RIZWAN RAZA - Academia.edu (original) (raw)

Papers by RIZWAN RAZA

RSC Advances, 2012

The electronic/semi-conducting materials in the single-component device were prepared for LiNiCuZ... more The electronic/semi-conducting materials in the single-component device were prepared for LiNiCuZn based oxides by solid state reaction methods. Stoichiometric amounts of Li 2 CO 3 , NiCO 3 .2Ni (OH) 2 •6H 2 O, CuCO 3 •Cu (OH) 2 and Zn (NO 3) 2 •6H 2 O (Sigma-Aldrich, USA) were mixed grounded and sintered at 800 °C for 2-4 hours. Some typical compositions with a molar ratio among metal elements are: Li:Ni:Cu:Zn =3:6:3:6. The material obtained was again mixed with an ionic conductor, Ce 0.8 Sm 0.2−x O 2−δ-Na 2 CO 3 (NaSDC) nanocomposite 10 with 2: 1 to 1: 2 weight ratios. The mixed powder was further heated at 700 °C for 1 hour then pressed uniaxially with a 100-300 MPa load to flat tablets of the single-component material, on which both end surfaces were pasted by silver as current collectors. The tablet diameter was normally 1.3 cm and its thickness 0.06 − 0.10 cm. The larger area units of 6 × 6 cm 2 were constructed for the single-component device by

International Journal of Hydrogen Energy, 2016

Abstract Solid oxide fuel cells (SOFCs) have the ability to operate with different variants of hy... more Abstract Solid oxide fuel cells (SOFCs) have the ability to operate with different variants of hydro carbon fuel such as biogas, natural gas, methane, ethane, syngas, methanol, ethanol, hydrogen and any other hydrogen rich gas. Utilization of these fuels in SOFC, especially the natural gas, would significantly reduce operating cost and would enhance the viability for commercialization of FC technology. In this paper, the performance of two indigenously manufactured nanocomposite electrolytes; barium and samarium doped ceria (BSDC-carbonate); and lanthanum and samarium doped ceria (co-precipitation method LSDC-carbonate) using natural gas as fuel is discussed. The nanocomposite electrolytes were synthesized using co-precipitation and wet chemical methods (here after referred to as nano electrolytes). The structure and morphology of the nano electrolytes were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The fuel cell performance (OCV) was tested at temperature (300–600 °C). The ionic conductivity of the nano electrolytes were measured by two probe DC method. The detailed composition analysis of nano electrolytes was performed with the help of Raman Spectroscopy. Electrochemical study has shown an ionic conductivity of 0.16 Scm−1 at 600 °C for BSDC-carbonate in hydrogen atmosphere, which is higher than conventional electrolytes SDC and GDC under same conditions. In this article reasonably good ionic conductivity of BSDC-carbonate, at 600 °C, has also been achieved in air atmosphere which is comparatively greater than the conventional SDC and GDC electrolytes.

Reviews in Plasmonics, 2016

An extensive research has been carried out in synthesizing and characterizing single and double l... more An extensive research has been carried out in synthesizing and characterizing single and double layer metal thin films of different thicknesses including ultrathin films. We discuss the experimental data of surface plasmon resonance (SPR) occurring at the interface between air, single and bimetallic thin layers of gold (Au) and silver (Ag) prepared on glass substrates. The bilayer configuration allowed for the measurements of the optical constants of metallic films that are ultra thin; e.g., below 10 nm of thickness since SPR modes on such thin films in a single layer configuration are shallow. In addition, using SPR technique, the optical constants of a natural biological thin layer (Allium cepa) is also estimated. Thickness and refractive index of metallic films were determined by matching experimental SPR curves to the theoretical ones. Thickness and roughness of the films were also measured by atomic force microscopy. The results obtained by experimental measurements are in good agreement with AFM analysis. It is estimated that the value of the real part of the dielectric constant of an onion epidermis is existing between the dielectric constants of water and air.

