Fabrication of solid thin film electrolyte and LiCoO2 by aerosol flame pyrolysis deposition

Aerosol flame pyrolysis deposition method was applied to deposit the oxide glass electrolyte film and LiCoO₂ cathode for thin film type Li-ion secondary battery. The thicknesses of as-deposited porous LiCoO₂ and Li₂O–B₂O₃–P₂O₅ electrolyte film were about 6 μm and 15 μm, respectively. The deposited LiCoO₂ was sintered for 2 min at 700 °C to make partially densified cathode layer, and the deposited Li₂O–P₂O₅–B₂O₃ glass film completely densified by the sintering at 700 °C for 1 h. After solid state sintering process the thicknesses were reduced to approximately 4 μm and 6 μm, respectively. The cathode and electrolyte layers were deposited by continuous deposition process and integrated into a layer by co-sintering. It was demonstrated that Aerosol flame deposition is one of the good candidates for the fabrication of thin film battery.     

Surface structures and electrochemical characteristics of surface-modified carbon anodes for lithium ion battery

Petroleum coke and those heat-treated at 1860 °C, 2100 °C, 2300 °C 2600 °C and 2800 °C (abbreviated as PC, PC1860, PC2100, PC2300, PC2600 and PC2800) were fluorinated by elemental fluorine of 3 × 10⁴ Pa at 200 °C and 300 °C for 2 min. Natural graphite powder samples with average particle sizes of 5 μm, 10 μm and 15 μm (abbreviated as NG5μm, NG10μm and NG15μm) were also fluorinated by ClF₃ of 3 × 10⁴ Pa at 200 °C and 300 °C for 2 min. Transmission electron microscopic (TEM) observation revealed that closed edge of PC2800 was destroyed and opened by surface fluorination, which increased the first coulombic efficiencies of PC2300, PC2600 and PC2800 by 12.1–18.2% at 60 mA/g and by 13.3–25.8% at 150 mA/g in 1 mol/dm³ LiClO₄–ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1 in volume). Light fluorination of NG10μm and NG15μm increased the first coulombic efficiencies by 22.1–28.4% at 150 mA/g in 1 mol/dm³ LiClO₄–EC/DEC/PC (PC: propylene carbonate, 1:1:1 in volume).     

Effect of Fluoride or Chloride Ions on the Morphology of ZrO2 Thin Film Grown in Ethylene Glycol Electrolyte by Anodization

0.3 wt % ammonium fluoride (NH₄F) or ammonium chloride (NH₄Cl) was added to ethylene glycol (EG) as an active ingredient for the formation of anodic oxide comprising of ZrO₂ nanotubes (ZNTs) by anodic oxidation of zirconium (Zr) at 20 V for 10 min. It was observed that nanotubes were successfully grown in EG/NH₄F/H₂O with aspect ratio of 144.3. Shorter tubes were formed in EG/NH₄F/H₂O₂. This could be due to higher excessive chemical etching at the tip of the tubes. When fluoride was replaced by chloride in both electrolytes, multilayered oxide resembling pyramids was observed. The pyramids have width at the bottom of 3-4 μm and the top is 1-2 μm with 10.7 μm height. Oxidation of Zr in EG/NH₄Cl/H₂O₂ was rater rapid. The multilayered structure is thought to have formed due to the re-deposition of ZrO₂ or hydrated ZrO₂ on the foil inside pores formed within the oxide layer. XRD result revealed an amorphous structure for as-anodized samples regardless of the electrolytes used for this work.     

In situ synthesis of composite MTiO3–Al2O3 coatings via laser zone melting

Laser zone melting was employed in this work to prepare MTiO₃ based coatings over commercial, polycrystalline Al₂O₃ substrates, using the corresponding mixtures of powdered alkaline earth carbonates and TiO₂ as starting materials. In situ synthesis of the series M = Ca, Sr, Ba was studied using a CO₂ laser as the heating source, emitting at 10.6 μm, following substrate preheating to a temperature of 750 °C and sample displacement speed of 500 mm h⁻¹. Microstructure (SEM) and phase composition (XRD) demonstrated in situ formation of crystalline MTiO₃ perovskite (M = Ca, Sr), MAl₂O₄ (M = Ca), MAl₁₂O₁₉ magnetoplumbite type (M = Sr) and MAl₁₄O₂₂ β-alumina type (M = Ba) phases. Substantial interaction with the substrate resulted in stable, 50–150 μm thick, composite coatings.     

