20 Å) Np–Ag bond lengths. There are two inequivalent Ag sites. In the first Ag site, Ag is bonded to four equivalent Np and eight Ag atoms to form distorted AgNp4Ag8 cuboctahedra that share corners with twelve equivalent AgNp4Ag8 cuboctahedra, edges with eight equivalent NpAg12 cuboctahedra, edges with sixteen AgNp4Ag8 cuboctahedra, faces with four equivalent NpAg12 cuboctahedra, and faces with fourteen AgNp4Ag8 cuboctahedra. There are four shorter (3.11 Å) and four longer (3.20 Å) Ag–Ag bond lengths. In the second Ag site, Ag is bonded to four equivalent Np and eight equivalent Ag atoms to form AgNp4Ag8 cuboctahedra that share corners with four equivalent AgNp4Ag8 cuboctahedra, corners with eight equivalent NpAg12 cuboctahedra, edges with twenty-four AgNp4Ag8 cuboctahedra, faces with six equivalent NpAg12 cuboctahedra, and faces with twelve AgNp4Ag8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpH28C12(N2O3)6 by Materials Project

Np(CO2)8(CN3H6)4(H2O)2 crystallizes in the monoclinic C2/c space group. The structure is one-dimensional and consists of sixteen guanidinium molecules; eight water molecules; and two Np(CO2)8 ribbons oriented in the (0, 0, 1) direction. In each Np(CO2)8 ribbon, Np4+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Np–O bond distances ranging from 2.40–2.61 Å. There are four inequivalent C+3.33+ sites. In the first C+3.33+ site, C+3.33+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.27 Å. In the second C+3.33+ site, C+3.33+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the third C+3.33+ site, C+3.33+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the fourth C+3.33+ site, C+3.33+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Np4+ and one C+3.33+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Np4+ and one C+3.33+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+3.33+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Np4+ and one C+3.33+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one Np4+ and one C+3.33+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Np4+ and one C+3.33+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one C+3.33+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one C+3.33+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpGa5Rh by Materials Project

NpRhGa5 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Np is bonded to twelve Ga atoms to form NpGa12 cuboctahedra that share corners with four equivalent NpGa12 cuboctahedra, faces with four equivalent NpGa12 cuboctahedra, and faces with four equivalent GaNp4Ga8 cuboctahedra. There are eight shorter (2.95 Å) and four longer (3.04 Å) Np–Ga bond lengths. Rh is bonded in a body-centered cubic geometry to eight equivalent Ga atoms. All Rh–Ga bond lengths are 2.55 Å. There are two inequivalent Ga sites. In the first Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Np, two equivalent Rh, and two equivalent Ga atoms. Both Ga–Ga bond lengths are 2.95 Å. In the second Ga site, Ga is bonded to four equivalent Np and eight equivalent Ga atoms to form GaNp4Ga8 cuboctahedra that share corners with four equivalent GaNp4Ga8 cuboctahedra, faces with four equivalent NpGa12 cuboctahedra, and faces with four equivalent GaNp4Ga8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpSc3 by Materials Project

NpSc3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded to twelve Sc atoms to form NpSc12 cuboctahedra that share corners with four equivalent NpSc12 cuboctahedra, corners with eight equivalent ScNp4Sc8 cuboctahedra, edges with eight equivalent NpSc12 cuboctahedra, edges with sixteen equivalent ScNp4Sc8 cuboctahedra, faces with four equivalent NpSc12 cuboctahedra, and faces with fourteen ScNp4Sc8 cuboctahedra. There are four shorter (3.19 Å) and eight longer (3.28 Å) Np–Sc bond lengths. There are two inequivalent Sc sites. In the first Sc site, Sc is bonded to four equivalent Np and eight Sc atoms to form ScNp4Sc8 cuboctahedra that share corners with twelve equivalent ScNp4Sc8 cuboctahedra, edges with eight equivalent NpSc12 cuboctahedra, edges with sixteen ScNp4Sc8 cuboctahedra, faces with four equivalent NpSc12 cuboctahedra, and faces with fourteen ScNp4Sc8 cuboctahedra. There are four shorter (3.19 Å) and four longer (3.28 Å) Sc–Sc bond lengths. In the second Sc site, Sc is bonded to four equivalent Np and eight equivalent Sc atoms to form ScNp4Sc8 cuboctahedra that share corners with four equivalent ScNp4Sc8 cuboctahedra, corners with eight equivalent NpSc12 cuboctahedra, edges with twenty-four ScNp4Sc8 cuboctahedra, faces with six equivalent NpSc12 cuboctahedra, and faces with twelve ScNp4Sc8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(NpSe3)2 by Materials Project

K(NpSe3)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. K1+ is bonded in a distorted body-centered cubic geometry to eight equivalent Se2- atoms. All K–Se bond lengths are 3.41 Å. Np+5.50+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Np–Se bond distances ranging from 2.89–2.95 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to two equivalent K1+ and two equivalent Np+5.50+ atoms. In the second Se2- site, Se2- is bonded to four equivalent Np+5.50+ atoms to form a mixture of distorted edge and corner-sharing SeNp4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm3Np by Materials Project

