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At least 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Efficient Construction of a C 60 Interlayer for Mechanically Robust, Dendrite-free, and Ultrastable Solid-State Batteries

Interfacial instability between solid electrolytes (SEs) and lithium metal remains a daunting challenge for solid-sate batteries. Here, a conformal C 60 interlayer is efficiently constructed on Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP) SEs by physical vapor deposition, and an ideal interfacial contact is achieved via forming an ionically conducting matrix of LixC60 with lithium metal. The obtained Li x C 60 is beneficial to hinder the growth of lithium dendrites at interface and release the local stress during the lithiation and delithiation. As a result, the Li/LAGP-C 60 /Li symmetric cells demonstrate ultra-stable cycling performance for more than 4,500 h at a current density of 0.034 mA cm -2 . The Li/LAGP-C 60 /LiFePO 4 full cells deliver a reversible capacity of 152.4 mAh g -1 at room temperature, and the capacity retention rate is 85% after more than 100 cycles. This work provides a feasible and scalable strategy to improve the SEs/Li interface for high-performance solid-state batteries.

25 ENERGY STORAGE↗
DOE OSTI2015

An algebraic method for constructing stable and consistent autoregressive filters

In this paper, we introduce an algebraic method to construct stable and consistent univariate autoregressive (AR) models of low order for filtering and predicting nonlinear turbulent signals with memory depth. By stable, we refer to the classical stability condition for the AR model. By consistent, we refer to the classical consistency constraints of Adams–Bashforth methods of order-two. One attractive feature of this algebraic method is that the model parameters can be obtained without directly knowing any training data set as opposed to many standard, regression-based parameterization methods. It takes only long-time average statistics as inputs. The proposed method provides a discretization time step interval which guarantees the existence of stable and consistent AR model and simultaneously produces the parameters for the AR models. In our numerical examples with two chaotic time series with different characteristics of decaying time scales, we find that the proposed AR models produce significantly more accurate short-term predictive skill and comparable filtering skill relative to the linear regression-based AR models. These encouraging results are robust across wide ranges of discretization times, observation times, and observation noise variances. Finally, we also find that the proposed model produces an improved short-time prediction relative to the linear regression-based AR-models in forecasting a data set that characterizes the variability of the Madden–Julian Oscillation, a dominant tropical atmospheric wave pattern.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

The construction of arbitrary order ERKN methods based on group theory for solving oscillatory Hamiltonian systems with applications

In general, extended Runge–Kutta–Nyström (ERKN) methods are more effective than traditional Runge–Kutta–Nyström (RKN) methods in dealing with oscillatory Hamiltonian systems. However, the theoretical analysis for ERKN methods, such as the order conditions, the symplectic conditions and the symmetric conditions, becomes much more complicated than that for RKN methods. Therefore, it is a bottleneck to construct high-order ERKN methods efficiently. In this paper, we first establish the ERKN group Ω for ERKN methods and the RKN group G for RKN methods, respectively. We then rigorously show that ERKN methods are a natural extension of RKN methods, that is, there exists an epimorphism η of the ERKN group Ω onto the RKN group G. This epimorphism gives a global insight into the structure of the ERKN group by the analysis of its kernel and the corresponding RKN group G. Meanwhile, we establish a particular mapping φ of G into Ω so that each image element is an ideal representative element of the congruence class in Ω. Furthermore, an elementary theoretical analysis shows that this map φ can preserve many structure-preserving properties, such as the order, the symmetry and the symplecticity. From the epimorphism η together with its section φ, we may gain knowledge about the structure of the ERKN group Ω via the RKN group G. In light of the theoretical analysis of this paper, we obtain high-order structure-preserving ERKN methods in an effective way for solving oscillatory Hamiltonian systems. Numerical experiments are carried out and the results are very promising, which strongly support our theoretical analysis presented in this paper.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Design and construction of porous metal-organic frameworks based on flexible BPH pillars