Preparation and photocatalytic activity of Cu-deposited TiO2 film with high transparency

Cu-deposited TiO₂ films were prepared by photoreduction of Cu(II) in the presence of sodium formate. With the initial Cu(II) concentrations more than 100 mg L^?1, induction periods were observed before the transmittance decreased. Scanning electron microscopy indicated that Cu particles of 2.6 ± 0.5 μm were deposited isolatedly with much open space in the induction periods. The films prepared by changing the irradiation time within the induction periods showed a higher photocatalytic activity than a pure TiO₂ for the degradation of methylene blue under the reaction condition without purging air.     

Enhancing the bioactivity of zirconium with the coating of anodized ZrO2 nanotubular arrays prepared in phosphate containing electrolyte

Bioactive zirconium oxide nanotubular arrays on zirconium alloys are prepared electrochemically in fluoride and phosphate containing electrolyte. Geometric factors of the ZrO₂ nanotubular layers, particularly the pore diameter and thickness, are affected by the electrochemical conditions, including applied potential and anodization time. Under specific sets of conditions, highly ordered ZrO₂ nanotubular arrays are formed with diameters varying from 30 nm to 75 nm and lengths varying from 2 μm to 12 μm. XPS shows that the nanotubular layer contains a significant amount of phosphate species distributed almost homogeneously over the entire tubular length. The ZrO₂ nanotubular layer formed in fluoride and phosphate containing electrolyte highly enhances the formation of bioactive hydroxyapatite coating in simulated biological fluid (SBF).     

Photocatalytic activity of TiO2 nanotube layers loaded with Ag and Au nanoparticles

Ag and Au nanoparticles were found to significantly enhance the photocatalytic activity of self-organized TiO₂ nanotubular structures. The catalyst systems are demonstrated to be highly efficient for the UV-light induced photocatalytic decomposition of a model organic pollutant – Acid Orange 7. The metallic nanoparticles with a diameter of ∼10 ± 2 nm (Ag) and ∼28 ± 3 nm (Au) were attached to a nanotubular TiO₂ layer that consists of individual tubes of ∼100 nm of diameter, ∼2 μm in length and approx. 15 nm of wall thickness. Both metal particle catalyst systems enhance the photocatalytic decomposition significantly more on the nanotubes support than placed on a compact TiO₂ surface.     

LixV2O5 nanobelts for high capacity lithium-ion battery cathodes

5–10 μm long, typically 200–300 nm wide, and several nanometers thick Li_xV₂O₅ (× ～ 0.8) nanobelts with the δ-type crystal structure were synthesized by a hydrothermal treatment of Li⁺-exchanged V₂O₅ gel. When dried at 200 °C under vacuum prior to electrochemical testing, the as-prepared nanobelts underwent the well-known δ → ε → γ-phase transition giving a mixture of ε and γ phases as a nanocomposite electrode material. Such a simple preparation procedure guarantees a yield of material with drastically enhanced initial discharge specific capacity of 490 mAh/g and great cyclability. The enhanced electrochemical performance is attributed to the complex of experimental procedures including post-synthesis treatment of the single-crystalline Li_xV₂O₅ nanobelts.     

Mechanical Properties of 1.5 wt.% TiB2-added Hypoeutectic Al-Mg- Si Alloys Processed by Equal Channel Angular Pressing

In order to improve the mechanical properties and to optimize grain refinement of Al-Mg-Si alloy, ECAP processing with an addition of hard particle TiB₂ is applied in this work. Mechanical property and microstructural evolution of Al-0.3Mg-7Si+1.5 wt.% TiB₂ specimen were investigated by using hardness-testing, optical micrograph observation and electron-backscattering diffraction (EBSD). ECAP processing was done through B_A route for 4 passes at room temperature. Hardness test results show that the ECAP process doubled the hardness of the specimen compared to annealed specimen, and from EBSD/OIM analysis, the ECAP processing refined grains from an average grain size of 35 μm to 0.79 μm and led to producing grains having high misorientation angle (≥15).     