Alkali-carbonates effects @ doped ceria as a composite electrolyte for Low temperature (300-600 o... more Alkali-carbonates effects @ doped ceria as a composite electrolyte for Low temperature (300-600 oC) solid oxide fuel cell

Our recent developments have been made on the single layer or electrolyte-free fuel cells using a... more Our recent developments have been made on the single layer or electrolyte-free fuel cells using a homogeneous mixed semi- and ion conducting layer which can function as the electrodes, anode and cathode, and electrolyte simultaneously. We have achieved near 800 mW/cm2 at 550oC. A number of material groups have also been developed for advanced SLFCs. This radical new invention has made this nice concept of SLFC into practical application and also opens a new fuel cell R&D strategy.

Wiley Interdisciplinary Reviews: Energy and Environment, 2012

In this article, a planar, low-temperature, solid-oxide fuel cell based on nanocomposite material... more In this article, a planar, low-temperature, solid-oxide fuel cell based on nanocomposite materials is developed by cost-effective tape casting and hot-pressing methods. First, a single cell with active area of 6 × 6 cm 2 was manufactured and tested to determine the cell performance. The power density of 0.4 and 0.7 W cm −2 were achieved at stable open-circuit voltages at operating temperature of 550 • C using the syngas and hydrogen, respectively. Based on these experimental results, a 5-kW low-temperature, solid-oxide fuel cell polygeneration system is designed and analyzed. This system can provide electrical power and heating concurrently from a single source of fuel. The system design and the energy and mass balance are presented and a simulation based on syngas is performed. Finally, effects of fuel utilization factor, fuel cell operating temperature, and air temperature at cathode inlet on performance of polygeneration system is investigated.

Advanced Energy Materials, 2011

Page 1. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim FULL P APER 1 wileyonli... more Page 1. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim FULL P APER 1 wileyonlinelibrary.com Adv. Energy Mater. 2011, XX, 1–9 www.MaterialsViews. com www.advenergymat.de 1. Introduction In recent decades ...

Advanced Energy Materials, 2015

Nano Energy, 2013

Electrolyte-separator-free fuel cell (EFFC) is a new emerging energy conversion technology. The E... more Electrolyte-separator-free fuel cell (EFFC) is a new emerging energy conversion technology. The EFFC consists of a single-component of nanocomposite material which works as a one-layer fuel cell device contrary to the traditional three-layer anode-electrolyte-cathode structure, in which an electrolyte layer plays a critical role. The nanocomposite of a single homogenous layer consists of a mixture of semiconducting and ionic materials that provides the necessary electrochemical reaction sites and charge transport paths for a fuel cell. These can be accomplished through tailoring ionic and electronic (n, p) conductivities and catalyst activities, which enable redox reactions to occur on nano-particles and finally accomplish a fuel cell function.

Applied Surface Science, 2015

Structural and photovoltaic characteristics of hierarchical ZnO nanostructures solar cell have be... more Structural and photovoltaic characteristics of hierarchical ZnO nanostructures solar cell have been studied in relation to growth reaction temperature. It is found that the hierarchical ZnO nanostructures network to act not only as large surface area substrates but also as a transport medium for electrons injected from the dye molecules. The incident photon-to-current conversion efficiency is decreased by increasing the growth reaction temperature of ZnO electrodes. The best conversion efficiency of a 0.25 cm 2 cell is measured to be 1.24% under 100 mW cm −2 irradiation.

Solid State Ionics, 2011

The purpose of this study is to develop new oxide ionic conductors based on nanocomposite materia... more The purpose of this study is to develop new oxide ionic conductors based on nanocomposite materials for an advanced fuel cell (NANOCOFC) approach. The novel two phase nanocomposite oxide ionic conductors, Ce 0.8 Sm 0.2 O 2 − δ (SDC)-Y 2 O 3 were synthesized by a co-precipitation method. The structure and morphology of the prepared electrolyte were investigated by means of X-ray diffraction (XRD) and high resolution scanning electron microscopy (HRSEM). XRD results showed a two phase composite consisting of yttrium oxide and samaria doped ceria and SEM results exhibited a nanostructure form of the sample. The yttrium oxide was used on the SDC as a second phase. The interface between two constituent phases and the ionic conductivities were studied with electrochemical impedance spectroscopy (EIS). An electrochemical study showed high oxide ion mobility and conductivity of the Y 2 O 3-SDC two phase nanocomposite electrolytes at a low temperature (300-600°C). Maximum conductivity (about 1.0 S cm −1) was obtained for the optimized Y 2 O 3-SDC composite electrolyte at 600°C. It is found that the nanocomposite electrolytes show higher conductivities with the increased concentration of yttrium oxides but decreases after reaching a certain level. A high fuel cell performance, 0.75 W cm −2 , was achieved at 580°C.

