| 1. |
- Mushtaq, Irrum, et al.
(författare)
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Engineering electroactive and biocompatible tetra(aniline)-based terpolymers with tunable intrinsic antioxidant properties in vivo
- 2020
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : Elsevier. - 0928-4931 .- 1873-0191. ; 108
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Tidskriftsartikel (refereegranskat)abstract
- Under different pathological conditions, high levels of reactive oxygen species (ROS) cause substantial damage to multiple organs. To counter these ROS levels in multiple organs, we have engineered highly potent novel terpolymers. We found that combination of FDA-approved polyethylene glycol, fumaric acid moieties and electroactive tetra(aniline) by varying the content of tetra(aniline) results into a novel drug composition with biologically active tunable intrinsic antioxidant properties. To test tunable intrinsic antioxidative properties of these engineered novel terpolymers, we used alloxan to induce diabetes in rats where ROS generation is known to be higher. The systemic administration of terpolymers to the diabetic rats showed strong electroactive antioxidant behavior which normalized ROS levels, enzymatic antioxidants including superoxide dismutase, catalase, but also reduced glutathione. As a proof-of-principle, we here show TANI based novel drug composition of terpolymers with tunable intrinsic antioxidant effects confirmed in multiple organs.
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| 2. |
- Akbar, Muhammad, et al.
(författare)
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Effect of sintering temperature on properties of LiNiCuZn-Oxide: a potential anode for solid oxide fuel cell
- 2019
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Ingår i: Materials Research Express. - : IOP PUBLISHING LTD. - 2053-1591. ; 6:10
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Tidskriftsartikel (refereegranskat)abstract
- Crystal structure and surface morphology play vital role in the performance of Solid Oxide Fuel cells (SOFCs) anode. Sufficient electrocatalytic activity and high conductivity are the key requirements for anode to enhance the electrochemical capability. In current work, sintering temperature effects are investigated on the properties of advanced LiNiCuZn-Oxide based electrode for solid oxide fuel cells (SOFCs). The powders were prepared by simple solid-state reaction method was followed by sintering at different temperatures (700 degrees C-1200 degrees C). Moreover, various characterization techniques have been employed to investigate the sintering temperatures effects on the crystallite size, morphology, particle size, energy band gap and absorption peaks. The energy gap (Eg) was observed to increase from 2.94 eV to 3.32 eV and dc conductivity decreased from 9.084 Scm(-1) to 0.46 Scm(-1) by increasing sintering temperature from 700 degrees C to 1200 degrees C. Additionally, the best fuel cell performance of 0.90 Wcm(-2) was achieved for LiNiCuZn-Oxide sintered at 700 degrees C using H-2/air as a fuel and oxidant and it decreased to 0.17 Wcm(-2) for powders sintered at 1200 degrees C. Based on these results, we can conclude that 700 degrees C is the best optimum temperature for these chemical compositions, where all parameters of electrode are as per SOFCs requirement.
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| 3. |
- Ali, Amjad, et al.
(författare)
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A potential electrolyte (Ce1-x CaxO2-delta) for fuel cells:Theoretical andexperimental study
- 2018
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Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 44:11, s. 12676-12683
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Tidskriftsartikel (refereegranskat)abstract
- First-principles calculations are performed using density function theory to explore the effects of dopant Ca in ceria (Ce1-x CaxO2-delta). The impact of oxygen vacancy on band gap and density of states is examined in doped ceria using generalized gradient approximations. Vacancy association and vacancy formation energies of the doped ceria are calculated to reveal the effect of dopant on ion conduction. The experimental study of the sample Ce0.875Ca0.125O2-delta) was performed to compare with the theoretical results. The obtained results from theoretical calculation and experimental techniques show that oxygen vacancy increases the volume, lattice constant (5.47315 angstrom) but decrease the band gap (1.72 eV) and bulk modulus. The dopant radius (1.173 angstrom) and lattice constant (5.4718 angstrom) are also calculated by equations which is close to the DFT lattice parameter. The result shows that oxygen vacancy shifts the density of states to lower energy region. Band gap is decreased due to shifting of valence states to conduction band. Vacancy formation shows a significance increase in density of states near the Fermi level. Density of states at Fermi level is proportional to the conductivity, so an increase in density of states near the Fermi level increases the conductivity. The experimental measured ionic conductivity is found to 0.095 S cm(-1) at 600 degrees C. The microstructural studies is also reported in this work.
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| 4. |
- Liu, Xueqi, et al.