Nanorods of transition metal oxalates: A versatile route to the oxide nanoparticles

A versatile route has been explored for the synthesis of nanorods of transition metal (Cu, Ni, Mn, Zn, Co and Fe) oxalates using reverse micelles. Transmission electron microscopy shows that the as-prepared nanorods of nickel and copper oxalates have diameter of 250 nm and 130 nm while the length is of the order of 2.5 μm and 480 nm, respectively. The aspect ratio of the nanorods of copper oxalate could be modified by changing the solvent. The average dimensions of manganese, zinc and cobalt oxalate nanorods were 100 μm, 120 μm and 300 nm, respectively, in diameter and 2.5 μm, 600 nm and 6.5 μm, respectively, in length. The aspect ratio of the cobalt oxalate nanorods could be modified by controlling the temperature.The nanorods of metal (Cu, Ni, Mn, Zn, Co and Fe) oxalates were found to be suitable precursors to obtain a variety of transition metal oxide nanoparticles. Our studies show that the grain size of CuO nanoparticles is highly dependent on the nature of non-polar solvent used to initially synthesize the oxalate rods. All the commonly known manganese oxides could be obtained as pure phases from the single manganese oxalate precursor by decomposing in different atmospheres (air, vacuum or nitrogen). The ZnO nanoparticles obtained from zinc oxalate rods are ～55 nm in diameter. Oxides with different morphology, Fe₃O₄ nanoparticles faceted (cuboidal) and Fe₂O₃ nanoparticles (spherical) could be obtained.     

Fast fabrication of Ta2O5 nanotube arrays and their conversion to Ta3N5 for efficient solar driven water splitting

This work shows that highly ordered and mechanically stable micrometer-long Ta₂O₅ nanotube arrays can be fabricated by galvanostatic anodization in a few seconds. Typically, ~ 7.7 μm long nanotubes can be grown at 1.2 A cm^− 2 in only 2 s. Such nanotubes can be converted to Ta₃N₅ nanotube arrays by nitridation. Photoelectrochemical (PEC) water splitting using AM 1.5G illumination yields for the Ta₃N₅ nanotube photoanode modified with cobalt phosphate (Co–Pi) remarkable photocurrents of 5.9 mA cm ⁻² at 1.23 V_RHE and 12.9 mA cm ⁻² at 1.59 V_RHE and after Ba-doping a value of 7.5 mA cm ⁻² at 1.23 V_RHE is obtained.     

Electrolysis of solid MoS2 in molten CaCl2 for Mo extraction without CO2 emission

Sintered (300 °C) porous pellets of MoS₂ were electrolysed to elemental S and Mo in molten CaCl₂ (800–900 °C) under argon at 1.0–3.0 V for 1–20 h. On a graphite anode, the product was primarily S (but traces of CS₂ could not yet be excluded by this work) and evaporated from the molten salt, allowing the electrolysis to continue. It then condensed to solid at the lower temperature regions of the system. The anode remained intact after repeated uses. The MoS₂ pellet was highly conducting at high temperatures and could be fast electro-reduced to fine Mo powders (0.1–1.0 μm) in which the S content could be below 1000 ppm. No reduction occurred at voltages below 0.5 V. Partial reduction was seen at 0.5–0.7 V, and converted MoS₂ to a mixture of MoS₂ and Mo₃S₄, or Mo₃S₄ and Mo with the Mo content increasing with the voltage. Cyclic voltammetry of the MoS₂ powder in a Mo-cavity electrode, together with the electrolysis results, revealed the reduction mechanism to include two steps: MoS₂ to Mo₃S₄ at −0.28 V (potential vs. Ag/AgCl), and then to Mo at −0.43 V.     

