Oxygen reduction behavior of RuO2/Ti,IrO2/Ti and IrM (M: Ru,Mo, W,V) Ox/Ti binary oxide electrodes in a sulfuric acid solution

Some oxide catalysts, such as RuO₂/Ti, IrO₂/Ti and IrM(M: Ru, Mo, W, V)O_x/Ti binary oxide electrodes, were prepared by using a dip-coating method on a Ti substrate. Their catalytic behavior for the oxygen reduction reaction (ORR) was evaluated by cyclic voltammetry in 0.5 M H₂SO₄ at 60 °C. These catalysts were found to exhibit considerably high activity, and the most active one among them was Ir_0.6V_0.4O₂/Ti prepared at 450 °C, showing onset potential for the ORR at about 0.86 V–0.90 (vs RHE).     

FeAgMo2O8 — A novel oxygen evolution catalyst material for alkaline metal–air batteries

This paper reports about FeAgMo₂O₈ — a novel oxygen evolution catalyst material for secondary (rechargeable) metal–air batteries. Bifunctional air electrodes were made using FeAgMo₂O₈ as a charging catalyst for oxygen evolution reaction (OER) and silverized carbon black (Ag/C) was employed as a discharging catalyst for oxygen reduction reaction (ORR). Corresponding air electrodes were investigated using 10 M KOH as an electrolyte. At current densities between 20 and 50 mA per cm² we observed discharging and charging voltages of 1.20 to 1.15 V and 1.96 to 2.05 V, respectively.     

Supramolecular hybrid composites of metalloporphyrins and fullerene encapsulated in the ordered nano-channels of FSM-16 as oxygen carriers,and photo-catalysis for selective propene oxidation towards acetone

The planar oxomolybdenum(IV) and Fe(II) tetraphenylporphyrins (tpp) and fullerene C₆₀ are encapsulated by monolayer dispersion technique in the mesoporous ordered channels(2.7, 4.7 nm diameter) of FSM-16. They exhibit a stoichiometric adsorption of O₂ at 300 K and 50–250 Torr forming a 1:1 dioxygen complexes(ν(O–O)=928 and 1025 cm^-1) with Mo^IVO(tpp) and Fe^II(tpp) entrapped in FSM-16, although the Mo(=O) and Fe porphyrins are inactive for O₂ uptake in crystal and solution. The mesoporous cylindrical channels of FSM-16 act as the confined hydrophobic circumstances to accommodate isolated Mo and Fe porphyrins and prevent the irreversible formation of a paramagnetic μ-oxo dimer, similar to the picket-fenced porphyrin complexes such as Mo^IVO(tmp)=5,10,15,20-tetramesitylporphyrin). The reversible removal of O₂ bound with the Mo and Fe porphyrins proceeds at 300 K by high-pressure Hg photoirradiation. The isotopic labeling tracer studies reveal that they are catalytically active for oxygen transfer via fullerene C₆₀ in the selective photo-oxidation of propene towards acetone at 303–393 K.     

X-ray and vibrational spectra on metal complexes with indolecarboxylic acids: Part IV. Catena-poly[{aqua(η2-indole-3-carboxylato-O,O′)zinc}-μ-indole-3-carboxylato-O:O′]

The new zinc(II) coordination polymer catena-poly[{aqua(η²-indole-3-carboxylato-O,O′)zinc}-μ-indole-3-carboxylato-O:O′], [Zn(I3CA)₂(H₂O)]_n [Zn(I3CA)₂(H₂O)]_n has been synthesized and characterized using infrared and Raman spectroscopy and X-ray single-crystal diffraction analysis. The crystals are monoclinic, space group Cc, with a = 33.319(7), b = 5.985(1), c = 8.291(2) Å, V = 1653.1(6) Å³ and z = 4. Each zinc centre is five-coordinated by the bidentate chelating indole-3-carboxylato, one oxygen atom bridging indole-3-carboxylato, water molecule and one oxygen atom bridging indole-3-carboxylato from an adjacent [Zn(I3CA)₂(H₂O)] unit. The Zn–O distances of 1.978(4), 1.987(3), 1.977(4), 1.983(3) and 2.519(4) Å, are typical for distances of such complexes. The infrared and Raman spectroscopic data of [Zn(I3CA)₂(H₂O)]_n in the solid state are supported by X-ray analysis. The theoretical wavenumbers, infrared intensities and Raman scattering activities have been calculated by the density functional methods (B3LYP and mPW1PW) with the D95V^**/LanL2DZ and 6-311++G(d,p)/LanL2DZ basis sets. The theoretical wavenumbers, infrared intensities and Raman scattering activities show a good agreement with experimental. Detailed band assignment has been made on the basis of the calculated potential energy distribution (PED). The results provide information on the strength of zinc-ligand bonding in complex.     

