Synthesis and characterization of a new carbon particle are investigated in this study. The carbon particle, which possesses a very high surface area (682 cm2/g), is suitable for catalysts loading in application of fuel cell. As well known, carbon materials are used to be a support of Pt catalyst to achieve high dispersion to enhance the activity of Pt. The synthesis was performed by conventional arc discharge process between two graphite electrodes in vacuum. A high-current range from 100∼ 300 ampere was utilized to evaporate the cathode electrode in order to produce carbon soot onto the wall of chamber, and further high production rate of 10 g/hr was achieved. The morphology and microstructure of the materials were investigated by SEM, HRTEM, XRD and Raman spectroscopy.

Observations of the soot by SEM and HRTEM have shown that it consists agglomerations of carbon particles linked each other to form a chain-like structure. Most carbon particles are approximate 30 ∼ 60 nm in diameter. HRTEM observation reveals that a carbon particle is comprised of several defective onions with different diameters and extremely curled graphene sheets, which appear as double-sheet layers.

Direct liquid crystal templating from non-ionic polyoxyethylene surfactants has been utilised to produce well-defined birefringent films of nanostructured cadmium telluride with mesoporous architectures of extended spatial periodicities. The template mixtures and films were characterised by X-ray diffraction, transmission electron microscopy and polarising optical microscopy to ascertain the presence of a regular nanostructure. UV-VIS reflectance spectroscopy was employed to investigate the films' optical properties.

In this paper, we address the theory of electric field demixing of the cations in semi-conducting and initially homogeneous mixed ceramic oxides. We include the off-diagonal phenomenological transport coefficients by assuming a random distribution of cations and making use of an exact sum-rule expression. The steady state atomic composition profiles are shown to be quite different when different assumptions are made about vacancy equilibration. We show that in the case of large grained material (where vacancies in the interior do not equilibrate easily to the external oxygen partial pressure), a maximum develops in the steady state vacancy composition profiles. This behaviour is verified by independent Monte Carlo simulations.

A new method of depositing epitaxial ZnO nanocolumns on sputter-coated ZnO substrates is described that utilizes supersaturated zincate species in sodium hydroxide solutions and requires no complexing agents. Uniform arrays of columns are grown reproducibly over entire substrates in 10 to 50 min. Columns are 50 to 2000 nm long and 50 to 100 nm wide. Strict substrate cleaning and/or preparations are not necessary with this method, in contrast to many other techniques. Films grow only on substrates pre-coated with ZnO, not on bare glass or ITOor SnO2-coated glass. Factors affecting the column growth are elucidated and experimental observations are correlated with crystal growth theory.

Polymer/TiO2 composite solar cells (CSCs) are currently being investigated by academic research groups and industrial companies due to the prospect of achieving good power conversion efficiencies and lifetime stability at a low production cost. We present data of the initial period of operation (up to several hours) of such devices, which show that during this period the CSCs operate in a non-steady state regime. The transient behaviour is accounted for using an equivalent circuit model (ECM) of the photovoltaic device with time-dependent resistors.

We investigate the behavior of a polymer blend (M3EH-PPV:CN-ether-PPV) bulk heterojunction solar cell using a numeric model that self-consistently solves Poisson's equation and the charge continuity equation while incorporating electric field dependent mobilities. We obtain good quantitative agreement with present experimental data for J-V curves and photocurrent action spectra. To reproduce experimental photocurrent action spectra, our model predicts 36% exciton dissociation efficiencies in the bulk of the polymer. We also study the limiting conditions of polymer solar cell development by simulating an ideal solar cell using an AM1.5 global spectrum and assuming all absorbed photons hitting a M3EH-PPV:CN-ether-PPV polymer blend (band gap ∼2.0 eV) based solar cell at normal incidence contribute to current. If such a solar cell has 100 nm length, open circuit voltage=0.6 V and 50% fill factor, then the maximum theoretical power conversion efficiency is ηp=5.6%. A similar analysis for a M3EH-PPV:PCBM bulk heterojunction cell yields, ηp=3.5%. These results further highlight the need to develop smaller band gap materials and help explain why the best polymer based solar cells have power conversion efficiencies that remain stuck at about 3%. Our model is used to investigate the important increase in power conversion efficiencies we can expect as lower band gap polymers become available.