Three metal-organic frameworks (MOFs), [Co{sub 2}(BPDC){sub 2}(4-BPH){center_dot}3DMF]{sub n} (1), [Cd{sub 2}(BPDC){sub 2}(4-BPH){sub 2}{center_dot}2DMF]{sub n} (2) and [Ni{sub 2}(BDC){sub 2}(3-BPH){sub 2} (H{sub 2}O){center_dot}4DMF]{sub n} (3) (H{sub 2}BPDC=biphenyl-4,4 Prime -dicarboxylic acid, H{sub 2}BDC=terephthalic acid, BPH=bis(pyridinylethylidene)hydrazine and DMF=N,N Prime -dimethylformamide), have been solvothermally synthesized based on the insertion of heterogeneous BPH pillars. Framework 1 has 'single-pillared' MOF-5-like motif with inner cage diameters of up to 18.6 A. Framework 2 has 'double pillared' MOF-5-like motif with cage diameters of 19.2 A while 3 has 'double pillared' 8-connected framework with channel diameters of 11.0 A. Powder X-ray diffraction (PXRD) shows that 3 is a dynamic porous framework. - Graphical abstract: By insertion of flexible BPH pillars based on 'pillaring' strategy, three metal-organic frameworks are obtained showing that the porous frameworks can be constructed in a much greater variety. Highlights: Black-Right-Pointing-Pointer Frameworks 1 and 2 have MOF-5 like motif. Black-Right-Pointing-Pointer The cube-like cages in 1 and 2 are quite large, comparable to the IRMOF-10. Black-Right-Pointing-Pointer Framework 1 is 'single-pillared' mode while 2 is 'double-pillared' mode. Black-Right-Pointing-Pointer PXRD and gas adsorption analysis show that 3 is a dynamic porous framework.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Synthesis, structures of four coordination compounds constructed from o-methacrylamidobenzoic acid and their relationship between structure and solid state luminescence

Four new coordination compounds, namely, Zn(o-MAABA){sub 2}(Phen) (1), [Cd(o-MAABA){sub 2}·2H{sub 2}O]{sub 2} (2), ([Pb{sub 2}Cl{sub 2}(o-MAABA){sub 2}(Phen){sub 4}])·2H{sub 2}O (3·2H{sub 2}O), [Pb(NO{sub 3})(o-MAABA)(Phen)]{sub n} (4), where o-MAABA=o-methacrylamidobenzoic acid and phen=1, 10-phenanthroline, have been synthesized. All compounds were fully confirmed by FT-IR, elemental analysis and TGA analysis. Their structures were determined by single crystal X-ray diffraction, in which compound 1 shows a mononuclear structure, compounds 2 and 3 have binuclear structures and compound 4 shows an infinite chain. In 2 and 4, the adjacent chains are extended into a 3D supramolecular architecture via π–π interactions. Solid-state room temperature luminescence spectra revealed that emission bands of compound 1 were located at 524 nm (λ{sub ex}=352 nm) and compound 4 at 479 and 584 nm (λ{sub ex}=390 nm) assigned to the excimer formation. The emission at 454 nm (λ{sub ex}=340 nm) of compound 2 was mainly ascribed to the Ligand–Metal Charge Transfer (LMCT). - Graphical abstract: Four coordination compounds constructed by o-methacrylamidobenzoic, phenanthroline and metal ions are reported. The photoluminescent properties is studied, which is affected by the molecular stacking and LMCT.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Five new Mn(II)/Co(II) coordination polymers constructed from flexible multicarboxylate ligands with varying magnetic properties