“Water-in-Salt” electrolyte enabled LiMn2O4/TiS2 Lithium-ion batteries

High electrochemical reversibility of the TiS₂ anode in “Water-in-Salt” electrolyte (21 m LiTFSI in H₂O) is demonstrated for the first time. The wide electrochemical window and low chemical activity of H₂O in the “Water-in-Salt” electrolyte not only significantly enhanced the electrochemical reversibility of TiS₂ but also effectively suppressed the hydrolysis side reaction in the aqueous electrolyte. Paired with a LiMn₂O₄ cathode, the LiMn₂O₄/TiS₂ full cell delivers a relatively high discharge voltage of 1.7 V and an energy density of 78 Wh kg^− 1 as well as a satisfactory rate performance.     

A novel all-solid-state thin-film-type lithium-ion battery with in situ prepared positive and negative electrode materials

A novel all-solid-state thin-film-type rechargeable lithium-ion battery employing in situ prepared both positive and negative electrode materials is proposed. A lithium-ion conducting solid electrolyte sheet of Li₂O–Al₂O₃–TiO₂–P₂O₅-based glass–ceramic manufactured by OHARA Inc. (OHARA sheet) was used as the solid electrolyte, which was sandwiched by Cu and Mn metal films. The Cu/OHARA sheet/Mn layer became an all-solid-state lithium-ion battery after applying d.c. 16 V to the layer, and the resultant battery operated at 0.3–0.8 V with reversible capacity of 0.45 μAh cm^?2. High voltage battery was successfully prepared by applying the d.c. high voltage to a five-series of Cu/OHARA sheet/Mn layer, resulting in all-solid-state battery operating at 1.5–4.0 V. The proposed fabrication process will become a new technology to develop advanced all-solid-state rechargeable lithium-ion batteries.     

X-ray and infrared spectrum on metal complexes with indolecarboxylic acids: Part V. Catena-poly[{aqua(η2-indole-3-propionato-O,O′)zinc}-η2-:-μ-indole-3-propionato-O,O′:-O]

The catena-poly[{aqua(η²-indole-3-propionato-O,O′)zinc}-η²-:-μ-indole-3-propionato-O,O′:-O], [Zn(I3PA)₂(H₂O)]_n was prepared and characterized by infrared spectroscopy and X-ray structure determination. The crystals are monoclinic, space group Pc, with a = 21.380(2), b = 5.9076(7), c = 8.1215(9) Å, V = 1020.2(2) Å³ and Z = 2. The central zinc atom shows the coordination distorted from ideal octahedral. Each zinc centre is coordinated by two oxygen atoms of the bidentate chelating indole-3-propionato (I3PA), two oxygen atoms tridentate chelating-bridging I3PA, water molecule and one oxygen atom tridentate chelating-bridging I3PA from an adjacent [Zn(I3PA)₂(H₂O)] unit. The infrared spectrum of [Zn(I3PA)₂(H₂O)]_n in the solid state is supported by X-ray analysis. The theoretical wavenumbers and infrared intensities have been calculated by the density functional methods (B3LYP and mPW1PW) with the 6-311++G(d,p)/LanL2DZ basis sets. The theoretical wavenumbers, infrared intensities show a good agreement with experimental data. Detailed band assignment has been made on the basis of the calculated potential energy distribution (PED).     

