| 1. |
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| 2. |
- Hu, Enyi, et al.
(författare)
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Junction and energy band on novel semiconductor-based fuel cells
- 2021
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Ingår i: iScience. - : Elsevier BV. - 2589-0042. ; 24:3
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Forskningsöversikt (refereegranskat)abstract
- Fuel cells are highly efficient and green power sources. The typical membrane electrode assembly is necessary for common electrochemical devices. Recent research and development in solid oxide fuel cells have opened up many new opportunities based on the semiconductor or its heterostructure materials. Semiconductor-based fuel cells (SBFCs) realize the fuel cell functionality in a much more straightforward way. This work aims to discuss new strategies and scientific principles of SBFCs by reviewing various novel junction types/interfaces, i.e., bulk and planar p-n junction, Schottky junction, and n-i type interface contact. New designing methodologies of SBFCs from energy band/alignment and built-in electric field (BIEF), which block the internal electronic transport while assisting interfacial superionic transport and subsequently enhance device performance, are comprehensively reviewed. This work highlights the recent advances of SBFCs and provides new methodology and understanding with significant importance for both fundamental and applied R&D on new-generation fuel cell materials and technologies.
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| 3. |
- Mehran, Muhammad Taqi, et al.
(författare)
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A comprehensive review on durability improvement of solid oxide fuel cells for commercial stationary power generation systems
- 2023
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Ingår i: Applied Energy. - 1872-9118 .- 0306-2619. ; 352
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Tidskriftsartikel (refereegranskat)abstract
- Solid oxide fuel cells (SOFCs) are recognized as an alternative for power generation applications due to their high efficiency and environment-friendly behaviour. The electronic devices and power age could be revolutionized with the commercialization of such devices. Stationary power generation systems based on SOFCs are a step closer to commercialization due to the latest developments in the technology that promises to overcome the inherent bottleneck of high-temperature fuel cells, i.e., durability. According to the US Department of Energy (DOE), the stationary power generation system should have a lifetime of 40,000 h continuous operation. The efficiency of SOFCs is mainly dependent on their components such as anode, cathode, interconnect, and electrolyte. There are numerous factors affecting the efficiency of SOFCs that include the composition of the fuel, kinetics, and thermodynamics of the cell, and working temperature. In this paper, we have presented a comprehensive review of the recent developments to produce durable SOFCs for commercial stationary power generation systems. The review summarizes several prominent degradation mechanisms involved in the SOFC components and methods to reduce the degradation process. In addition, the methods and techniques adopted for the degradation analysis are fully demonstrated, followed by a detailed durability diagnostic through in-situ and ex-situ durability testing. The review is complemented by a lucid presentation of future research challenges and the knowledge gaps coupled with potential recommendations to fill the gaps. The new engineering designs, the material development and the new knowledge presented in this study could provide useful guidance for the key stakeholders, policymakers and power generation entities to commercially implement the application of durable SOFCs for stationary power generation.
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| 4. |
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| 5. |
- Naseer, Amtul, et al.
(författare)
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The robust catalysts (Ni1-x-Mo-x/doped ceria and Zn1-x-Mo-x/doped ceria, x=0.1 and 0.3) for efficient natural gas reforming in solid oxide fuel cells
- 2020
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 361
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Tidskriftsartikel (refereegranskat)abstract
- Nickel is a promising catalyst in Solid Oxide fuel cell (SOFC) due to its electrocatalytic performance, however, the practical utilization of Ni-based materials is hindered by the undesirable carbon deposition during methane decomposition. Herein, molybdenum is incorporated into the Ni- and Zn-based cermets (Ni1-x-Mo-x/GDC and Zn1-x-Mo-x/GDC, x = 0.1 and 0.3) to enhance electrocatalytic properties and avoid the carbon deposition during cell operation. The desired composites are synthesized by the impregnation method and adopted as anode in SOFCs. The catalytic activity for methane oxidation has been significantly improved due to the introduction on Mo, which hindered the carbon deposition due to higher graphitization and abundant active sites accessible to fuel. The detailed Raman spectroscopy and conductivity analysis revealed that addition of Mo reduced the amount of deposited carbon and enhanced the electrical conductivity. By using natural gas, as a fuel, the as-prepared Mo-doped Ni-GDC rendered a maximum power density of 690 mW cm(-2) at 600 degrees C. It is worth mentioning that the achieved stable power density is one of the best in existing literature. The current study presents a novel strategy to improve the catalytic behavior of electrode materials and demonstrate the optimal performance at low operating temperature. (C) 2020 Elsevier Ltd. All rights reserved.
