| 1. |
- Cao, Qi, et al.
(författare)
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N-Type Conductive Small Molecule Assisted 23.5% Efficient Inverted Perovskite Solar Cells
- 2022
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Ingår i: Advanced Energy Materials. - : John Wiley & Sons. - 1614-6832 .- 1614-6840. ; 12:34
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Tidskriftsartikel (refereegranskat)abstract
- Because of the compatibility with tandem devices and the ability to be manufactured at low temperatures, inverted perovskite solar cells have generated far-ranging interest for potential commercial applications. However, their efficiency remains inadequate owing to various traps in the perovskite film and the restricted hole blocking ability of the electron transport layer. Thus, in this work, a wide-bandgap n-type semiconductor, 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2-phenylpyrimidine (B4PyPPM), to modify a perovskite film via an anti-solvent method is introduced. The nitrogen sites of pyrimidine and pyridine rings in B4PyPPM exhibit strong interactions with the undercoordinated lead ions in the perovskite material. These interactions can reduce the trap state densities and inhibit nonradiative recombination of the perovskite bulk. Moreover, B4PyPPM can partially aggregate on the perovskite surface, leading to an improvement in the hole-blocking ability at its interface. This modification can also increase the built-in potential and upshift the Fermi level of the modified perovskite film, promoting electron extraction to the electron transport layer. The champion device achieves a high efficiency of 23.51%. Meantime, the sealed device retains approximate to 80% of its initial performance under a maximum power point tracking for nearly 2400 h, demonstrating an excellent operational stability.
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| 2. |
- Espinoza Andaluz, Mayken, et al.
(författare)
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A-Asterisk Algorithm as an Alternative to Evaluate the Geometric Tortuosity in Digitally Created SOFC Anodes
- 2021. - 1
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Ingår i: 17th International Symposium on Solid Oxide Fuel Cells, SOFC 2021. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. - 9781607685395 ; 103:1, s. 1665-1671
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Konferensbidrag (refereegranskat)abstract
- A solid oxide fuel cell (SOFC) contains complex materials that facilitate the energy conversion process. The diffusion media play an important role in facilitating the reactant gases to reach the electrochemical active regions. Porosity and tortuosity are crucial parameters describing the diffusion to be analyzed in a SOFC anode. This paper aims to evaluate the feasibility of using the A-asterisk algorithm to compute the geometric tortuosity within SOFC anodes. A three-dimensional structure, which is digitally created, represents the SOFC anode, in which the possible paths that follow the fluid flow are analyzed. A-asterisk algorithm is used to generate possible paths, and therefore the geometric tortuosity can be computed considering an averaged distance. A tortuosity-porosity correlation is proposed, and the results are compared with previous studies. Results show that the A-asterisk algorithm is a capable algorithm to evaluate the geometric tortuosity values in SOFC anodes with different particle size distribution and porosities.
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| 3. |
- Zhang, Xiaoqiang, et al.
(författare)
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Mechanism of chromium poisoning the conventional cathode material for solid oxide fuel cells
- 2018
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 381, s. 26-29
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Tidskriftsartikel (refereegranskat)abstract
- Chromium poisoning the La0.875Sr0.125MnO3 (LSM) cathode for solid oxide fuel cells is a critical issue that can strongly affect the stability. In this study, we evaluate the temperature distribution in a SOFC based on a 3D model and then combine conductivity test and material computation to reveal the effects of chromium in SUS430 stainless steels on LSM conductivities. The starch concentration in LSM pellets and the applied pressure on the contact with interconnect materials show close relationships with the chromium poisoning behavior. The density functional theory (DFT) computing results indicate that chromium atoms preferably adsorb on the MnO2-terminated and La (Sr)-O-terminated (001) surfaces. The resulting conclusions are expected to deeply understand mechanism of chromium deactivating conventional cathodes at some typical operational conditions, and offer crucial information to optimize the structure to avoid the poisoning effect.
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| 4. |
- An, Xiaoqiang, et al.