Five new Mn(II)/Co(II) coordination polymers [Mn{sub 2}(Adi){sub 2}(DMA)]{sub n} (1), [Mn{sub 2}(Adi){sub 2}(DMF)]{sub n} (2), [Mn{sub 4}(Adi){sub 4}(DMF){sub 2}]{sub n} (3), [Co{sub 4}(Adi){sub 4}(DMF){sub 2}]{sub n} (4) and ([Co{sub 3}(Cit){sub 2}(H{sub 2}O){sub 3}]·(H{sub 2}O)){sub n} (5) [Adi=adipate anion, Cit=citrate anion, DMA=N,N′-dimethylacetamide and DMF=N,N′-dimethylformamide] have been successfully constructed from two flexible multicarboxylate ligands under solvothermal conditions. Complexes 1 and 2 exhibit 2-D network featured 1-D Mn{sup II} chain, 3 and 4 are 3-D frameworks containing different 1-D carboxylate–metal chain, while 5 shows a 3-D structure based on Co{sub 6} wheel clusters. Magnetic investigations indicate antiferromagnetic behaviors for 1–4 and weak ferromagnetic behavior for 5 because of distinct linkage modes of metal ions. - Graphical abstract: Five new Mn(II)/Co(II) coordination polymers display 2-D/3-D structures containing 1-D carboxylate–metal chains or wheel clusters. Magnetic analyses reveal that they show antiferromagnetic, canted antiferromagnetic and weak ferromagnetic behaviors, respectively. Highlights: ●Five new Mn(II)/Co(II) coordination polymers have been synthesized. ●A complex-based Co{sub 6} wheel cluster was obtained. ●The different magnetic properties of the complexes are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Two new coordination polymers constructed by naphthalene-1,4-dicarboxylic acid and 2,4-diamino-6-methyl-triazine

Two new transition metal coordination complexes, ([MnO(nda)](H{sub 2}dmt)(H{sub 2}O)){sub n} (1), [Ag{sub 5}(nda){sub 2.5}(dmt)]{sub n} (2), (H{sub 2}nda=naphthalene-1,4-dicarboxylic acid, dmt=2,4-diamine-6-methyl-1,3,5-triazine) have been hydrothermally synthesized by the reactions of H{sub 2}nda and dmt with the homologous MnCl{sub 2}·4H{sub 2}O and AgNO{sub 3}, respectively, and characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis, thermogravimetric analysis (TGA). The compound 1 exhibits a 3D network comprising 1D metal chain (MnO(CO{sub 2}){sub 2}){sub n} connected by the ligand nda{sup 2−}, featuring a four-connected uninodal diamond -like topology. In compound 2, it is firstly observed that decanuclear silver units as secondary building units to construct 3D network by the ligands dmt and nda{sup 2−}, with a rare 2-nodal (3,8)-connected tfz-d topology ((4{sup 3}){sub 2}(4{sup 6}.6{sup 18}.8{sup 4})). The interactions within each Mn(II)—Mn(II) pair of compound 1 are antiferromagnetic (g=2.07, J=−1.42(1) cm{sup −1}, zj′=−0.73(2) cm{sup −1}). In addition, compound 2 exhibits photoluminescent property at about 472 nm (λ{sub ex}=394 nm). - Graphical abstract: Two new transition metal coordination complexes 1–2 have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis thermogravimetric analysis (TGA). Highlights: • The compound 1 exhibits a 3D network with four-connected uninodal diamond-like topology. • The first 3D network of 2 with a rare tfz-d topology consists of decanuclear silver clusters as secondary building units. • The magnetic measurement indicates the compound 1 shows antiferromagnetic interactions. • The photoluminescent property of 2 has been measured.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

([M(NH{sub 3}){sub 6}][Ag{sub 4}M{sub 4}Sn{sub 3}Se{sub 13}]){sub ∞} (M=Zn, Mn): Three-dimensional chalcogenide frameworks constructed from quaternary metal selenide clusters with two different transition metals

