Selective preparation of zero- and one-dimensional gold nanostructures in a TiO2 nanocrystal-containing photoactive mesoporous template

Nanocrystallized SiO2-TiO2 with tubular mesopores was prepared via the sol-gel technique. Gold was deposited in the tubular mesopores of the nanocrystallized SiO2-TiO2. The shape of the gold was varied from one-dimensional [1-D] to zero-dimensional [0-D] nanostructures by an increase in TiO2 content and ultraviolet [UV] irradiation during gold deposition. 1-D gold nanostructures [GNSs] were mainly obtained in the mesopores when a small amount of TiO2-containing mesoporous SiO2-TiO2 was used as a template, whereas the use of a template containing a large amount of TiO2 led to the formation of shorter 1-D or 0-D GNSs. UV irradiation also resulted in the formation of 0-D GNSs

FABRICATION OF POROUS, CRYSTALLINE-ORIENTED TITANIA LAYER ON TRANSPARENT ELECTRODE BY MAGNETIC FIELD-ASSISTED EPD

Dye-sensitized solar cells (DSSCs) are the most extensively investigated systems for the conversion of solar energy into electricity, since it can convert light at longer wavelengths into electricity and can be manufactured using less energy compared to the bulk semiconductor-type cells with a p-n junction. Despite these advantages, DSSC commercialization is still limited because of its low conversion efficiency and low reliability of the liquid electrolyte. The low conversion efficiency is due to the non-uniformity of the electrode components with respect to the packing density of TiO2 particles and film thickness of the electrode. Therefore the research on DSSC in general has been directed toward improving the photo-current and photo-potential. In order to significantly enhance the cell performance, it is important to optimize the photo-anode structure of the DSSC on the basis of its fundamental properties. In this study, crystalline-oriented porous TiO2 thin films were fabricated on indium-tin oxide (ITO) or fluorine-doped tin oxide (FTO) glass substrates by electrophoretic deposition (EPD) in a superconducting magnet. Please click Additional Files below to see the full abstract

Electrophoretic deposition of Ag nanoparticles into TiO2 nanotube arrays and their performance as photoanode of dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) are known as next-generation solar cells because their production process costs low and is environmentally friendly compared to silicon-type solar cells, which are currently most widely used in the world. However, power conversion efficiency (PCE) of DSSCs is still lower than 12%, which is much lower than that of silicon-type solar cells. Since one of the main reasons of such a low PCE of DSSCs is a weak light absorption ability of dye molecules, researchers have been studying to improve the light harvesting ability of DSSCs by, for instance, producing new dyes, designing new DSSC structures, adding light absorbing/scattering elements/materials, etc. The addition of metal nanoparticles (NPs) to an photoanode is one of the ways to improve light harvesting ability of DSSCs, because the NPs exhibit surface plasmon resonance (SPR) which absorb and scatter light strongly. SPR is a collective oscillation of free electrons of metal, thus strong electro-magnetic (EM) field is created near the surface of metal NPs. The electrons of dyes can be easily excited by the enhanced EM field and thus the PCE of DSSCs improved. However, the improvement of PCE of DSSCs by metal NPs is generally not as high as expected, because it is difficult to control dispersion state of metal NPs in an photoanode. In this work, Ag NPs were used as metal NPs because Ag NPs are known to create the strongest EM field by SPR among all metals. Anodic TiO2 nanotube (TNT) arrays were employed as a photoanode since the morphology of TNT arrays is known to be appropriate to reduce an electrical resistivity at photoanode. Several methods of Ag NP deposition on TNT arrays were investigated for controlling the dispersion state of Ag NPs Please click Additional Files below to see the full abstract

EPD FOR COMPOSITE CATHODE LAYER IN ALL-SOLID-STATE LITHIUM ION BATTERY BASED ON SULFIDE ELECTROLYTE

All-solid-state lithium ion batteries (LIBs), in which liquid-organic electrolytes are replaced with solid state inorganic electrolytes, are expected to be the optimal rechargeable batteries in the next generation because of their higher energy density, cycle stability and ignition safety. In order to develop all-solid-state LIBs with practical performance, controlling architecture in electrode layer consisting of active materials and solid electrolyte, to obtain good contact of the solids interfaces, with high packing ratio is necessary. However, there are few studies on controlled fabrication of macrostructure. We would like to propose a novel method which is employs electrophoretic deposition (EPD) for preparing composite cathode layer, with LiNi1/3Mn1/3Co1/3O2 (NMC) and 75Li2S-25P2S5 (LPS) used as the cathodic active material and solid electrolyte, respectively. The EPD technique can be used to prepare a cathodic layer with a desired structure because its equipment set up is simple but can be used to obtain complex composite structures. Please click Additional Files below to see the full abstract

