J. Appl. Cryst.の発刊に際して

2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

Photoelectrochemical (PEC) cells offer the ability to convert electromagnetic energy from our largest renewable source, the Sun, to stored chemical energy through the splitting of water into molecular oxygen and hydrogen. Hematite (α-Fe(2)O(3)) has emerged as a promising photo-electrode material due to its significant light absorption, chemical stability in aqueous environments, and ample abundance. However, its performance as a water-oxidizing photoanode has been crucially limited by poor optoelectronic properties that lead to both low light harvesting efficiencies and a large requisite overpotential for photoassisted water oxidation. Recently, the application of nanostructuring techniques and advanced interfacial engineering has afforded landmark improvements in the performance of hematite photoanodes. In this review, new insights into the basic material properties, the attractive aspects, and the challenges in using hematite for photoelectrochemical (PEC) water splitting are first examined. Next, recent progress enhancing the photocurrent by precise morphology control and reducing the overpotential with surface treatments are critically detailed and compared. The latest efforts using advanced characterization techniques, particularly electrochemical impedance spectroscopy, are finally presented. These methods help to define the obstacles that remain to be surmounted in order to fully exploit the potential of this promising material for solar energy conversion.

Solar Water Splitting: Progress Using Hematite (α‐Fe2O3) Photoelectrodes

Energy harvesting generators are attractive as inexhaustible replacements for batteries in low-power wireless electronic devices and have received increasing research interest in recent years. Ambient motion is one of the main sources of energy for harvesting, and a wide range of motion-powered energy harvesters have been proposed or demonstrated, particularly at the microscale. This paper reviews the principles and state-of-art in motion-driven miniature energy harvesters and discusses trends, suitable applications, and possible future developments.

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Energy Harvesting From Human and Machine Motion for Wireless Electronic Devices

Review of the proton exchange membranes for fuel cell applications

The performance of a solar-assisted chemical heat pump dryer has been studied under the meteorological conditions of Malaysia. The system consists of four mean components: solar collector (evacuated tubes type), storage tank, solid--gas chemical heat pump (CHP) unit and dryer chamber. A solid--gas CHP unit consists of a reactor, condenser and evaporator. The reaction (CaCl 2 --NH 3 ) has been used in this study. A series of experiments have been performed on the system under varied conditions for two days. The maximum values of solar fraction from the experiments on clear and cloudy days are 0.713 and 0.322, respectively; whereas the coefficient of performance of CHP (COP-super-h) maximum values of 2 and 1.42 are obtained from the experiments on clear and cloudy days, respectively. The total system energy output from the experiment on a clear day is 51 kWh against 25 kWh on a cloudy day. Any reduction of energy at the condenser as a result of decrease in solar radiation will decrease the coefficient of performance as well as the efficiency of drying. Copyright The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.

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An experimental analysis of solar-assisted chemical heat pump dryer

The effect of varying N/C ratios of nitrogen precursors during non-metal graphene catalyst synthesis

Composite cathodes made of perovskite La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and SDC carbonates (SDC-(Li/Na)2CO3) were investigated in relation to their structure, morphology, thermal expansion coefficient and porosity. As a first step, the LSCF powder was prepared by sol-gel technique. This was followed by the preparation of the LSCF-SDC carbonates composite cathode by mixing the LSCF with SDC-(Li/Na)2CO3 electrolyte via solid state reaction in various compositions, i.e. 30, 40 and 50 wt.%, namely 70LSCF-30SDC7030, 60LSCF-40SDC7030 and 50LSCF-50SDC7030, respectively. The powder mixtures were then calcined at 680oC. The resultant powder was fine with surface area of about 3.39-7.42 m2/g and particle size of 0.56-0.66µm. The powder consists of two distinct phases, i.e. LSCF and SDC-(Li/Na)2CO3 as confirmed with x-ray diffraction. The microstructures were observed under scanning electron microscopy (SEM). Increasing the amount of the SDC-(Li/Na)2CO3 electrolyte in the composite cathode was found to bring the thermal expansion of the cathode closer to that of the electrolyte. The cathode pellets were later compacted at different pressures (27, 32 and 37 MPa) and sintered at 600oC. The optimum porosity (20.99-24.98%) was achieved for samples with SDC-(Li/Na)2CO3 content of 30-50% sintered at 600oC and cold pressed at 37 MPa.

Fabrication of Porous LSCF-SDC Carbonates Composite Cathode for Solid Oxide Fuel Cell (SOFC) Applications

Characterization and the hydrogen storage capacity of titania-coated electrospun boron nitride nanofibers

Cesium dihydrogen phosphate (CDP) powders were synthesized by cetyltrimethylammoniumbromide (CTAB), polyoxyethylene-polyoxypropylene (F-68) and mixture of both surfactants F-68: CTAB with two molar ratios 0.06 and 0.12 as surfactant solutions at room temperature. The synthesized CsH2PO4 is characterized by ICP, XRD, TEM, SEM, FT-IR, BET and IS techniques. Based on the width of the (011) XRD diffraction peak and BET measurement, the average size of nanoparticles was ∼ 10 nm in diameter, while the TEM images indicate smaller size than both techniques. The analysis reveals existence of P and Cs with mole ratio 1.02 ± 0.03 which is compatible to molar ratio CsH2PO4 formula. The experimental results show that the conductivities increase in the order of CDPCTAB > CDP(F-68: CTAB)0.12 > CDP(F-68:CTAB)0.06 > CDPF-68. The sequence of increasing conductivity is in accordance with the ion exchange capacities of the samples that has direct proportional effect on the proton mobility of samples. Indeed CTAB as cationic surfactant shows the highest proton mobility in the as-obtained samples.

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Wan Ramli Wan Daud

Papers

An experimental analysis of solar-assisted chemical heat pump dryer

The effect of varying N/C ratios of nitrogen precursors during non-metal graphene catalyst synthesis

Fabrication of Porous LSCF-SDC Carbonates Composite Cathode for Solid Oxide Fuel Cell (SOFC) Applications

Characterization and the hydrogen storage capacity of titania-coated electrospun boron nitride nanofibers

Effect of surfactants in synthesis of CsH2PO4 as protonic conductive membrane