Journal of Power Sources, 2012

h i g h l i g h t s < SCFCs are assembled by mixed ion and electron conductive composites. < The ... more h i g h l i g h t s < SCFCs are assembled by mixed ion and electron conductive composites. < The performances are influenced by the composition and thickness of the pellets. < A maximum power density of 350 mW cm À2 is achieved at 550 C. < The performance is correlated with the mixed conduction (ionic and electronic, p and n-type) properties and the porous microstructure.

Journal of Power Sources, 2012

Low temperature solid oxide fuel cells (SOFCs) with metal oxide composite cathode on the ceria-ca... more Low temperature solid oxide fuel cells (SOFCs) with metal oxide composite cathode on the ceria-carbonate composite electrolyte have shown promising performance. However, the role of individual elements or compound is seldom investigated. We report here the effect of the ZnO on the physico-chemical and electrochemical properties of lithiated NiO cathode. The materials and single cells are characterized by X-ray diffraction, scanning electron microscopy, DC polarization electrical conductivity, electrochemical impedance spectroscopy and fuel cell performance. The ZnO modified lithiated NiO composite materials exhibit smaller particle size and lower electrical conductivity than lithiated NiO. However, improved electro-catalytic oxygen reduction activity and power output are achieved after the ZnO modification. A maximum power density of 808 mW cm −2 and the corresponding interfacial polarization resistance of 0.22 cm 2 are obtained at 550 • C using ZnO modified cathode and 300 m thick composite electrolyte. The single cell keeps reasonable stability over 300 min at 500 • C. Thus, ZnO modified lithiated NiO is a promising cathode candidate for low temperature SOFCs.

Journal of Power Sources, 2011

Single-component and three-component fuel cell devices have been studied using mixed ionic and el... more Single-component and three-component fuel cell devices have been studied using mixed ionic and electronic conductor. The three-component fuel cell means a conventional fuel cell which is the configuration consists of anode, electrolyte and cathode; while the single-component fuel cell uses only one component that can function as the electrodes and electrolyte simultaneously. The single-component fuel cell showed the same or even better performance compared to conventional three-component fuel cell. A maximum power density of 700 mW cm −2 has been achieved by the single-component fuel cell at 550 • C.

Journal of Power Sources, 2010

Bin Zhu, "Novel core-shell SDC/amorphous Na 2 CO 3 nanocomposite electrolyte for low-temperature ... more Bin Zhu, "Novel core-shell SDC/amorphous Na 2 CO 3 nanocomposite electrolyte for low-temperature SOFCs"

Journal of Power Sources, 2012

A co-doped ceria-carbonate (Ce 0.8 Sm 0.2−x Ca x O 2−ı-Na 2 CO 3) has been synthesized by a co-pr... more A co-doped ceria-carbonate (Ce 0.8 Sm 0.2−x Ca x O 2−ı-Na 2 CO 3) has been synthesized by a co-precipitation method. The detailed electrochemical characterizations (e.g. impedance spectra, polarization curve and IV curves) of this composite material are reported and discussed. The two phase nanocomposite electrolytes with carbonate coated on the co-doped ceria displays dual (H + /O 2−) ion conduction at low temperature (300-600 • C) in solid oxide fuel cell. The observed remarkable temperature-dependent of conductivity is attributed to the softening/melting of carbonate phase as the physical state of carbonate phase transforms from solid to molten state. Coexistence of various charge carriers, oxide phase composition, and the oxide-carbonate interfacial area are investigated by Raman spectra. The enhancement of conductivity is also discussed by the general mixing rule/percolation theory of composite interfaces. The co-doping with 2nd phase gives a good approach to realize challenges for solid oxide fuel cell.

