Synthesis and electrochemical characterization of La0.75Sr0.25Mn0.5Cr0.5‐xAlxO3, for IT- and HT- SOFCs

The authors, A M Abdalla and S Hossain, are grateful to Suez Canal University and Universiti Brunei Darussalam and their collaborative for supporting this research work.The main emphasis of this work is to create a new perovskite material with three different compositions (La0.75Sr0.25Mn0.5Cr0.5‐xAlxO3, x = 0.1, 0.2, 0.3) applied in both Intermediate and high Temperature ‐ Solid Oxide Fuel Cells (IT & HT‐SOFCs). Perovskite‐type polycrystalline La0.75Sr0.25Mn0.5Cr0.5‐xAlxO3‐δ (x = 0.1, 0.2, 0.3) powders were synthesized and formed in a single phase structure by a dry chemistry route (standard solid‐state reaction method). The effect of Al‐doping on physicochemical and surface properties has been discovered. The compounds were crystallized in single phase rhombohedral symmetry (R‐3C Space. Group). Total conductivity of Al‐doping in wet 5% H2 was higher than both dry 5% H2 and air. The obtained results enhance the electro‐catalytic performance and the material conductivity as well, which will be good for anode materials in IT‐ HT‐SOFCs and the optimum doping is 10%.PostprintPeer reviewe

Gafor : Genetic algorithm based fuzzy optimized re-clustering in wireless sensor networks

Acknowledgments: The authors are grateful to the Deanship of Scientific Research at King Saud University for funding this work through Vice Deanship of Scientific Research Chairs: Chair of Pervasive and Mobile Computing. Funding: This research was funded by King Saud University in 2020.Peer reviewedPublisher PD

Novel layered perovskite SmBaMn2O5+δ for SOFCs anode material

The authors Abdalla M. Abdalla and Shahzad Hossain are thankful to the Graduate Research Office of Universiti Brunei Darussalam for Graduate Research Scholarship (GRS) for funding this research work done.SmBaMn2O5+δ (SBMO), a novel layered perovskite compound with samarium based material (Sm+3) as rare earth doped in A-site was synthesized and processed by using dry chemistry method (solid state solution). Structural characterization of SBMO has been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). While, thermal and electrochemical testing were done by using thermogravimetric analysis (TGA) and current voltage measurements. The Rietveld analysis of XRD data shows that SBMO was crystallized in the orthorhombic structure with the Pmmm space group. The surface morphology images showed a porous structure which indicates that this material can be used as a potential electrode in solid oxide fuel cells (SOFCs). TGA result showed the mass loss of 0.022% for SmBaMn2O5+δ which is very small and indicates that the material is very stable. DC conductivity and performance test were done at RT in air atmosphere. The performance tests have done at 800 °C and 750 °C and the maximum power density was found to be 0.4 W/cm2 at 800 °C.PostprintPeer reviewe

Highly dense and novel proton conducting materials for SOFC electrolyte

S. Hossain and A. M. Abdalla are thankful to graduate studies office of Universiti Brunei Darussalam for graduate research scholarship (GRS) for this research work done. Authors are also grateful to Professor John T. S. Irvine for managing a visiting scholarship for SH and AMA to perform the research work at University of St Andrews, Scotland, UK.Highly dense proton conducting materials of BCZYSZn (BaCe0.8-xZrxY0.15Sm0.05O3-δ (x = 0.15, 0.20) with 4 wt.% ZnO as sintering additive), to be used as an intermediate temperature solid oxide fuel cells (IT-SOFCs) electrolyte, have been processed by the conventional solid state reaction method. The crystalline phase, microstructure, electrical properties, cell performance and chemical stability of the materials have been investigated. The ionic conductivity of BCZYSZn 3 (x = 0.20) material has been measured to be ~2.56 × 10-3 S cm−1 and ~8.32 × 10-3 S cm−1 at 600 °C and 850 °C, respectively in wet 5%H2 in Ar atmosphere. Microstructural characterizations of the zinc containing materials (BCZYSZn) show the formation of highly dense morphology with very large grains. The chemical stability test of BCZYSZn in pure CO2 shows that the material is very stable up to 1000 °C. The maximum power density for the BCZYSZn 3 electrolyte cell is found to be 0.42 W/cm2 at 700 °C under the testing atmosphere. The performed characterizations reveal that these are suitable proton-conducting candidate materials for efficient electrochemical devices.PostprintPeer reviewe

NdBaMn2O5+δ layered perovskite as an active cathode material for solid oxide fuel cells

A layered perovskite, NdBaMn2O5+δ (NBMO), was synthesized by solid state reaction method in air. Rietveld analysis of X-Ray Diffraction (XRD) data showed the material crystallizing in orthorhombic symmetry (Pmmm space group). Scanning electron microscopy (SEM) was used to check the morphology and, the analysis of the micrographs exhibited a porous structure with in-situ growth of nanoparticles. Electrochemical Impedance Spectroscopy (EIS) measurements from 600 °C to 800 °Cshows the highest conductivity value of 1.17 × 10−1 S/cm obtained at 800 °C with low activation energy (Ea) of 0.3 eV in air. In 5% H2/Ar gas mixture, the conductivity and activation energy values were 1.97 × 10−2 S/cm and 0.4 eV, respectively at 800 °C. The DC conductivity measurements also showed that this material is highly conductive in air with a conductivity value of 0.75 S/cm at 850 °C. Dual chamber fuel cell measurements on Ni-YSZ/YSZ/NBMO cell using 5% H2/Ar as fuel (from 700 °C to 800 °C) showed a maximum power density of 0.202 W/cm2 at 800 °C. The relatively high conductivity of the material in air and low activation energy makes it a potential candidate as cathode for solid oxide fuel cells.PostprintPeer reviewe

