Introducing hydroxyl groups to tailor the d-band center of Ir atom through side anchoring for boosted ORR and HER

Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts.Herein,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of hydrogen-substituted graphdiyne(HsGDY),and coordinated with OH as an Ir atomic catalyst(Ir_(1)-N-HsGDY).The electron structures,especially the d-band center of Ir atom,are optimized by these specific coordination atoms.Thus,the as-synthesized Ir_(1)-N-HsGDY exhibits excellent electrocatalytic performances for oxygen reduction and hydrogen evolution reactions in both acidic and alkaline media.Benefiting from the unique structure of HsGDY,IrN_(2)(OH)_(3) has been developed and demonstrated to act as the active site in these electrochemical reactions.All those indicate the fresh role of the sp-N in graphdiyne in producing a new anchor way and contributing to promote the electrocatalytic activity,showing a new strategy to design novel electrochemical catalysts.

Engineering hierarchical quaternary superstructure of an integrated MOF-derived electrode for boosting urea electrooxidation assisted water electrolysis

Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary structure.Notably,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical NiCo-LDH.Employing NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of OER.This work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.

Synthesis and Structural Characterization of a New Cadmium(II) Complex with a Double Betaine

A new flexible double betaine L (L = 1,4-bis(pyridinio-4-carboxylato-N-methyl)- benzene, C20H16N2O4) and its cadmium(II) complex [Cd(H2O)4L(NO3)]NO3?H2O 1 were synthe- sized. Complex 1 was obtained by self-assembly reaction of [Cd(NO3)2]?4H2O and L in hot water, and its crystal structure was determined by single-crystal X-ray diffraction analysis. Crystallo- graphic data for complex 1: C20H24CdN4O14?H2O, Mr = 674.85, monoclinic, space group P21/c, a = 13.7854(3), b = 14.2820(3), c = 14.9188(4) ?, β = 116.418(1)o, V = 2630.5(1) ?3, Z = 4, Dc = 1.704 g/cm3, μ(MoKα) = 0.911 mm-1, F(000) = 1368, the final R = 0.0315 and wR = 0.0768 for 3637 observed reflections with I > 2σ(I). In complex 1, L acts as a monodentate ligand to link a Cd(II) ion in a novel coordination mode of double betaines. The mononuclear [Cd(H2O)4L(NO3)] units are connected through intermolecular hydrogen bonds and π-π stacking reactions to generate a 3D network.

Prediction of the Frontier Electronic States in a Finite Single-wall Carbon Nanotube

A theoretical model is summarized into the shorter vector principle. It is used to predict the topological structure of wave function and the oscillation rule of energy gap in various types of finite carbon nanotubes (CNTs). The theoretical model indicates that the characteristics of the electronic states only depend on the nanotube size and its symmetry along the shorter vector direction. In this direction, the wave functions of the original 3m (or 3m/2) periodicity are also suitable for armchair, chiral and zigzag finite CNTs with the C2 (Cs), C1 and Cn point groups, respectively. Energy gaps present the oscillation with 3m (or 3m/2) or odd-even n. The first principle calculations for some prototype systems are performed. The results are consistent with the theoretical model.

A Novel 3D Extended Network Cobalt Paradodecatungstate:Synthesis,Characterization and Crystal Structure of [Co(H_2O)_5]_2[Co(H_2O)_4]_3[H_2W_(12)O_(42)]·11H_2O

A cobalt paradodecatungstate [Co(H2O)5]2[Co(H2O)4]3[H2W12O42]·11H2O has been successfully synthesized and structurally characterized by X-ray crystallography. Structure analysis indicates that the title compound is of monoclinic, space group P21/n, with a = 13.449(3), b = 19.585(4), c = 13.990(3) , β = 113.79(3)°, V = 3371.8(12) ?3, Z = 2, R = 0.0519 and wR = 0.1242. The title compound exhibits a novel 3D extended network structure constructed by interconnecting the paradodecatungstate polyanion [H2W12O42]10- clusters and cobaltII coordination ions.