Journal of Nanoscience and Nanotechnology, 2011

ABSTRACT Our previous work has demonstrated that novel core-shell SDC/Na2CO3 nanocomposite electr... more ABSTRACT Our previous work has demonstrated that novel core-shell SDC/Na2CO3 nanocomposite electrolyte possesses great potential for the development of low temperature (300-600 degrees C) solid oxide fuel cells. This work further characterizes the nanocomposite SDC/Na2CO3 electrochemical properties and conduction mechanism. The microstructure of the nanocomposite sintered at different temperatures was analyzed through scanning electron microscope (SEM) and X-ray diffraction (XRD). The electrical and electrochemical properties were studied. Significant conductivity enhancement was observed in the H2 atmosphere compared with that of air atmosphere. The ratiocination of proton conduction rather than electronic conduction has been proposed consequently based on the observation of fuel cell performance. The fuel cell performance with peak power density of 375 mW cm(-2) at 550 degrees C has been achieved. A.C. impedance for the fuel cell under open circuit voltage (OCV) conditions illustrates the electrode polarization process is predominant in rate determination.

Journal of Nanoscience and Nanotechnology, 2011

ABSTRACT This paper reports a new approach to develop functional solid oxide fuel cells (SOFC) el... more ABSTRACT This paper reports a new approach to develop functional solid oxide fuel cells (SOFC) electrolytes based on nanotechnology and two-phase nanocomposite approaches using non-oxygen ion or proton conductors, e.g., lithium aluminate-lithium sodium carbonate, with great freedom in material design and development. Benefited by nanotechnology and nanocomposite technology, the lithium aluminate-lithium sodium carbonate two-phase composite electrolytes can significantly enhance the material conductivity and fuel cell performance at low temperatures, such as 300 °C – 600 °C compared to non-nano scale materials. The conductivity mechanism and fuel cell functions are discussed to be benefited by the interfacial behavior between the two constituent phases in nano-scale effects, where oxygen ion and proton conductivity can be created, although there are no intrinsic mobile oxygen ions and protons. It presents a new scientific approach to design and develop fuel cell materials in breaking the structural limitations by using non-ionic conductors on the desired ions i.e., proton and oxygen ions, and creating high proton and oxygen ion conductors through interfaces and interfacial mechanism.

Journal of Fuel Cell Science and Technology, 2011

Bio-ethanol based fuel cell is an energy source with a promising future. The low temperature soli... more Bio-ethanol based fuel cell is an energy source with a promising future. The low temperature solid oxide fuel cell fed by direct bio-ethanol is receiving considerable attention as a clean and highly efficient for the production of both electricity and high grade waste heat. The comparison of fuel cell performance with different metal-oxide based electrodes was investigated. The power densities of 584 mW cm-2 and 514 mW cm-2 at 520 °C and 570 °C respectively were found. The effect of electrode catalyst function, ethanol concentration on the electrical performance was investigated at different temperature ranged in between 300 °C−600 °C. The effect of deposited carbon on the electrode was investigated by energy-dispersive X-ray spectroscopy and scanning electron microscope after testing the cell with bio-ethanol.

International Journal of Hydrogen Energy, 2010

The novel core-shell nanostructured SDC/Na 2 CO 3 composite has been demonstrated as a promising ... more The novel core-shell nanostructured SDC/Na 2 CO 3 composite has been demonstrated as a promising electrolyte material for low-temperature SOFCs. However, as a nanostructured material, stability might be doubted under elevated temperature due to their high surface energy. So in order to study the thermal stability of SDC/Na 2 CO 3 nanocomposite, XRD, BET, SEM and TGA characterizations were carried on after annealing samples at various temperatures. Crystallite sizes, BET surface areas, and SEM results indicated that the SDC/Na 2 CO 3 nanocomposite possesses better thermal stability on nanostructure than pure SDC till 700 C. TGA analysis verified that Na 2 CO 3 phase exists steadily in the SDC/Na 2 CO 3 composite. The performance and durability of SOFCs based on SDC/Na 2 CO 3 electrolyte were also investigated. The cell delivered a maximum power density of 0.78 W cm À2 at 550 C and a steady output of about 0.62 W cm À2 over 12 h operation. The high performances together with notable thermal stability make the SDC/Na 2 CO 3 nanocomposite as a potential electrolyte material for long-term SOFCs that operate at 500-600 C.

