Structural evolution of carbon deposition on a Ni/YSZ cermet of a SOFC analyzed by soft x-ray XANES spectroscopy

Watanabe, Hirotatsu; Okino, Ryota; Hanamura, Katsunori

doi:10.1016/j.ijhydene.2019.07.122

Cited by 30 publications

(10 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For amorphous carbon, important information about the chemical composition is the sp 2 /sp 3 ratio which determines key physical properties of the system, such as the Young’s modulus . There have been a few attempts to predict the hybridization composition in carbon materials based on XANES spectra. , However, the traditional σ*/π* ratio method overestimates sp 3 concentrations because it does not consider the existence of sp carbon . Here, we demonstrate the development of a NN model for predicting contributions of sp, sp 2 , and sp 3 carbons.…”

Section: Resultsmentioning

confidence: 95%

“…59 There have been a few attempts to predict the hybridization composition in carbon materials based on XANES spectra. 60,61 However, the traditional σ*/π* ratio method overestimates sp 3 concentrations because it does not consider the existence of sp carbon. 62 Here, we demonstrate the development of a NN model for predicting contributions of sp, sp 2 , and sp 3 carbons.…”

Section: ■ Computational Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Harnessing Neural Networks for Elucidating X-ray Absorption Structure–Spectrum Relationships in Amorphous Carbon

Kwon,

Sun,

Hsu

et al. 2023

J. Phys. Chem. C

View full text Add to dashboard Cite

Improved understanding of structural and chemical properties through local experimental probes, such as X-ray absorption near-edge structure (XANES) spectroscopy, is crucial for the understanding and design of functional materials. In recent years, significant advancements have been made in the development of data science approaches for the automated interpretation of XANES structure−spectrum relationships. However, existing studies have primarily focused on crystalline solids and small molecules, while fewer efforts have been devoted to disordered systems. Thus, in this work, we demonstrate the development of neural network models for predicting and interpreting XANES spectra of amorphous carbon (a-C) from local structural descriptors. Comparison between different structural descriptors expectedly shows that the inclusion of both bond length and bond angle information is necessary for an accurate prediction of the spectra. Among the descriptors considered in this work, we find that the local many-body tensor representation yields the highest accuracy and greatest interpretability so that it can be leveraged to understand the importance of structural motifs in determining XANES spectra. We also discuss performance of neural network models for predicting both local structure features, such as bond lengths and bond angles, and global chemical composition, such as the sp:sp 2 :sp 3 ratio.

show abstract

Section: Resultsmentioning

confidence: 95%

Section: ■ Computational Methodsmentioning

confidence: 99%

Harnessing Neural Networks for Elucidating X-ray Absorption Structure–Spectrum Relationships in Amorphous Carbon

Kwon,

Sun,

Hsu

et al. 2023

J. Phys. Chem. C

View full text Add to dashboard Cite

show abstract

“…Early deposition of carbon on Ni can involve H-containing species such as CH. As carbon deposition continues, amorphous carbon gradually develops to graphite [161]. Most stable carbon developed on Ni surface, specially at higher temperatures was reported to be graphite [162] while amorphous carbon may be thermodynamically preferred below 600 • C [163].…”

Section: Degradation Of the Ni-ysz Electrode Due To Carbon Depositionmentioning

confidence: 99%

“…Chen et al [164] studied carbon formation in CH 4 atmosphere at temperatures between 400 • C and 800 • C. They detected different morphologies for deposited carbon (film 400 • C-450 • C, fibers 500 • C-600 • C and particles 650 • C-800 • C) as well as amorphous carbon slowly changing to graphite by increasing the temperature. Watanabe et al [161] studied the coke formation in Ni-YSZ electrode using EDS and SEM analysis. They found out coke formation takes place on Ni grains in Ni-YSZ cermet when exposed to CH 4 at 800 • C. Another research showed preferential carbon deposition on selective crystal planes of Ni grains during exposure to C 3 H 8 at 550 • C [165].…”

