Search results for " nanowire"
showing 10 items of 103 documents
Mixed-Mode Operation of Hybrid Phase-Change Nanophotonic Circuits
2016
Phase change materials (PCMs) are highly attractive for nonvolatile electrical and all-optical memory applications because of unique features such as ultrafast and reversible phase transitions, long-term endurance, and high scalability to nanoscale dimensions. Understanding their transient characteristics upon phase transition in both the electrical and the optical domains is essential for using PCMs in future multifunctional optoelectronic circuits. Here, we use a PCM nanowire embedded into a nanophotonic circuit to study switching dynamics in mixed-mode operation. Evanescent coupling between light traveling along waveguides and a phase-change nanowire enables reversible phase transition b…
Electrochemical pH Control at Gold Nanowires
2018
In this work, interdigitated arrays of nanowire electrodes are used with one array acting as the working electrode while the other is used to generate the required protons. Finite element simulations of the pH control electrodes were performed to provide insight on the generation and subsequent diffusion of protons. This informed the inter-tine spacing of the electrodes used.. This electrochemical pH control method was then used to enable the detection of analytes of interest.
Core-shell Zn-doped TiO2-ZnO nanofibers fabricated via a combination of electrospinning and metal-organic chemical vapour deposition
2010
Zn-doped TiO2 nanofibers shelled with ZnO hierarchical nanoarchitectures have been fabricated combining electrospinning of TiO2 (anatase) nanofibers and metal-organic chemical vapor deposition (MOCVD) of ZnO. The proposed hybrid approach has proven suitable for tailoring both the morphology of the ZnO external shell as well as the crystal structure of the Zn-doped TiO2 core. It has been found that the Zn dopant is incorporated in calcined electrospun nanofibers without any evidence of ZnO aggregates. Effects of different Zn doping levels of Zn-doped TiO2 fibers have been scrutinized and morphological, structural, physico-chemical and optical properties evaluated before and after the hierarc…
Template electrodeposition and characterization of nanostructured Pb as a negative electrode for lead-acid battery
2019
Abstract Despite Lead Acid Battery (LAB) is the oldest electrochemical energy storage system, diffusion in the emerging sectors of technological interest is inhibited by its drawbacks. The principal ones are low energy density and negative plate sulphating on high rate discharging. In this work, it is shown the possibility of overcoming such drawbacks by using nanostructured lead as a negative electrode. Lead nanowires (NWs) were fabricated by electrochemical deposition in template, which is an easy, cheap, and easily scalable process. Their morphology and crystal structure have been characterized by electron microscopy and X-ray diffraction, respectively. An electrochemical cell simulating…
Toward Tin-Based High-Capacity Anode for Lithium-Ion Battery
2014
Electrochemical deposition of SnCo alloys inside the nanometric pores of commercial membranes is described. Composition, morphology and crystallographic structure of the synthesized nanostructured alloys are reported as well as the results of electrochemical tests carried out both in half-cell and in full battery configuration to investigate the performance of these SnCo alloys as anodes for lithium-ion batteries. Optimized depositions yielded nanostructured alloys that performed 200 deep galvanostatic cycles at C/2 and 30 °C with 80 % capacity retention and coulombic efficiency higher than 97 % after 40 cycles Moreover, charge-discharge rate capability tests showed the high performance of …
Surface plasmon propagation in metal nanowires
2012
Plasmonic circuitry is considered as a promising solution-effectivetechnology for miniaturizing and integrating the next generation ofoptical nano-devices. The realization of a practical plasmonic circuitry strongly depends on the complete understanding of the propagation properties of two key elements: surface plasmons and electrons. The critical part constituting the plasmonic circuitry is a waveguide which can sustain the two information-carriers simultaneously. Therefore, we present in this thesis the investigations on the propagation of surface plasmons and the co-propagation of surface plasmons and electrons in single crystalline metal nanowires. This thesis is therefore divided into …
Vertical standing copper nanowires for electrochemical sensor of nitrate in water
2020
Nitrogen, in the forms of nitrate (NO3-), nitrite, or ammonium, is a nutrient needed for plant growth and it is a common constituent of fertilizers [1]. When fertilizers are overused, they contaminate the ground water and then the food chain. For humans, a low level of nitrate is advisable because it increases the blood flow and has a good effect on both blood pressure and cardiovascular system. On the contrary, a high concentration of nitrate can be dangerous for humans. Nitrate ions undergoes different chemical transformations (i.e. to nitrite ions by Escherichia coli) producing different nitrogen-based compound such as nitrite ions, nitric oxide and ammonia [2]. These chemicals lead to s…
Fuel Cell Performances of Bio-Membranes Made of Chitosan-Polyelectrolyte Thin Films and Nanowires into Anodic Alumina Membranes
2012
Chitosan (CS) / Phosphotungstic acid (PTA) polyelectrolytes in the shape of thin films and nanowires supported by Anodic Alumina Membranes (AAM) have been fabricated through solution cast and filtration techniques, respectively. Their ability to function in a H2/O2 fuel cell under mild conditions (room temperature, low humidity and low Pt loading) is proved for the first time. The fabricated membrane electrode assemblies produce power peaks of ~20 mW cm-2 for both films and nanowires. The CS/PTA films (20-40 μm thick) are able to produce a quite constant power density of ~10 mW cm-2 recorded for at least 7 h. The gradual decrease of the power output with time observed for CS/PTA nanowires i…
Struktūra un fotofizikālie procesi 0D un 1D InGaN kompozītu materiālos
2014
Šajā disertācijā tiek aprakstīti strukturālās un fotofizikālās MOCVD izaudzēto GaN nanovadu (NV) un InGaN kvantu punktu (KP) īpašības. Abos gadījumos ir parādīts, ka ex-situ RHEED mērījumi ir iespējami un sniedz kvalitatīvu informāciju par struktūru. Kombinācijā ar citām metodēm, pirmkārt, ir parādīts, ka nemetāliskā katalizatora veicinātā GaN NV īpašības, kad sintezēts uz GaN (0001) virsmas, atšķiras no tradicionāli iegūtajiem. Šinī gadījumā katalizators lokalizējas pie nanovadu pamatnes nevis tā galā un augšanas virziens ir atšķirīgs no kristalogrāfiskās c-ass, rezultātā iegūstot semipolārās NV struktūras. Otrkārt, InGaN kvantu punktos ir konstatēt saspiesta kristāliskā režģa struktūra au…
Influence Of The Electrical Parameters On The Fabrication Of Copper Nanowires Into Anodic Alumina Templates
2009
Abstract Metallic copper nanowires have been grown into the pores of alumina membranes by electrodeposition from an aqueous solution containing CuSO 4 . and H 3 BO 3 at pH 3. In order to study the influence of the electrical parameters on growth and structure of nanowires, different deposition potentials (both in the region where hydrogen evolution reaction is allowed or not) and voltage perturbation modes (constant potential or unipolar pulsed depositions) were applied. In all cases, pure polycrystalline Cu nanowires were fabricated into template pores, having lengths increasing with the total deposition time. These nanowires were self-standing, because they retain their vertical orientati…