Dye sensitized solar cells of the Graetzel type are usually fabricated with TiO2 covered with dye after its synthesis as one electrode. ZnO is, aside from TiO2, a promising alternative semiconducting material for solar energy conversion due to its enhanced surface area and a strong attachment of non-aggregated sensitizer dyes. We investigate ZnO/dye electrodes where the dye is already added during the electro-deposition process of the ZnO. We examine the influence of the dye species and the dye concentration on the surface morphology by means of atomic force and scanning electron microscopy imaging. The electrical properties of the films are characterized by means of current-voltage measurements. In order to study the integral properties of the charge carrier transport in the lateral direction of the film we characterized ZnO thin films electro-deposited across an insulating gap between two microstructured electrodes made of gold.

We report on recent progress in fabricating an inorganic solid state solar cell based on a nano-structured substrate with an extremely thin absorber, the so-called eta-cell. The cell uses HgCdTe as an absorber layer and TiO2 as a substrate. By adjusting the Hg/Cd ratio the conduction band edges in these two materials can be brought into alignment. This tuning provides an ideal tool to optimize the optical and electrical properties of the cell. In qualitative agreement with earlier work we find a band offset of 0.25 eV to give maximum transfer rates across the interface. The optimized cell has a short circuit current of 15 mA/cm2 and an open-circuit voltage of 0.6 V. We discuss the optical and electrical properties of the cell, and outline ideas to further improve the performance.

Composite technology is a new approach to solid oxide fuel cell (SOFC) fabrication. It is based on the net shape processing, which uses a combination of colloidal suspension and polymer precursor techniques. Different elements of SOFC can be prepared and optimized using this approach and the flexibility of the net shape processing. The goal of this research was to develop net shape procedures for different elements of SOFC, to show the real possibility preparing all these elements of SOFC and to investigate the advantages of composite technology. A nickel-YSZ composite was prepared and investigated as the prospective anode material. High electronic conductivity and stability in REDOX cycles were shown for this material. Different cathode compositions were prepared using composite technology and tested. It was shown, that these materials ensure low overpotentials and are time stable at operation temperature up to 800°C. All three SOFC designs were tested: anode, cathode and electrolyte supported SOFCs. It was possible to achieve low resistance of SOFC structure for all designs, but electrode supported SOFCs had limitation in the current connected with the gas diffusion through thick electrode substrates. The best performance was achieved on an electrolyte supported system with 100 [.proportional]m YSZ electrolyte and composite anode and cathode: 0.75W/cm2 power density at 0.6 V at 800°C.

Cuprous oxide (Cu2O) is a direct-gap semiconductor with band-gap energy of 2.0 eV and has been extensively investigated as a candidate for a photovoltaic material. However, practical applications have not been achieved to date due to the difficulty in controlling its physical properties. We have investigated the controllability of the formation of pure Cu2O thin films deposited by the reactive DC sputtering method and analysis by XPS and Raman spectrometer to identify the Cu+1 in the cuprous oxide. The formation of pure Cu2O films is not only dependent on the substrate temperature but also strongly effected by the oxygen and argon flow rate ratio. When the substrate temperature was kept constant at 100°C and varied the oxygen and argon flow rate ratio from 3ml/min to 10ml/min, it is found a mixture of Cu2O and CuO phases is formed. At the flow rate of oxygen to 5ml/min, the pure and single phase of Cu2O is formed. Further increasing the oxygen flow rate, the phase is changed to be the CuO phase. The crystallity is improved as increasing the substrate temperature. The electrical resistivity of Cu2O obtained in this study is about 316 ohm-cm at 100°C substrate temperature and 2.66Pa condition. The dependence of cupper oxides resistivity is not only on the substrate temperature and reactive gases but also on the sputter pressure. Because the characteristic resistivity values change with sputter pressure variation due to different phase compositions forming in the films. The lowest resistivity of Cu2O film is obtained when the Cu2O single phase exists in the films.