RSC Advances, 2012

The electronic/semi-conducting materials in the single-component device were prepared for LiNiCuZ... more The electronic/semi-conducting materials in the single-component device were prepared for LiNiCuZn based oxides by solid state reaction methods. Stoichiometric amounts of Li 2 CO 3 , NiCO 3 .2Ni (OH) 2 •6H 2 O, CuCO 3 •Cu (OH) 2 and Zn (NO 3) 2 •6H 2 O (Sigma-Aldrich, USA) were mixed grounded and sintered at 800 °C for 2-4 hours. Some typical compositions with a molar ratio among metal elements are: Li:Ni:Cu:Zn =3:6:3:6. The material obtained was again mixed with an ionic conductor, Ce 0.8 Sm 0.2−x O 2−δ-Na 2 CO 3 (NaSDC) nanocomposite 10 with 2: 1 to 1: 2 weight ratios. The mixed powder was further heated at 700 °C for 1 hour then pressed uniaxially with a 100-300 MPa load to flat tablets of the single-component material, on which both end surfaces were pasted by silver as current collectors. The tablet diameter was normally 1.3 cm and its thickness 0.06 − 0.10 cm. The larger area units of 6 × 6 cm 2 were constructed for the single-component device by

International Journal of Hydrogen Energy, 2016

Abstract Solid oxide fuel cells (SOFCs) have the ability to operate with different variants of hy... more Abstract Solid oxide fuel cells (SOFCs) have the ability to operate with different variants of hydro carbon fuel such as biogas, natural gas, methane, ethane, syngas, methanol, ethanol, hydrogen and any other hydrogen rich gas. Utilization of these fuels in SOFC, especially the natural gas, would significantly reduce operating cost and would enhance the viability for commercialization of FC technology. In this paper, the performance of two indigenously manufactured nanocomposite electrolytes; barium and samarium doped ceria (BSDC-carbonate); and lanthanum and samarium doped ceria (co-precipitation method LSDC-carbonate) using natural gas as fuel is discussed. The nanocomposite electrolytes were synthesized using co-precipitation and wet chemical methods (here after referred to as nano electrolytes). The structure and morphology of the nano electrolytes were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The fuel cell performance (OCV) was tested at temperature (300–600 °C). The ionic conductivity of the nano electrolytes were measured by two probe DC method. The detailed composition analysis of nano electrolytes was performed with the help of Raman Spectroscopy. Electrochemical study has shown an ionic conductivity of 0.16 Scm−1 at 600 °C for BSDC-carbonate in hydrogen atmosphere, which is higher than conventional electrolytes SDC and GDC under same conditions. In this article reasonably good ionic conductivity of BSDC-carbonate, at 600 °C, has also been achieved in air atmosphere which is comparatively greater than the conventional SDC and GDC electrolytes.

Reviews in Plasmonics, 2016

An extensive research has been carried out in synthesizing and characterizing single and double l... more An extensive research has been carried out in synthesizing and characterizing single and double layer metal thin films of different thicknesses including ultrathin films. We discuss the experimental data of surface plasmon resonance (SPR) occurring at the interface between air, single and bimetallic thin layers of gold (Au) and silver (Ag) prepared on glass substrates. The bilayer configuration allowed for the measurements of the optical constants of metallic films that are ultra thin; e.g., below 10 nm of thickness since SPR modes on such thin films in a single layer configuration are shallow. In addition, using SPR technique, the optical constants of a natural biological thin layer (Allium cepa) is also estimated. Thickness and refractive index of metallic films were determined by matching experimental SPR curves to the theoretical ones. Thickness and roughness of the films were also measured by atomic force microscopy. The results obtained by experimental measurements are in good agreement with AFM analysis. It is estimated that the value of the real part of the dielectric constant of an onion epidermis is existing between the dielectric constants of water and air.

Alkali-carbonates effects @ doped ceria as a composite electrolyte for Low temperature (300-600 o... more Alkali-carbonates effects @ doped ceria as a composite electrolyte for Low temperature (300-600 oC) solid oxide fuel cell

Our recent developments have been made on the single layer or electrolyte-free fuel cells using a... more Our recent developments have been made on the single layer or electrolyte-free fuel cells using a homogeneous mixed semi- and ion conducting layer which can function as the electrodes, anode and cathode, and electrolyte simultaneously. We have achieved near 800 mW/cm2 at 550oC. A number of material groups have also been developed for advanced SLFCs. This radical new invention has made this nice concept of SLFC into practical application and also opens a new fuel cell R&D strategy.