Improved mechanical strength, proton conductivity and power density in an ‘all-protonic’ ceramic fuel cell at intermediate temperature

The authors AA and NR would like to thank Universiti Brunei Darussalam for providing a UGS scholarship to perform this research. This work was supported by the UBD CRG project: UBD/OVACRI/CRGWG(006)/161201.Protonic ceramic fuel cells (PCFCs) have become the most efficient, clean and cost-effective electrochemical energy conversion devices in recent years. While significant progress has been made in developing proton conducting electrolyte materials, mechanical strength and durability still need to be improved for efficient applications. We report that adding 5 mol% Zn to the Y-doped barium cerate-zirconate perovskite electrolyte material can significantly improve the sintering properties, mechanical strength, durability and performance. Using same proton conducting material in anodes, electrolytes and cathodes to make a strong structural backbone shows clear advantages in mechanical strength over other arrangements with different materials. Rietveld analysis of the X-ray and neutron diffraction data of BaCe0.7Zr0.1Y0.15Zn0.05O3−δ (BCZYZn05) revealed a pure orthorhombic structure belonging to the Pbnm space group. Structural and electrochemical analyses indicate highly dense and high proton conductivity at intermediate temperature (400–700 °C). The anode-supported single cell, NiO-BCZYZn05|BCZYZn05|BSCF-BCZYZn05, demonstrates a peak power density of 872 mW cm−2 at 700 °C which is one of the highest power density in an all-protonic solid oxide fuel cell. This observation represents an important step towards commercially viable SOFC technology.Publisher PDFPeer reviewe

Highly dense and chemically stable proton conducting electrolyte sintered at 1200 °C

The authors S. Hossain and A. M. Abdalla are grateful to the graduate studies office of Universiti Brunei Darussalam for graduate research scholarship (GRS) for funding this research. The authors are thankful to Professor John T. S. Irvine for managing a visiting scholarship for SH and AMA at Center for Advanced Materials at School of Chemistry in University of St Andrews, UK for the research works done.The BaCe0.7Zr0.1Y0.2−xZnxO3−δ (x = 0.05, 0.10, 0.15, 0.20) has been synthesized by the conventional solid state reaction method for application in protonic solid oxide fuel cell. The phase purity and lattice parameters of the materials have been studied by the room temperature X-ray diffraction (XRD). Scanning electron microscopy (SEM) has been done for check the morphology and grain growth of the samples. The chemical and mechanical stabilities have been done using thermogravimetric analysis (TGA) in pure CO2 environment and thermomechanical analysis (TMA) in Argon atmosphere. The XRD of the materials show the orthorhombic crystal symmetry with Pbnm space group. The SEM images of the pellets show that the samples sintered at 1200 °C are highly dense. The XRD after TGA in CO2 and thermal expansion measurements confirm the stability. The particles of the samples are in micrometer ranges and increasing Zn content decreases the size. The conductivity measurements have been done in 5% H2 with Ar in dry and wet atmospheres. All the materials show high proton conductivity in the intermediate temperature range (400–700 °C). The maximum proton conductivity was found to be 1.0 × 10−2 S cm−1 at 700 °C in wet atmosphere for x = 0.10. From our study, 10 wt % of Zn seems to be optimum at the B-site of the perovskite structure. All the properties studied here suggest it can be a promising candidate of electrolyte for IT-SOFCs.PostprintPeer reviewe

Globalisation, economic growth and energy consumption in the BRICS region: the importance of asymmetries.

This paper examines the asymmetric impact of globalisation and economic growth on energy consumption in BRICS countries, applying the NARDL bounds approach to explore the presence of asymmetric cointegration across variables. The empirical results reveals that energy consumption is positively and negatively affected by the positive and negative globalisation shocks, respectively. A positive shock in economic growth promotes energy consumption, while a negative shock reduces energy consumption.N/

Globalisation, economic growth and energy consumption in the BRICS region: the importance of asymmetries.

This paper examines the asymmetric impact of globalisation and economic growth on energy consumption in BRICS countries, applying the NARDL bounds approach to explore the presence of asymmetric cointegration across variables. The empirical results reveals that energy consumption is positively and negatively affected by the positive and negative globalisation shocks, respectively. A positive shock in economic growth promotes energy consumption, while a negative shock reduces energy consumption.N/

Influence of polymer ratio and surfactants on controlled drug release from cellulosic microsponges

Microsponge refers to a highly cross-linked particle system with a capacity to adsorb (like a dry sponge) pharmaceutical materials. There are various methods available to prepare microsponge formulations, in this study we used quasi emulsion-solvent diffusion method with a combination of hydrophobic (ethyl cellulose) and hydrophilic polymers (hydroxypropyl methylcellulose) mediated via Tween 80 and polyvinyl alcohol. Various ratios and amounts of the polymers and surfactants were used to prepare microsponge formulations using ketoprofen as a model drug and extensively characterised. Our results, for the first time, indicate successful and optimised formulation with desired pharmaceutical characteristics using a combination of hydrophobic and hydrophilic polymers