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Dopamine (DA) and its derivatives are promising for the fabrication of functional films and devices with excellent conductivity and long-term stability; nevertheless its polymerization process is typically prolonged. We have proposed the accelerated deposition process using ultraviolet (UV) irradiation with the existence of nanotitanium dioxide (nano-TiO more...

The paper is concerned on the properties of the new ideal circuit element, a memristor. We proposed memristor with nanothin three layers of Pt/ TiO2-x/TiO2/TiO2+x/Pt sandwiched structure in this paper,based on study of the working principles of HP memristor. As the new TiO2+xlayer and its expansion effect,the switching speed of the new structure memristor mentioned would be faster. The paper gives the test result and mechanism of the new structure memristor, such as characteristic analysis results of Pt nanowire, memristor, repetitiveness and V-I characteristic hysteretic curve of three layers memristor by using semiconductor tester. more...

The proton exchange membrane fuel cell (PEMFC) directly converts chemical energy into electricity with a high energy conversion rate, environmental friendliness, and the ability to start working quickly. The key material that determines the performance, lifetime, and cost of the PEMFC is the electrocatalyst, but the Pt catalyst used is very expensive, which is the major factor limiting the commercial use of the PEMFC. The Pt nanowire catalyst has demonstrated good performance in improving the utilization ratio of Pt, electrochemical activity, CO tolerance, and durability. This article reviewed the preparation and characterization of the Pt nanowire catalyst and its electrochemical activity. more...

Focused ion beam (FIB) is an important tool in microfabrication technique. In recent years, FIB was used to fabricate the nanodevices. In this paper, Pt nanowires with differ radius were deposited with FIB. The component and resistance of nanowires were investigated. Results indicate that the component of Pt naowires is mainly Pt, C and Ga. The high content of Pt in nanowires is 49.36%. The resistivity of Pt nanowire is from 545.74µΩ•cm to 5.16µΩ•cm. Pt nanowires with the diameter up to 60nm take on characteristic of metal; others take on that of semiconductor. more...

A vertically aligned three dimensional (3D) Pt nanowire array electrode has been fabricated by electrodeposition of Pt into an anodic aluminium oxide (AAO) template. After immobilizing horseradish peroxidase (HRP) on this 3D nanowire platform, its electrochemical behavior has been examined for the detection of hydrogen peroxide (H2O2). The HRP/Pt nanowire platform showed a remarkable sensitivity of 345 µAmM-1cm-2 with a linearity range up to 2.5 mM towards H2O2. more...

We report Pt nanowire electrodes fabricated by means of electrodeposition method as a function of molecular weight of polyvinylpyrrolidone (PVP-L and PVP-H). The higher molecular weight of PVP results in a smaller grain size of Pt nanophases in the electrode. The Pt nanowire array electrode electrodeposited with PVP-H shows the smallest gain size of Pt and an excellent catalytic activity for methanol electrooxidation in comparison with pure Pt nanowire array electrodes electrodeposited without PVP and with PVP-L. more...

The electron-transport property of single-row Pt atomic nanowires is examined by first-principles calculations based on the density functional theory. I found that oscillation patterns with a period longer than two-atom length are dominant in the conductance of Pt nanowire, although the transmission of the s−dz2 channel still exhibits even−odd oscillatory behavior. When the nanowires are deformed into zigzag configurations from the straight configuration, the oscillation behavior of the patterns with long periods changes and the oscillations eventually disappear. On the other hand, the even−odd oscillatory behavior of the s−dz2 channel still survives even in the deformed nanowire. The even−odd oscillation in the conductance of Pt nanowire is interpreted to be due to the low sensitivity of the oscillation of the s−dz2 channel to the spatial deformation of the nanowires. more...

We described a new method to fabricate Fe−Pt binary alloy nanomaterials (nanocrystalline thin films and nanowire arrays embedded in porous alumina films) through a direct current electrodeposition ... more...

High-loading carbon supported Pt nanowire electrocatalysts are successfully synthesized in a mild one-pot template- and surfactant-free route. The high electrocatalytic activity, Pt utilization, and long-term stability toward methanol are ascribed to the anisotropic structural properties, exposure of specified planes, and the role of support on good dispersion. more...

Developing hydrogen (H2) sensors with a high sensitivity, rapid response, long-term stability, and high throughput is one of the critical issues in energy and environmental technology [Hübert et al. Sens. Actuators, B 2011, 157, 329]. To date, H2 sensors have been mainly developed using palladium (Pd) as the channel material because of its high selectivity and strong affinity to the H2 molecule [(Xu et al. Appl. Phys. Lett. 2005, 86, 203104), (Offermans et al. Appl. Phys. Lett. 2009, 94, 223110), (Yang et al. Nano Lett. 2009, 9, 2177), (Yang et al. ACS Nano 2010, 4, 5233), and (Zou et al. Chem. Commun. 2012, 48, 1033)]. Despite significant progress in this area, Pd based H2 sensors suffer from fractures on their structure due to hydrogen adsorption induced volumetric swelling during the α → β phase transition, leading to poor long-term stability and reliability [(Favier et al. Science 2001, 293, 2227), (Walter et al. Microelectron. Eng. 2002, 61–62, 555), and (Walter et al. Anal. Chem. 2002, 74, 1546)]. In this study, we developed a platinum (Pt) nanostructure based H2 sensor that avoids the stability limitations of Pd based sensors. This sensor exhibited an excellent sensing performance, low limit of detection (LOD, 1 ppm), reproducibility, and good recovery behavior at room temperature. This Pt based H2 sensor relies on a highly periodic, small cross sectional dimension (10–40 nm) and a well-defined configuration of Pt nanowire arrays over a large area. The resistance of the Pt nanowire arrays significantly decreased upon exposure to H2 due to reduced electron scattering in the cross section of the hydrogen adsorbed Pt nanowires, as compared to the oxygen terminated original state. Therefore, these well-defined Pt nanowire arrays prepared using advanced lithographic techniques can facilitate the production of high performance H2 sensors. more...