Wiley Interdisciplinary Reviews: Energy and Environment, 2012

In this article, a planar, low-temperature, solid-oxide fuel cell based on nanocomposite material... more In this article, a planar, low-temperature, solid-oxide fuel cell based on nanocomposite materials is developed by cost-effective tape casting and hot-pressing methods. First, a single cell with active area of 6 × 6 cm 2 was manufactured and tested to determine the cell performance. The power density of 0.4 and 0.7 W cm −2 were achieved at stable open-circuit voltages at operating temperature of 550 • C using the syngas and hydrogen, respectively. Based on these experimental results, a 5-kW low-temperature, solid-oxide fuel cell polygeneration system is designed and analyzed. This system can provide electrical power and heating concurrently from a single source of fuel. The system design and the energy and mass balance are presented and a simulation based on syngas is performed. Finally, effects of fuel utilization factor, fuel cell operating temperature, and air temperature at cathode inlet on performance of polygeneration system is investigated.

Advanced Energy Materials, 2011

Page 1. © 2011 WILEY-VCH Verlag GmbH &amp;amp;amp; Co. KGaA, Weinheim FULL P APER 1 wileyonli... more Page 1. © 2011 WILEY-VCH Verlag GmbH &amp;amp;amp; Co. KGaA, Weinheim FULL P APER 1 wileyonlinelibrary.com Adv. Energy Mater. 2011, XX, 1–9 www.MaterialsViews. com www.advenergymat.de 1. Introduction In recent decades ...

Advanced Energy Materials, 2015

Nano Energy, 2013

Electrolyte-separator-free fuel cell (EFFC) is a new emerging energy conversion technology. The E... more Electrolyte-separator-free fuel cell (EFFC) is a new emerging energy conversion technology. The EFFC consists of a single-component of nanocomposite material which works as a one-layer fuel cell device contrary to the traditional three-layer anode-electrolyte-cathode structure, in which an electrolyte layer plays a critical role. The nanocomposite of a single homogenous layer consists of a mixture of semiconducting and ionic materials that provides the necessary electrochemical reaction sites and charge transport paths for a fuel cell. These can be accomplished through tailoring ionic and electronic (n, p) conductivities and catalyst activities, which enable redox reactions to occur on nano-particles and finally accomplish a fuel cell function.

Applied Surface Science, 2015

Structural and photovoltaic characteristics of hierarchical ZnO nanostructures solar cell have be... more Structural and photovoltaic characteristics of hierarchical ZnO nanostructures solar cell have been studied in relation to growth reaction temperature. It is found that the hierarchical ZnO nanostructures network to act not only as large surface area substrates but also as a transport medium for electrons injected from the dye molecules. The incident photon-to-current conversion efficiency is decreased by increasing the growth reaction temperature of ZnO electrodes. The best conversion efficiency of a 0.25 cm 2 cell is measured to be 1.24% under 100 mW cm −2 irradiation.

Solid State Ionics, 2011

The purpose of this study is to develop new oxide ionic conductors based on nanocomposite materia... more The purpose of this study is to develop new oxide ionic conductors based on nanocomposite materials for an advanced fuel cell (NANOCOFC) approach. The novel two phase nanocomposite oxide ionic conductors, Ce 0.8 Sm 0.2 O 2 − δ (SDC)-Y 2 O 3 were synthesized by a co-precipitation method. The structure and morphology of the prepared electrolyte were investigated by means of X-ray diffraction (XRD) and high resolution scanning electron microscopy (HRSEM). XRD results showed a two phase composite consisting of yttrium oxide and samaria doped ceria and SEM results exhibited a nanostructure form of the sample. The yttrium oxide was used on the SDC as a second phase. The interface between two constituent phases and the ionic conductivities were studied with electrochemical impedance spectroscopy (EIS). An electrochemical study showed high oxide ion mobility and conductivity of the Y 2 O 3-SDC two phase nanocomposite electrolytes at a low temperature (300-600°C). Maximum conductivity (about 1.0 S cm −1) was obtained for the optimized Y 2 O 3-SDC composite electrolyte at 600°C. It is found that the nanocomposite electrolytes show higher conductivities with the increased concentration of yttrium oxides but decreases after reaching a certain level. A high fuel cell performance, 0.75 W cm −2 , was achieved at 580°C.

