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Zinc batteries are a more sustainable alternative to lithium-ion batteries due to its components being highly recyclable. With the improvements in the screen printing technology, high quality devices can be printed with at high throughput and precision at a lower cost compared to those manufactured using lithographic techniques. In this paper we describe the fabrication and characterization of printed zinc batteries. Different binder materials such as polyvinyl pyrrolidone (PVP) and polyvinyl butyral (PVB), were used to fabricate the electrodes. The electrodes were first evaluated using three-electrode cyclic voltammetry, x-ray diffraction (XRD), and scanning electron microscopy before being fully assembled and tested using charge-discharge test and two-electrode cyclic voltammetry. The results show that the printed ZnO electrode with PVB as binder performed better than PVP-based ZnO. The XRD data prove that the electro-active materials were successfully transferred to the sample. However, based on the evaluation, the results show that the cathode electrode was dominated by the silver instead of Ni(OH)2, which leads the sample to behave like a silver-zinc battery instead of a nickel-zinc battery. Nevertheless, the printed zinc battery electrodes were successfully evaluated, and more current collector materials for cathode should be explored for printed nickel-zinc batteries.

The present work describes a self-sustaining bioelectrochemical system that adopts simple cell configurations and operates in uncontrolled ambient surroundings. The microbial fuel cell (MFC) was comprised of white-rot fungus of Phanaerochaete chrysosporium fed with oil palm empty fruit bunch (EFB) as the substrate. This fungal strain degrades lignin by producing ligninolytic enzymes such as laccase, which demonstrates a specific affinity for oxygen as its electron acceptor. By simply pairing zinc and the air electrode in a membraneless, single-chamber, 250-mL enclosure, electricity could be harvested. The microbial zinc/air cell is capable of sustaining a 1 mA discharge current continuously for 44 days (i.e., discharge capacity of 1056 mAh). The role of the metabolic activities of P. chrysosporium on EFB towards the MFC’s performance is supported by linear sweep voltammetry measurement and scanning electron microscopy observations. The ability of the MFC to sustain its discharge for a prolonged duration despite the fungal microbes not being attached to the air electrode is attributed to the formation of a network of filamentous hyphae under the submerged culture. Further, gradual lignin decomposition by fungal inocula ensures a continuous supply of laccase enzyme and radical oxidants to the MFC. These factors promote a self-sustaining MFC devoid of any control features.

This paper discusses the synthesis of magnetic adsorbents from agricultural waste and their applications in heavy metals removal. The general methods for preparing magnetic adsorbents and the mechanisms of heavy metal sorption are also reviewed in detail. These mechanisms are related to the utilization of magnetic adsorbents, particularly sugarcane bagasse in heavy metals removal, such as nickel, cadmium, lead, and arsenic. Converting sugarcane bagasse into magnetic adsorbents could solve environmental problems, such as agricultural waste and water pollution. A brief summary of the synthesis of magnetic biochar from sugarcane bagasse and its applications in heavy metals removal is also presented. Thus, this study proposes magnetic-based materials as potential candidates for wastewater treatment, and this adds new dimensions to numerous applications of the carbon family.

Various production methods have been developed for graphene production, but each of them falls short in either the economic or quality aspect. In this paper, we present the flame deposition method, a modi ed chemical vapor deposition (CVD) that uses an open- flame. In this method, resulting carbon deposits were found to be graphitic in nature, thereby suggesting multilayer graphene growth in a very short reaction time of 5 min. Furthermore, the deposits were transferred onto a cyanoacrylate plastic substrate and its sheet resistance was measured to be 81 ohm/square. The results showed that open- flame deposition exhibits high potential for low-cost, low-energy and high-quality production of graphene.

Keris is an exceptional Malay heritage object that has gained considerable attention. However, because its fabrication process has not been well documented, the techniques of keris making have been dying exponentially. This study aims to report the keris blade-making process and the microstructural changes that occur in the process, as well as investigate the homogeneity of elemental composition. A keris sample was obtained through the cooperation of a local keris-making workshop and the National Museum Department of Malaysia. The sample was inspected using optical microscopy (OM), field-emission scanning electron microscopy (FE-SEM), electron probe microscopy analysis (EPMA), X-ray fluorescence (XRF), and Vickers microhardness tester. The FE-SEM result shows that keris has a lamellar pearlite phase and an internal oxide layer with an average thickness of 20 m. The EPMA result shows that keris is composed mainly of Fe–2.99% C and contains an enriched layer of trace elements, such as Mn, Ni, and Si. Results lead to the conclusion that the fabrication techniques of keris contribute to the formation of a complex metal composite in its microstructure

Historically, the use and produce of Malay traditional ink were closely associated with the palaces and pondoks (Islamic religious school) where the early Malay manuscripts were traced. These Malay manuscripts can be traced dated back to the 16th century and the fact that those manuscripts have survived until today proves the durability and permanency of the traditional ink. Unfortunately, the documentation and description of such an indigenous ink making are scarce from the literature. Therefore, this work is dedicated to uncovering the legacy of Malay traditional ink recipe through several approaches, namely, analyse the recipe through historical literature and inspecting the characteristics of ink’s and its behaviour on existing early manuscript through microscopic analysis. The black ink was produced traditionally using natural resources that were available within a particular locality and applied on papers from foreign origin, either occidental or oriental. Ingredients used are varied which consists three important elements; colouring agent, adhesive and additives. The colouring agent determines the black ink’s pigment. As for the adhesive, its function is to ensure that the ink adheres well to the paper fibre, provide fluidity to the ink flow and improve the permanency and durability of the ink. Finally, the additives were often added to complement the roles of additives. Besides, they also serve to neutralize the odour of the solution and to shorten the ink drying time. The Malay manuscripts were examined under microscopic analyses revealed the characteristic qualities that prove the stability and permenancy of this traditional ink have prolonged the age of the manuscripts.

