Nanoporous Nb2O5 hydrogen gas sensor

This work presents the development of gas sensors based on nanoporous niobium oxide (Nb2O5) films for hydrogen gas sensing. Nanoporous Nb2O5 films were successfully synthesized by the anodization of niobium foil in fluoride-organic solvent containing a small percentage of water at 50 °C. These conditions helped to obtain nanovein-like networks with pore diameters of 30-50 nm. After annealing at 440 °C an orthorhombic phase of Nb2O5 was obtained. Contacts of the sensors were then established using platinum (Pt) that also acted as catalytic layers. The gas sensing properties of these nanoporous contacts were investigated for hydrogen gas sensing at different film thicknesses and temperatures

Fuel saving analysis and stability assessments of malaysian offshore fishing vessels fitted with dual fuel diesel and compressed natural gas

Malaysia fishing industries are heavily dependent on the fossil fuels to satisfy its energy demand. Fuel cost of fishing vessels normally accounts for more than 50% of the annual operating expenses. With the increasing of global fuel prices, the future of this industry has exposed fishermen to uncertain future. Nowadays, clean burning alternative fuel such natural gas has become a great interest for fuel saving. A duel fuel diesel engine is a diesel engine that has been fitted to use compressed natural gas (CNG). Dual fuel engines provide numerous potential advantages such as cost saving, fuel flexibility, lower emissions, better efficiency and easy conversion of existing diesel engines without major modifications. This paper describes a study to reduce fuel consumption by introducing a dual fuel diesel and CNG for Malaysian offshore fishing vessel. An analysis of fuel consumption reduction is presented, together with stability assessments. The results reveals that dual fuel diesel can provide noticeable lower fuel consumption compared to existing diesel engines and stability assessment signify that the conversion to dual fuel engine has no adverse effects to vessel stability

Characterization of metal contacts for two-dimensional MoS2 nanoflakes

While layered materials are increasingly investigated for their potential in nanoelectronics, their functionality and efficiency depend on charge injection into the materials via metallic contacts.This work explores the characteristics of different metals (aluminium, tungsten, gold, and platinum) deposited on to nanostructured thin films made of two-dimensional (2D) MoS2 flakes. Metals are chosen based on their work functions relative to the electron affinity of MoS2. It is observed, and analytically verified that lower work functions of the contact metals lead to smaller Schottky barrier heights and consequently higher charge carrier injection through the contact

Status and Prospects of ZnO-Based Resistive Switching Memory Devices

In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges

A NEW APPROACH IN DEALING WITH CONFLICT CRITERIA AND COMPLEX INTERRELATIONSHIPS USING SIMULATION AND ARTIFICIAL NEURAL NETWORK

ABSTRACT Ship design is complex due to the high degree of interaction among the many disciplines e.g. Naval Architecture, Mechanical and Electrical engineering. In preliminary design stage, major decisions on the dimensions and components should be confirmed. A holistic understanding of the engineering economics is crucial factor in order to make decisions correctly. Thus the aims of this paper is to develop a methodology for (1) selecting a prescriptive combination set of the specific component values that produced the values of the given criteria, and (2) a set of results produced from the above prescriptive values. The multi objective optimization software created manages to solve many conflicting criteria with complex interrelationships not limited to ship design. It is using combination of mathematical models with LabVIEW and Artificial Neural Network. The benefit of the software is not limited for the ship-owner, shipbuilding companies and shipyard operators, but also very useful for the engineers as an option tool when dealing with Conflict Criteria and Complex Interrelationships problems

Thin films and nanostructures of niobium pentoxide: Fundamental properties, synthesis methods and applications

As one of the transition metal oxides, niobium pentoxide (Nb2O5) offers a broad variety of properties that make it a potentially useful and highly applicable material in many different areas. In comparison to many other transition metal oxides, Nb2O5 has received relatively little attention, which presents a significant opportunity for future investigations aimed at fundamentally understanding this material and finding new and interesting applications for it. In this article, a general overview of Nb2O5 is presented which focuses on its fundamental properties, synthesis methods and recent applications, along with a discussion on future research directions relevant to this material