(författare)
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Study on charge transportation in the layer-structured oxide composite of SOFCs
- 2018
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 43:28, s. 12773-12781
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Tidskriftsartikel (refereegranskat)abstract
- In the past few years, triple (H+/O2-/e(-)) conducting materials have been regarded as one of the most promising electrode categories for solid oxide fuel cells (SOFCs). In this work, a layer-structured LiNi0.8Co0.15Al0.05O2-delta (LNCA) with triple conduction has been studied. The semiconductor-ionic conductor (SIC) LNCA-SDC composite has been fabricated by compositing the LNCA material with ionic conductor, i.e., samarium doped ceria (SDC). The electrochemical performance of the LNCA-SDC composite was studied by electrochemical impedance spectroscopy, while its electronic conductivity was confirmed by d.c. polarization method. It is found that the ionic conductivity of the composite is higher than the electronic conductivity by several orders of magnitude. The charge carriers and transportation properties of LNCA-SDC were studied using H+ and O2- blocking layer cells respectively. Results prove that the LNCA-SDC composite is a hybrid oxygen ion-proton conducting material. The oxygen ion conduction is dominated at low temperature (425 -500 degrees C), however, it is comparable with H+ conduction at high temperature (550 degrees C). Additionally, the formation of Li2CO3 under fuel cell operation environment was observed and the mechanism of the hybrid conductivity of LNCA-SDC was studied.
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| 5. |
- Liu, Yanyan, et al.
(författare)
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A Single-Phase Mixed-Conductive Pr-Doped CeO2 Membrane for Advanced Fuel-to-Electricity Technology
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Pr-doped CeO2 has exhibited many interesting properties relying on the flexible valence of praseodymium. The tailorable doping contents of praseodymium determine the ionic or mixed electronic-ionic conductivity properties of the Pr-doped CeO2. Interestingly, the characteristic feature that praseodymium element preferably attributes on the surface of ceria particles facilitates the surface exchange kinetics for oxygen transport relying on oxygen vacancies and resulting in high ionic conduction. Hereby, we investigated a 10 mol.% Pr-doped CeO2 (Pr-CeO2) synthesized by hydrothermal method focusing on its surface conductive properties. The as-prepared Pr-CeO2 exhibited a high electrical conductivity of 0.36 S cm-1 at 600 ℃. Using this mixed conductive Pr-CeO2, we fabricated a solid oxide fuel cell (SOFC) device in a ‘sandwich’ configuration while p-type semiconductor Ni0.8Co0.15Al0.05Li-oxide was pasted on both sides of Pr-CeO2 membrane layer. This device exhibited a comparable peak power density of 776 mW cm-2 at 600 ℃ to the conventional ionic conducting electrolyte-based SOFCs. Furthermore, the mechanism for surface conductivity enhancement has been discussed. These findings reveal an alternative methodology to prepare materials with significant impacts on advanced R&D SOFC technology.
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| 6. |
- Liu, Yanyan, et al.
(författare)
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Single-phase electronic-ionic conducting Sm3+/Pr3+/Nd3+ triple-doped ceria for new generation fuel cell technology
- 2018
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 43:28, s. 12817-12824
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Tidskriftsartikel (refereegranskat)abstract
- Co-doped CeO2 materials have exhibited promising potential for low temperature solid oxide fuel cell (LT-SOFC) applications. Sm3+, Pr3+ and Nd3+ triple-doped ceria has been synthesized via two-step wet chemical approach. First samarium doped ceria (SDC) was prepared and then the Pr3+/Nd3+ ions as doping elements (secondary process) was added. The structural structure was studied by X-ray diffraction (XRD), that indicate Sm3+, Prat and Nd3+ ions are doped into the ceria lattice up to the certain limit (Pr3+/Nd3+ 10 wt%). The impurity peaks are detected as doping contents increased above the certain limit (Pr3+/Nd3+ 20 wt %). In this work, further we investigated the effect increasing Pr3+/Nd3+ doping concentration on the performance of SOFC device. Here, we studied that high-concentration triple-doped ceria samples with mixed electrons/ions conductive property, as the semiconductor-ionic conducting layer, combined with commercial p-type semiconductor Ni0.8Co0.15Al0.05LiO2-delta (NCAL) to fabricate the 'sandwich' configuration for a developing fuel cell technology-electrolyte free fuel cells (EFFCs). This button size fuel cell delivered a maximum power output of 1011 mW cm(-2). The demonstrated findings show that the single-phase semiconductor-ionic material-Sm3+/Pr3+/Nd3+ triple-doped CeO2 can be selected potential candidate for the further development the EFFC technology.