A template synthetic method to prepare densely packed metal nanostructures in functionalized (MCM)-41 and MCM-48 is described. The intrachannel surface of host silica has been functionalized to carry positive charges for the accommodation of highly concentrated and negatively charged metal complexes. After reduction, Au and Pt nanowire bundles in MCM-41 as well as Pd nanowire networks in MCM-48 are formed. The Pt nanowire bundles in MCM-41 are observed to grow along a preferred direction and stack along Pt {111} planes relative to the pore wall of the host. Furthermore, bimetallic AuPt alloy nanowire bundles in MCM-41 have also been prepared and characterized. more...

Supervisor:水谷五郎, マテリアルサイエンス研究科, 博士

The process of the reductive amination of aldehydes or ketones in the presence of ammonia using unsupported ultra-thin Pt nanowires has been developed. This catalytic system shows high activity and selectivity under mild reaction conditions. more...

A simplified cost-effective template approach for preparing efficient gold-free bimetal Ag–Pt nanowire motors, where the silver segment is obtained by a partial removal of the silver sacrificial layer is described (see figure). The unusual behavior, reflecting the ‘active’ role of the Ag segment and the asymmetry of the catalytic surface provides the ultrafast motion of these nanomotors. more...

By means of band structure calculations within the density functional theory and the generalized gradient approximation, we investigate the electronic structure of self-organized Pt nanowires on the Ge(001) surface. In particular, we deal with a novel one-dimensional surface state confined in the nanowire array and clarify its origin. Due to large Pt contributions, the novel state is rather a mixed Ge-Pt hybrid state than a confined Ge surface state. Moreover, we compare our results to data from scanning tunneling microscopy., 3 pages, 3 figures, accepted by Eur. Phys. J. B more...

We have measured optical second harmonic generation (SHG) intensity from three types of Pt nanowires with 7 nm widths of elliptical and boomerang cross-sectional shapes, and with 2 nm width elliptical cross-sectional shapes on the MgO faceted templates. From the SHG intensities, we calculated the absolute value of the nonlinear susceptibility χ^(2) integrated in the direction of the wire-layer thickness. The tentatively obtained bulk χ^(2)B of the wire layer was very large, approaching the value of the well-known nonlinear optical material BaTiO_3. more...

The electrical properties of individual NiFe/Pt multilayer nanowires have been measured in situ by nanomanipulators in a scanning electron microscope. The electrical measurement of ∼50 nm diameter individual NiFe/Pt multilayer nanowires with polycrystalline microstructure shows that the nanowires have a resistivity of ∼2.2 × 10−7 Ω m (corresponding to a conductivity of ∼4.5× 106 Ω−1 m−1) and average resistance of individual NiFe-Pt interfaces of ∼0.2 Ω. The maximum failure current density of an individual NiFe/Pt nanowire was measured to be ∼9.63 × 1011 A m−2. more...

The process of the reductive amination of aldehydes or ketones in the presence of ammonia using unsupported ultra-thin Pt nanowires has been developed. This catalytic system shows high activity and selectivity under mild reaction conditions. more...

We have fabricated Pt nanowires with boomerang-like cross-sectional shapes on the We have fabricated Pt nanowires with boomerang-like cross-sectional shapes on the MgO(110) faceted template and observed their optical second-harmonic generation (SHG) response. In the TEM images the Pt nanowires on the MgO substrate had macroscopic C_ symmetry, however, their structure had microscopic imperfections. In the SHG response, as a function of the sample rotation angle around the substrate normal, we found contributions from the nonlinear susceptibility elements χ_, χ_, χ_, χ_, and χ_ originating from the broken symmetry in the 3; [110] direction of the MgO substrate. The indices 1 and 2 denote the [001] and [11^^-0] directions, respectively. Under C_ symmetry no SHG is expected in the s-in/s-out polarization configuration, however, a finite SHG was observed in this polarization configuration. We suggest that the SHG in the forbidden configuration might originate from the imperfections in the nanowire structure. more...

The anisotropic structure and unique surface properties of one-dimensional (1D) Pt-nanowire (PtNW) make it a promising new type of electrocatalyst for various catalyst applications, especially for fuel cells. However, due to the critical synthesis process, a finely tuning of the synthesis temperature for precisely controlling the morphology and distribution of PtNWs in catalyst electrodes still remains a grand challenge. In this work, we present the temperature-controlled growth of PtNWs with large-area 16cm2 carbon paper piece as a direct support. The relationship between the growth temperature and PtNW behavior is studied by physical characterization, and their catalytic activity is measured towards oxygen reduction reaction (ORR) by testing as the cathode in a hydrogen-air fuel cell. The results show that the growth temperature plays a vital role on the behavior of PtNWs thus influencing their properties. The catalyst electrode with PtNWs grown at 40°C shows the best power performance. A possible mechanism for the influence of temperature on PtNW growth is suggested. The comparison with the state-of-the-art commercial TKK catalyst also shows a better performance and durability. The understanding gained in our work from PtNW catalyst electrode could aid in the design of other novel nanostructures in practical applications. more...