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| 6. |
- Rafique, Asia, et al.
(författare)
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Design and Modeling of a Fuel Cell System Using Biomass Feedstock as a Biofuel
- 2020
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Ingår i: Fuel Cells. - : Wiley. - 1615-6846 .- 1615-6854. ; 20:1, s. 89-97
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Tidskriftsartikel (refereegranskat)abstract
- This paper aims to model ceramic fuel cell system based on low-temperature planar solid oxide fuel cell (SOFC) different biogases fuels from multiple biomasses, that is, animal waste, redwood, rice husk and sugar cane. Biomass is a better choice for the generation of energy globally. Therefore, there is a focus on the most available biomass resources in the country that can be used as clean energy sources. This developed model is designed by thermodynamic analysis and electrochemical calculations using MATLAB. The designed model is a lumped parameter model based on the steady-state one-dimensional flow. In this model, all calculated power and flow rate values were kept as positive values. Also, the system is considered to be free of leaks, and heat loss is neglected. The operating temperature and pressure are assumed to be 500–700 °C and the partial pressure is set at three different pressures; P1 (1 bar), P2 (2 bar), and P3 (3 bar), respectively, and fuel utilization factor is 80%. It is observed that the best performance is obtained with animal-waste based biogas at 700 °C and P3 (3 bar).
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| 7. |
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| 8. |
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| 9. |
- Raza, Rizwan, 1980-, et al.
(författare)
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Advanced Multi-Fuelled Solid Oxide Fuel Cells (ASOFCs) Using Functional Nanocomposites for Polygeneration
- 2011
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Ingår i: Advanced Energy Materials. - Germany : Wiley-VCH Verlagsgesellschaft. - 1614-6832 .- 1614-6840. ; 1:6, s. 1225-1233
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Tidskriftsartikel (refereegranskat)abstract
- An advanced multifuelled solid oxide fuel cell (ASOFC) with a functional nanocomposite was developed and tested for use in a polygeneration system. Several different types of fuel, for example, gaseous (hydrogen and biogas) and liquid fuels (bio-ethanol and bio-methanol), were used in the experiments. Maximum power densities of 1000, 300, 600, 550 mW cm−2 were achieved using hydrogen, bio-gas, bio-methanol, and bio-ethanol, respectively, in the ASOFC. Electrical and total efficiencies of 54% and 80% were achieved using the single cell with hydrogen fuel. These results show that the use of a multi-fuelled system for polygeneration is a promising means of generating sustainable power.
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| 10. |
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| 11. |
- Raza, Rizwan, 1980-, et al.
(författare)
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Biogas fuel based Single functional layer fuel cell
- 2011
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Ingår i: Proceedings of the 4th European Fuel Cell Piero Lunghi Conference & Exhibition. - Italy : ENEA. - 9788882862541 ; , s. 267-268
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Konferensbidrag (refereegranskat)
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| 12. |
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| 13. |
- Raza, Rizwan, 1980-, et al.
(författare)
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Enhancement of conductivity in ceria-carbonate nanocomposites for LTSOFCs
- 2009
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Ingår i: Journal of nano research. - STAFA-ZUERICH : Trans Tech Publications Inc.. - 1662-5250. ; 6, s. 197-204
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Tidskriftsartikel (refereegranskat)abstract
- This work first explores high resolution transmission electron microscopy (TEM) to determine the interfacial regions and provide experimental evidences for interfaces between the SDC and carbonate constituent phases of the SD-carbonate two-phase composites to further investigate the superionic conduction mechanism in the ceria-carbonate composite systems and enhancement of conductivity. Schober first reported interfacial superionic conduction in ceria-based composites but without direct experimental proofs. Such superionic conduction mechanism remains unknown. Especially, in the nano-scale, this region is trifle to be detected.