Journal of Power Sources, 2012

h i g h l i g h t s < SCFCs are assembled by mixed ion and electron conductive composites. < The ... more h i g h l i g h t s < SCFCs are assembled by mixed ion and electron conductive composites. < The performances are influenced by the composition and thickness of the pellets. < A maximum power density of 350 mW cm À2 is achieved at 550 C. < The performance is correlated with the mixed conduction (ionic and electronic, p and n-type) properties and the porous microstructure.

Journal of Power Sources, 2012

Low temperature solid oxide fuel cells (SOFCs) with metal oxide composite cathode on the ceria-ca... more Low temperature solid oxide fuel cells (SOFCs) with metal oxide composite cathode on the ceria-carbonate composite electrolyte have shown promising performance. However, the role of individual elements or compound is seldom investigated. We report here the effect of the ZnO on the physico-chemical and electrochemical properties of lithiated NiO cathode. The materials and single cells are characterized by X-ray diffraction, scanning electron microscopy, DC polarization electrical conductivity, electrochemical impedance spectroscopy and fuel cell performance. The ZnO modified lithiated NiO composite materials exhibit smaller particle size and lower electrical conductivity than lithiated NiO. However, improved electro-catalytic oxygen reduction activity and power output are achieved after the ZnO modification. A maximum power density of 808 mW cm −2 and the corresponding interfacial polarization resistance of 0.22 cm 2 are obtained at 550 • C using ZnO modified cathode and 300 m thick composite electrolyte. The single cell keeps reasonable stability over 300 min at 500 • C. Thus, ZnO modified lithiated NiO is a promising cathode candidate for low temperature SOFCs.

Journal of Power Sources, 2011

Single-component and three-component fuel cell devices have been studied using mixed ionic and el... more Single-component and three-component fuel cell devices have been studied using mixed ionic and electronic conductor. The three-component fuel cell means a conventional fuel cell which is the configuration consists of anode, electrolyte and cathode; while the single-component fuel cell uses only one component that can function as the electrodes and electrolyte simultaneously. The single-component fuel cell showed the same or even better performance compared to conventional three-component fuel cell. A maximum power density of 700 mW cm −2 has been achieved by the single-component fuel cell at 550 • C.

Journal of Power Sources, 2010

Bin Zhu, "Novel core-shell SDC/amorphous Na 2 CO 3 nanocomposite electrolyte for low-temperature ... more Bin Zhu, "Novel core-shell SDC/amorphous Na 2 CO 3 nanocomposite electrolyte for low-temperature SOFCs"

Journal of Power Sources, 2012

A co-doped ceria-carbonate (Ce 0.8 Sm 0.2−x Ca x O 2−ı-Na 2 CO 3) has been synthesized by a co-pr... more A co-doped ceria-carbonate (Ce 0.8 Sm 0.2−x Ca x O 2−ı-Na 2 CO 3) has been synthesized by a co-precipitation method. The detailed electrochemical characterizations (e.g. impedance spectra, polarization curve and IV curves) of this composite material are reported and discussed. The two phase nanocomposite electrolytes with carbonate coated on the co-doped ceria displays dual (H + /O 2−) ion conduction at low temperature (300-600 • C) in solid oxide fuel cell. The observed remarkable temperature-dependent of conductivity is attributed to the softening/melting of carbonate phase as the physical state of carbonate phase transforms from solid to molten state. Coexistence of various charge carriers, oxide phase composition, and the oxide-carbonate interfacial area are investigated by Raman spectra. The enhancement of conductivity is also discussed by the general mixing rule/percolation theory of composite interfaces. The co-doping with 2nd phase gives a good approach to realize challenges for solid oxide fuel cell.

