In recent years, solid oxide fuel cells fueled with ammonia have been attracting intensive attention. In this work, ammonia fuel was supplied to the Ni/yttria-stabilized zirconia (YSZ) cermet anode at 600 and 700 °C, and the change of electrochemical performance and microstructure under the open-circuit state was studied in detail. The influence of ammonia exposure on the microstructure of Ni was also investigated by using Ni/YSZ powder and Ni film deposited on a YSZ disk. The obtained results demonstrated that Ni in the cermet anode was partially nitrided under an ammonia atmosphere, which considerably roughened the Ni surface. Moreover, the destruction of the anode support layer was confirmed for the anode-supported cell upon the temperature cycling test between 600 and 700 °C because of the nitriding phenomenon of Ni, resulting in severe performance degradation.

In this study, Ni/BaCe0.75Y0.25O3-δ (Ni/BCY25) was investigated as an anode for direct ammonia-fueled solid oxide fuel cells. The catalytic activity of Ni/BCY25 for ammonia decomposition was found to be remarkably higher than Ni/8 mol % Y2O3-ZrO2 and Ni/Ce0.90Gd0.10O1.95. The poisoning effect of water and hydrogen on ammonia decomposition reaction over Ni/BCY25 was evaluated. In addition, an electrolyte-supported SOFC employing BaCe0.90Y0.10O3-δ (BCY10) electrolyte and Ni/BCY25 anode was fabricated, and its electrochemical performance was investigated at 550-650 °C with supply of ammonia and hydrogen fuel gases. The effect of water content in anode gas on the cell performance was also studied. Based on these results, it was concluded that Ni/BCY25 was a promising anode for direct ammonia-fueled SOFCs. An anode-supported single cell denoted as Ni/BCY25|BCY10|Sm0.5Sr0.5CoO3-δ was also fabricated, and maximum powder density of 216 and 165 mW cm(-2) was achieved at 650 and 600 °C, for ammonia fuel, respectively.

In the current work, we investigate the performance of solid oxide fuel cells (SOFCs) with Ni-yttria-stabilized zirconia (Ni-YSZ) and Ni-gadolinia-dope ceria (Ni-GDC) cermet anodes fueled with H2 or NH3 in terms of the catalytic activity of ammonia decomposition. The cermet of Ni-GDC shows higher catalytic activity for ammonia decomposition than Ni-YSZ. In response to this, the performance of direct NH3-fueled SOFC improved by using Ni-GDC anode. Moreover, we observe further enhancement in the cell performance and the catalytic activity for ammonia decomposition with applying Ni−GDC anode synthesised by the glycine-nitrate combustion process. These results reveal that the high performance of Ni-GDC anode for the direct NH3-fueled SOFC results from its mixed ionic-electronic conductivity as well as high catalytic activity for ammonia decomposition.

In this study the electrochemical performances of Ni-YSZ anode in humidified H 2 , NH 3 and CH 4 fuels were compared under almost the same partial pressure of oxygen at 500-800 • C. The cell performance was significantly affected by fuel species and operating temperature. The single cell exhibited higher performance in wet NH 3 as compared with that in CH 4 , which was caused by the difference in the catalytic activity of anode for the hydrogen production in wet NH 3 and CH 4 . Thus, it was clarified that NH 3 is a preferable fuel rather than CH 4 for the direct use in SOFCs. Furthermore, the kinetics study on ammonia decomposition over Ni-YSZ anode was conducted at 600 • C. Although the ammonia decomposition increased with increasing ammonia concentration, the decomposition reduced in the presence of hydrogen in the reactant gas. Such a behavior was not confirmed at 850 • C. These results indicated the inhibition effect of hydrogen for ammonia decomposition, which will be the key factor for the design of anode and the operating condition setting. Nowadays one of the most important challenges is producing energy from clean, renewable, durable, efficient and economically feasible sources. Solid oxide fuel cells (SOFCs) meet these goals. Variety of fuels can be used without the external reforming process because of high operating temperature of SOFCs. [1][2][3] Hydrogen is an ideal energy carrier and water is the only product of its combustion. For the massive utilization of hydrogen, however, there are still some difficulties in production, transportation, storage, and safety control. 4,5 Therefore, it is important to use hydrogen containing chemicals such as methane, ethanol and ammonia as alternative fuels.Methane has been studied extensively as a fuel for direct internal reforming SOFCs due to higher energy density compared to hydrogen. In SOFCs, Ni-based cermet anodes such as Ni-YSZ are widely used because nickel is a good catalyst for methane steam reforming as well as electrochemical hydrogen oxidation. However, the low tolerance to carbon deposition of Ni-based cermets is the main obstacle for the direct use of methane. In most of cases, the excess amount of steam is added to the fuel gas to prevent the coke formation, leading to the reduction in the energy conversion efficiency. The development of alternative anodes such as copper-based and perovskite-based materials will be a fundamental solution to this matter. 6,7 At the current state, however, the catalytic activity of these anodes for methane steam reforming is not sufficiently high. [8][9][10] The cell performance is also insufficient for the practical application since this catalytic activity significantly affects the hydrogen concentration in the vicinity of anode. 11,12 Recently ammonia was proven as one of the promising hydrogen carriers for SOFCs because of following reasons; high energy density comparable to that of methane, 4 carbon free, ease in liquefaction at ambient temperature, low production cost, and ease in leakage detection. [13][14]...

The present work aims to study 6-amino-4-aryl-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile derivatives namely: 6-Amino-2-oxo-1,4-diphenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-H), 6-Amino-2-oxo-1-phenyl-4-(p-tolyl)-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-Me) and 6-Amino-4-(4-hydroxyphenyl)-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-OH) as corrosion inhibitors to provide protection for carbon steel in a molar hydrochloric acid medium. Chemical measurements such as (weight loss) and electrochemical techniques such as (Potentiodynamic polarization, electrochemical impedance spectroscopy, and Electron frequency modulation) were applied to characterize the inhibitory properties of the synthesized derivatives. The adsorption of these derivatives on the carbon steel surface was confirmed by Attenuated Total Refraction Infrared (ATR-IR), Atomic Force Microscope (AFM), and X-ray Photoelectron Spectroscopy (XPS). Our findings revealed that the tested derivatives have corrosion inhibition power, which increased significantly from 75.7 to 91.67% on the addition of KI (PdC-OH:KI = 1:1) to inhibited test solution with PdC-OH derivative at 25 °C. The adsorption process on the metal surface follows the Langmuir adsorption model. XPS analysis showed that the inhibitor layer consists of an iron oxide/hydroxide mixture in which the inhibitor molecules are incorporated. Computational chemical theories such as DFT calculations and Mont Carlo simulation have been performed to correlate the molecular properties of the investigated inhibitors with experimental efficiency. The theoretical speculation by Dmol3 corroborates with the results from the experimental findings.