Nanotechnology is utilized well in the development and improvement of the performance in Solid Oxide Fuel Cells (SOFCs). The high operating temperature of SOFCs (700–900°C) has resulted in serious ...demerits regarding their overall performance and durability. Therefore, the operating temperature has been reduced to an intermediate temperature range of approximately 400–700°C which improved performance and, subsequently, commercialized SOFCs as portable power sources. However, at reduced temperature, challenges such as an increase in internal resistance of the fuel cell components arise. Although, this may not be as serious as problems encountered at high temperature, it still significantly affects the performance of SOFCs. This review paper addresses the work of researchers in the application of nanotechnology in fabricating SOFCs through distinct methods. These methods have successfully omitted or at least reduced the internal resistance and showed considerable improvement in power density of the SOFCs at reduced temperatures.
Hydrogen clean energy carrier as one of most essential clean and sustainable resource with main applications in both research and industry diverse.
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•H2 exists mostly in plant ...materials and is not readily available in nature.•H2 fuel is nonmetallic, non-toxic and can show higher energy compared to other fuels.•H2 industry key challenges are clarified to facilitate H2 usage as alternative energy.
The energy demand worldwide has increased significantly with the increase in population. This is because energy is needed in almost every activity. For example, in industry, working, cleaning, transportation and commuting from one place to another. The majority of energy being used is obtained from fossil fuels, which are not renewable resources and require a longer time to recharge or return to its original capacity. Energy from fossil fuels is cheaper but it faces some challenges compared to renewable energy resources. Thus, one of the most potential candidates to fulfill the energy requirements are renewable resources and the most environmentally friendly fuel is hydrogen (H2). Hydrogen exists mostly in plant materials and is not readily available in nature. It is necessary to produce hydrogen from available feedstock (water), which covers 70% of the earth. Moreover, hydrogen under standard pressure and temperature has an important merit; it can be obtained from renewable resources. Although, currently it is produced from fossil fuels. Hydrogen as a fuel is nonmetallic, non-toxic and can generate higher energy than gasoline on a mass basis. However, to employ hydrogen as a fuel, extensive research is essential to investigate and design on-board applications. Also, the cost of producing hydrogen (renewable) is expensive compared to gasoline (fossil). Thus, the production of H2 from renewable resources and from fossil fuels requires tremendous effort. One of these efforts is to generate H2 from biofuels as it is considered a promising technique that can help manage hydrogen from food waste. In addition, hydrogen storage materials are still lacking in both volumetric and gravimetric density. In this review, the key challenges that hydrogen industry are confronting are introduced and highlighted to facilitate the use of hydrogen as an alternative energy.
The aims of this review article is to understand the mechanism of proton-conducting solid oxide fuel cells (SOFCs) and compare it with conventional SOFC, to understand how dopants help to improve the ...conductivity and stability of doped materials, to investigate and analyze the effect or impact (in terms of conductivity and stability) of different types of dopants on the materials as proton-conducting electrolyte in intermediate temperature solid oxide fuel cell (IT-SOFC) and to study the experimental reviews on the methods in synthesizing the materials. Emphasis is given on the relationship between structural and mechanistic features of the crystalline materials and their ion conduction properties. This review will be focusing more on BaCeO3 and BaZrO3 as these electrolyte materials were in the focus of research during the past decades due to their considerable proton conductivity and stability.
Polarization is one of the basic properties of electromagnetic waves conveying valuable information in signal transmission and sensitive measurements. Conventional methods for advanced polarization ...control impose demanding requirements on material properties and attain only limited performance. We demonstrated ultrathin, broadband, and highly efficient metamaterial-based terahertz polarization converters that are capable of rotating a linear polarization state into its orthogonal one. On the basis of these results, we created metamaterial structures capable of realizing near-perfect anomalous refraction. Our work opens new opportunities for creating high-performance photonic devices and enables emergent metamaterial functionalities for applications in the technologically difficult terahertz-frequency regime.
Recently, the development and fabrication of electrode component of the solid oxide fuel cell (SOFC) have gained a significant importance, especially after the advent of electrode supported SOFCs. ...The function of the electrode involves the facilitation of fuel gas diffusion, oxidation of the fuel, transport of electrons, and transport of the byproduct of the electrochemical reaction. Impressive progress has been made in the development of alternative electrode materials with mixed conducting properties and a few of the other composite cermets. During the operation of a SOFC, it is necessary to avoid carburization and sulfidation problems. The present review focuses on the various aspects pertaining to a potential electrode material, the double perovskite, as an anode and cathode in the SOFC. More than 150 SOFCs electrode compositions which had been investigated in the literature have been analyzed. An evaluation has been performed in terms of phase, structure, diffraction pattern, electrical conductivity, and power density. Various methods adopted to determine the quality of electrode component have been provided in detail. This review comprises the literature values to suggest possible direction for future research.