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| 14. |
- Raza, Rizwan, 1980, et al.
(författare)
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Functional ceria-based nanocomposites for advanced low-temperature (300–600 °C) solid oxide fuel cell: A comprehensive review
- 2020
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Ingår i: Materials Today Energy. - : Elsevier BV. - 2468-6069. ; 15
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Forskningsöversikt (refereegranskat)abstract
- There is world tendency to develop SOFC to lower temperatures and two technical routes and approaches are going in parallel. One is to use thin film technology, focussing on reducing the electrolyte thickness on conventional electrolyte, e.g. YSZ (yttria-stabilized zirconia) and SDC (samaria-doped ceria) to reduce the cell resistance i.e. to lower the operational temperatures. Another technique is to develop new materials, e.g. functional nanocomposites. This paper presents a state-of-the-art of nanocomposite electrolytes-based advanced fuel cell technology, i.e. low-temperature (300–600 °C) ceria-based fuel cells, a new scenario for fuel cell R&D with an overview of important aspects and frontier subjects. A typical nanocomposite has a core–shell type structure in nano-scale, in which ceria forms a core and a salt, e.g. carbonate or another oxide develops a shell layer covering the core. The functionality of nanocomposites is determined by the interfaces between the constituent phases, which can lead to super or fast ions transport (H+ and O2−) at interfaces. Ionic conductivities >0.1 S cm−1 already at ~300 °C have been reported. Five major characteristics of nanocomposites have been identified as important to their properties and applications in fuel cells: i) advanced materials design based on non-structure or interfacial properties/mechanisms; ii) dual or hybrid H+ and O2− conduction; iii) interfacial super-ionic conduction; iv) transition from non-functional to functional materials; v) use of interfacial and surface redox agents and reactions. In the fuel cell context, it is refer to these functional nano-composites as NANOCOFC (Nanocomposites for Advanced Fuel Cells) to distinguish them from the traditional SOFCs and to be oriented to a new fuel cell R&D strategy.
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| 15. |
- Raza, Rizwan, 1980-
(författare)
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Functional nanocomposites for advanced fuel cell technology and polygeneration
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In recent decades, the use of fossil fuels has increased exponentially with a corresponding sharp increase in the pollution of the environment. The need for clean and sustainable technologies for the generation of power with reduced or zero environment impact has become critical. A number of attempts have been made to address this problem; one of the most promising attempts is polygeneration. Polygeneration technology is highly efficient and produces lower emissions than conventional methods of power generation because of the simultaneous generation of useable heat and electrical power from a single source of fuel. The overall efficiency of such systems can be as high as 90%, compared to 30-35% for conventional single-product power plants.A number of different technologies are available for polygeneration, such as micro gas turbines, sterling engines, solar systems, and fuel cells. Of these, fuel cell systems offer the most promising technology for polygeneration because of their ability to produce electricity and heat at a high efficiency (about 80%) with either low or zero emissions. Various fuel-cell technologies can be used in polygeneration systems. Of these, solid oxide fuel cells (SOFCs) are the most suitable because they offer high system efficiency for the production of electricity and heat (about 90%) coupled with low or zero emissions. Compared to other types of fuel cells, SOFCs have fuel flexibility (direct operation on hydrocarbon fuels, such as biogas, bio-ethanol, bio-methanol, etc.) and produce high-quality heat energy. The development of polygeneration systems using SOFCs has generally followed one of two approaches. The first approach involves the design of a SOFC system that operates at a temperature of 850 oC and uses natural gas as a fuel. The second approach uses low-temperature (generally 400-600 oC) SOFC (LTSOFC) systems with biomass, e.g., syngas