Nonenzymatic glucose fuel cells with an anion exchange membrane as an electrolyte

Nonenzymatic glucose fuel cells were prepared by using a polymer electrolyte membrane and Pt-based metal catalysts. A fuel cell with a cation exchange membrane (CEM), which is often used for conventional polymer electrolyte fuel cells, shows an open circuit voltage (OCV) of 0.86 V and a maximum power density (P_max) of 1.5 mW cm^?2 with 0.5 M d-glucose and humidified O₂ at room temperature. The performance significantly increased to show an OCV of 0.97 V and P_max of 20 mW cm^?2 with 0.5 M d-glucose in 0.5 M KOH solution when the electrolyte membrane was changed from a CEM to an anion exchange membrane (AEM). This is due to the superior catalytic activity for both glucose oxidation and oxygen reduction in alkaline medium than in acidic medium. The anodic reaction of the fuel cell can be estimated to be the oxidation of glucose to gluconic acid via a two-electron process under these experimental conditions. The crossover of glucose through an electrolyte membrane was negligibly small compared with methanol and may not represent a serious technical problem due to the cross-reaction.     

Excess thermodynamic properties of binary mixtures of N,N-dimethylacetamide with water or water-d2 at temperatures from 277.13 K to 318.15 K

Densities of binary mixtures of N,N-dimethylacetamide (DMA) with water (H₂O) or water-d₂ (D₂O) were measured at the temperatures from T=277.13 K to T=318.15 K by means of a vibrating-tube densimeter. The excess molar volumes V_m^E, calculated from the density data, are negative for the (H₂O + DMA) and (D₂O + DMA) mixtures over the entire range of composition and temperature. The V_m^E curves exhibit a minimum at x(DMA)≅0.4. At each temperature, this minimum is slightly deeper for the (D₂O + DMA) mixtures than for the corresponding (H₂O + DMA) mixtures. The difference between D₂O and H₂O systems becomes smaller when the temperature increases. The V_m^E results were correlated using a modified Redlich–Kister expansion. The partial molar volume of DMA plotted against x(DMA) goes through a sharp minimum in the water-rich region around x(DMA)≅0.08. This minimum is more pronounced the lower the temperature and is deeper in D₂O than in H₂O at each temperature. Again, the difference becomes smaller as the temperature increases. The excess expansion factor α^E plotted against x(DMA) exhibit a maximum in the water rich region of the mole fraction scale. At each temperature, this maximum is higher for the (D₂O + DMA) mixtures than for the corresponding (H₂O + DMA) mixtures, and the difference becomes smaller as the temperature increases. At its maximum, α^E can be even more than 25 per cent of total value of the cubic expansion coefficient α in the (H₂O + DMA) and (D₂O + DMA) mixtures.     

Ab initio crystal structure of nickel(II) hydroxy-terephthalate by synchrotron powder diffraction and magnetic study

The structure of the new hybrid compound [Ni₃(OH)₂(tp)₂(H₂O)₄]·2H₂O (tp = C₈H₄O₄²⁻) has been determined ab initio from synchrotron powder diffraction data and refined with the Rietveld method: space group P-1, a = 10.2077(6) Å, b = 8.0135(5) Å, c = 6.3337(4) Å, α = 97.70 (1)°, β = 97.21(1)°, γ = 108.77(1)°, D_x = 2.124 g/cm³, Rp = 0.045, R_B = 0.095 (757 independent reflections). H atoms were placed geometrically and their position optimized by DFT calculation. The repeating structural unit is the chain [Ni(1)O₆]₂Ni(2)O₆, consisting of two edges sharing octahedrons related by the symmetry center and linked via μ3-OH to a vertex of Ni(2) octahedron. The Ni(1) coordination is ensured by two oxygen atoms from two water molecules, two OH and two oxygen atoms from carboxylate groups. The linkage of the chains by the tp anions forms infinite layers parallel to the (010) planes. Interchain hydrogen bonds between the water molecules coordinating the metal ensure the cohesion of the 2D structure. The structural and magnetic properties are compared with that of the 3D fumarate-based compound [Ni₃(OH)₂(fum)₂(H₂O)₄]·2H₂O (fum = C₄H₂O₄²⁻).     

Fabrication of a large area cathode-supported thin electrolyte film for solid oxide fuel cells via tape casting and co-sintering techniques

A large area cathode-supported electrolyte film, comprising porous (La_0.8Sr_0.2)_0.95MnO₃ (LSM95) cathode substrate, LSM95/Zr_0.89Sc_0.1Ce_0.01O_2?x (SSZ) cathode active layer, and SSZ electrolyte, has been successfully fabricated by tape casting and co-sintering techniques. The interface reaction between cathode and electrolyte was inhibited by using A-site deficient LSM. A dense enough SSZ thin film with a thickness of ～26 μm was obtained at 1250 °C. By using Pt as anode, the obtained single cell reached the maximum power density of 0.54 W cm^?2 at 800 °C in O₂/humidified H₂, with open circuit voltage (OCV) value of 1.08 V.     