NpTm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded to twelve Tm atoms to form NpTm12 cuboctahedra that share corners with four equivalent NpTm12 cuboctahedra, corners with eight equivalent TmTm8Np4 cuboctahedra, edges with eight equivalent NpTm12 cuboctahedra, edges with sixteen equivalent TmTm8Np4 cuboctahedra, faces with four equivalent NpTm12 cuboctahedra, and faces with fourteen TmTm8Np4 cuboctahedra. There are four shorter (3.42 Å) and eight longer (3.47 Å) Np–Tm bond lengths. There are two inequivalent Tm sites. In the first Tm site, Tm is bonded to four equivalent Np and eight Tm atoms to form TmTm8Np4 cuboctahedra that share corners with twelve equivalent TmTm8Np4 cuboctahedra, edges with eight equivalent NpTm12 cuboctahedra, edges with sixteen TmTm8Np4 cuboctahedra, faces with four equivalent NpTm12 cuboctahedra, and faces with fourteen TmTm8Np4 cuboctahedra. There are four shorter (3.42 Å) and four longer (3.47 Å) Tm–Tm bond lengths. In the second Tm site, Tm is bonded to four equivalent Np and eight equivalent Tm atoms to form TmTm8Np4 cuboctahedra that share corners with four equivalent TmTm8Np4 cuboctahedra, corners with eight equivalent NpTm12 cuboctahedra, edges with twenty-four TmTm8Np4 cuboctahedra, faces with six equivalent NpTm12 cuboctahedra, and faces with twelve TmTm8Np4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpCoS2(NO2)6 by Materials Project

(Np(SO5)2)2(CoN3)2(N2)3(O2)2 crystallizes in the orthorhombic Pnma space group. The structure is one-dimensional and consists of four azanide;cobalt(3+) molecules; four triaziridine molecules; two Np(SO5)2 ribbons oriented in the (1, 0, 0) direction; and two O2 ribbons oriented in the (1, 0, 0) direction. In each Np(SO5)2 ribbon, Np4+ is bonded to seven O2- atoms to form distorted NpO7 pentagonal bipyramids that share corners with three equivalent SO4 tetrahedra and an edgeedge with one SO4 tetrahedra. There are a spread of Np–O bond distances ranging from 1.77–2.46 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three equivalent NpO7 pentagonal bipyramids. There are a spread of S–O bond distances ranging from 1.43–1.52 Å. In the second S2- site, S2- is bonded to four O2- atoms to form SO4 tetrahedra that share an edgeedge with one NpO7 pentagonal bipyramid. There is two shorter (1.46 Å) and two longer (1.53 Å) S–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Np4+ and one S2- atom. In the second O2- site, O2- is bonded in a single-bond geometry to one S2- atom. In the third O2- site, O2- is bonded in a single-bond geometry to one Np4+ atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Np4+ and one S2- atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one Np4+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one S2- atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one S2- atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Np4+ and one S2- atom. In each O2 ribbon, there are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to two equivalent O2- atoms. Both O–O bond lengths are 1.61 Å. In the second O2- site, O2- is bonded in a linear geometry to two equivalent O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Grain‐Boundary‐Rich Noble Metal Nanoparticle Assemblies: Synthesis, Characterization, and Reactivity

Abstract Here, a comprehensive study on the synthesis, characterization, and reactivity of grain‐boundary (GB)‐rich noble metal nanoparticle (NP) assemblies is presented. A facile and scalable synthesis of Pt, Pd, Au, Ag, and Rh NP assemblies is developed, in which NPs are predominantly connected via Σ3 (111) twin GBs, forming a network. Driven by water electrolysis, the random collisions and oriented attachment of colloidal NPs in solution lead to the formation of Σ3 (111) twin boundaries and some highly mismatched GBs. This synthetic method also provides convenient control over the GB density without altering the crystallite size or GB type by varying the NP collision frequency. The structural characterization reveals the presence of localized tensile strain at the GB sites. The ultrahigh activity of GB‐rich Pt NP assembly toward catalytic hydrogen oxidation in air is demonstrated, enabling room‐temperature catalytic hydrogen sensing for the first time. Finally, density functional theory calculations reveal that the strained Σ3(111) twin boundary facilitates oxygen dissociation, drastically enhancing the hydrogen oxidation rate via the dissociative pathway. This reported large‐scale synthesis of the Σ3 (111) twin GB‐rich structures enables the development of a broad range of high‐performance GB‐rich catalysts.