Solar energy promises a viable solution to meet the ever-increasing power demand by providing a clean, renewable energy alternative to fossil fuels. For solar thermophotovoltaics (STPV), ...high-temperature absorbers and emitters with strong spectral selectivity are imperative to efficiently couple solar radiation into photovoltaic cells. Here, we demonstrate refractory metasurfaces for STPV with tailored absorptance and emittance characterized by in situ high-temperature measurements, featuring thermal stability up to at least 1200 °C. Our tungsten-based metasurface absorbers have close-to-unity absorption from visible to near-infrared and strongly suppressed emission at longer wavelengths, while our metasurface emitters provide wavelength-selective emission spectrally matched to the band-edge of InGaAsSb photovoltaic cells. The projected overall STPV efficiency is as high as 18% when a fully integrated absorber/emitter metasurface structure is employed, which is comparable to the efficiencies of the best currently available commercial single-junction PV cells and can be further improved to potentially exceed those in mainstream photovoltaic technologies. Our work opens a path forward for high-performance STPV systems based on refractory metasurface structures.
Human alveolar macrophages (HAM) are primary bacterial niche and immune response cells during Mycobacterium tuberculosis (M.tb) infection, and human blood monocyte-derived macrophages (MDM) are a ...model for investigating M.tb-macrophage interactions. Here, we use a targeted RNA-Seq method to measure transcriptome-wide changes in RNA expression patterns of freshly obtained HAM (used within 6 h) and 6 day cultured MDM upon M.tb infection over time (2, 24 and 72 h), in both uninfected and infected cells from three donors each. The Ion AmpliSeq™ Transcriptome Human Gene Expression Kit (AmpliSeq) uses primers targeting 18,574 mRNAs and 2,228 non-coding RNAs (ncRNAs) for a total of 20,802 transcripts. AmpliSeqTM yields highly precise and reproducible gene expression profiles (R2 >0.99). Taking advantage of AmpliSeq's reproducibility, we establish well-defined quantitative RNA expression patterns of HAM versus MDM, including significant M.tb-inducible genes, in networks and pathways that differ in part between MDM and HAM. A similar number of expressed genes are detected at all time-points between uninfected MDM and HAM, in common pathways including inflammatory and immune functions, but canonical pathway differences also exist. In particular, at 2 h, multiple genes relevant to the immune response are preferentially expressed in either uninfected HAM or MDM, while the HAM RNA profiles approximate MDM profiles over time in culture, highlighting the unique RNA expression profile of freshly obtained HAM. MDM demonstrate a greater transcriptional response than HAM upon M.tb infection, with 2 to >10 times more genes up- or down-regulated. The results identify key genes involved in cellular responses to M.tb in two different human macrophage types. Follow-up bioinformatics analysis indicates that approximately 30% of response genes have expression quantitative trait loci (eQTLs in GTEx), common DNA variants that can influence host gene expression susceptibility or resistance to M.tb, illustrated with the TREM1 gene cluster and IL-10.
Ammonia-fed fuel cells: a comprehensive review Afif, Ahmed; Radenahmad, Nikdalila; Cheok, Quentin ...
Renewable & sustainable energy reviews,
July 2016, 2016-07-00, 20160701, Volume:
60
Journal Article
Peer reviewed
The use of an ammonia-fed solid oxide fuel cell (SOFC) is the most efficient method of generating power. In terms of CO2 emission, ammonia is a good indirect hydrogen storage material because it does ...not contain carbon and therefore will not release CO2 when used as fuel in a fuel cell or gas turbine. Using ammonia like hydrogen directly in a fuel-cell system provides high power density. Compared with other fuel cells, the ammonia-fed SOFC has many advantages. The availability of NH3 is one of the main reasons for the high output.
This paper presents a comparative study of the working principles, analyses, applications, advantages and disadvantages of various technologies available for ammonia fuel cells. The aim of the paper is to review and describe the suitability of ammonia as a fuel for the next generation of fuel cells, including direct ammonia-fed SOFCs, the development of different types of fuel cells using ammonia as a fuel, and the potential applications of ammonia-fed fuel cells.
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