Section: Degradation Of the Ni-ysz Electrode Due To Carbon Depositionmentioning

confidence: 99%

Microstructure and long-term stability of Ni–YSZ anode supported fuel cells: a review

et al. 2022

View full text Add to dashboard Cite

Nickel-yttria stabilized zirconia (Ni-YSZ) cermet is the most commonly used anode in solid oxide fuel cells (SOFCs). The current article provides an insight into parameters which affect cell performance and stability by reviewing and discussing the related publications in this field. Understanding the parameters which affect the microstructure of Ni-YSZ such as grain size and ratio of Ni to YSZ, volume fraction of porosity, pore size and its distribution, tortuosity factor, characteristic pathway diameter and density of triple phase boundaries (TPBs) is the key to design a fuel cell which shows high electrochemical performance. Lack of stability has been the main barrier to commercialization of SOFC technology. Parameters influencing the degradation of Ni-YSZ supported SOFCs such as Ni migration inside the anode during prolonged operation are discussed. The longest Ni-supported SOFC tests reported so far are examined and the crucial role of chromium poisoning due to interconnects (ICs), stack design and operating conditions in degradation of SOFCs is highlighted. The importance of calcination and milling of YSZ on development of porous structures suitable for Ni infiltration is explained and several methods to improve the electrochemical performance and stability of Ni-YSZ anode supported SOFCs are suggested.

show abstract

“…Whereas degraded catalysts are easily exchangeable and cheaper. Degradation of the SOFC anode can have several reasons: (i) solid carbon deposition, which is one major challenge when using carbonaceous fuels as shown in [23][24][25][26][27][28][29], (ii) oxidation of the anode material, especially nickel, (iii) agglomeration of the nickel grains and (iv) poisoning by sulphur and chlorine, which is examined within [30,31]. The likelihood of degradation due to carbon deposition and nickel oxidation can be estimated by the C-H-O (Carbon-Hydrogen-Oxygen) ratio of the fuel gas composition as shown in [32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Holistic Approach to Design, Test, and Optimize Stand-Alone SOFC-Reformer Systems

et al. 2021

View full text Add to dashboard Cite

Reliable electrical and thermal energy supplies are basic requirements for modern societies and their food supply. Stand-alone stationary power generators based on solid oxide fuel cells (SOFC) represent an attractive solution to the problems of providing the energy required in both rural communities and in rurally-based industries such as those of the agricultural industry. The great advantages of SOFC-based systems are high efficiency and high fuel flexibility. A wide range of commercially available fuels can be used with no or low-effort pre-treatment. In this study, a design process for stand-alone system consisting of a reformer unit and an SOFC-based power generator is presented and tested. An adequate agreement between the measured and simulated values for the gas compositions after a reformer unit is observed with a maximum error of 3 vol% (volume percent). Theoretical degradation free operation conditions determined by employing equilibrium calculations are identified to be steam to carbon ratio (H2O/C) higher 0.6 for auto-thermal reformation and H2O/C higher 1 for internal reforming. The produced gas mixtures are used to fuel large planar electrolyte supported cells (ESC). Current densities up to 500 mA/cm2 at 0.75 V are reached under internal reforming conditions without degradation of the cells anode during the more than 500 h long-term test run. More detailed electrochemical analysis of SOFCs fed with different fuel mixtures showed that major losses are caused by gas diffusion processes.

show abstract

Structural evolution of carbon deposition on a Ni/YSZ cermet of a SOFC analyzed by soft x-ray XANES spectroscopy

Cited by 30 publications

References 42 publications

Harnessing Neural Networks for Elucidating X-ray Absorption Structure–Spectrum Relationships in Amorphous Carbon

Harnessing Neural Networks for Elucidating X-ray Absorption Structure–Spectrum Relationships in Amorphous Carbon

Microstructure and long-term stability of Ni–YSZ anode supported fuel cells: a review

Holistic Approach to Design, Test, and Optimize Stand-Alone SOFC-Reformer Systems

Contact Info

Product

Resources

About