Field emission investigation of single Fe-doped SnO2 wire

Tin oxide submicronwires doped with Fe element were prepared by the thermal evaporation method. Morphological and structural characterizations revealed wires with sub micron size and crystalline in nature. The field electron emission from the single Fe:SnO₂ wire was carried out in conventional field emission microscope. The Fowler–Nordheim plot obtained from I–V characteristics of the wire showed a linear behavior typical that of metal. The field enhancement factor estimated from the slope of the F–N plot is 7455 cm^?1, indicating that the field emission is from nanometric features of the emitter. A current density of 10 A/cm² has been obtained at an applied field of 4.845 × 10³ V/μm. The field emission current–time record at a current level of 1 μA for more than 3 h duration is promising for various field emissions based applications.     

Visible LED light photoelectrochemical sensor for detection of L-Dopa based on oxygen reduction on TiO2 sensitized with iron phthalocyanine

The present work describes the development of a new strategy to photoelectrochemical detection of L-Dopa at low potential based on oxygen reduction on TiO₂ sensitized with iron phthalocyanine (FePc/TiO₂). The FePc/TiO₂ composite shows a photocurrent 10-fold higher than that of pure TiO₂ nanoparticles and it was 4-fold higher than that of FePc exploiting visible light. The band gaps of pure TiO₂ nanoparticles, FePc and FePc/TiO₂, calculated according to the Kubelka–Munk equation, were 3.22 eV, 3.11 eV and 2.82 eV, respectively. The FePc/TiO₂ composite showed a low charge transfer resistance in comparison to the photoelectrode modified with FePc or TiO₂. Under optimized conditions, the photoelectrochemical sensor shows a linear response range from 20 up to 190 μmol L^− 1 with a sensitivity of 31.8 μA L mmol^− 1 and limit of detection of 1.5 μmol L^− 1 for the detection of L-Dopa.     

Ferromagnetic interaction between [Ni(bdt)2]− anions in [Mn2(Saloph)2(μ-OH)][Ni(bdt)2](CH3CN)2

A new molecule-based magnetic material [Mn₂(Saloph)₂(μ-OH)][Ni(bdt)₂](CH₃CN)₂ was prepared by the metathesis of [Mn(Saloph)(H₂O)(ClO₄)] (S = 2) and TBA[Ni(bdt)₂] (S = 1/2). In the crystal, [Ni(bdt)₂]^? anions form square lattices which are separated from each other by the layers of antiferromagnetically coupled binuclear cations [Mn₂(Saloph)₂(μ-OH)]⁺. The magnetic susceptibility of the material coincides with the sum of the S = 2 van Vleck dimer model and S = 1/2 Heisenberg ferromagnetic square lattice model with 2J = ?92.4 and +4.5 K, respectively. The origin of the ferromagnetic interaction can be explained by the T-shaped intermolecular overlap mode of SOMOs which spreads to the ends of [Ni(bdt)₂]^? molecules.     

Spin-crossover in dimeric hydrogen-bonded iron(II) 2-(pyrazolyl)-pyridine and 2-(imidazolyl)-pyridine complexes

Five new hydrogen-bonded solvated iron(II) complexes of pyrazolyl- and imidazolyl-based N,N-chelating ligands have been synthesised. Water to ligand-NH hydrogen-bonded bridges occur in the pseudo-dimeric complexes {cis-[Fe(pypzH)₂(NCX)₂]₂(μ-OH₂)(H₂O)₂} · H₂O · MeOH (where X = S or Se), and in the chain complex {cis-[Fe(pypzH)₂(NCS)₂](μ-OH₂)}_n. A “half” spin-crossover (T_c = 125 K) was observed in the dimeric X = Se complex by means of magnetic measurements and no thermal hysteresis occurred between 4 and 300 K. The crystal structure at 123 K showed Fe–N distances consistent with the magnetism. Each Fe in the dimeric unit was structurally equivalent in the HS–LS state. Removal of the solvate molecules led to HS–HS behaviour over the temperature range 4–300 K. The pseudo-dimer with X = S also showed HS–HS behaviour as did the monomeric analogue cis-[Fe(pypzH)₂(NCS)₂]H₂O and a structurally different methanol-bridged dimer {cis-[Fe(pyimH)₂(NCS)₂]₂(μ-MeOH)₂} · 2MeOH (pypzH = 2-(1H-pyrazol-3-yl)-pyridine; pyimH = 2-(1H-imidazol-2-yl)-pyridine).     