Structural engineering of cathodes for improved Zn-ion batteries

Aqueous zinc-ion batteries(ZIBs) are attracting considerable attention because of their low cost,high safety and abundant anode material resources.However,the major challenge faced by aqueous ZIBs is the lack of stable and high capacity cathode materials due to their complicated reaction mechanism and slow Zn-ion transport kinetics.This study reports a unique 3 D ’flower-like’ zinc cobaltite(ZnCo_(2)O_(4-x)) with enriched oxygen vacancies as a new cathode material for aqueous ZIBs.Computational calculations reveal that the presence of oxygen vacancies significantly enhances the electronic conductivity and accelerates Zn^(2+) diffusion by providing enlarged channels.The as-fabricated batteries present an impressive specific capacity of 148.3 mAh g^(-1) at the current density of 0.05 A g^(-1),high energy(2.8 Wh kg^(-1)) and power densities(27.2 W kg^(-1)) based on the whole device,which outperform most of the reported aqueous ZIBs.Moreover,a flexible solid-state pouch cell was demonstrated,which delivers an extremely stable capacity under bending states.This work demonstrates that the performance of Zn-ion storage can be effectively enhanced by tailoring the atomic structure of cathode materials,guiding the development of low-cost and eco-friendly energy storage materials.

Research progress in electrospinning engineering for all-solid-state electrolytes of lithium metal batteries

Owing to safety issue and low energy density of liquid lithium-ion batteries(LIBs),all-solid-state lithium metal batteries(ASLMBs)with unique all-solid-state electrolytes(SEs)have attracted wide attentions.This arises mainly from the advantages of the SEs in the suppression of lithium dendrite growth,long cycle life,and broad working temperature range,showing huge potential applications in electronic devices,electric vehicles,smart grids,and biomedical devices.However,SEs suffer from low lithiumion conductivity and low mechanical integrity,slowing down the development of practical ASLMBs.Nanostructure engineering is of great efficiency in tuning the structure and composition of the SEs with improved lithium-ion conductivity and mechanical integrity.Among various available technologies for nanostructure engineering,electrospinning is a promising technique because of its simple operation,cost-effectiveness,and efficient integration with different components.In this review,we will first give a simple description of the electrospinning process.Then,the use of electrospinning technique in the synthesis of various SEs is summarized,for example,organic nanofibrous matrix,organic/inorganic nanofibrous matrix,and inorganic nanofibrous matrix combined with other components.The current development of the advanced architectures of SEs through electrospinning technology is also presented to provide references and ideas for designing high-performance ASLMBs.Finally,an outlook and further challenges in the preparation of advanced SEs for ASLMBs through electrospinning engineering are given.

Synthesis and Structural Characterization of a New Polyoxovanadium Borate: (H_3NCH_2CH_2NH_3)_4[(VO)_6(B_(10)O_(22))_2]·(H_3O)_7

The title compound (H3NCH2CH2NH3)4[(VO)6(B10O22)2]·(H3O)7 1 has been synthe- sized by the hydrothermal method and determined by X-ray crystallography. Crystallographic data: monoclinic, space group C2/c, a = 20.250(4), b = 13.448(3), c = 21.655(4) ?, β = 97.05(3)°, Mr = 851.74 (C4H30.5B10N4O28.5V3), V = 5852(2) ?3, Z = 8, Dc = 1.933 g/cm3, μ = 1.057 mm-1, F(000) = 3436, R = 0.0500 and wR = 0.1442 for 4511 observed reflections with I > 2σ(I). The structure con- sists of [(VO)6(B10O22)2]15- cluster anions that have a central band of six trans-edge-sharing VO5 square pyramids capped by two [B10O22]14- polyborate ligands. Other characterizations are also describ- ed by elemental analysis, IR spectrum and thermal analysis.

Synthesis and Structural Characterization of [Mn(sapn)(H_2O)_2]Br

The crystal structure of the title compound [Mn(sapn)(H2O)2]Br (H2sapn = N,N?bis-(salicylidene)-1,3-diaminopropane) with formula C17H18N2O4MnBr and Mr = 449.18 has been determined by X-ray diffraction. The crystal is triclinic with space group P , a = 7.777(1), b = 10.459(2), c = 11.96(3), = 78.22(1), =75.16(8), = 86.80(5)? V = 919(3)3, Dc = 1.631g/cm3, F(000) = 456, = 2.917 cm-1 and Z = 2, with R = 0.0428 and wR = 0.1092 for 2427 reflections (I > 2s(I)). Two nitrogen and two oxygen atoms from the sapn group chelate to the MnⅢ ion, forming a distorted octahedral geometry together with two coordinated water molecules. A bromide anion exists outside as a counter ion.