or liquid fuels, such as bio-methanol and bio-ethanol. The latter systems have strong potential for use in polygeneration.High-temperature SOFCs have obvious disadvantages, and challenges remain for lowering the cost to meet commercial interest. The SOFC systems need lower operating temperatures to reduce their overall costs.This thesis focuses on the development of nanocomposites for advanced fuel-cell technology (NANOCOFC), i.e., the next generation SOFCs, which are low-temperature (400-600 oC), marketable, and affordable SOFCs. In addition, new concepts that pertain to fuel-cell science and technology—NANOCOFC (www.nanocofc.com)—are explored and developed. The content of this thesis is divided into five parts:In the first part of this thesis (Papers 1-5), the two-phase nanocomposite electrolytes, viz. ceria-salt and ceria-oxide, were prepared and studied using different electrochemical techniques. The microstructure and morphology of the composite electrolytes were characterised using XRD, SEM and TEM, and the thermal analysis was conducted using DSC. An ionic conductivity of 0.1 S/cm was obtained at 300 ºC, which is comparable to that of conventional YSZ operating at 1000 ºC. The maximum output power density was 1000 mW/cm2 at 550 oC. A co-doped ceria-carbonate was also developed to improve the ionic conductivity, morphology, and performance of the electrolyte.In the second part of this thesis (Papers 7-9), composite electrodes that contained less or no nickel (Ni) were developed for a low-temperature SOFC. All of the elements were highly homogenously distributed in the composite electrode, which resulted in high catalytic activity and good ASOFC performance. The substitution of Ni by Zn in these electrodes could reduce their cost by a factor of approximately 25.In the third part of this thesis (Papers 10), an advanced multi-fuelled solid-oxide fuel cell (ASOFC) with functional nanocomposites (electrolytes and electrodes) was developed. Several different types of fuel, such as gaseous (hydrogen and biogas) and liquid fuels (bio-ethanol and bio-methanol), were tested. Maximum power densities of 1000, 300, 600, and 550 mW/cm2 were achieved with hydrogen, bio-gas, bio-methanol, and bio-ethanol, respectively, in the ASOFC. Electrical and total efficiencies of 54% and 80%, respectively, were achieved when the single cell was used with hydrogen.The fourth part of this thesis (Papers 11) concerns the design of a 5 kW ASOFC system based on the demonstrated advanced SOFC technology. A polygeneration system based on a low-temperature planar SOFC was then designed and simulated. The efficiency of the overall system was approximately 80%.The fifth part of this thesis (Paper 12) describes a single-layer multi-fuelled electrolyte-free fuel cell that is a revolutionary innovation in renewable-energy sources. Conventional fuel cells generate electricity by ion transport through the electrolyte. However, this new device works without an electrolyte, and all of the processes occur at particle surfaces in the material. Based on a theoretical calculation, an additional 18% enhancement of the fuel cell’s efficiency will be achieved using this new technology compared to the conventional technologies.Our developed ASOFC systems with functional nanocomposites offer significant advantages in reducing the operational and capital costs for the production of power and heat by using different fuels based on the fuel-cell technology. ASOFC systems can be used for polygeneration with renewable fuels (i.e., biomass fuels) at high efficiency as a sustainable solution to energy generation in our society. The results have been achieved for this thesis work has demonstrated an advanced fuel cell technology.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Samavati, Mahrokh, et al.
(författare)
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Design of a 5-kW advanced fuel cell polygeneration system
- 2012
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Ingår i: Wiley Interdisciplinary Reviews: Energy and Environment. - : WIRES. - 2041-8396. ; 1:2, s. 173-180
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Tidskriftsartikel (refereegranskat)abstract
- 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 cm2 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.
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| 20. |
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| 21. |
- Ullah, Muhammad Kaleem, et al.