(författare)
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Sodium-Directed Photon-Induced Assembly Strategy for Preparing Multisite Catalysts with High Atomic Utilization Efficiency
- 2023
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 145:3, s. 1759-1768
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Tidskriftsartikel (refereegranskat)abstract
- Integrating different reaction sites offers new prospects to address the difficulties in single-atom catalysis, but the precise regulation of active sites at the atomic level remains challenging. Here, we demonstrate a sodium-directed photon-induced assembly (SPA) strategy for boosting the atomic utilization efficiency of single-atom catalysts (SACs) by constructing multifarious Au sites on TiO2 substrate. Na+ was employed as the crucial cement to direct Au single atoms onto TiO2, while the light-induced electron transfer from excited TiO2 to Au(Na+) ensembles contributed to the self-assembly formation of Au nanoclusters. The synergism between plasmonic near-field and Schottky junction enabled the cascade electron transfer for charge separation, which was further enhanced by oxygen vacancies in TiO2. Our dual-site photocatalysts exhibited a nearly 2 orders of magnitude improvement in the hydrogen evolution activity under simulated solar light, with a striking turnover frequency (TOF) value of 1533 h(-1) that exceeded other Au/TiO2-based photocatalysts reported. Our SPA strategy can be easily extended to prepare a wide range of metal-coupled nanostructures with enhanced performance for diverse catalytic reactions. Thus, this study provides a well-defined platform to extend the boundaries of SACs for multisite catalysis through harnessing metal-support interactions.
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| 5. |
- Guo, Mengyuan, et al.
(författare)
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High gas tightness ZrO2-added silicate glass sealant with low thermal stress for solid oxide fuel cells
- 2023
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842. ; 49:12, s. 19708-19716
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Tidskriftsartikel (refereegranskat)abstract
- A low leakage rate sealant of 10 wt% ZrO2-added CaO–K2O–Na2O–BaO silicate glass for SOFC has been studied. The structure of the sealant is stable at high temperatures with leakage rates less than 10−4 sccm∙cm−1, and no crystal except for ZrO2 is found in XRD analysis after heating at 800 °C for 100 h. ZrO2 is distributed in the glass matrix and plays a supporting role in avoiding over-softening at operating temperature. Good compatibility in both oxidizing and reducing atmospheres between the sealant and SUS430 interconnect was proved by SEM at 750 °C for 100 h. A fully coupled 3D Multiphysics button SOFC is constructed for mechanical analyses. The results show that the increase of ZrO2 in the sealant will decrease the stress and displacement in the SOFC. Besides, the width of the sealant also affects the stress value and distribution. The results show that GZ10 is a competitive sealing material compared with other ZrO2-added sealants.
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| 6. |
- Hu, Peiji, et al.
(författare)
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In-situ exsolution of FeCo nanoparticles over perovskite oxides for efficient electrocatalytic nitrate reduction to ammonia via localized electrons
- 2024
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Ingår i: Applied Catalysis B: Environmental. - 0926-3373. ; 357
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Tidskriftsartikel (refereegranskat)abstract
- FeCo nanoparticles exsolved from Co-doped Sm0.9FeO3 nanofibers with abundant oxygen vacancies (Vos) are proposed as an efficient electrocatalyst to promote nitrate reduction reaction (NITRR). Such catalyst achieves a maximum Faradaic efficiency (FE) of 90.3 % and a large NH3 yield of 17.2 mg h−1 mg−1cat. at a negatively shifted potential of −0.9 V in 0.1 M PBS with 0.1 M NaNO3, and the alloy nanoparticles socketed into nanofibers remain extremely stable during long-term electrolysis. The reaction pathway favoring the formation of NH2OH is uncovered by in situ electrochemical tests and theoretical calculations reveal the exsolution of FeCo alloy combined with the generation of Vos enhances nitrate adsorption and lowers energy increase of the potential determining step. Finite-element simulations unveil the applied current and charges are localized on the alloys along the nanofiber, which confirms the exsolved FeCo nanoparticles are the main active sites for NITRR.
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| 7. |
- Parbey, Joseph, et al.
(författare)
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Progress in the use of electrospun nanofiber electrodes for solid oxide fuel cells : A review
- 2019
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Ingår i: Reviews in Chemical Engineering. - : Walter de Gruyter GmbH. - 2191-0235 .- 0167-8299. ; 36:8, s. 879-931
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Tidskriftsartikel (refereegranskat)abstract
- The application of one-dimensional nanofibers in the fabrication of an electrode greatly improves the performance of solid oxide fuel cells (SOFCs) due to its advantages on electron transfer and mass transport. Various mixed ionic-electronic conducting materials with perovskites and Ruddlesden-Popper-type metal oxide structures are successfully electrospun into nanofibers in recent years mostly in solvent solution and some in melt forms, which are used as anode and cathode electrodes for SOFCs. This paper presents a comprehensive review of the structure, electrochemical performance, and development of anode and cathode nanofiber electrodes including processing, structure, and property characterization. The focuses are first on the precursor, applied voltage, and polymer in the material electrospinning process, the performance of the fiber, potential limitation and drawbacks, and factors affecting fiber morphology, and sintering temperature for impurity-free fibers. Information on relevant methodologies for cell fabrication and stability issues, polarization resistances, area specific resistance, conductivity, and power densities are summarized in the paper, and technology limitations, research challenges, and future trends are also discussed. The concluded information benefits improvement of the material properties and optimization of microstructure of the electrodes for SOFCs.