Geng, Xin↗
DOE OSTI2021

Atomic Structure Evolution of Pt–Co Binary Catalysts: Single Metal Sites versus Intermetallic Nanocrystals

Due to their exceptional catalytic properties for the oxygen reduction reaction (ORR) and other crucial electrochemical reactions, PtCo intermetallic nanoparticle (NP) and single atomic (SA) Pt metal site catalysts have received considerable attention. However, their formation mechanisms at the atomic level during high-temperature annealing processes remain elusive. Furthermore, the thermally driven structure evolution of Pt–Co binary catalyst systems is investigated using advanced in situ electron microscopy, including PtCo intermetallic alloys and single Pt/Co metal sites. The pre-doping of CoN 4 sites in carbon supports and the initial Pt NP sizes play essential roles in forming either Pt 3 Co intermetallics or single Pt/Co metal sites. Importantly, the initial Pt NP loadings against the carbon support are critical to whether alloying to L1 2 -ordered Pt 3 Co NPs or atomizing to SA Pt sites at high temperatures. High Pt NP loadings (e.g., 20%) tend to lead to the formation of highly ordered Pt 3 Co intermetallic NPs with excellent activity and enhanced stability toward the ORR. In contrast, at a relatively low Pt loading (<6 wt%), the formation of single Pt sites in the form of PtC 3 N is thermodynamically favorable, in which a synergy between the PtC 3 N and the CoN 4 sites could enhance the catalytic activity for the ORR, but showing insufficient stability.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Dual‐Scale Nanostructures via Evaporative Assembly

Abstract Dual‐scale hierarchical structures with regular microscale patterns and varying degree of nanoscale crystalline order are synthesized on physically and chemically homogeneous substrates by evaporative self‐assembly with a suspension of DNA‐functionalized nanoparticles (NPs) with a charged core shell. For a certain NP concentration range, periodic concentric rings in a stripe‐like micropattern are produced over macroscale surface areas by an NP monolayer with hexagonal lattice structure at the nanoscale. The stripe width, spacing, and nanoparticle ordering can be controlled by varying the NP concentration. The results indicate that the interplay between “stick‐slip” motion of the droplet contact line and coulombic and steric NP interactions control the formation of the observed structures. A simple analytical model is proposed to account for the experimental observations and guide the future design of different nanostructure morphologies. This work demonstrates a simple cost‐effective mask‐free method for fabricating large‐area nanostructured 2D materials and metasurfaces for applications ranging from energy conversion/storage to optoelectronics and nanophotonics.

Srivastava, Sunita↗
DOE OSTI2023

Divergent Stabilities of Tetravalent Cerium, Uranium, and Neptunium Imidophosphorane Complexes**

Abstract The study of the redox chemistry of mid‐actinides (U−Pu) has historically relied on cerium as a model, due to the accessibility of trivalent and tetravalent oxidation states for these ions. Recently, dramatic shifts of lanthanide 4+/3+ non‐aqueous redox couples have been established within a homoleptic imidophosphorane ligand framework. Herein we extend the chemistry of the imidophosphorane ligand (NPC=[N=P t Bu(pyrr) 2 ] − ; pyrr=pyrrolidinyl) to tetrahomoleptic NPC complexes of neptunium and cerium ( 1‐M , 2‐M , M=Np, Ce) and present comparative structural, electrochemical, and theoretical studies of these complexes. Large cathodic shifts in the M 4+/3+ (M=Ce, U, Np) couples underpin the stabilization of higher metal oxidation states owing to the strongly donating nature of the NPC ligands, providing access to the U 5+/4+ , U 6+/5+ , and to an unprecedented, well‐behaved Np 5+/4+ redox couple. The differences in the chemical redox properties of the U vs . Ce and Np complexes are rationalized based on their redox potentials, degree of structural rearrangement upon reduction/oxidation, relative molecular orbital energies, and orbital composition analyses employing density functional theory.

Otte, Kaitlyn S.↗
DOE OSTI2023

Divergent Stabilities of Tetravalent Cerium, Uranium, and Neptunium Imidophosphorane Complexes

The study of the redox chemistry of mid-actinides (U–Pu) has historically relied on cerium as a model, due to the accessibility of trivalent and tetravalent oxidation states for these ions. Recently, dramatic shifts of lanthanide 4+/3+ non-aqueous redox couples have been established within a homoleptic imidophosphorane ligand framework. Herein we extend the chemistry of the imidophosphorane ligand (NPC=[N=P t Bu(pyrr) 2 ] – ; pyrr=pyrrolidinyl) to tetrahomoleptic NPC complexes of neptunium and cerium (1-M, 2-M, M=Np, Ce) and present comparative structural, electrochemical, and theoretical studies of these complexes. Large cathodic shifts in the M 4+/3+ (M=Ce, U, Np) couples underpin the stabilization of higher metal oxidation states owing to the strongly donating nature of the NPC ligands, providing access to the U 5+/4+ , U 6+/5+ , and to an unprecedented, well-behaved Np 5+/4+ redox couple. Furthermore, the differences in the chemical redox properties of the U vs. Ce and Np complexes are rationalized based on their redox potentials, degree of structural rearrangement upon reduction/oxidation, relative molecular orbital energies, and orbital composition analyses employing density functional theory.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