(författare)
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Tri-doped ceria (M0.2Ce0.8O2-δ, M= Sm0.1 Ca0.05 Gd0.05) electrolyte for hydrogen and ethanol-based fuel cells
- 2019
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 773, s. 548-554
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Tidskriftsartikel (refereegranskat)abstract
- In recent scientific research, an interest has been gained significantly by rare earth metals such as cerium (Ce), samarium (Sm) and gadolinium (Gd) due to their use in fuel cells as electrolyte and catalysts. When used in an electrolyte, these materials lower the fuel cell's operating temperature compared to a conventional electrolyte, for example, yittria-stabilized zirconia (YSZ) which operates at a high temperature (≥800 °C). In this paper, the tri-doped ceria, M0.2Ce0.8O2-δ(M = Sm0.1Ca0.05Gd0.05) electrolyte powders was synthesized using the co-precipitation method at 80 °C. These dopants were used for CeO2with a total molar ratio of 1 M. Dry-pressed powder technique was used to make fuel cell pellets from the powder and placed them in the furnace to sinter at 700 °C for 60 min. Electrical conductivity of such a pellet in air was 1.2 × 10−2S cm−1at 700 °C measured by the ProboStat-NorECs setup. The crystal structure was determined with the help of X-ray diffraction (XRD), which showed that all the dopants were successfully doped in CeO2. Raman spectroscopy and UV-VIS spectroscopy were also carried out to analyse the molecular vibrations and absorbance, respectively. The maximum open-circuit voltages (OCVs) for hydrogen and ethanol fuelled at 550 °C were observed to be 0.89 V and 0.71 V with power densities 314 mW cm−2and 52.8 mW cm−2, respectively.
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| 22. |
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| 23. |
- Zahra, M., et al.
(författare)
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Tailoring the ions and bandgaps in a novel semi-ionic energy conversion device for electrochemical performance
- 2020
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Ingår i: Materials Today Energy. - : Elsevier BV. - 2468-6069. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- The new semi-ionic energy conversion (SIEC) device has attracted remarkable attention owing to its clean and environmentally friendly applications. In this device, novel materials and mechanisms have been explored using electronic and ionic conductor materials. The tuning effect of the ions and bandgap has been studied to investigate the structural, optical, and electrochemical performance of the material. Composite materials, gadolinium-doped ceria-cadmium-doped ZnO (GDC-ZnCdO), based on ionic gadolinium-doped ceria (GDC) and semiconductor (ZnCdO) in molar ratios of 1:4, 2:3, 3:2, and 4:1 have been prepared by a wet chemical route. The crystalline structure of the GDC-ZnCdO was studied and found to have cubic and hexagonal wurtzite phases with an average crystallite size of 30–40 nm. The morphology of the prepared composite materials is a homogenous and porous structure. It was found that the addition of GDC increases the transmittance and shows a red shift in the bandgap from 2.70 eV to 2.46 eV. The maximum conductivity of 2.0 S/cm1 was achieved for the sample 4GDC-1ZnCdO at 700°C. Electrochemical impedance spectra and X-ray photoelectron spectroscopy analysis were performed to investigate the electrochemical properties of the prepared semi-ionic composite materials. The SIEC device showed a much better performance than a conventional solid oxide fuel cell. The maximum open-circuit voltage (OCV) of about 1.013 Vand power density of 0.65 W/cm2 were obtained using hydrogen fuel at 600°C, as compared with a conventional fuel cell with 0.72 V and 0.27 W/cm2, respectively. Hence, the results reveal that the ions and bandgap tuning play a crucial role in fuel cell functions. Therefore, it has been determined that the bandgap can be tuned to obtain a better and more stable performance of the SIEC device. This study presents a novel approach to enhance the electrochemical performance with the tailoring of the new semi-ionic materials.
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| 24. |
- Zhu, Bin, 1956-, et al.
(författare)
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A new energy conversion technology joining electrochemical and physical principles
- 2012
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Ingår i: RSC Advances. - 2046-2069. ; 2:12, s. 5066-5070
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Tidskriftsartikel (refereegranskat)abstract
- We report a new energy conversion technology joining electrochemical and physical principles. This technology can realize the fuel cell function but built on a different scientific principle. The device consists of a single component which is a homogenous mixture of ceria composite with semiconducting materials, e.g. LiNiCuZn-based oxides. The test devices with hydrogen and air operation delivered a power density of 760mWcm(-2) at 550 degrees C. The device has demonstrated a multi-fuel flexibility and direct alcohol and biogas operations have delivered 300-500 mW cm(-2) at the same temperature. Device physics reveal a key principle similar to solar cells realizing the function based on an effective separation of electronic and ionic conductions and phases within the single-component. The component material multi-functionalities: ion and semi-conductions and bi-catalysis to H-2 or alcohol (methanol and ethanol) and air (O-2) enable this device realized as a fuel cell.
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