In the present work, the screen printing technique has been used to deposit thick films of Zr0.84Y016O1.92 (8YSZ). In order to control the final porosity in view of a specific application (SOFCs or gas sensor), an experimental design based on analysis of variances (ANOVA) has been carried out. From this, we were able to determine the influence of several technological parameters on films porosity and grain size. The films obtained have been analysed with both Scanning Electron Microscopy (SEM) and Focused Ion Beam (FIB) combined with SEM. We show that only the combination of experimental design and advanced observation technique such as Focused Ion Beam allowed us to extract significant information for the improvement of the deposition process.

LiCoO2 and LiNiO2, two important cathode materials for Li-ion batteries, were studied in their respective bulk and thin-film form. X-ray absorption spectroscopy (XAS) has been used to probe the local atomic structure and structural defects in the thin-film and bulk cathodes. Results comparing Li(Co,Ni)O2 in the bulk and thin-film forms suggests a correlation between intrinsic stress and local strain in the thin-film. This local strain is manifested by a collapse of the six-fold rotational symmetry within the metal-metal layer of the Li(Co,Ni)O2 system into a two fold one. The relationship between annealing conditions and the resulting local strain in these films is examined.

Nanoporous TiO2 electrodes were sensitized by different porphyrin derivatives, terahydroxyphenyl porphyrin (THPP) and tera-carboxylphenyl porphyrin (TCPP). Both kinds of sensitized electrodes were characterized by UV-vis, XRD and XPS. The results showed that the interaction between TiO2 and TCPP was stronger than that between TiO2 and THPP. Both kinds of the sensitized electrodes were assembled to photoelectrochemical cells. The photocurrent responses of the photoelectrochemical cell under different incident illumination directions were different significantly. The overall light-to-electric energy conversion yield (η) of TCPPsensitized cell was 0.11%, while the conversion efficiency of THPP-sensitized cell was 0.06%.

Hybrid proton-carrier polymer composites were fabricated in an effort to develop high-performance high-temperature proton exchange membranes (PEMs) for fuel cell applications in the 100°–200°C range. The solution-cast hybrid membranes comprise a polymer host and a SiO2-based proton-carrier composite that was synthesized via sol gel approach using a functional silane and tetraethoxysilane (TEOS) in acidic conditions. The primary H+-carrying component was either a heteropoly silicotungstic acid (STA) or a sulfonic acid (SFA) that was thermooxidatively converted from a mercapto (-SH) group. The embedding level of STA on the silane-modified SiO2 sol gel composites was strongly affected by the presence and the functional group of the silane. Ion exchange capacity (IEC) of the water-washed, SiO2-based STA and SFA proton-carrier composite powders is in the range of 1.8–3.5 mmol/g, two to three times higher than that for Nafion 117 (0.9 meq/mol). A glycidylmethacrylate-type copolymer, PEMAGMA, which is stable up to ∼225°C, was able to produce mechanically robust and flexible hybrid membranes. Upon curing, the PEMAGMA composite membranes showed a ∼75% gel under the present formulation and retained the "free" STA effectively with slight loss when extracted in an 85°C water. The W12-STA-containing PEMAGMA membranes followed the weight loss trends of water from STA and the SiO2-based sol gel composite, showing a 10 wt% loss at 150°C and a 15 wt% loss at 225°C. Fuel cell performance tests of the preliminary films gave a Voc in the 0.85–0.93 V range, but a low current density of <4 mA/cm2. The resistive characteristics were attributed to inhomogeneous distribution of the sol gel nanoparticles in the PEMAGMA matrix, a result of phase separation and particulate agglomeration during film forming.