Pulse radiolysis of aqueous diphenyloxide

Pulse radiolysis of aqueous diphenyloxide (DPO) has been performed under various experimental conditions. The OH radicals react with DPO on various positions of the molecule with a rate constant, k=2.1×10¹⁰ l mol⁻¹ s⁻¹. The major reaction step appears to be a cleavage of the C–O bond of DPO resulting into C₆H₄OH (λ=285 nm) and C₆H₅O(λ=325 nm) radicals in addition to DPO–OH adducts. They disappear according to a second-order reaction. In the presence of air or in a gas mixture of N₂O:O₂=4:1 the DPO–OH adducts are scavenged by oxygen, resulting into peroxyl radicals, which are long-lived species. For the reaction of e_aq⁻ with DPO a rate constant, k=2×10¹⁰ l mol⁻¹ s⁻¹ was found.     

A new carbon fuel cell with high power output by integrating with in situ catalytic reverse Boudouard reaction

Solid carbon was investigated as the fuel for an intermediate-temperature solid oxide fuel cell (IT-SOFC). An innovative, indirect operating method involving internal catalytic gasification of carbon to gaseous carbon monoxide via the reverse Boudouard reaction (C(s) + CO₂(g) → 2CO(g)) was proposed. The carbon gasification reaction rate was greatly enhanced by adopting Fe_mO_n–M_xO (M = Li, K, Ca) as a catalyst. A peak power density of ～297 mW cm^?2 was achieved at 850 °C for an anode-supported SOFC with scandium-stabilized zirconia electrolyte and a La_0.8Sr_0.2MnO₃ cathode by applying a catalyst-loaded, activated carbon as fuel. This peak power density was only modestly lower than that obtained using gaseous hydrogen as the fuel.     

Synthesis,thermal behaviour and crystal structure of RbSrP3O9·3 H2O

Rubidium strontium cyclo-triphosphate trihydrate, RbSrP₃O₉·3 H₂O, was synthesized by reaction between cyclo-triphosphoric acid H₃P₃O₉ and rubidium and strontium carbonates. It crystallizes in the othorhombic system, space group Pnma, with a = 9.120(1) Å, b = 8.141(1) Å, c = 15.234(1) Å, V = 1 131.1(3) Å³, Z = 4. Crystal structure determination from single crystal data collected at 300 K shows that the P₃O₉ groups exhibit C_s symmetry and are not connected to each other. Rubidium (distorted octahedron) and strontium (distorted square antiprism) are coordinated by oxygen and water molecules yielding the formation of infinite chains interconnected to each other and to the P₃O₉ groups. The IR valence vibration bands of the P₃O₉ cycle have been identified in the domain 1 400–650 cm^–1 and related to the structural results. After water loss, the anhydrous phase crystallizes from an intermediate amorphous phase and further decomposes into Rb₂SrP₄O₁₂ and SrP₂O₆.     

A novel anode supported BaCe0.7Ta0.1Y0.2O3−δ electrolyte membrane for proton-conducting solid oxide fuel cell

A novel composition of BaCe_0.7Ta_0.1Y_0.2O_3−δ (BCTY10) electrolyte membrane was successfully fabricated on porous NiO-BCTY10 anode substrate. The anode was prepared through a route combining a solid state reaction and a wet chemical method. After sintering at 1450 °C for 5 h, the BCTY10 membrane showed adequate chemical stability against CO₂ and H₂O. With a mixture of La_0.7Sr_0.3FeO_3−δ (LSF) and BaCe_0.7Zr_0.1Y_0.2O_3−δ (BZCY7) as cathode, a single fuel cell with 25 μm thick BCTY10 electrolyte generated maximum power densities of 195, 137, 84, 44 mW/cm² at 700, 650, 600 and 550 °C, respectively. The interface resistance of the cell under open circuit condition was also investigated.     