Herein we report solvothermal syntheses of two new three-dimensional chalcogenide frameworks ([M(NH{sub 3}){sub 6}][Ag{sub 4}M{sub 4}Sn{sub 3}Se{sub 13}]){sub n} (M=Zn (1), Mn (2)), which consist of quaternary metal selenide clusters with two different transition metals. The compounds represent the first Ag–Zn/Mn–Sn–Se based quaternary anionic frameworks. The optical studies show that the band gaps for 1 and 2 are 2.09 eV and 1.71 eV, respectively. Moreover, the photoelectrochemical study indicates that compound 1 displays n-type semiconducting behaviour and is photoactive under visible light illumination (λ>400 nm). - Graphical abstract: Two 3D framework selenides, [M(NH{sub 3}){sub 6}][Ag{sub 4}M{sub 4}Sn{sub 3}Se{sub 13}] (M=Zn (1), Mn (2)), constructed from quaternary metal selenide clusters, have been solvothermally synthesized and are photoactive under visible light illumination. - Highlights: • Two new three-dimensional selenide frameworks. • Quaternary metal selenide clusters with two different transition metals. • Photoelectrochemical study.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Hydrothermal synthesis, crystal structure and properties of a novel chain coordination polymer constructed by tetrafunctional phosphonate anions and cobalt ions

A novel cobalt phosphonate, [Co(HL)(H{sub 2}O){sub 3}]{sub n} (1) (L=N(CH{sub 2}PO{sub 3}H){sub 3}{sup 3−}) has been synthesized by hydrothermal reaction at 150 °C and structurally characterized by X-ray diffraction, infrared spectroscopy, elemental and thermogravimetric analysis. Complex 1 features a 1D chain structure with double-channel built from CoO{sub 6} octahedra bridged together by the phosphonate groups. Each cobalt ion is octahedrally coordinated by three phosphonate oxygen atoms and three water molecules. The coordinated water molecules can form the hydrogen bonds with the phosphonate oxygen atoms to link the 1D chains, building a 2D layered structure, further resulting in a 3D network. The luminescence spectrum indicates an emission maximum at 435 nm. The magnetic susceptibility curve exhibits a dominant antiferromagnetic behavior with a weakly ferromagnetic component at low temperatures. - Graphical abstract: The connectivity between cobalt ions and the ligands results in a chain structure with a 1D double-channel structure, which is constructed by A-type subrings and B-type subrings. - Highlights: • The tetrafunctional phosphonate ligand was used as the ligand. • A novel chain structure can be formed by A-type rings and B-type rings. • Two types of rings can form a 1D double-channel structure, along the c-axis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

A series of Zn/Cd coordination polymers constructed from 1,4-naphthalenedicarboxylate and N-donor ligands: Syntheses, structures and luminescence sensing of Cr{sup 3+} in aqueous solutions

A novel series of Zn/Cd coordination polymers based on H{sub 3}L, namely, [Zn{sub 2}(HL){sub 2}(bipy){sub 2}(H{sub 2}O){sub 6}]{sub n} (1), [Zn(HL)(phen)]{sub n} (2), [Cd{sub 3}L{sub 2}(bbi){sub 3}]{sub n} (3), [Zn{sub 3}L{sub 2}(bbi){sub 3}]{sub n} (4) [(H{sub 3}L =4-[(1-carboxynaphthalen-2-yl)oxy]phthalic acid, bipy =4,4′-bipyridine, phen =1,10-phenanthroline, bbi =1,1′-(1,4-butanediyl)bis(imidazole] have been successfully synthesized by solvothermal reaction. Compound 1 possesses two diverse 1D chains constructed by different bipy coligands, which were further connected to form a 3D supramolecular architecture by hydrogen bonding interactions. Compound 2 possesses a complicated 1D chain based on secondary building unit (SBU) with binuclear Zn cluster. Compounds 3 and 4 exhibit similar 2D→3D framework, which can be rationalized as (3,4,4)-connected 3D net with a Schläfli symbol of (6{sup 3}.8.10{sup 2}){sub 2}(6{sup 3}){sub 2}(6{sup 4}.8.10). In particular, compound 3 exhibited a high sensitivity for Cr{sup 3+} in aqueous solutions, which suggest that compound 3 is a promising luminescent probe for selectively sensing Cr{sup 3+}. - Graphical abstract: A series of novel Zn/Cd coordination polymers have been successfully synthesized by solvothermal reaction. The unique 3D Cd{sup 2+} polymer containing bbi as second ligand demonstrates high sensitivity for detection of toxic Cr{sup 3+} in aqueous solutions. Display Omitted - Highlights: • π-conjugated semirigid tricarboxylate ligands with naphthalene rings(H{sub 3}L) were rationally designed. • Four Zn/Cd coordination polymers based on H{sub 3}L have been successfully synthesized by solvothermal reaction. • Compound 3 is a promising luminescent probe for selectively sensing Cr{sup 3+} with high sensitivity in aqueous solutions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