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| 8. |
- Zeng, Shumao, et al.
(författare)
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Modeling of solid oxide fuel cells with optimized interconnect designs
- 2018
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 125, s. 506-514
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Tidskriftsartikel (refereegranskat)abstract
- A 3D model is developed to investigate solid oxide fuel cells (SOFCs) contacting with optimized interconnect designs and the results indicate that the current density and thermal stress are closely related to both the shape of tip in interconnects and the depth of it in the cathode. The interconnect with triangular rips can yield the best electrochemical performance compared to those with tips of rectangle and trapezium, and the current densities increase with the depth of tips in cathodes, except the trapezoidal ribs, which shows a concaving change with the depth. The 1st principle stress reaches around 21.9 MPa and 16.6 MPa at the interfaces of electrodes and electrolytes, but it rises to 60 MPa and 18 MPa for the rectangular tips at the air and fuel inlets, respectively, which sharply decreases to nearly 25 MPa and 10 MPa with the depth in cathodes approaching 5 μm. The maximum shear stresses are found to reach 34.4 MPa and 32.1 MPa at the two interfaces, and the triangular tips will induce the most intensive stresses at electrolyte-cathode interface. The resulting conclusions are beneficial to optimize interconnect design to improve the efficiency of current collection and also reduce the risk of generation of remarkable thermal stresses.
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| 9. |
- Zhang, Xiaoqiang, et al.
(författare)
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Analysing Tortuosity for Solid Oxide Fuel Cell Anode Material : Experiments and Modeling
- 2023
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Ingår i: Journal of the Electrochemical Society. - 0013-4651. ; 170
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Tidskriftsartikel (refereegranskat)abstract
- Solid oxide fuel cells (SOFCs) directly convert chemical energy to electricity with high electrical efficiency. It involves gas transport through the porous electrode to the three-phase boundaries (TPB). The tortuosity of gas transport relates the bulk diffusion of gas in free space to the effective diffusion coefficient of gas migrating through a porous material. Therefore, determining the tortuosity is of great importance. This paper tests button SOFCs with NiO-YSZ as anode material followed by dual beam-focused ion beam scanning electron microscopy (FIB-SEM) to obtain 2D serial slice images. Based on processed 2D images and reconstructed 3D microstructure, the tortuosity is calculated using three approaches i.e., porosity-tortuosity correlations, voxel-based, and path-length-based approaches. The test results show that a decrease in Ni content in the anode greatly decreases the cell performance due to a decreased percolated electronic phase. The sample with low performance has high tortuosity. Different approaches vary regarding the tortuosity value and computational time. The path-length-based approach can achieve reasonable accuracy in a relatively short time but is only valid for using the longest path length.
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| 10. |
- Zhang, Xiaoqiang, et al.
(författare)
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Numerical simulation of solid oxide fuel cells comparing different electrochemical kinetics
- 2021
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 45:9, s. 12980-12995
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Tidskriftsartikel (refereegranskat)abstract
- Solid oxide fuel cells (SOFCs) produce electricity with high electrical efficiency and fuel flexibility without pollution, for example, CO2, NOx, SOx, and particles. Still, numerous issues hindered the large-scale commercialization of fuel cell at a large scale, such as fuel storage, mechanical failure, catalytic degradation, electrode poisoning from fuel and air, for example, lifetime in relation to cost. Computational fluid dynamics (CFD) couples various physical fields, which is vital to reduce the redundant workload required for SOFC development. Modeling of SOFCs includes the coupling of charge transfer, electrochemical reactions, fluid flow, energy transport, and species transport. The Butler-Volmer equation is frequently used to describe the coupling of electrochemical reactions with current density. The most frequently used is the activation- and diffusion-controlled Butler-Volmer equation. Three different electrode reaction models are examined in the study, which is named case 1, case 2, and case 3, respectively. Case 1 is activation controlled while cases 2 and 3 are diffusion-controlled which take the concentration of redox species into account. It is shown that case 1 gives the highest reaction rate, followed by case 2 and case 3. Case 3 gives the lowest reaction rate and thus has a much lower current density and temperature. The change of activation overpotential does not follow the change of current density and temperature at the interface of the anode and electrolyte and interface of cathode and electrolyte, which demonstrates the non-linearity of the model. This study provides a reference to build electrochemical models of SOFCs and gives a deep understanding of the involved electrochemistry.
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