Synthesis and structural characterization of a photoresponsive organodirhodium complex with active S–S bonds: [(CpPhRh)2(μ-CH2)2(μ-O2SSO2)] (CpPh = η5-C5Me4Ph)

A photoresponsive rhodium dinuclear complex having phenyltetramethylcyclopentadienyl (Cp^Ph = η⁵-C₅Me₄Ph) and photosensitive dithionite (μ-O₂SSO₂) ligands, [(Cp^PhRh)₂(μ-CH₂)₂(μ-O₂SSO₂)] (1), has been synthesized. The crystal of complex 1 (monoclinic, C2/m (No. 12), a = 24.805(2) Å, b = 29.111(2) Å, c = 10.8475(11) Å, β = 105.9830(7)°, V = 7530.0(12) Å³, Z = 8) consists of two independent molecules, 1-cis and 1-trans, with different arrangement of the Cp^Ph ligands. The flexibility, volume, and shape of the reaction cavities around the dithionite unit of 1-cis and 1-trans in the crystal are discussed. The crystal structures of the precursors of 1, trans-[(Cp^PhRh)₂(μ-Cl)₂Cl₂] and trans-[(Cp^PhRh)₂(μ-CH₂)₂Me₂], are also reported.     

High temperature superconductor micro SQUID magnetometer for molecular-based magnets

We have developed a high temperature superconductor (HTS) micro SQUID magnetometer for molecular-based magnets. By employing the dipole approximation, we verified the flux value of 40Φ₀ from the saturation magnetic moment of the ferrimagnetic microcrystal of [Mn₂(H₂O)₂(CH₃COO)][W(CN)₈] · 2H₂O (15 × 15 × 13 μm). Considering the relative arrangement of the sample and the SQUID loop, including the influence of the film and grease, the calculated the flux values were Φ = 71Φ₀ and 31Φ₀ at distances of 20 and 30 μm between the sample bottom face and the SQUID plane, respectively. Thus, the experimentally obtained flux value is reasonable.     

Development of micro-tubular SOFCs with an improved performance via nano-Ag impregnation for intermediate temperature operation

Micro-tubular solid-oxide fuel cell consisting of a 10-μm thick (ZrO₂)_0.89(Sc₂O₃)_0.1(CeO₂)_0.01 (ScSZ) electrolyte on a support NiO/(ScSZ) anode (1.8 mm diameter, 200 μm wall thickness) with a Ce_0.8Gd_0.2O_1.9 (GDC) buffer-layer and a La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF)/GDC functional cathode has been developed for intermediate temperature operation. The functional cathode was in situ formed by impregnating the well-dispersed nano-Ag particles into the porous LSCF/GDC layer using a citrate method. The cells yielded maximum power densities of 1.06 W cm⁻² (1.43 A cm⁻², 0.74 V), 0.98 W cm⁻² (1.78 A cm⁻², 0.55 V) and 0.49 W cm⁻² (1.44 A cm⁻², 0.34 V), at 650, 600 and 550 °C, respectively.     

Fabrication and supercapacitive performance of long anodic TiO2 nanotube arrays using constant current anodization

A galvanostatic anodization is used to prepare long TiO₂ nanotube arrays (TNTAs). TNTAs of over 100 μm in length, with similar nanotube size and structural regularity to the classic TNTAs made from potentiostatic mode, are achieved at 10 mA cm^− 2. After a post-anodization in a H₃PO₄-based electrolyte, the TNTAs with long nanotubes exhibit good adhesion to Ti substrate. The as-prepared long TNTAs yield a larger areal capacitance of 128.4 mF cm^− 2. Further, the long TNTAs possess a higher surface area, making them suitable as support templates for other active materials.