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

Stress applying in the stack of Proton Exchange Membrane Fuel Cell (PEMFC) effects the performance of PEMFC. High pressure in the Membrane Electrode Assembly (MEA) can reduce electrical contact resistance between bipolar plate and MEA. Nevertheless, too high pressure in the PEMFC can destroy MEA. Performance of PEMFC can be optimized by make proportional stress in the assembly of PEMFC. Finite element analysis (FEA) is one of method that can be used for analysis of stress in the PEMFC stack. However, setting of parameter in the analysis using FEA still became one of problem if realistic result must be desired. This paper reports setting of parameters in the stress analysis of PEMFC assembly using FEA method and study relationship of stress analysis with electrical contact resistance.

Study Effect of Stress in the Electrical Contact Resistance of Bipolar Plate and Membrane Electrode Assembly in Proton Exchange Membrane Fuel Cell: A Review

Hot-pressing conditions for fabricating a membrane-electrode assembly (MEA) were optimized. The key parameters were time, temperature, and pressure, varying from 1 to 5 min, 100 to 170°C, and 21 to 93 kg cm ―2 , respectively. The MEAs were fabricated with 50 cm 2 active electrode area and their performance was investigated using a fuel cell test station. The most suitable hot-pressing time for MEA was 3 min, the optimized pressure and temperature for MEA fabrication were 21 kg·cm ―2 and 130 °C with 1.6 A and 0.56 V. At 100 °C, the current and voltage of the produced MEAs were low due to the trapped liquid formed inside the electrode. However, at more than 150°C, the obstructed/distorted polytetrafluor-oethylene (PTFE) will block the pores inside the gas diffusion layer (GDL) and cause a loss of performance of the fuel cell. Physical properties of the GDL were observed using scanning electron microsopy (SEM). The GDL exhibited a uniform pore distribution after application of hot-pressing.

Analysis and Optimization of Operating Parameters of a Membrane‐Electrode Assembly

The design and performance of two types of solar assisted drying systems is presented. The V-groove solar collector is used in the first dryer and the double-pass solar collector with porous media in the lower channel is used in the second dryer. The drying chambers are of the cabinet and flat bed types for the former and later respectively. Several agricultural produces have been used in the first dryer namely chilies and green tea. Ground oil palm fronds used animal feedstock is dried using the second dryer. The lower channel of the double-pass solar collector are filled up with porous media and acted as a storage medium for the system. Hence, the second solar dryer is suitable for higher temperature drying of agricultural produce. At a solar radiation level of 700 W/m2 and ambient temperature of 30 °C, the outlet temperatures are 60 °C and 80° C for the first and second dryers respectively.

Wan Ramli Wan Daud

Papers

Study Effect of Stress in the Electrical Contact Resistance of Bipolar Plate and Membrane Electrode Assembly in Proton Exchange Membrane Fuel Cell: A Review

Analysis and Optimization of Operating Parameters of a Membrane‐Electrode Assembly

Solar Drying Technology for Agricultural Produce

Comparative Study on Water Uptake and Ionic Transport Properties of Pre- and Post Sulfonated Chitosan/PVA polymer Exchange Membrane

Experimental Study on the Mixing of Binary Polymer Particles in Different Types of Mixer