This project investigates the influence of dopants use via hot-isostatic pressing (HIP) sintering technique on thermoelectric properties. A total of 8 samples weighing 3 g each at different compositions (Zn4-xMxSb3) (M = Cu, Al) (x = 0, 0.3, 0.6 at.%) were prepared via powder metallurgy technique and followed by HIP sintering process. The relative density of all the samples recorded 85-95% which is comparable to the published data. From the XRD results, a near single phase of Zn4Sb3 was obtained. The SEM images revealed a minor of porous surface exist and showed metallurgical bonding formed in the prepared samples. From thermoelectric properties characterization, Cu showed as an effective element to lower the electrical resistivity as compared to Al when Sample 6 (Zn3.4Cu0.6Sb3) recorded 16.18×10−5 Ωm and Sample 8 (Zn3.4Cu0.6Sb3) was 27.09×10−5 Ωm. The results showed that HIP sintering technique at lower temperature compare to others studies offers potential processing route to produce a good thermoelectric material associated with the doping element.

This present work reports on the study of controllable aluminium doped zinc oxide (AZO) patterning by chemical etching for MEMS application. The AZO thin film was prepared by RF magnetron sputtering as it is capable of producing uniform thin film at high deposition rates. X-Ray diffraction (XRD) and atomic force microscopy (AFM) characterization were done to characterize AZO thin film. The sputtered AZO thin film shows c-axis (002) orientation, low surface roughness and high crystalline quality. To pattern AZO thin film for MEMS application, wet etching was chosen due to its ease of processing with few controlling parameters. Four etching solutions were used namely: 10 % Nitric acid, 10 % Phosphoric acid, 10 % Acetic acid and Molybdenum etch solutions. For the first time, chemical etching using Molybdenum etch that consist of a mixture of CH3COOH, HNO3 and H3PO4 was characterized and reported. The effect of these acidic solutions on the undercut etching, vertical and lateral etch rate were studied. The etched AZO were characterized by scanning electron microscopy (SEM) and stylus profilometer. The investigations showed that the Molybdenum etch has the lowest undercut etching of 7.11 µm, and is highly effective in terms of lateral and vertical etching with an etch ratio of 1.30. Successful fine patterning of AZO thin films was demonstrated at device level on a surface acoustic wave resonator fabricated in 0.35 μm CMOS technology. The AZO thin film acts as the piezoelectric thin film for acoustic wave generation. Patterning of the AZO thin film is necessary for access to measurement probe pads. The working acoustic resonator showed resonance peak at 1.044 GHz at 45.28 dB insertion loss indicating that the proposed Molybdenum etch method does not adversely affect the device’s operating characteristics.

Treating and cleaning corroded artefact has resulted in long-term loss of artefact integrity and intangible historical value in museum preservation method. Inhibitors and coatings are preferable methods applied in heritage conservation as it is the easiest way for corrosion protection. However, issue of health and environment has led conservators to find a better inhibitor, natural or green corrosion inhibitors. Surprisingly, Malay traditional practice has since long ago used Coconut water (CW) as corrosion inhibitor to preserve keris blades, showing that the knowledge in corrosion protection has been practiced in old Malay civilization for metal preservation. This paper intends to clarify the compositional effect of CW in the inhibition efficiency to iron-based keris blade. Through Tafel and Electrochemical Impedance Spectroscopy (EIS) and Energy dispersive analysis of X-rays (EDAX) analysis, the study showed that CW formed passivation with the highest IE of 92% as compared to other natural inhibitors existing and used in industries such as Ascorbic Acid (AA) and Tartaric acid (TA). EIS and Scanning Electron Microscope (SEM) study has shown and conclude that CW has displayed protective abilities that exceeds both AA and TA.

A simple and economical route based on a ZnCl2mediated process was developed to synthesize hierarchical flower-like ZnO micro/nanoflakes on the surface of copper foil by 2 stages electrodeposition method (2M ZnCl2– 0.5M ZnCl2). The prepared flakes were characterized by XRD and SEM. The morphology of ZnO can be tuned from simple isolated nanoflakes to ordered flower-like shape using this method. The surfaces retain good hydrophobic stability in long period time.