Hydrothermal Synthesis, Structural Characterization and Proton-conducting Property of a 3-D Framework Based on Zr_3Na_3-Substituted Polyoxometalate Building Blocks

A novel Zr-substituted polyoxometalate(POM) H_2K_3[Na_6(H_2O)_9][Zr_3Na_3O_3(H_2O)_3-(GeW_9O_(34))_2]·12H_2O(1) has been made under hydrothermal conditions. 1 was characterized by infrared spectrum, thermogravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. Crystal data are: H_(50)O_(95)Na_9K_3Ge_2Zr_3W(1)_8, hexagonal space group P63/mmc, a = 15.2251(6), b = 15.2251(6), c = 25.035(2) ?, V = 5025.7(6) ?~3, Z = 2, D_c = 3.716 mg/m^3, μ = 21.648 mm^(-1), F(000) = 4726, the final R = 0.0259 and w R = 0.0647 for 1487 observed reflections with I > 2σ(I). Single-crystal X-ray structure analysis reveals that 1 exhibits a 3-dimensional framework structure based on Zr_3Na_3-substituted polyanions [Zr_3Na_3O_3(H_2O)3(GeW_9O_(34))_2]^(11-) and [Na_6(H_2O)_9]^(6+) clusters building blocks. UV-Vis spectrum indicates that 1 is a wide-gap semiconductor. In addition, the proton-conducting property of 1 was also investigated.

Hydrothermal Synthesis and Structural Characterization of two Hybrid Keggin-based Polyoxometalates

Two new hybrid polyoxotungstates,[Co(2,2′-bipy)3][α-H5PW11CoO40]·3H2O 1 and [Fe(2,2′-bipy)3]2[α-HBW12O40]·2.5H2O 2(2,2′-bipy = 2,2′-dipyridyl),have been hydrothermally synthesized and characterized by IR,TGA and single-crystal X-ray structural analyses.The results of X-ray crystallography analyses exhibit that 1 consists of one α-Keggin anion [α-H5PW11CoO40]2- and one isolated [Co(2,2′-bipy)3]2+ complex,while 2 is constructed from one α-Keggin anion [α-HBW12O40]4- and two isolated [Fe(2,2′-bipy)3]2+ cations.The data for 1:orthorhombic system,space group Pbcn,a = 16.062(6),b = 27.278(10),c = 16.951(6) ,V = 7427(5) 3 and Z = 4;and those for 2:triclinic system,space group P,a = 13.787(3),b = 17.857(5),c = 18.918(5) ,α = 88.009(12),β = 72.768(10),γ = 74.935(10)o,V = 4291(2) 3 and Z = 2.

Three Inorganic-organic Composite Polyoxotungstates:Syntheses,Characterization and Structures of [Cu(2,2ˊ-bpy)_2]_5[α-PW_(11.5)Cu_(0.5)O_(40)]·2H_2O,[Co(2,2ˊ-bpy)_2(N_3)_2]_4H_3[α-PW_(12)O_(40)]·3H_2O and [Cu(2,2ˊ-bpy)_2(4,4ˊ-bpy)]_2[α-GeW_(12)O_

Three new inorganic-organic composite polyoxotungstates [Cu(2,2ˊ-bpy)2]5[α-PW11.5Cu0.5O40]·2H2O 1, [Co(2,2ˊ-bpy)2(N3)2]4H3[α-PW12O40]·3H2O 2 and [Cu(2,2ˊ-bpy)2(4,4ˊ-bpy)]2[α-GeW12O40]·4H2O 3 (2,2ˊ-bpy = 2,2ˊ-bipyridine, 4,4ˊ-bpy = 4,4ˊ-bipyridine) have been hydrothermally synthesized and structurally characterized. 1 crystallizes in the orthorhombic space group Pna21 with a = 27.847(3), b = 21.597(2), c = 20.1179(19) , V = 12099(2) 3, Z = 4, GOF = 1.038, R = 0.0427 and wR = 0.1035; 2 belongs to the triclinic space group P1 with a = 12.31150(10), b = 16.1954(4), c = 19.36290(10) , α = 99.366(11), β =105.168(8), γ = 111.836(8)°, V = 3309.98(9) 3, Z = 1, GOF = 1.024, R = 0.0739 and wR = 0.2216; and 3 crystallizes in the monoclinic space group P21/n with a = 12.858(4), b = 20.943(6), c = 15.598(5) , β = 102.338(5)°, V = 4103(2) 3, Z = 2, GOF = 1.026, R = 0.0557 and wR = 0.1316. The common structural features of 1～3 are that their molecular structures all consist of a saturated α-Keggin polyoxoanion and several discrete metal-organic moieties. Intriguingly, 2 and 3 are composed of metal-organic coordination moieties with two mixed ligands.

