Durability of Ni anodes during reoxidation cycles

Ettler, Manuel; Timmermann, H.; Malzbender, Jürgen; Weber, André; Menzler, Norbert H.

doi:10.1016/j.jpowsour.2010.03.049

Cited by 168 publications

(140 citation statements)

References 49 publications

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“…These well-defined systems were further studied with respect to oxidative dehydrogenation of methanol with the aim to understand the support effects observed on this reaction on the real catalysts [12]. Methanol oxidation on vanadia supported on both CeO 2 (1 1 1) single crystal and polycrystalline ceria has previously been studied by the group of Vohs [13,48,55,56].…”

Section: Vo X Oxide Clusters Supported On Ceo 2 (1 1 1) For Methanol mentioning

confidence: 99%

Oxygen activation on oxide surfaces: A perspective at the atomic level

Freund

2014

Catalysis Today

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a b s t r a c tThin oxide films have been used as model supports to unravel the influence of the oxide-metal and oxide-gas interface. We discuss the influence of defects in the oxide lattice and the oxide surface on properties of adsorbed species, in particular the formation of oxide particles from a deposited transition metal onto ceria and of adsorbed oxygen from the gas phase. Here we correlate the structure of the particles, as revealed by a combination of STM and spectroscopic as well as theoretical calculations, with their reactive properties. The nature of the involved defects is characterized by adsorption of Au as a way to correlate the influence of various defects of different structure on the Au charge state. In a second case study, we demonstrate the influence of dopants within the supporting oxide on the adsorption of oxygen on a defect free surface. This is shown to be potentially relevant for the activation of methane in oxidative methane coupling reactions, as recently demonstrated.

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Section: Vo X Oxide Clusters Supported On Ceo 2 (1 1 1) For Methanol mentioning

confidence: 99%

Oxygen activation on oxide surfaces: A perspective at the atomic level

Freund

2014

Catalysis Today

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“…Although there are several works in the literature about this subject, there is no general agreement on how these parameters affect the final sample properties. Experimental characterization is possibly the most reliable procedure of elucidating how the reduction process affects each given microstructure, as described in detail in the review of Ettler et al [13] In this trend, Pihlatie et al [14] found that the initial electrical conductivity and the short-term conductivity loss of Ni-YSZ cermets depend closely on the operating temperature and steam content, being both processes nearly instantaneous. They also observed that there are at least two overlapping processes contributing to the change of conductivity, depending on the initial particle size distribution of Ni and cermet microstructure.…”

Section: Introductionmentioning

confidence: 99%

The influence of the reducing conditions on the final microstructure and performance of nickel-yttria stabilized zirconia cermets

Monzón

Laguna‐Bercero

2016

Electrochimica Acta

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Ni-YSZ (yttria stabilized zirconia) cermets are the most widespread composite materials to be used as SOFC fuel electrodes. These materials are generally fabricated by the reduction of NiO to Ni in a NiO-YSZ composite, where the reducing conditions have a great effect in the final microstructure of the electrode. In the present work, several reducing conditions were explored in order to find the most suitable microstructure for anode-supported microtubular solid oxide fuel cells (SOFCs). Samples were firstly reduced in either pure or diluted H2 (dry or humidified), at temperatures ranging from 400 to 800 °C while their DC conductivity was monitored. The highest conductivity value was measured for the sample reduced in pure humidified hydrogen at 800°C. However, this sample experienced conductivity degradation in comparison with samples reduced under dry conditions. For the studied temperature range, nucleation of nano-porous nickel particles is firstly formed during reduction. However, from our experiments it was concluded that those nanoparticles are not stable with time, at least at temperatures between 600 ºC and 800 ºC. Electrochemical characterization of complete microtubular cells under real wet conditions was also performed under current load, confirming that the microstructure of the Ni-YSZ cermet is still evolving during operation.

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“…The oxidation of the nickel leads to structural changes of the substrate's porous microstructure and subsequent to stresses and crack growth in the electrolyte resulting in a complete failure of the SOFC. 37,38 Thus, the inner surface coating can improve the reoxidation tolerance of anode-supported SOFCs. The study of the influence of ALD coatings on the oxidation tolerance will be presented in another paper.…”

Section: Introductionmentioning

confidence: 99%

Modeling precursor diffusion and reaction of atomic layer deposition in porous structures

Keuter

Menzler

Mauer

et al. 2014

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Atomic layer deposition (ALD) is a technique for depositing thin films of materials with a precise thickness control and uniformity using the self-limitation of the underlying reactions. Usually, it is difficult to predict the result of the ALD process for given external parameters, e.g., the precursor exposure time or the size of the precursor molecules. Therefore, a deeper insight into ALD by modeling the process is needed to improve process control and to achieve more economical coatings. In this paper, a detailed, microscopic approach based on the model developed by Yanguas-Gil and Elam is presented and additionally compared with the experiment. Precursor diffusion and second-order reaction kinetics are combined to identify the influence of the porous substrate's microstructural parameters and the influence of precursor properties on the coating. The thickness of the deposited film is calculated for different depths inside the porous structure in relation to the precursor exposure time, the precursor vapor pressure, and other parameters. Good agreement with experimental results was obtained for ALD zirconiumdioxide (ZrO2) films using the precursors tetrakis(ethylmethylamido)zirconium and O2. The derivation can be adjusted to describe other features of ALD processes, e.g., precursor and reactive site losses, different growth modes, pore size reduction, and surface diffusion.

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Durability of Ni anodes during reoxidation cycles

Cited by 168 publications

References 49 publications

Oxygen activation on oxide surfaces: A perspective at the atomic level

Oxygen activation on oxide surfaces: A perspective at the atomic level

The influence of the reducing conditions on the final microstructure and performance of nickel-yttria stabilized zirconia cermets

Modeling precursor diffusion and reaction of atomic layer deposition in porous structures

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