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| 7. |
- Mushtaq, Naveed, et al.
(författare)
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Tuning the Energy Band Structure at Interfaces of the SrFe0.75Ti0.25O3-delta-Sm0.25Ce0.75O2-delta Heterostructure for Fast Ionic Transport
- 2019
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 11:42, s. 38737-38745
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Tidskriftsartikel (refereegranskat)abstract
- Interface engineering holds huge potential for enabling exceptional physical properties in heterostructure materials via tuning properties at the atomic level. In this study, a heterostructure built by a new redox stable semiconductor SrFe0.75Ti0.25O3-delta (SFT) and an ionic conductor Sm0.25Ce0.75O2 (SDC) is reported. The SFT-SDC heterostructure exhibits a high ionic conductivity >0.1 S/cm at 520 degrees C, which is 1 order of magnitude higher than that of bulk SDC. When it was applied into the fuel cell, the SFT-SDC can realize favorable electrolyte functionality and result in an excellent power density of 920 mW cm(-2) at 520 degrees C. The prepared SFT-SDC heterostructure materials possess both electronic and ionic conduction, where electron states modulate local electrical field to facilitate ion transport. Further investigations to calculate the structure and electronic structure/state of SFT and SDC are done using density functional theory (DFT). It is found that the reconstruction of the energy band at interfaces is responsible for such enhanced ionic conductivity and cell power output. The current study about the perovskite-based heterostructure presents a novel strategy for developing advanced ceramic fuel cells.
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| 8. |
- Sarfraz, Amina, et al.
(författare)
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Catalytic Effect of Silicon Carbide on the Composite Anode of Fuel Cells
- 2021
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Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 4:7, s. 6436-6444
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Tidskriftsartikel (refereegranskat)abstract
- High efficiency, fuel flexibility, and sustainable energy conversion make fuel cells attractive compared to conventional energy systems. The direct ethanol fuel cells have attracted much attention because of the direct utilization of ethanol fuel. Anode materials are required to enhance the catalytic activity of the liquid fuel, which oxidize the fuel at lower operating temperature. Therefore, the catalytic effect using silicon carbide has been investigated in the LiNiO2-delta anode. The material has been characterized, and it is found that SiC shows a cubic structure and LiNiO2-delta exhibits a hexagonal structure, while the LiNiO2-delta-SiC composite exhibits a mixed cubic and hexagonal phase. Scanning electron microscopy depicts that the material is porous. The Fourier transform infrared spectroscopy analysis shows the presence of Si-O-Si, Si-C, C=O, and Si-OH bonding. The LiNiO2-delta-SiC composite (1:0.3) exhibited a maximum electrical conductivity of 1.34 S cm(-1) at 650 degrees C with an electrical band gap of 0.84 eV. The fabricated cell with the LiNiO2-delta-SiC anode exhibits a power density of 0.20 W cm(-2) at 650 degrees C with liquid ethanol fuel. The results show that there is a promising catalytic activity of SiC in the fuel cell anode.
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| 9. |
- Yousaf, Muhammad, et al.
(författare)
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Electrochemical properties of Ni0.4Zn0.6 Fe2O4 and the heterostructure composites (Ni-Zn ferrite-SDC) for low temperature solid oxide fuel cell (LT-SOFC)
- 2020
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Ingår i: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 331
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Tidskriftsartikel (refereegranskat)abstract
- In solid oxide fuel cell, the redox reactions (HOR and ORR) demand good catalyst functions at the anode and cathode. Triple phase boundary (TPB) is an important mechanism to determine HOR and ORR as key factors to improve the reaction rate, charge transfer and ion diffusion processes. In the present work, Ni0.4Zn0.6Fe2O4 (Ni-Zn ferrite) and its heterostructures with Sm0.2Ce0.8O2 (SDC) are prepared and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to analyze the phase structure and morphology of the material. X-ray photoelectron spectroscopy (XPS) confirms the phase of Ni-Zn ferrite nanoparticles (NPs) and chemical states on the heterostructure surface. The electrical and conductive behaviors of synthesized samples are investigated through electrochemical impedance spectroscopy (EIS) and fuel cell measurements. Unlike to conventional way, the as-prepared samples promote redox reactions from two aspects: a) as an electrolyte for ion transport; b) as a mixed conductor to extend the ionic transport on TPB region. The ionic transfer mechanism of Ni-Zn ferrite/SDC composite leads the improved fuel cell performance up to 760 mW/cm(2) at 550 degrees C. Further investigations verify the appreciable proton conduction in the prepared devices in a range of 0.012-0.048 Scm(-1).
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