Thermodynamic properties of Na2Ti6O13 and Na2Ti3O7: electrochemical and calorimetric determination

Standard values of Gibbs free energy, entropy, and enthalpy of Na₂Ti₆O₁₃ and Na₂Ti₃O₇ were determined by evaluating emf-measurements of thermodynamically defined solid state electrochemical cells based on a Na–β″-alumina electrolyte. The central part of the anodic half cell consisted of Na₂CO₃, while two appropriate coexisting phases of the ternary system Na–Ti–O are used as cathodic materials. The cell was placed in an atmosphere containing CO₂ and O₂. By combining the results of emf-measurements in the temperature range of 573⩽T/K⩽1023 and of adiabatic calorimetric measurements of the heat capacities in the low-temperature region 15⩽T/K⩽300, the thermodynamic data were determined for a wide temperature range of 15⩽T/K⩽1100. The standard molar enthalpy of formation and standard molar entropy at T=298.15 K as determined by emf-measurements are Δ_fH_m⁰=(−6277.9±6.5) kJ · mol⁻¹ and S_m⁰=(404.6±5.3) J · mol⁻¹ · K⁻¹ for Na₂Ti₆O₁₃ and Δ_fH_m⁰=(−3459.2±3.8) kJ · mol⁻¹ and S_m⁰=(227.8±3.7) J · mol⁻¹ · K⁻¹ for Na₂Ti₃O₇. The standard molar entropy at T=298.15 K obtained from low-temperature calorimetry is S_m⁰=399.7 J · mol⁻¹ · K⁻¹ and S_m⁰=229.4 J · mol⁻¹ · K⁻¹ for Na₂Ti₆O₁₃ and Na₂Ti₃O₇, respectively. The phase widths with respect to Na₂O content were studied by using a Na₂O-titration technique.     

Cobalt-free cathode material SrFe0.9Nb0.1O3−δ for intermediate-temperature solid oxide fuel cells

A cobalt-free cubic perovskite oxide, SrFe_0.9Nb_0.1O_3?δ (SFN) was investigated as a cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). XRD results showed that SFN cathode was chemically compatible with the electrolyte Sm_0.2Ce_0.8O_1.9 (SDC) for temperatures up to 1050 °C. The electrical conductivity of SFN sample reached 34–70 S cm^?1 in the commonly operated temperatures of IT-SOFCs (600–800 °C). The area specific resistance was 0.138 Ω cm² for SFN cathode on SDC electrolyte at 750 °C. A maximum power density of 407 mW cm^?2 was obtained at 800 °C for single-cell with 300 μm thick SDC electrolyte and SFN cathode.     

The quest for magnets composed of vanadium and 1,4-benzoquinones

The reaction of V^o(CO)₆ and representative quinones, A (A = benzoquinone, chloranil, 2,3-dicyano-1,4-naphthoquinone, and dihydroxy-1,4-benzoquinone), form materials of V(A)₂ · zCH₂Cl₂ (z < 0.1) composition, which exhibits antiferromagnetic coupling and do not magnetically order above 5 K.     

Partial oxidation of ethane to syngas in an oxygen-permeable membrane reactor

A perovskite-type oxide of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCFO) with mixed electronic and oxygen ionic conductivity at high temperatures was used as an oxygen-permeable membrane. A tubular membrane of BSCFO made by extrusion method has been used in the membrane reactor to exclusively transport oxygen for the partial oxidation of ethane (POE) to syngas with catalyst of LiLaNiO/γ-Al₂O₃ at temperatures of 800–900 °C. After only 30 min POE reaction in the membrane reactor, the oxygen permeation flux reached at 8.2 ml cm⁻² min⁻¹. After that, the oxygen permeation flux increased slowly and it took 12 h to reach at 11.0 ml cm⁻² min⁻¹. SEM and EDS analysis showed that Sr and Ba segregations occurred on the used membrane surface exposed to air while Co slightly enriched on the membrane surface exposed to ethane. The oxygen permeation flux increased with increasing of concentration of C₂H₆, which was attributed to increasing of the driving force resulting from the more reducing conditions produced with an increase of concentration of C₂H₆ in the feed gas. The tubular membrane reactor was successfully operated for POE reaction at 875 °C for more than 100 h without failure, with ethane conversion of ∼100%, CO selectivity of >91% and oxygen permeation fluxes of 10–11 ml cm⁻² min⁻¹.