Nanostructured electrodes were assembled layer-by-layer from polyacrylate-capped Pt nanoparticles (<d>=2.5 ± 0.6 nm) in a cationic polyelectrolyte. Cyclic voltammetry revealed hydrogen adsorption peaks at the modified nanoparticles characteristic of an activated polycrystalline Pt surface, with a negative shift in the peak potentials indicating a less facile electro-adsorption relative to the polycrystalline electrode, possibly due to nanoparticle surface modification. Current-voltage measurements at multilayers of Pt nanoparticles in polyelectrolytes indicated the feasibility of charge hopping between the particles embedded in the insulating matrix. Such feasibility was also evidenced in photoluminescence quenching of Q-CdS dots (<d>=3.6 ± 0.5 nm) assembled in polyelectrolytes upon inserting Pt nanoparticles in the architecture.

The spinel structured lithium manganate (LMO) is a promising cathode material for lithium ion rechargeable micro-batteries due to its higher energy density, environmentally benign nature, and low cost. To date, self-discharge and capacity fading (4 and 3V range), especially at elevated temperatures, still remains major research issues of LMO based cathodes. In the present work we have successfully synthesized lithium manganate thin films by a cost effective solution growth technique. These films exhibited excellent reversible lithium ion intercalation behavior with a discharge capacity of about 55.08:Ahcm−2:m−1 at a load of 20:Acm−2. The Li+ diffusivity was found to increase by substituting a part of manganese with aluminum (Al) in LMO lattice. Al substituted LMO films exhibited better cycleability as compared to the undoped LMO films. Further studies are in progress to investigate the effect of Al substitution on the cycleability of the films.

Phenolic resin-based nanoscopic carbonaceous materials have been prepared by doping different proportions of ZnCl2 into phenolic resin (PR) precursor at various heat-treatment temperatures and characterized by means of Brunner-Emmett-Teller method (BET), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy analyses. The results show that as the ratio of PR to ZnCl2 is 1:3, the average size of grains and apertures are about from 40 to 60 nm and 3.86 nm, respectively, reaching nanometer level. When this material is used as electrode material of lithium ion battery, the reversible capacity the battery could be kept at 370 mA•h•g−1 after 10 charge/discharge cycles.

Nanometric particles of manganese (oxihydr)oxides (Hausmannite, Manganite, Nsutite, Pyrolusite and Vernadite) have been synthesized by thermohydrolysis of MnCl2 and/or KMnO4in aqueous medium. The modification of various chemical parameters (pH and precursors concentration, nature of the reducer or oxidizer, temperature and duration of the thermolysis) allow the control of the nature, the size and the morphology of the obtained particles.

Cu/Sn alloy electrode, as an anode for Li ion secondary batteries, was fabricated by annealing of Sn thin film electroplated on copper thin foil. The structure of Cu/Sn alloy electrode was determined using XRD, SEM and TEM. The thin film was consisted of Cu6Sn5, Cu3Sn and so on, the major component was a few ten nanometer sized Cu6Sn5 grains and the minor (Cu3Sn and β-(Cu,Sn)) was dispersed among the Cu6Sn5 grains. The electrochemical properties of Cu6Sn5 thin film were evaluated in coin type half-cell, which was configured with Cu6Sn5, thin film electrode, Li metal electrode and typical 1 mol LiPF6 in EC:DMC (1:1) electrolyte. Annealed Cu/Sn electrode took and released Li ions well during Li insertion and de-insertion. Cycle performance of annealed Cu/Sn electrode was better than that of as-deposited Sn electrode, which was caused by topotactic reaction of Cu6Sn5and composite structure of Cu/Sn alloys.

The vapor deposition methods of planar magnetron sputtering and electron-beam evaporation are used to synthesize materials with nanostructured morphological features that have ultra-high surface areas with continuous open porosity at the nanoscale. These nanostructured membranes are used in a variety of fuel cells to provide electrode and catalytic functions. Specifically, stand alone and composite nickel electrodes for use in thin film solid-oxide, and molten carbonate fuel cells are formed by sputter deposition and electron beam evaporation, respectively. Also, a potentially high-performance catalyst material for the direct reformation of hydrocarbon fuels at low temperatures is deposited as a nanostructure by the reactive sputtering of a copper-zinc alloy using a partial pressure of oxygen at an elevated substrate temperature.