Hydrothermal Synthesis, Crystal Structure and Magnetic Property of a Novel Mixed Valence Decatungstate: [Cu(2,2′-bipy)_2]_2Na_2W_6~VW4^(VI)O_(30)·2H_2O

A novel Cu(II)-2,2′-bipy-supported (bipy = bipyridine) mixed valence decatungstate, [Cu(2,2′-bipy)2]2Na2W6VW4VIO30·2H2O 1, has been synthesized and structurally characterized by X-ray analysis. The crystal of 1 is of triclinic, space group P1 with a = 10.9393(10), b = 12.0492(2), c = 12.3783(2) , α = 80.631(10), β = 70.226(10), γ = 72.329(9)°, V = 1459.64(4) 3, Z = 1, Dc = 3.582 g/cm3, F(000) = 1404, R = 0.0553 and wR = 0.1242 for 4607 observed reflections (I > 2σ(I)). The EPR spectrum of 1 indicates that its unpaired electrons are placed in the dx2-y2 orbital of the ground state of CuII. Furthermore, compound 1 shows an antiferromagnetic interaction.

Synthesis, Crystal Structure and Quantum Chemistry Calculation of a Bis(dafone) Di(dmf) Copper(Ⅱ) Complex

The title compound [Cu(dafone)2(DMF)2]?2ClO4 1 (dafone = 4,5-diazafluoren- 9-one, dmf = N,N?-dimethyl formamide) was synthesized by the reaction of Cu(ClO4 )2 and dafone in DMF solution at room temperature with pH = 3.0. The single-crystal X-ray analysis has revealed that 1 crystallizes in monoclinic, space group P21/n with a = 8.4853(8), b = 13.1520 (14), c = 14.3866(12) ?, β = 102.629(3)o, V = 1566.7(3) ?3, C28H26Cl2CuN6O12, Mr = 773.00, Z = 2, Dc = 1.639 g/cm3 , F(000) = 790, μ = 0.942 mm-1, the final R = 0.0438 and wR = 0.1214 for 3165 obser- ved reflections with I > 2σ(I). X-ray analysis shows that compound 1 has unsymmetric chelation of dafone with one Cu–N bond being much longer than the other. Coordination geometry of Cu is a highly distorted octahedron and the whole structure is stabilized by π-π stacking and static attractive forces from [ClO4]- anions. Based on the crystal data, quantum chemistry calculation at the DFT/ B3LPY level was used to reveal the electronic structure of 1.

DFT Study on the Electronic and Structural Properties of ReO_5^(-/0) Clusters

The electronic and structural properties of ReO5 and ReO5 clusters are investigated using density functional theory (DFT) calculations. The lowest energy structures for both the anionic and neutral clusters are determined, and the corresponding photoelectron spectrum is simulated. Our results show that ReO5 can be described as an unusual peroxo molecule, Re(O)3(η2-O2) , while ReO5 is found to be exhibiting the O2 o radical character. Molecular orbital analyses and spin density analyses are performed to elucidate the chemical bonding and the electronic and structural properties in these two rhenium oxide clusters.

Syntheses and Structural Characterizations of a Series of Capped Keggin Derivatives

Hydrothermal reactions of Na2 Mo O2·2H2O and NH4VO3(or V2O5) with appropriate reducing agents such as organic amines, NH2OH·HCl and Mo(CO)6 gave rise to the formation of a series of capped Keggin derivatives, [N(CH3)4]2Na3(NH4)2[(VVO4)MoVI8VIV4O36(VIVO)2]·-13H2O(1), [NH4]7[(VVO4)MoVI8VIV4O36(VIVO)2]·7H2O(2), [HN(CH2CH2)3NH][(PO4)MoV3MoVI9O36(VIVO)2]·-3[N(CH2CH2)3N]·(en)·4.5H2O(3) and [HNH2OH][NH4]2[(VVO4)MoVI8VIV4O36(VIVO)4]·24H2O(4). Single-crystal X-ray diffraction analysis revealed that the anions in 1~3 are two-capped Keggin derivatives with characteristic trans vanadium-oxygen caps, whereas the heteropoly anion in 4 is a tetra-capped α-Keggin derivative with characteristic vanadium-oxygen caps on the equatorial plane.