Instead of titanium dioxide (TiO2), many researches have been done to explore the compatibility of zinc oxide (ZnO) to be used as the active layer of memristor. In this study, an Au/ZnO-Cu2O-CuO/Cu memristor was fabricated using dilute electrodeposition and subsequently thermal oxidation. The XRD result indicates that Zn was oxidized to ZnO and has a wurzite structure while copper (Cu) substrate was also oxidized to copper (I) oxide (Cu2O) and copper (II) oxide (CuO). The surface morphology of ZnO shows the formation of needle-like structure on the surface after the thermal oxidation process. 15 s deposited ZnO-Cu2O-CuO gave the thinnest film of 81 nm with largest value of resistance difference of 14.11 k3 and resistive switching ratio of 3.76. Empirical study on thermodynamics of metal oxides and diffusivity of Zn2+ and O21 in ZnO shows that the structure is formed due to the difference of diffusivity of each species during the thermal oxidation process. The synthesized Au/ZnO-Cu2O-CuO/Cu memristor shows a potential application in production of a non-complex and low cost memristor.

Numerical Methods is a course that can be conducted using workshops and group discussion. This study has been implemented on undergraduate students of level two at the Faculty of Engineering, International Islamic University Malaysia. The Numerical Method course has been delivered to two Sections 1 and 2 with 44 and 22 students in each section, respectively. Systematic steps have been followed to apply the student centered learning approach in teaching Numerical Method course. Initially, the instructor has chosen the topic which was Euler’s Method to solve Ordinary Differential Equations (ODE) to be learned. The students were then divided into groups with five members in each group. Initial instructions have been given to the group members to prepare their subtopics before meeting members from other groups to discuss the subtopics in an expert group inside the classroom. For the time assigned for the classroom discussion, the setting of the classroom was rearranged to accommodate the student centered learning approach. Teacher strength was by monitoring the process of learning inside and outside the class. The students have been assessed during the migrating to the expert groups, recording of a video explanation outside the classroom and during the final examination. Euler’s Method to solve the ODE was set as part of Question 3(b) in the final exam. It is observed that none of the students from both sections obtained a zero grade in Q3(b), compared to Q3(a) and Q3(c). Also, for Section 1(44 students), 29 students obtained the full mark of 7/7, while only 10 obtained 7/7 for Q3(a) and no students obtained 6/6 for Q3(c). Finally, we can recommend that the Numerical Method course be moved toward more student-centered Learning classrooms where the students will be engaged in group discussion rather than having a teacher one man show.

CMOS integration for RF-MEMS is desired to yield compact, low-power and portable devices. In this work, we illustrate the usage of double electrode CMOS SAW resonators using both ZnO and AlN as its piezoelectric material. Double electrode transducers were chosen, as they are better at suppressing undesired acoustic reflections compared to single electrodes. The structure and dimension of the device is based on 0.35 μm CMOS process where the IDTs are fabricated using standard CMOS fabrication process. 2D Finite element modeling of the CMOS SAW resonator using COMSOL Multiphysics® is presented. Two-step eigenfrequency and frequency domain analyses were performed. The acoustic velocities generated are 3,925 and 5,953 m/s for ZnO and AlN CMOS SAW resonator respectively. Higher acoustic displacement and surface potential were observed in ZnO compared to AlN. It can be concluded that ZnO thin films have higher electromechanical coupling coefficients and are more efficient than AlN thin films.

This paper describes the growth of ZnxCd1-xO nanorods (NRs) by a single step electrodeposition process. Thin films of polycrystalline nature with cadmium and zinc concentration changing from 10% - 90% were electrodeposited onto ITO conductive glass substrates. XRD analysis confirms a hexagonal wurtzite structure having grain size 57.2 nm. From the FESEM analysis, the synthesized ZnxCd1-xO nanorods have uniform hexagonal crystallographic planes, and their diameters are about 100 nm. Remarkably, the ultra-violet (UV) near-band-edge (NBE) emission was red-shifted from 2.75 eV to 3.02 eV due to the direct modulation of band gap caused by Zn/Cd substitution, revealed by UV visible spectroscopy. Finally, ZnCdO thin film deposited on ITO glass substrate is used as one electrode in photovoltaic cells to produce energy by absorbing the energy from the sun, this single junction cells have been put forward as a potential low-cost alternative to the widely used solar cells.

The electrochemical performance of Al-air cell employing seawater and NaCl electrolyte of various concentrations has been investigated. The open circuit voltage and discharge capacity of the cell correlate well with the electrolyte conductivity data. Using 4 M NaCl electrolyte which possesses the highest conductivity, the Al-air cell registers an open circuit potential (OCV) of 1.1 V and demonstrates discharge capacity of 250 mAh, rated at 1 mA. Upon employing seawater, the OCV reduced to 0.68 V and discharge capacity decreased to 150 mAh. However, utilizing an exposed cell configuration which mitigates the hydroxide gel water binding effect, the Al-air seawater cell performance is greatly enhanced until almost compatible to Al-air cell employing 4 M NaCl.

The degradation of most of metals, with the exception of gold is a universal reaction. It is a constant and on-going problems, make it often difficult to eliminate completely causing either industrial or heritage conservation losing a lot of money. One way and most practical for corrosion protection are using green inhibitor. Therefore it is widely use either industry or heritage conservation. Unfortunately, the inhibitors used in conservation are frequently hazardous to conservator, either through inhaler or touch with skin. Responding to this, several researches has been conducted to look into environmental friendly inhibitors or green inhibitors. This paper will review current practice use of inhibitor in metal preservation before propose a new inhibitor which been used a long time ago in Malay traditional practice in Keris preservation.