A series of coordination polymers constructed from R-isophthalic acid (R=–SO{sub 3}H, –NO{sub 2}, and –OH) and N-donor ligands: Syntheses, structures and fluorescence properties

Six novel Zn(II), Cd(II), and Cu(II) mixed-ligand coordination complexes, namely, [Zn{sub 2}Na(sip){sub 2}(bpp){sub 3}(Hbpp)(H{sub 2}O){sub 2}]·8H{sub 2}O (1), [Cd{sub 3}(sip){sub 2}(nbi){sub 6}(H{sub 2}O){sub 2}]·7H{sub 2}O (2), [Zn(sip)(nbi){sub 2}(H{sub 2}O)]·Hnbi·3H{sub 2}O (3), [Cd(hip)(nbi){sub 2}(H{sub 2}O)]·nbi·5H{sub 2}O (4), [Cd{sub 2}(nip){sub 2}(nbi){sub 2}(H{sub 2}O){sub 2}]·DMF (5), and [Cu(nip)(nbi)(H{sub 2}O){sub 2}]·H{sub 2}O (6) (H{sub 3}sip=5-sulfoisophthalic acid, H{sub 2}hip=5-hydroxylisophthalic acid, H{sub 2}nip=5-nitroisophthalic acid, bpp=1,3-bis(4-pyridyl)propane, and nbi=6-nitrobenzimidazole) have been synthesized hydrothermally by the self-assembly of R-isophthalic acid (R=–SO{sub 3}H, –NO{sub 2}, and –OH) and N-donor ligands. Single crystal X-ray analyses reveal that two Zn(II) ions and one Na(I) ion of complex 1 are linked through O atoms to generate a 1D linear chain. Then the 2D supramolecular architectures are constructed via intermolecular interactions. In complex 2, the Cd1 ions are connected by bridging carboxyl groups from sip{sup 3−} anions to form 1D double chain, which are further connected by Cd2 ions to afford 2D layer structure. The adjacent 2D layers are further linked via hydrogen-bonding interactions to give 3D supramolecular network. Compounds 3–5 show 1D chain structures, which are assembled into 2D or 3D supramolecular frameworks via weak interactions. In compound 6, the Cu(II) ions are bridged by the nip{sup 2−} ligands to form 48-membered ring, which is assembled into 1Dchain via the π-π stacking interaction. In addition, the thermal stabilities and fluorescence properties of these compounds have also been studied. - Graphical abstract: A series of Cd(II)/Zn(II)/ Cu(II) coordination polymers based on R-isophthalic acid (R=–SO{sub 3}H, –NO{sub 2}, and –OH) and N-donor ligands have been synthesized under hydrothermal conditions and structurally characterized. Photoluminescent properties have been discussed. - Highlights: • Six coordination polymers were synthesized based on mixed-ligand strategy. • The polycarboxylate acids play a crucial role in determining the final structures. • Each complex shows diverse structures and different supramolecular interactions.

