Hierarchically ordered porous nickel oxide array film with enhanced electrochemical properties for lithium ion batteries

Hierarchically ordered porous nickel oxide array film was prepared by electrodeposition through monolayer polystyrene spheres template. The as-prepared film had a highly porous structure of interconnected macrobowls array possessing nanopores. As anode material for lithium ion batteries, the porous array NiO film exhibited weaker polarization, higher coulombic efficiency and better cycling performance in comparison with the dense NiO film. After 50 cycles, the discharge capacity of porous array NiO film was 518 mAh g^? 1 at 1 C rate, higher than that of the dense NiO film (287 mAh g^? 1). The enhancement of the electrochemical properties was due to the unique hierarchical porous architecture, which provided fast ion/electron transfer and alleviated the structure degradation during the cycling process.     

Electrochemical supercapacitor application of pervoskite thin films

We have explored electrochemically deposited pervoskite nanocrystalline porous bismuth iron oxide (BiFeO₃) thin film electrode from alkaline bath for electrochemical supercapacitors. The pervoskite BiFeO₃ nanocrystalline thin film electrode showed comparable specific capacitance of 81 F g⁻¹ and electrochemical supercapacitive performance and stability in an aqueous NaOH electrolyte to that of commonly used ruthenium based pervoskites.     

Multicolor and fast electrochromism of nanoporous NiO/poly(3,4-ethylenedioxythiophene) composite thin film

We report a nanoporous NiO/poly(3,4-ethylenedioxythiophene) (PEDOT) composite film using a highly porous NiO film as a template by the combination of chemical bath deposition and electro-polymerization methods. The as-prepared NiO/PEDOT composite film has an interconnecting reticular morphology with nanometer sized pores ranging from 20–150 nm. The NiO/PEDOT composite film exhibits multicolor electrochromism with reversible color changes from purple to light blue brown and presents a transmittance variation of 31% at 600 nm. Fast switching speed is achieved in this composite film, and the response time for oxidation and reduction is 500 and 600 ms, respectively.     

Spray deposited amorphous RuO2 for an effective use in electrochemical supercapacitor

The structural, surface morphological and optical properties of sprayed ruthenium oxide thin film were investigated using XRD, SEM and optical absorption measurements. The structural analysis from XRD pattern showed the formation of RuO₂ in amorphous phase. The scanning electron micrographs revealed network-like morphology of ruthenium oxide. The optical studies showed a direct band gap of 2.4 eV for ruthenium oxide films. Ruthenium oxide thin film exhibited a cyclic voltammogram indicative high reversibility of a typical capacitive behavior in 0.5 M H₂SO₄ electrolyte. A specific capacitance of 551 F/g was obtained with ruthenium oxide thin film (electrode) prepared by spray pyrolysis method. The specific capacitances of 551 and 450 F/g at the scan rate of 5 and 125 mV/s, respectively, indicate that the capacitance value varies inversely with scan rate.     

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.     

Investigation of O7+ swift heavy ion irradiation on molybdenum doped indium oxide thin films

Molybdenum (0.5 at%) doped indium oxide thin films deposited by spray pyrolysis technique were irradiated by 100 MeV O⁷⁺ ions with different fluences of 5×10¹¹, 1×10¹² and 1×10¹³ ions/cm². Intensity of (222) peak of the pristine film was decreased with increase in the ion fluence. Films irradiated with the maximum ion fluence of 1×10¹³ ions/cm² showed a fraction of amorphous nature. The surface microstructures on the surface of the film showed that increase in ion fluence decreases the grain size. Mobility of the pristine molybdenum doped indium oxide films was decreased from ～122 to 48 cm²/V s with increasing ion fluence. Among the irradiated films the film irradiated with the ion fluence of 5×10¹¹ ions/cm² showed relatively low resistivity of 6.7×10^?4 Ω cm with the mobility of 75 cm²/V s. The average transmittance of the as-deposited IMO film is decreased from 89% to 81% due to irradiation with the fluence of 5×10¹¹ ions/cm².     