A vein-like nanoporous network of Nb2O5 with a higher lithium intercalation discharge cut-off voltage

A novel morphology of a criss-cross vein-like nanoporous network of Nb 2O5 produced using a simple electrochemical anodization method is presented as a superior electrode for safe lithium-ion batteries. Scanning electron microscopy (SEM) observations demonstrate that the synthesised Nb2O5 is made of a continuous and highly packed vein-like nanoporous network with many lateral interconnections, which provides excellent channels for the fast transfer of both Li+ ions and electrons. Even without surface coating or cation doping, the porous Nb2O5 electrode could deliver durable capacity within the operating voltage window of 1.0-3.0 V vs. Li/Li+, with a reversible capacity of 201 mA h g -1 after 300 cycles at a current density of 0.4 A g-1. At the higher discharge cut-off voltage window of 1.2-3.0 V, the reversible capacity decreased to 175 mA h g-1. The first cycle Coulombic efficiency was above 94% for both operating voltage windows with a negligible capacity fading up to 300 cycles. The porous Nb2O5 electrode demonstrates several advantages as an anode including: (i) Improved cell safety due to a higher, V ≥ 1.0, discharge cut-off voltage which reduces dangerous high-temperature reactions; (ii) low level of irreversibility in the first cycle by preventing the formation of a solid electrolyte interface layer; (iii) high Coulombic efficiency due to sufficient infiltration of the electrolyte and fast diffusion of Li+ ions and (iv) high rate capability. Moreover, the synthesis method reports a novel smart design of nanostructured anode electrode materials capable of overcoming the existing limitations

Anodic formation of a thick three-dimensional nanoporous WO3 film and its photocatalytic property

We report an efficient solar-light-driven photocatalyst based on three-dimensional nanoporous tungsten trioxide (WO3) films. These films are obtained by anodizing W foils in fluoride-containing electrolytes at room temperature and under low applied voltages with an efficient growth rate of 2 μm h− 1. The maximum thickness of the films is ~ 3 μm that exceeds those of previously reported anodized WO3 films in fluoride-containing electrolytes. By investigating the photocatalytic properties of the films with thicknesses ranging from ~ 0.5 to ~ 3 μm, the optimum thickness of the nanoporous film is found to be ~ 1 μm, which demonstrates an impressive 120% improvement in the photocatalytic performance compared to that of a RF-sputtered nanotextured film with similar weights. We mainly ascribe this to large surface area and smaller bandgap

Reduced impurity-driven defect states in anodized nanoporous Nb2O5: the possibility of improving performance of photoanodes

Anodized nanoporous Nb2O5 films are synthesized using two different types of electrolyte compositions onto transparent conductive glasses and their impurities induced during the anodization process are assessed. These films are incorporated as photoanodes in dye sensitized solar cells (DSSCs). The one with no traces of impurity-driven defects exhibits higher current density and longer electron lifetimes, and consequently, an improvement in photoconversion efficiencies compared to the one that contains impurities

Electrospun granular hollow SnO2 nanofibers hydrogen gas sensors operating at low temperatures

In this paper, we present H2 gas sensors based on hollow and filled, wellaligned electrospun SnO2 nanofibers, operating at a low temperature of 150 °C. SnO2 nanofibers with diameters ranging from 80 to 400 nm have been successfully synthesized in which the diameter of the nanofibers can be controlled by adjusting the concentration of polyacrylonitrile in the solution for electrospinning. The presence of this polymer results in the formation of granular walls for the nanofibers. We discussed the correlation between nanofibers morphology, structure, oxygen vacancy contents and the gas sensing performances. X-ray photoelectron spectroscopy analysis revealed that the granular hollow SnO2 nanofibers, which show the highest responses, contain a significant number of oxygen vacancies, which are favorable for gas sensor operating at low temperatures