36 MATERIALS SCIENCE↗
DOE OSTI2017

A family of entangled coordination polymers constructed from a flexible V-shaped long bicarboxylic acid and auxiliary N-donor ligands: Luminescent sensing

Eight Zn(II)-based coordination polymers, namely, [Zn{sub 2}L{sub 2}(2,2’-bipy)]{sub n}·nH{sub 2}O (1), [Zn{sub 2}L{sub 2}(phen)]{sub n}·nH{sub 2}O (2), [ZnL(phen)(H{sub 2}O)]{sub n} (3), [Zn{sub 3}L{sub 3}(4,4’-bipy)]{sub n} (4), [Zn{sub 2}L{sub 2}(4,4’-bipy){sub 2}]{sub n} [Zn{sub 2}L{sub 2}(H{sub 2}O){sub 2}]{sub n}·2nH{sub 2}O (5), [Zn{sub 4}L{sub 4}(bpp){sub 2}]{sub n} (6), [ZnL(bbi){sub 0.5}]{sub n} (7), [ZnL(bpz)]{sub n} (8) (H{sub 2}L=4,4’-([1,2-phenylenebis-(methylene)]bis(oxy))dibenzoic acid, 2,2’-bipy =2,2’-bipyridine, phen =1,10-phenanthroline, 4,4’-bpy=4,4’-bipyridine, bpp =1,3-bis(4-pyridyl)propane, bbi=1,4-bis(imidazol-1-yl)butane, bpz=3,3′,5,5′-tetramethyl-4,4′-bipyrazole), have been hydrothermally synthesized and structurally characterized. 1–8 display various coordination motifs with different entangled forms and conformations due to the effect of the assistant N-donor ligands. The photoluminescent properties of compounds 1–8 in solid state were studied. Interestingly, 3 exhibits highly efficient luminescent sensing for Cu{sup 2+} cations and CrO{sub 4}{sup 2-} anions, as well as detection ability for the different organic solvents and nitro explosives. These results indicated that it could be utilized as a multi-responsive luminescent sensor. Furthermore, compound 3 also shows good chemical resistance to both acidity and alkalinity solutions with pH ranging from 2 to 13. Thus, multi-photofunctionality and fluorescent response to pH have been combined in the 3, which is the first example in the Zn-based hybrid materials. - Graphical abstract: Eight new Zn(II)-based coordination polymers constructed from a flexible V-shaped long bicarboxylic acid and different N-donor ligands have been hydrothermally synthesized through fixing the metal salts and the solvent systems. The photoluminescent properties of complexes 1−8 in solid state were studied. Interestingly, 3 exhibits highly efficient luminescent sensing for Cu{sup 2+} cations and CrO{sub 4}{sup 2-} anions, as well as detection ability for the different organic solvents and nitro explosives, in which indicates it could be utilized as a multi-responsive luminescent sensor. Furthermore, compound 3 also shows good chemical resistance to both acidity and alkalinity solutions with pH ranging from 2 to 13. Thus, multiphotofunctionality and fluorescent response to pH have been combined in the 3, which is the first example in the Zn-based hybrid materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Syntheses, structures, and luminescence of a series of novel trimetallic coordination polymers constructed by Cu-I clusters and alkaline-carboxyl- alkaline-earth building units

Seven novel trimetallic coordination polymers, namely, [Li{sub 2}SrCu{sub 2}I{sub 2}(IN){sub 4}(DMF){sub 3}]{sub n}·nDMF (1), [LiSr{sub 2}Cu{sub 2}I{sub 2}(IN){sub 5}(DMF){sub 2}]{sub n} (2), [NaSr{sub 2}Cu{sub 2}I{sub 2}(IN){sub 4}(NO{sub 3})(DMF){sub 4}]{sub n}·nDMF·0.5nH{sub 2}O (3), [NaSr{sub 2}Cu{sub 2}I{sub 2}(IN){sub 5}(DMF){sub 4}]{sub n}·3nDMF·3nH{sub 2}O (4), [Li{sub 2}BaCu{sub 2}I{sub 2}(IN){sub 4}(DMF){sub 3}]{sub n}·nDMF (5), [Li{sub 2}Ba{sub 2}Cu{sub 2}I{sub 2}(IN){sub 4}(OAc){sub 2}(DMF){sub 3}]{sub n}·nDMF·0.5nH{sub 2}O (6), [Li{sub 2}Ba{sub 2}Cu{sub 2}I(IN){sub 7}(H{sub 2}O){sub 1.5}]{sub n}·0.5nH{sub 2}O (7) (IN = isonicotinic anion, DMF = N, N-dimethylformamide) have been synthesized via solvothermal method. All of the coordination polymers were characterized by single-crystal X-ray diffraction, FT-IR spectroscopy, elemental analysis and thermogravimetric analysis. Single-crystal X-ray diffraction determinations revealed that compounds 1–7 were three dimensional frameworks. Compounds 1–6 were assembled by Cu{sub 2}I{sub 2} units and different alkaline-carboxyl- alkaline-earth rod building units with different topologies; while, compound 7 was constructed by Cu{sub 2}I units and alkaline-carboxyl- alkaline-earth honeycomb layers. The photoluminscent investigations revealed that the compounds 1, 3, 5 and 6 emitted strong yellow, while compounds 2, 4 and 7 emitted strong orange light.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Construction of reduced graphene oxide supported molybdenum carbides composite electrode as high-performance anode materials for lithium ion batteries