Preparation and optical absorption of electrodeposited or sputtered,dense or porous nanocrystalline CuInS2 thin films

Copper indium disulphide thin films were obtained by one-step deposition with two different techniques. Films are synthesised by electrodeposition using a single electrolytic bath and by r.f. sputtering using a single target. Deposition rates were about 75 nm/min and 2.5–6.5 nm/min, respectively. Electrodeposited films have rough and porous surfaces, with no preferential orientation. Smooth or particle-covered surfaces were observed for sputtered films with a highly (112)-oriented chalcopyrite structure. Absorption coefficients calculated from transmittance spectra have high values in visible range. Electrodeposited samples present higher absorption coefficients on a larger wavelength range. A relationship between morphology and optical properties was found; absorption coefficients increase with porosity and roughness of the films. Band gap values of about 1.3 eV for electrodeposited and 1.5 eV for sputtered thin films were calculated.     

Synthesis of nanoporous activated iridium oxide films by anodized aluminum oxide templated atomic layer deposition

Iridium oxide (IrOx) has been widely studied due to its applications in electrochromic devices, pH sensing, and neural stimulation. Previous work has demonstrated that both Ir and IrOx films with porous morphologies prepared by sputtering exhibit significantly enhanced charge storage capacities. However, sputtering provides only limited control over film porosity. In this work, we demonstrate an alternative scheme for synthesizing nanoporous Ir and activated IrOx films (AIROFs). This scheme utilizes atomic layer deposition to deposit a thin conformal Ir film within a nanoporous anodized aluminum oxide template. The Ir film is then activated by potential cycling in 0.1 M H₂SO₄ to form a nanoporous AIROF. The morphologies and electrochemical properties of the films are characterized by scanning electron microscopy and cyclic voltammetry, respectively. The resulting nanoporous AIROFs exhibit a nanoporous morphology and enhanced cathodal charge storage capacities as large as 311 mC/cm².     

Transparent graphene/PEDOT–PSS composite films as counter electrodes of dye-sensitized solar cells

Composite films of graphene and polystyreneslufonate doped poly(3,4-ethylenedioxythiophene) (graphene/PEDOT–PSS) were deposited on indium tin oxide (ITO) substrates by spin coating at room temperature and applied as counter electrodes of dye-sensitized solar cells (DSSCs). A 60 nm thick composite film (contained 1 wt% graphene) coated ITO electrode exhibited high transmittance (>80%) at visible wavelengths and high electrocatalytic activity. The energy conversion efficiency of the cell with this film as counter electrode reached 4.5%, which is comparable to 6.3% of the cell with platinum counter electrode under the same experimental condition.     

Thickness dependent physical properties of close space evaporated In2S3 films

In recent years, In₂S₃ is considered as a promising buffer layer in the fabrication of heterojunction solar cells. Film thickness is one of the important parameters that alters the physical characteristics of the grown layers significantly. The effect of film thickness on the structural, morphological, optical and electrical properties of close space evaporated In₂S₃ layers has been studied. In₂S₃ thin films with different thicknesses in the range, 100–700 nm were deposited on Corning glass substrates at a constant substrate temperature of 300 °C. The films were polycrystalline exhibiting strong crystallographic orientation along the (103) plane. The deposited films showed mixed phases of both cubic and tetragonal structures up to a thickness of 300 nm. On further increasing the film thickness, the layers showed only tetragonal phase. With increase of film thickness, both the crystallite size and surface roughness in the films were found to be increased. The optical constants such as refractive index and extinction coefficient of the as-grown layers have been calculated from the optical transmittance data in the wavelength range, 300–2500 nm. The optical transmittance of the films was decreased from 82% to 64% and the band gap varied in the range, 2.65–2.31 eV with increase of film thickness. The electrical resistivity as well as the activation energy was evaluated and found to decrease with film thickness. The detailed study of these results was presented and discussed.     

Physical properties,biological applications and biocompatibility studies on biosynthesized single phase cobalt oxide (Co3O4) nanoparticles via Sageretia thea (Osbeck.)