We investigate the influence of buffer electrolyte and pH on the electrochemical performance of glucose oxidase-laccase biofuel cell (BFC). A simplified system design is adopted i.e. we employ freely-suspended glucose oxidase and laccase enzymes. The BFC comprises nickel mesh as the oxidative current collector and a carbon-based air electrode as the reductive current collector, enclosed in acrylic casing of 3 ml volumetric capacity. The air electrode also serves as the ambient oxygen diffusion site to continuously feed oxygen into the system. Three types of anolyte/catholyte buffer electrolyte are studied – citrate/citrate, phosphate/phosphate and citrate/phosphate, in the pH range 5 – 6.5. A biocatalytic electrochemical system is highly sensitive. Consequently, any variation in the electrolyte formulation would affect the cell discharge performance. Thus, we utilize the discharge profile capacity of the BFC to elucidate the optimum electrolyte formulation. Though the approach is indirect, the observed changes are obvious, suggesting the method is viable. It is found that the citrate/citrate buffer electrolyte of pH 5 exhibits the highest power output of 1074 mWh or volumetric power density of 1.7 Wh/l. The cell is able to sustain continuous discharge current of 30µA for about 31.75 hours with operating voltage around 1.0 V, in an uncontrolled open environment. Interestingly, the observed discharge performance and power density are comparable to BFC employing immobilized enzymes and mediators, in a controlled environment.

Alloys for high temperature application always rely on their ability to form protective, dense Cr2O3 and Al2O3 scales. In case of Ni-Cr binary alloy, a minimum composition of Cr is required for the formation of continuous protective scale. However, addition of small amount of third element such as Al may results in decrease of required Cr composition to form protective scale. This study aims to clarify the effect of ternary element on the formation of protective scale quantitatively. Ni-Cr alloys composed with 2 mass% and 4 mass% of Al were exposed in oxidizing environment under Cr/Cr2O3, Fe/FeO and Ni/NiO oxygen partial pressure. The oxidation of all samples is following parabolic rate’s law. XRD and SEM results show that Al2O3 and Cr2O3 are formed internally. Parabolic rate’s constant of samples oxidized in Ni/NiO oxygen partial pressure is higher by few magnitude orders. Higher Al concentration decreases the parabolic rate’s constant. It is concluded that the formation of protective scale is enhanced by the addition of Al as ternary element in Ni-Cr alloys.

Zinc anode is electrodeposited from a 2-M zinc chloride electrolytic bath with varying ammonium chloride supporting electrolyte concentrations (0-5 M) and plating current density (0.1 – 0.6 A cm-2). The total charge quantity supplied during electrodeposition is fixed at 150 mAh. Alkaline zinc-air cell is fabricated using the electrodeposited zinc anode and characterized according to its discharge capacity at constant load current of 20 mA. The effect of various qualities of zinc electrodeposits on the cell discharge performance is discussed. It is found that zinc electrodeposits prepared from electrolytic bath of 5-M ammonium chloride and 0.5 A cm-2 plating current density produced zinc-air cell with the highest output energy i.e. 24 mWh. We observe that the influence of plating current density is more prominent than the plating bath formulation on the zinc anode performance in the cell.

A zinc–air cell utilizing an inorganic MCM-41 membrane separator, in its dry form, reveals a unique behavior in response to relative humidity variation. The open circuit voltage (OCV) of the cell shows a linear dependence on relative humidity content. This is due to water adsorption–desorption characteristics of the mesoporous MCM-41 material. Comparison between relative humidity data obtained from commercial digital humidity sensor with data deduced from the OCV readings of Zn/MCM-41/air cell shows good sensitivity and high reliability.

The present work reports the performance characteristics of Zn/MnO2 Leclanché cell employing an inorganic MCM-41 membrane separator. MCM-41 material comprises of one-dimensional, hexagonally ordered silicates mesostructure. The main advantage of MCM-41 membrane is its 3-in-1 functional features, viz. as ionic exchange channels, insulating layer between electrodes and electrolyte reservoir. Zn/MnO2 cell is constructed approximately to the size of R2025 coin cell. As the fabrication technique of MCM-41 membrane is merely by dip-coating process, it offers two advantages. First, the membrane could be prepared sufficiently thin and thus minimizing the internal losses of the cell. Second, it enables the construction of bipolar cell configuration with ease. Consequently, the results obtained demonstrate the volumetric energy density of Zn/MCM-41/MnO2 R2025 button cell has been extended by almost fivefold from 5.6 Wh/l to 26 Wh/l as bipolar cell configuration is utilized.

Thin film piezoelectric materials play an essential role in micro electro mechanical system (MEMS) energy harvesting due to its low power requirement and high available energy densities. Non-ferroelectric piezoelectric materials such as ZnO and AlN are highly silicon compatible making it suitable for MEMS energy harvesters in self-powered microsystems. This work primarily describe the design, simulation and fabrication of aluminium doped zinc oxide (AZO) cantilever beam deposited on silicon substrate. AZO was chosen due its high piezoelectric coupling coefficient, ease of deposition and excellent bonding with silicon substrate. Doping of ZnO with Al has improved the electrical properties, conductivity and thermal stability. The proposed design operates in transversal mode (d31 mode) which was structured as a parallel plated capacitor using Si/Al/AZO/Al layers. The highlight of this work is the successful design and fabrication of Al/AZO/Al on silicon as the substrate to make the device CMOS compatible for electronic functionality integration. Design and finite element modeling was conducted using COMSOL™ software to estimate the resonance frequency. RF Magnetron sputtering was chosen as the deposition method for aluminium and AZO. Material characterization was performed using X-ray diffraction and field emission scanning electron microscopy to evaluate the piezoelectric qualities, surface morphology and the cross section. The fabricated energy harvester generated 1.61 V open circuit output voltage at 7.77 MHz resonance frequency. The experimental results agreed with the simulation results. The measured output voltage is sufficient for low power wireless sensor nodes as an alternative power sources to traditional chemical batteries.