Journal of Nanoscience and Nanotechnology, 2011

ABSTRACT Our previous work has demonstrated that novel core-shell SDC/Na2CO3 nanocomposite electr... more ABSTRACT Our previous work has demonstrated that novel core-shell SDC/Na2CO3 nanocomposite electrolyte possesses great potential for the development of low temperature (300-600 degrees C) solid oxide fuel cells. This work further characterizes the nanocomposite SDC/Na2CO3 electrochemical properties and conduction mechanism. The microstructure of the nanocomposite sintered at different temperatures was analyzed through scanning electron microscope (SEM) and X-ray diffraction (XRD). The electrical and electrochemical properties were studied. Significant conductivity enhancement was observed in the H2 atmosphere compared with that of air atmosphere. The ratiocination of proton conduction rather than electronic conduction has been proposed consequently based on the observation of fuel cell performance. The fuel cell performance with peak power density of 375 mW cm(-2) at 550 degrees C has been achieved. A.C. impedance for the fuel cell under open circuit voltage (OCV) conditions illustrates the electrode polarization process is predominant in rate determination.

Journal of Nanoscience and Nanotechnology, 2011

ABSTRACT This paper reports a new approach to develop functional solid oxide fuel cells (SOFC) el... more ABSTRACT This paper reports a new approach to develop functional solid oxide fuel cells (SOFC) electrolytes based on nanotechnology and two-phase nanocomposite approaches using non-oxygen ion or proton conductors, e.g., lithium aluminate-lithium sodium carbonate, with great freedom in material design and development. Benefited by nanotechnology and nanocomposite technology, the lithium aluminate-lithium sodium carbonate two-phase composite electrolytes can significantly enhance the material conductivity and fuel cell performance at low temperatures, such as 300 °C – 600 °C compared to non-nano scale materials. The conductivity mechanism and fuel cell functions are discussed to be benefited by the interfacial behavior between the two constituent phases in nano-scale effects, where oxygen ion and proton conductivity can be created, although there are no intrinsic mobile oxygen ions and protons. It presents a new scientific approach to design and develop fuel cell materials in breaking the structural limitations by using non-ionic conductors on the desired ions i.e., proton and oxygen ions, and creating high proton and oxygen ion conductors through interfaces and interfacial mechanism.

Journal of Fuel Cell Science and Technology, 2011

Bio-ethanol based fuel cell is an energy source with a promising future. The low temperature soli... more Bio-ethanol based fuel cell is an energy source with a promising future. The low temperature solid oxide fuel cell fed by direct bio-ethanol is receiving considerable attention as a clean and highly efficient for the production of both electricity and high grade waste heat. The comparison of fuel cell performance with different metal-oxide based electrodes was investigated. The power densities of 584 mW cm-2 and 514 mW cm-2 at 520 °C and 570 °C respectively were found. The effect of electrode catalyst function, ethanol concentration on the electrical performance was investigated at different temperature ranged in between 300 °C−600 °C. The effect of deposited carbon on the electrode was investigated by energy-dispersive X-ray spectroscopy and scanning electron microscope after testing the cell with bio-ethanol.

International Journal of Hydrogen Energy, 2010

The novel core-shell nanostructured SDC/Na 2 CO 3 composite has been demonstrated as a promising ... more The novel core-shell nanostructured SDC/Na 2 CO 3 composite has been demonstrated as a promising electrolyte material for low-temperature SOFCs. However, as a nanostructured material, stability might be doubted under elevated temperature due to their high surface energy. So in order to study the thermal stability of SDC/Na 2 CO 3 nanocomposite, XRD, BET, SEM and TGA characterizations were carried on after annealing samples at various temperatures. Crystallite sizes, BET surface areas, and SEM results indicated that the SDC/Na 2 CO 3 nanocomposite possesses better thermal stability on nanostructure than pure SDC till 700 C. TGA analysis verified that Na 2 CO 3 phase exists steadily in the SDC/Na 2 CO 3 composite. The performance and durability of SOFCs based on SDC/Na 2 CO 3 electrolyte were also investigated. The cell delivered a maximum power density of 0.78 W cm À2 at 550 C and a steady output of about 0.62 W cm À2 over 12 h operation. The high performances together with notable thermal stability make the SDC/Na 2 CO 3 nanocomposite as a potential electrolyte material for long-term SOFCs that operate at 500-600 C.