Cobalt oxide nanoparticles were successfully biosynthesized by complete green process using aqueous leaf extracts of Sageretia thea as chelating agent. Diverse techniques were applied for characterization. Antibacterial (with and without UV illumination), antileishmanial, antioxidant and enzyme inhibition applications were assessed, while freshly isolated macrophages and red blood cells were used for biocompatibility studies. Good antibacterial nature and enhancement of bactericidal nature upon UV modulation is reported. Staphylococcus aureus and Escherichia coli are indicated as most susceptible bacterial strains. Significant cytotoxic potential is revealed with IC₅₀ calculated as 12.82 µg/ml and 3.16 µg/ml against the axenic leishmanial promastigote and amastigote cultures respectively. Biogenic cobalt oxide nanoparticles indicated DPPH free radical scavenging potential, while moderate antioxidant capacity and reducing power was demonstrated. Bioinspired cobalt oxide also demonstrated alpha amylase and protein kinase inhibition at higher concentrations. Biogenic cobalt oxide was found as more cytotoxic to macrophages (IC₅₀ = 58.55 µg/ml) then to RBC’s (IC₅₀ >200 µg/ml). Our results indicate green synthesis as an alternative, effective and eco-friendly method for the biosynthesis of cobalt oxide nanoparticles with numerous biological applications.     

Spontaneous formation of an electroactive co-polymeric film derived from nordihydroguaiaretic acid and 4,4′-diaminobibenzyl

Binary solution of nordihydroguaiaretic acid (NDGA) and 4,4′-diaminobibenzyl (DABB) undergoes rapid oxidation by ambient oxygen to form a thin film of poly-NDGA-co-DABB on the surface of the reaction chamber and on immersed substrates. Electrochemistry of thus formed films was studied in 0.1 M sulfuric acid and in phosphate buffer (pH 7.4). Electrochemical behavior of the co-polymeric film is characterized by two redox couples, the predominant one being observed at more negative potentials comparing to parent NDGA i.e. 0.28 vs. 0.49 V (vs. Ag/AgCl) in 0.5 M H₂SO₄. The peak potentials were shifted toward lower values with solution pH at the rate of 59 mV/pH unit indicating a 2e/2H⁺ transition as expected for quinone-containing films. The poly-NDGA-co-DABB film exhibits catalytic activity toward electroreduction of nitrite to nitric oxide in acidic electrolytes. This reaction can be used to quantify nitrite in a broad concentration range with low detection limit (0.3 μM, S/N = 3).     

Oxidation of carbon black,propene and toluene on highly reducible Co/SBA-15 catalysts

Different cobalt loadings (3, 6, 12, 24 wt%) were impregnated using the double-solvent technique on SBA-15 calcined at 500 °C presenting a high specific surface area. The impregnated solids were stabilized at 450 °C in the air. The impregnation of cobalt led to the incorporation of cobalt oxide nanoparticles in the mesoporosity of the SBA-15. The cobalt nanoparticles were easily reducible compared to similar solids prepared by different methods. The presence of these nanoparticles enhanced significantly the reactivity of the catalysts in the considered reaction. The addition of more than 12 wt% of cobalt did not enhance the catalytic reactivity due to the deposition of cobalt oxide species on the surface of the support. The cobalt-impregnated solids are efficient in decreasing the oxidation temperature of different probe molecules and are totally selective towards the formation of CO₂ and H₂O.     

Structural and electrochemical properties of a porous nanostructured SnO2 film electrode for lithium-ion batteries

A B₂O₃-doped SnO₂ thin film was prepared by a novel experimental procedure combining the electrodeposition and the hydrothermal treatment, and its structure and electrochemical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, energy dispersive X-ray (EDX) spectroscopy and galvanostatic charge–discharge tests. It was found that the as-prepared modified SnO₂ film shows a porous network structure with large specific surface area and high crystallinity. The results of electrochemical tests showed that the modified SnO₂ electrode presents the largest reversible capacity of 676 mAh g^?1 at the fourth cycle, close to the theoretical capacity of SnO₂ (790 mAh g^?1); and it still delivers a reversible Li storage capacity of 524 mAh g^?1 after 50 cycles. The reasons that the modified SnO₂ film electrode shows excellent electrochemical properties were also discussed.     