Fe - 9 to 12%Cr alloys are a material for the thick sections boiler components and steam lines of a power plant. The role Fe - 9 to 12%Cr alloys is becoming more prominent in the development of a new generation of Ultra-Supercritical (USC) Power Plant due to the target operating temperature is reaching 620 °C (893 K), in 100% steam condition as well as pressure in excess of 300 bar (30 × 106 Pa). In such condition, the integrity of Fe - 9 to 12%Cr alloys relies on the oxide scale formed during the time of exposure. However due to the high temperature and water vapor condition, it is a well known fact that, the formation of oxide scale is accelerated thus depleting the structural integrity of the Fe - 9 to 12%Cr alloys over the time. Studies show that not only the formation of protective oxide scale was suppressed but the formation of non-protective oxide scale was accelerated instead. Decades of studies done by various groups around the globe has yet to have consensual on the exact mechanism of this phenomenon. Initial stage oxidation of these alloys plays great roles in hope to understand the formation of oxide scale in water vapor condition at high temperature. This paper reviews previous research works to understand the initial stage oxidation of Fe - 9 to 12%Cr alloys at high temperature in water vapor condition.

High quality ZnO thin films are required to produce CMOS SAW resonators operating with low losses and high Q. This work intends to develop high performance CMOS SAW resonators through optimization of both the quality of the ZnO and the design of the SAW resonator. Zinc oxide was chosen for this work as the piezoelectric material due to its superior acoustic propagation properties and compatibility with integrated circuit fabrication techniques. ZnO has demonstrated good performance characteristics for a variety of piezoelectric devices. For optimization of the quality of the deposited ZnO thin film, different RF-sputtering conditions will be used to investigate which condition produces the best piezoelectric quality of the ZnO thin film. The experiments were carried using Taguchi optimization method, which studies a large number of variables with a small number of experiments.

We investigate Zn/MnO2 Leclanché cell employing inorganic MCM-41 membrane separator. MCM-41 membrane is developed onto zinc anode substrate from dip coating procedure, performed at room temperature. The parent solution for synthesis consisted of quarternary ammonium surfactant, cethyltrimethylammonium bromide C16H33(CH3)3NBr (CTAB) as the organic template, sodium hydroxide, deionized wateSubscript textr, ethanol and tetraethylorthosilicate (TEOS). Zn/MCM-41/MnO2 cell, about the size of R2025 coin cell, is fabricated both in monopolar and bipolar designs. Bipolar cell configuration enhances the cell performance markedly. The cell demonstrates volumetric energy density - 42 Wh/l for bipolar design and 12 Wh/l for monopolar design, rated at continuous current drain of 1 mA.

This work explores the use of metal-air electrochemical system to evaluate porous electrode properties i.e. specific surface area and pore volume density. Porous zinc electrodes are prepared from an acidic, chloride electrolytic bath of varying supporting electrolyte (NH4Cl) formulation to produce electrodeposits of distinctive properties. Nitrogen physisorption at 77 K is utilized to evaluate the specific surface area and pore volume density of the electrodes. The zinc electrodeposits prepared from all electrolytic bath formulations are then assembled into zinc-air cells as the anodic electrode and characterized according to their limiting current density and discharge capacity. It is found that the variation in limiting current density matches that of BET surface area and the trend for discharge capacity follows that of pore volume density.

We investigate glucose oxidase-laccase EFC employing simplified system design – freely suspended enzymes in a membraneless, single chamber cell. The highly specific enzyme reaction mechanisms permit such system design. The EFC comprises nickel mesh as the oxidative current collector and a carbon-based air electrode as the reductive current collector, enclosed in acrylic casing of 3 ml volumetric capacity. The air electrode also serves as the ambient oxygen diffusion site to continuously feed oxygen into the system. The anolyte consists of glucose oxidase enzyme (10 U), glucose substrate (200 mM) and FAD co-enzyme (3.8 mM), while the catholyte consists of laccase enzyme (10 U) and syringaldazine substrate (216 µM). The cell employing citrate buffer electrolyte of pH 5 exhibits the best characteristics i.e. an open circuit voltage (OCV) around 960 mV and able to sustain continuous discharge current of 30µA for about 31.75 hours. The cell possesses volumetric power density of 286 W/cm3which is considered comparable to biocatalytic energy systems employing much more complicated design.