Synthesis and Structural Characterization of Cu(pic)_2[CO(NH_2)_2]_2 and (picH_2)_2[Cu(pic)_2(SCN)_2]

Two new compounds Cu(pic)2[CO(NH2)2]2 1 and (picH2)2[Cu(pic)2(SCN)2] 2 were prepared from the reaction of picolinic acid and copper(II) per-chlorate by using carbamide to adjust pH = 4 in the preparation of compound 1 and KSCN to adjust pH = 6 in the preparation of 2. Crystal data for 1: monoclinic system, space group P21/n with a = 7.441(1), b = 14.291(2), c = 7.790(1) ? b = 95.855(2), V = 824.0(2) ?, Dc = 1.724 g/cm3, F(000) = 438, C14H16N6O6Cu, Mr = 427.87, m(MoKa) = 1.375 mm-1, Z = 2 and the final R = 0.0365 for 1164 observed reflections. Crystal data for 2: monoclinic system, space group P21/c with a = 9.8237(3), b = 10.0409(3), c = 14.5867(2) ? b = 104.190(2), V = 1394.91(6) ?, Dc = 1.595 g/cm3, F(000) = 686, C26H20N6O8S2Cu, Mr = 672.14, m(MoKa) = 0.994 mm-1, Z = 2 and the final R = 0.0442 for 1651 observed reflections. The Cu(II) atom in both 1 and 2 has a 4+2 elongated octahedral environment with the pic ligands locating on the equatorial plane, and carbamide and SCN occupying the axial sites, respectively. In compound 2, there also exist two protonated picolinate cations for charge balance.

Comparing the Structures of Two Allomorphic Polyoxotungstates and the Difference in Weak Interactions by Thermal-dependent 2D-COS IR to Identify

A three-dimensional(3D) Keggin-type heteropolytungstate{Zn(phen)3}3[ZnW12O40]· 9H2O 1(phen=1,10-phenanthroline) has been synthesized through a conventional hydrothermal synthesis and was characterized by X-ray single-crystal diffraction analysis,X-ray powder diffraction(XRD),IR,UV-DRS,thermogravimetric analysis(TGA),thermal-dependent 2D-IR correlation spectroscopy(2D-COS IR) and Raman spectrum.Crystal data for compound 1:trigonal system,space group R3 with a=b=25.268(4),c=17.462(5) ?,γ=120o,V=9655(4) ?3 and Z=3.Compound 1 is allomorphic to {Co(phen)3}3[CoW12O40]·9H2O 2,which has been reported by Feng Chai et al.In compound 2,its prominent feature is that the decisive role of water molecules(O–H···O) builds a 3D supramolecular structure.However,in the structure of compound 1,the interlayer space is filled by Zn(phen)3]2+ cations which linked the layers via C–H···O hydrogen bonding interactions to construct a three-dimensional framework.Two compounds are different in weak interactions,so we identify them by Thermal-dependent 2D-COS IR.Moreover,the fluorescence of compound 1 was also described.

Microstructural Characteristics of Hydrothermally Synthesized LiFePO_4 and Relevant Impacts on the Electrochemical Performance

Phospho-olivine LiFePO 4 has been prepared using a facile hydrothermal method by optimizing the reaction temperatures.Structural and morphological properties of the as-prepared LiFePO 4 powders are systematically characterized using X-ray diffraction (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM),infrared spectra,UV-vis spectra,and M ssbauer spectroscopy.It is demonstrated that the samples prepared in the temperature range from 160 to 200 ℃ crystallize in a single phase of phospho-olivine structure.All particles are rod-like,showing dimensions of approximately 150～200 nm in width and 500～600 nm in length with a preferential growth direction of [001].Within the lattice of LiFePO 4 rods,Fe 2+ ions partially disorderly occupy the Li + sites,which increases the cell volume.The electrochemical performance of LiFePO 4 is investigated by charge/discharge experiments.It is found that LiFePO 4 rods prepared at 200 ℃ deliver a specific discharge capacity of 147 mAh g-1,which is apparently superior to those prepared at lower reaction temperatures like 160 and 180 ℃.This observation is explained in terms of the thinner surface noncrystalline layer and lower level of Fe 2+ disorderly occupying the Li + sites.

Theoretical Study on the Structural and Electronic Properties of the Reduced SnO_2 (110) Surface

The reduced SnO2(110) surface has been investigated by using first-principles method with a slab model. By examining the vacancy formation energy of three kinds of reduced SnO2(110) surfaces, the most energetically favorable defect surface is confirmed to be the surface with the coexistence of bridging and in-plane oxygen vacancies, which is different with the traditional model by only removing bridging oxygen. The results of band structure calculations indicate that the electronic structure of this defect surface is similar to the SnO surface.