Preparation of BaTiO3 nanotube arrays, CoFe2O4 nanoparticles and their composite

Multiferroic nanocomposites which possess both ferroelectric and ferromagnetic properties are attracting much attention because of their scientific interest and significant technological promise in the novel multifunctional devices. Gas-phase syntheses have been typically used to fabricate multiferroic nanocomposites [1]; however, high production cost has been hindering further expansion of the research field. In this research, the components of multiferroic nanocomposites are fabricated by anodization and hydrothermal treatment which were then used to fabricate multiferroic nanocomposites through electrophoretic deposition (EPD) as cheaper alternatives to the costly gas-phase processes. TiO2 nanotubes arrays were firstly formed on Ti metal foils by anodization in an electrolyte containing ethylene glycol, dimethyl sulfoxide, ammonium fluoride and water. Then, BaTiO3 nanotube arrays were obtained by hydrothermal treatment of TiO2 nanotube arrays using Ba-containing aqueous solution. The morphologies and crystal structure of BaTiO3 nanotube arrays were analyzed by a scanning electron microscope (SEM) and an X-ray diffractometer (XRD). Please click Additional Files below to see the full abstract

Indentation-induced stress distribution and pressure effect on the resistivity of YSZ

International audienceIonic conductivities measured under GPa-order high pressure provide various information about ion hopping mechanisms such as the activation volume (ΔV). Traditionally, anvil cells have been used for high-pressure measurements. We previously reported a new method for high-pressure impedance measurements, up to a few GPa, employing an indentation-induced local stress field. In this method, both mechanical and electrical (Young's modulus and high pressure impedance) properties can be obtained simultaneously. However, in this method, high pressures are induced only around the tip of the indenter, and such stress distribution should be considered for the estimation of ΔV accurately. In the present study, employing a finite element method (FEM) calculation, the stress distribution around the tip of the indenter, and effects of such GPa-order high pressures on the O2− ion conduction of Y2O3-doped zirconia (YSZ) are shown

Effects of cesium-substituted silicotungstic acid doped with polybenzimidazole membrane for the application of medium temperature polymer electrolyte fuel cells

Inorganic-organic composite membranes were prepared by using partly cesium-substituted silicotungstic acid (CHS-WSiA) and polybenzimidazole (PBI, MRS0810H) for medium temperature polymer electrolyte fuel cells (MT-PEFCs). Cesium hydrogen sulfate (CsHSO4, CHS) and silicotungstic acid (H4SiW12O40, WSiA) were milled to obtain 0.5CHS-0.5WSiA composites by dry and wet mechanical millings. N,Ndimethylacetamide (DMAc) was used as a disperse medium in the preparation of the inorganic solid acids by wet mechanical milling and also a casting agent for fabrication of membrane. Finally, flexible and homogeneous composite membranes with several phosphoric acid doping levels (PADLs) were obtained. The wet mechanical milling using DMAc was found to effectively promote good substitution of H+ ion in WSiA by Cs+ ion of CHS and promoted the formation of smaller grain sizes of composites, compared with dry milling. A high maximum power density of 378 mWcm-2 and a good constant current stability test were obtained from a single cell test using the PBI composite membrane containing 20 wt% of 0.5CHS-0.5WSiA from wet milling and phosphoric acid doping level (PADL) of 8 mol, at 150 °C under an anhydrous condition. Wet milling CHS-WSiA crystallites were highly dispersed in PBI to give homogenized membranes and played a significant role in the enhancemance of acidity by increasing the number of proton sites in the electrolyte membrane. After the addition of CHS-WSiA into PBI membrane, the acid and water retention properties were improved and incorporated as new proton conduction path by adsorbing phosphoric acid in these composite electrolyte membranes. These observations suggest that composite membranes with 8 mol of PADL are good promising PA dopedmembranes with effective electrochemical properties for the medium temperature fuel cells

Successful Treatment in a Case of Massive Hepatocellular Carcinoma with Paraneoplastic Syndrome

Paraneoplastic syndromes of hepatocellular carcinoma (HCC) are not uncommon. However, the prognosis is poor and follow-up and improvement of paraneoplastic syndromes with treatment have been reported rarely. We report a successful case in an aged man of a massive HCC with paraneoplastic syndrome, treated by combined intraarterial chemotherapy and hepatic resection. Paraneoplastic syndrome (erythrocytosis and hyperlipidemia) was monitored throughout the treatment and erythropoietin (EPO) mRNA also was analyzed in the resected liver. The hemoglobin level and serum levels of EPO and total cholesterol (T-cho) decreased dramatically with treatment, along with a decrease in serum levels of α-fetoprotein and protein induced by vitamin vitamin K absence II (PIVKA-II). Semiquantitative reverse transcription polymerase chain reaction (RT-PCR) revealed that the residual cancer expressed EPO RNA but the nontumor tissue did not. This was a rare case of paraneoplastic syndrome of HCC that was treated successfully. This case indicates that paraneoplastic syndrome reflected tumor progression and that serum levels of both EPO and T-cho might be used as tumor markers