Fungal biofuel cell comprising of liquid culture suspension of Gloeophyllum and Rhizopus fungal strains is studied. Gloeophyllum liquid culture forms the anolyte of the microbial fuel cell (MFC) while Rhizopus liquid culture which forms the catholyte. Bioenergy is harvested from biocatalytic redox reactions of glucose/oxygen as a result of metabolic activities of respective fungi. Pyranose-2-oxidase of Gloeophyllum catalyzes oxidation of glucose, whereas laccase produced by Rhizopus catalyzes oxygen reduction. Upon incubation period of 8 days, the Gloeophyllum-Rhizopus MFC is capable to deliver 5 mW of power output continuously for 21 days under uncontrolled, open ambient surroundings. MFC with such performance characteristics is sufficed to power remote sensing devices.

MCM-41 material, prepared by sol–gel method, reveals gel-like properties in a caustic alkaline environment, i.e., 6 M potassium hydroxide (KOH) electrolyte. The gellation of MCM-41 starts at a KOH weight ratio of 40 wt.%. The structural change of the material is verified with X-Ray diffractograms and supported by observation using Scanning Electron Microscope (SEM). As the KOH weight ratio increases, the MCM-41 hexagonal arrays structure gradually transforms into MCM-50 lamellar structure before disappearing completely at 80 wt.% KOH. The MCM gel phase is further characterized by rotational viscometry and texture analysis. The gel phase shows shear thinning or pseudoplastic behavior and possesses homogeneous matrix structure.

Porous organosilica is a promising material to be applied in water treatment due to high adsorption capacity of contaminants. Sol-gel method was used to fabricate mesoporous organosilioca from triblock copolymers, poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) as the template and tetraethylorthosilicate as silicate source. The organosilica is doped with Al powder and Al2SO3 in order to evaluate the effect of ions on their adsorption capacity. It was demonstrated that the adsorption capacity is proportional to Al concentration, and inversely proportional to porosity. Metallic compound doped in organosilica enhances the remediation process and optimize the water treatment process. Moreover, impregnation the samples into cellulosic sponge improves the adsorption efficiency by 25%.

The formation of protective Cr2O3scale at high temperature was evaluated using Wagner’s theory of binary alloy oxidation. The results show that at 1073 K, around 9.8 wt% of Cr is required to form external Cr2O3scale, and 3.5wt% of Cr is needed to maintain the scale. Introduction of water vapor has shifted the critical Cr concentration to higher value. The effects of water vapor in increasing Cr critical concentration to form external Cr2O3scale was disscussed from view of oxygen permeablility and Cr diffusivity in the alloy. It is concluded that Cr diffusivity has negligible effect, while oxygen permeability increase with the presence of water vapor, thus increase the oxidation rate.

An ultrathin, high energy density zinc–air cell has been developed for potential application in microsystems. The key design feature is the utilisation of an inorganic MCM-41 membrane material with three-in-one functional elements. It serves as an insulating layer between the electrodes, as ionic exchange channels and as an electrolyte reservoir matrix. As a result, a feasible, compact cell design with high discharge capability has been demonstrated. The MCM-41 material consists of a hexagonally ordered, nanopore structure. It possesses attractive features of large surface area and pore volume, narrow pore size distribution, tunable pore size, adjustable hydrophobicity and very good thermal stability. The Zn/MCM-41/air cell measuring 1 cm2 area and ∼300 μm thick is able to deliver a maximum discharge current of 30 mA and possesses an optimum capacity of 35 mAh.

Energy harvesters based on acoustic vibration sources can generate electrical power through piezoelectric transduction. Significant miniaturization of electro mechanical devices using MEMS fabrication technology has encouraged the creation of portable, miniature energy harvesters. A niche application is aero acoustics, where wasted, high dB and high frequency sound generated by aircrafts are transformed into useful energy. Having self-powered, miniature acoustic sensors allows noise detection monitoring systems to be self-sustaining. This paper illustrates an Aluminium doped Zinc Oxide (AZO) cantilever beam on stainless steel substrate with a top copper electrode. Design and finite element modelling of the design was conducted using Coventorware™. The AZO piezoelectric thin film was RF-sputtered on the stainless steel substrate. Characterizations were performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to evaluate the piezoelectric qualities and surface morphology, respectively. Experimental measurements indicate approximately 345.4 mV AC output voltage (open circuit voltage) is produced at vibration frequencies of 30 kHz. This is in accordance with the Coventorware™ simulation results. This measured power level is sufficient to power a miniature wireless acoustic sensor nodes to monitor noise generated by aircrafts.

The purpose of this study is to identify theZn2+ions concentrationat Sn-Zn coating which could be produced in the absence of a complexing agent. The electrolytic bath comprised of SnCl2 and ZnCl2. The ionic mole ratio Zn2+/Sn2+ of the electrolytic bath studied were 1:2, 1:1, 2:1, 4:1 and 10:1. Pure Zn and Sn electrodeposits were also prepared. The deposition process was performed at constant current of 5 mA and deposition time of 120 min. The electrodeposits were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that in the absence of complexing agent, even an electrolytic bath with Zn2+/Sn2+ ionic ratio of ten folds could not produce Zn-rich of Sn-Zn electrodeposits. Further, a unique method has been introduced to characterize the electrodeposits i.e. using the metal-air electrochemical cell. In this method, the electrodeposits were coupled with an air electrode in an alkaline electrolyte (6 M KOH) and discharged at 1 mA. Specific metallic element content will produce a distinct discharge profile thus enables it to be used in characterizing alloys or composites.