Asymmetric electrochemical capacitor microdevice designed with vanadium nitride and nickel oxide thin film electrodes

Vanadium nitride thin film has been coupled with electrodeposited nickel oxide in order to design an electrochemical capacitor microdevice. VN has been used as negative electrode while NiO was used as the positive one in 1 M KOH electrolyte. VN exhibits a pseudo-capacitive behavior while NiO shows a faradaic behavior. This asymmetric microdevice has been operated between 0.5 and up to 1.8 V in aqueous based electrolyte (1 M KOH). Long term cycling ability (10,000 charge/discharge cycles) has been demonstrated with interesting energy (1.0 μW h cm^− 2) and power (40 mW cm^− 2) densities.     

A study on solution deposited CuSCN thin films: Structural,electrochemical, optical properties

A cost-effective successive ionic layer adsorption and reaction (SILAR) method was used to deposit copper (I) thiocyanate (CuSCN) thin films on glass and steel substrates for this study. The deposited thin films were characterized for their structural, morphological, optical and electrochemical properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy and VersaSTAT potentiostat. A direct band gap of 3.88 eV and 3.6 eV with film thickness of 0.7 μm and 0.9 μm was obtained at 20 and 30 deposition cycles respectively. The band gap, microstrain, dislocation density and crystal size were observed to be thickness dependent. The specific capacitance of the CuSCN thin film electrode at 20 mV/s was 760 F g⁻¹ for deposition 20 cycles and 729 F g⁻¹ for deposition 30 cycles.     

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.     

Sputtered,electroless, and rolled palladium–ceramic membranes

Three techniques were used to produce palladium–ceramic (Pd–ceramic) composite membranes for hydrogen separation and production. They are sputtering, electroless deposition and rolling of thin Pd alloy films over ceramic porous tubes.After studying and developing the three coating techniques, an extensive testing and characterizing work was carried out on these thin film composite membranes. The results show that in the sputtered (0.5–5 μm) and electroless (2.5–20 μm) composite membranes, the thermal cycling of the hydrogenated metallic layer produces membrane failures. Such failures are characterized by crack formation and metal film peeling. This fact has been explained by an evaluation of the shear stresses at the metal–ceramic interface due to the differential elongation between the palladium (Pd) coating and the ceramic support under thermal cycling and hydrogen loading. The rolled membranes (50–70 μm), however, because of the particular coating solution, have shown a complete hydrogen selectivity and good chemical and physical stability in long-term tests.     

Nanocrystalline MnO thin film anode for lithium ion batteries with low overpotential

Nanocrystalline MnO thin film has been prepared by a pulsed laser deposition (PLD) method. The reversible lithium storage capacity of the MnO thin film electrodes at 0.125C is over 472 mAh g^?1 (3484 mAh cm^?3) and can be retained more than 90% after 25 cycles. At a rate of 6C, 55% value of the capacity at 0.125C rate can be obtained for both charge and discharge. As-prepared MnO thin film electrodes show the lowest values of overpotential for both charge and discharge among transition metal oxides. All these performances make MnO a promising high capacity anode material for Li-ion batteries.     

Enhanced oxygen evolution at hydrous nickel oxide electrodes via electrochemical ageing in alkaline solution

The effect of electrochemically ageing hydrous nickel oxide films via slow repetitive potential multi-cycling across the main nickel (II/III) redox peak was investigated in an aqueous base environment using cyclic voltammetry and steady state polarisation curves in the oxygen evolution reaction (OER) region. Similarities between hydrous nickel oxide films and electroprecipitated ‘battery type’ nickel oxide were shown due to their similar change in redox and oxygen evolving properties as a result of film ageing. This ageing method was found to significantly enhance the OER performance of the hydrous nickel oxide electrode with the OER overpotential decreasing by 60 ± 2 mV and experiencing a 10 fold increase in OER rate for a fixed overpotential over that of an un-aged electrode. The OER turnover frequency for an aged electrode was found to be 1.16 ± 0.07 s^− 1 in comparison to 0.05 ± 0.003 s^− 1 for a hydrous nickel oxide electrode not subjected to ageing.