Highlights: • Reduced graphene oxide supported molybdenum carbides are prepared by two-step strategy. • A unique sheet-on-sheet integrated nanostructure is favorable for fast ion/electron transfer. • The integrated electrode shows excellent Li ion storage performance. - Abstract: Metal carbides are emerging as promising anodes for advanced lithium ion batteries (LIBs). Herein we report reduced graphene oxide (RGO) supported molybdenum carbides (Mo{sub 2}C) integrated electrode by the combination of solution and carbothermal methods. In the designed integrated electrode, Mo{sub 2}C nanoparticles are uniformly dispersed among graphene nanosheets, forming a unique sheet-on-sheet integrated nanostructure. As anode of LIBs, the as-prepared Mo{sub 2}C-RGO integrated electrode exhibits noticeable electrochemical performances with a high reversible capacity of 850 mAh g{sup −1} at 100 mA g{sup −1}, and 456 mAh g{sup −1} at 1000 mA g{sup −1}, respectively. Moreover, the Mo{sub 2}C-RGO integrated electrode shows excellent cycling life with a capacity of ∼98.6 % at 1000 mA g{sup −1} after 400 cycles. Our research may pave the way for construction of high-performance metal carbides anodes of LIBs.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Nanoparticles-constructed spinel ZnFe2O4 anode material with superior lithium storage performance boosted by pseudocapacitance

Highlights: • Nanoparticles-constructed ZnFe{sub 2}O{sub 4} was fabricated by co-precipitation method. • The ZnFe{sub 2}O{sub 4} sample shows excellent high rate capability and cycling stability. • The lithium storage mechanism was analyzed by CV and EIS measurements. • Pseudocapacitive effect has a significant contribution to the total stored charge. - Abstract: The practical application of ZnFe{sub 2}O{sub 4} in lithium ion batteries (LIBs) is severely hampered by its fast capacity fading and poor rate performance. To overcome these issues, herein, ZnFe{sub 2}O{sub 4} powders consist of aggregated nanoparticles (50∼100 nm) with porosity were prepared by a facile co-precipitation method and subsequent thermal decomposition. When used as anode material for LIBs, the ZnFe{sub 2}O{sub 4} sample delivers capacities of 920, 820, 650, 485, and 421 mA h g{sup −1} at current densities of 0.5, 1, 3, 7, and 10 A g{sup −1}, respectively. Moreover, the sample can maintain a capacity of 814 mA h g{sup −1} even after 300 cycles at the current density of 1 A g{sup −1}, implying an excellent rate capability and cycling stability. Cyclic voltammetry analysis reveals that both diffusion-controlled lithium storage and surface pseudocapacitive lithium storage contribute to the total stored charge of ZnFe{sub 2}O{sub 4}, which boosts the high rate capability and superior cycling stability of the ZnFe{sub 2}O{sub 4}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Construction of N-doped TiO2/MoS2 heterojunction with synergistic effect for enhanced visible photodegradation activity