The viability of MCM-41 membrane as a separator material in secondary alkaline cell is investigated. The inorganic membrane was employed in an alkaline nickel-zinc system. MCM-41 mesoporous material consists of arrays of hexagonal nano-pore channels. The membrane was synthesized using sol-gel route from parent solution comprising of quarternary ammonium surfactant, cethyltrimethylammonium bromide C16H33(CH3)3NBr (CTAB), hydrochloric acid (HCl), deionized water (H2O), ethanol (C2H5OH), and tetraethylortosilicate (TEOS). Both the anodic zinc/zinc oxide and cathodic nickel hydroxide electrodeposited film were coated with MCM-41 membrane. The Ni/MCM-41/Zn alkaline cell was then subjected to 100-cycle durability test and the structural stability of MCM-41 separator throughout the progression of the charge-discharge cycles is studied. X-ray diffraction (XRD) analysis on the dismantled cell shows that MCM-41 began to transform to lamellar MCM-50 on the 5th cycle and transformed almost completely on the 25th cycle. The phase transformation of MCM-41 hexagonal structure into gel-like MCM-50 prevents the mesoporous cell separator from diminished in the caustic alkaline surround. This work has hence demonstrated MCM-41 membrane is viable to be employed in secondary alkaline cells.

Dye sensitized solar cells (DSSCs) rely on the absorption of photons by the dye molecules which are transported to the conduction band of the TiO2 electrode. The microstructure, energy gap and the absorption spectra of the TiO2 electrodes highly affects the efficiency of the cell. In this paper, the absorption spectra and energy gap has been studied by varying the thickness of the TiO2 paste. Nanocrystalline TiO2 thin films were deposited on ITO glass substrate with three different thickness (4.54μm, 7.12μm and 12.3μm) by using doctor blade method. After deposition all the samples were sintered at 450°C after deposition to enhance the particle bonding and for achieving better adhesion. The samples were characterized by UV-VIS spectra for determining the absorption spectra and Scanning Electron Microscopy (SEM) for investigating the thickness and the surface morphology. Fabricating the electrodes with different thickness showed significant changes in the energy gap and from the results it can be concluded that the energy gap increases with the increased thickness. The highest energy gap of 2.25ev and absorption 3.791 was achieved by 12.3μm thick sample. The absorption spectra also shows better absorption throughout the whole visible light range but the SEM images suggests that 12.3μm thick sample shows cracks all over the deposited region which will cause current leakage when the cell is assembled. Therefore, the optimum result was achieved by 7.12μm thick sample providing 1.9 ev energy gap and 3.91 absorption peak.

Zinc antimonite, Zn4Sb3 is a promising thermoelectric material because of its high thermoelectric performance and abundance of Zn and Sb in nature. Thus, in this study, samples of Zn-Sb alloy were prepared using electrodeposition method because of its simple experimental set-up, which also carried out in the room temperature. From the XRD results, all samples deposited exhibit Zn-Sb alloy compositions. The best results were S1 and S3 as they had dominant peaks that showed the crystal lattice of Zn4Sb3. From the SEM images, the surface morphology of Zn-Sb alloy deposited samples showed were all-irregular, course and rough structures. While, the atoms arrangement of the deposited samples were all flowery-like. Based on physical properties characterization, the best samples; S1 (0.1M ZnCl2-0.1M SbCl3, 100mA, 120min) and S3 (0.1M ZnCl2-0.1M SbCl3, 50mA, 120min), were selected and investigated their thermoelectric performances; electrical conductivity and Seebeck coefficient, to determine their power factor, PF. Heat capacity of the samples was also examined to relate it with thermal conductivity of Zn-Sb deposited samples. For thermoelectric performance, S1 obtained power factor of 1.37x10-7V/K. Ω.cm at 102°C with the Seebeck coefficient of 181μV/K. While as for S3, the power factor was 1.58x10-7V/K. Ω.cm with Seebeck coefficient of 113μV/K at 101°C. From DSC analysis, it showed that S3 obtained higher Cp than S1. Cp for S3 was 46.8093mJ/°C while S1 was 38.3722mJ/°C.

One of the major parts in the plasma display panel is its protecting layer. MgO thin film has been widely used as a protective layer for dielectric materials. Adding another material to the MgO base material is an alternative method for improving its property as protective layer. A study on reducing the surface discharge potential of a single pure MgO protecting layer by the addition of ZrO2 with several compositions is presented in this paper. The microstructural and mechanical properties are also described. The discharge properties were measured utilising the flashover treeing for material characterisation, produced by a scanning electron microscope. The mechanical properties were measured using the pure bending moment. The MgO and ZrO2 powders with 99·95 and 99% purity were used for powder mixtures of various desired compositions. In this work, investigation was carried out for sintered samples at 1250°C for 24 h. From observation, ZrO2 addition into high purity MgO has influenced the propertie...

A group key management has an important role in multicast security in order to achieve data integrity and confidentiality. The session key is a common secret key for a group of users in key trees that is shared securely and efficiently among them. It is used to encrypt other session keys and transmitted data in order to protect group communication. This paper proposed a new key management protocol using Multiple Logical key trees for dynamic groups. To minimize the communication overhead of rekeying process, a one-way key derivation are integrated with multiple logical key trees. New keys created by the server of the key tree are not sent to the members who are able to derive their own keys. As a result each rekeying process requires less number of encrypted keys sent within the group tree. The performance analysis of the proposed scheme shows that it has less communication cost than the other compared protocols.