Highlights: • An N-doped TiO{sub 2}/MoS{sub 2} heterojunction is successfully synthesized by a hydrothermal method. • N-doped TiO{sub 2}/MoS{sub 2} heterojunction photocatalyst exhibits enhanced visible photodegradation activity. • The synergistic effect is between N-doping and coupling with MoS{sub 2}. • Superoxide radicals (O{sub 2}{sup −}) and photogenerated holes (h{sup +}) are chiefly responsible for the degradation process. - Abstract: An N-doped TiO{sub 2}/MoS{sub 2} heterojunction photocatalyst constructed by two-dimension MoS{sub 2} nanosheets and N-doped TiO{sub 2} nanoparticles was successfully synthesized by a hydrothermal method. The synthesized N-TiO{sub 2}/MoS{sub 2} composites were characterized by XRD, XPS, TEM, UV–vis DRS and PL, and its visible photocatalytic activity was evaluated by degradation of methylene blue. The results showed that N-doped TiO{sub 2}/MoS{sub 2} heterojunction photocatalyst achieved more enhanced photocatalytic activity compared with pure TiO{sub 2}, MoS{sub 2} and N-doped TiO{sub 2} for degradation of MB. Trapping tests with different scavengers indicated that not hydroxyl radicals (OH) but superoxide radicals (O{sub 2}{sup −}) and photogenerated holes (h{sup +}) were highly responsible for the degradation process. The reusable experiments showed that the prepared N-doped TiO{sub 2}/MoS{sub 2} heterojunction photocatalyst was stable during the photodegradation of MB and will have practical applications for environmental remediation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

An efficient construction of nano-interfaces for excellent coking tolerance of cermet anodes

Solid oxide fuel cells (SOFCs) are promising energy conversion devices for the effective and convenient utilization of hydrocarbons (for example, methane) to electricity. However, the development of direct methane SOFCs is primarily hindered by the poor coking tolerance of the state-of-the-art Ni-based cermet anodes. Herein, we efficiently construct nano-interfaces in the anode by infiltrating a Ni 0.6 Y 0.064 Zr 0.336 O 2-δ (NYZ) catalyst onto the traditional Ni-based cermet anode to effectively enhance the coking tolerance. After being reduced in H 2 , Ni and Y 0.16 Zr 0.84 O 2-δ (YSZ) nanoparticles (NPs) are in situ formed on the surface of the Ni-YSZ substrate. The roughened anode demonstrates significantly improved fuel oxidation activity and coking tolerance, due likely to the formation of nano-interfaces. Specifically, when applied in the Ni-YSZ-based anode-supported SOFCs, a high peak power density of 1.785 W cm –2 and a stable operation of ~ 240 h with no observable degradation is achieved at 750 °C in nearly dry methane (3% H 2 O). Finally, a density functional theory study suggests that the excellent coking tolerance is attributed to the formation of OH species on Ni/YSZ nano-interfaces, which would further interact with intermediate carbon species to generate COH intermediates.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Enhanced long-term cyclability in Li-Rich layered oxides by electrochemically constructing a Li x TM 3-x O 4 -type spinel shell

The poor long-term cycling stability, including the fast capacity fade and the severe voltage decay, has become the main concern hindering the practical application of Li-rich layered oxides, a promising cathode for high- energy-density Li-ion battery. Herein, we design and electrochemically construct a ~10 nm-thick Li x TM 3-x O 4 - type (TM ¼Ni, Co, Mn, 0 3 O 4 -type spinel phase and the good Liþconductivity of LiMn 2 O 4 -type spinel phase. Systemic structural and electrochemical analysis demonstrate that, it slows down the activation rate of Li 2 MnO 3 component and efficiently alleviates the lattice O loss at high voltage (>4.5 V) and Mn dissolution, thereby suppressing the structural degradation from the layered phase to the spinel phase in the bulk, eventually significantly enhancing the long-term cycling stability. This study adds richness into the Mn-based spinel phase system and provides a new heterostructure design strategy to improve the electrochemical performance of Li-rich layered cathodes and beyond.

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