We report the deposition of high quality c-axis oriented Aluminium doped Zinc Oxide (AZO) on silicon substrate for surface acoustic wave (SAW) applications. AZO thin film is prepared by Radio frequency magnetron sputtering method. Sputtering is a preferred method because it is able to perform deposition at low temperature, produce uniform thin film and possesses high deposition rates. In preserving the functionality of the device during post CMOS process, low deposition temperature is crucial. In order to obtain the preferred AZO structural properties with strong acoustoelectric interaction, we investigate the influence of RF power on c-axis preferred orientation of AZO/Si multilayer. The deposited thin films are characterized by X-Ray diffractometer and scanning electron microscopy (SEM). The crystal structures are evaluated in terms of c-axis lattice constant, d-spacing and crystallite size. It is observed that as RF power increases, the AZO film is predominantly oriented at c-axis (002) and achieved high crystalline quality. However, if the applied RF power is too high, the energized ions would impede the growth of high quality film. The optimum RF power was found to be at 250 W, at which the material exhibits hexagonal wurtzite-type lattice of ZnO structure, high crystallinity (lowest FWHM value) and crystallite size, and high deposition rate.

X-ray diffraction (XRD) pattern reveals that potassium hydroxide (KOH) disrupts the crystalline nature of poly(vinyl alcohol) (PVA)-based polymer electrolytes and converts them into an amorphous phase. The PVA–KOH alkaline solid polymer electrolyte (ASPE) system with PVA/KOH wt.% ratio of 60:40 exhibits the highest room temperature ionic conductivity of 8.5×10−4 S cm−1. This electrolyte was used in the fabrication of a nickel–zinc (Ni–Zn) cell. The cell was charged at a constant current of 10 mA for 1 h providing it with 1.6 V. The cell was cycled 100 times. At the end of the last cycle, the cell still contained a capacity of 5.5 mA h.

The viability of hydroponics gel as a new alkaline electrolyte gelling agent is investigated. Zinc–air cells are fabricated employing 12 wt.% KOH electrolyte immobilised with hydroponics gel. The cells are discharged at constant currents of 5, 50 and 100 mA. XRD and SEM analysis of the anode plates after discharge show that the failure mode is due to the formation of zinc oxide insulating layers and not due to any side reactions between the gel and the plate or the electrolyte.

High discharge rate zinc electrode is prepared from electrodeposition process. The electrolytic bath consists of zinc chloride as the metal source and ammonium chloride as the supporting electrolyte. The concentration of the supporting electrolyte is varied from zero until 4 M, while the concentration of zinc chloride is fixed at 2 M. The aim is to produce a porous zinc coating with an enhanced and intimate interfacial area per unit volume. These characteristics shall contribute towards reduced ohmic losses, improved active material utilization, and subsequently producing high rate capacity electrochemical cell. Nitrogen physisorption at 77 K is used to measure the BET surface area and pore volume density of the zinc electrodeposits. The electrodeposited zinc electrodes are then fabricated into alkaline zinc-air microbattery measuring 1 cm2 area x ca. 305 µm thick. The use of inorganic MCM-41 membrane separator enables the fabrication of a compact cell design. The quality of the electrodeposited zinc electrodes is gauged directly from the electrochemical performance of zinc-air cell. Zinc electrodeposits prepared from electrolytic bath of 2 M NH4Cl produces the highest discharge capacity.ABSTRAK: Elektrod zink dengan kadar discas tinggi telah dihasilkan dengan proses saduran elektrokimia. Takungan elektrolit terdiri daripada zink klorida sebagai sumber logam dan ammonium klorida sebagai elektrolit sokongan. Kepekatan elektrolit sokongan diubah daripada sifar hingga 4 M, sementara kepekatan zink klorida ditetapkan pada 2 M. Ini bertujuan untuk mendapatkan saduran zink yang poros dengan luas permukaan per unit isipadu dan sentuhan antaramuka yang dipertingkatkan. Ciri-ciri ini akan menyumbang terhadap pengurangan kehilangan disebabkan kerintangan, pertambahan dalam gunapakai bahan aktif dan akhirnya menghasilkan sel elektrokimia berprestasi tinggi. Physisorpsi nitrogen pada 77 K telah digunakan untuk mengukur luas permukaan BET dan isipadu liang saduran zink. Saduran zink kemudiannya dijadikan elektrod bagi bateri mikro zink-udara beralkali dengan saiz 1 cm2 luas x ca. 305 µm tebal. Penggunaan membran tak organik MCM-41 membolehkan pembuatan sel dengan rekabentuk padat. Kualiti elektrod saduran zink telah dinilai secara lansung daraipada prestasi elektrokimia sel zink-udara. Saduran zink yang disediakan daripada takungan elektrolit 2 M NH4Cl menghasilkan kapasiti discas tertinggi.KEY WORDS (keyword)): Zinc electrodeposition, High discharge rate electrode, MCM-41 separator, Zinc-air cell and Alkaline microbattery.