bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Hydrogen Containing NH3 on Aemfc Performance
Authors: Kikkawa Yuki , Negishi Takayuki , Isomura Takenori 
Published: February 2020

Hydrogen is the most popular fuel source for fuel cell applications due to fast electrocatalytic reaction and very high energy to weight ratio. But its storage and distribution are still major issues. To solve these problems, it is necessary to use alternative other materials as hydrogen source.
Ammonia has attracted attention as one of the candidate hydrogen carrier materials1-3). Ammonia has following features.
-CO2-free energy carrier
-Simple storage as liquid
-High storage density at low pressure
-Essentially non-flammable, non-explosive
-Easy and efficient to crack to hydrogen
-Well-established transport and storage infrastructure already in place
Generally, a few ppm ammonia remains in ammonia cracking to hydrogen3). In case of this ammonia cracked hydrogen for proton exchange membrane fuel cells (PEMFC), significant performance loss will happen because of the decreased conductivity caused by the conducting ions’ convert to NH4
+ from H+ 4). On the other hand, it has been expected that this fuel can be used for anion exchange membrane fuel cells (AEMFC), because its conducting species is OH- and will not be substituted by NH4
+. However, there is little study dealing the effect of ammonia on AEMFC until today.
In this study, we operated AEMFC with hydrogen with different amount of NH3. As the results, we could confirm that their performance would not be affected by the existence of NH3 in hydrogen up to around 20%. We succeeded in demonstrating that AEMFC has the good adaptability of NH3-H2fuel compared to PEMFC.
This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “energy carrier” (Funding agency: JST).
References
1. K. Kordesch, V. Hacker, J. Gsellmann, M. Cifrain, G. Faleschini, P. Enzinger, R. Franlhauser, M. Ortner, M. Muhr, R. Aronson, J. Power Sources, 86, 162 (2000)
2. W. Wang, J. M. Herreros, A. Tsolakis, A. P.E. York, Int. J. Hydrogen Enegy, 38, 9907 (2013)
3. A. Klerke, C.H. Christensen, J.K. Nrslov, T. Vegge, J. Mater. Chem. 18, 2304 (2008)
4. F.A. Uribe, S. Gottesfeld, T.A. Zawodzinski, J. Electrochem. Soc. 149, A293 (2002)
Platinum Thin Catalyst Layer for Proton Exchange Membrane Fuel Cell
Authors: Kim Youngkwang , Kim Jiyong , Kwon Oh Joong 
Published: February 2020

As one of the renewable energy, polymer electrolyte membrane fuel cell (PEMFC) is a promising candidate because of its good performance efficiency and environment-friendly technique. However, high cost and poor durability of Pt catalys are main obstacles to a commercialization of PEMFC. As a solution for the problems, some researchers have focused on thin film catalyst layer instead of Pt/C catalyst for reducing the amount of platinum use and for enhancing performance at high current density. For example, NSTF (nanostructured thin film) catalyst layer and inverse opal structured catalyst layer were studied for improving mass-transfer and enhancing durability and stability of catalyst.[1-2]
In this study, we used ultrasound to form a thin catalyst layer. By using ultrasound, we synthesized Pt nanoparticle and coated it on MPL (microporous layer), simultaneously. It has being revealed that ultrasound is an effective way to create metal nanoparticle because of ultrasound’s cavitation effect.[3] Bang et al explained about cavitation effect. Bubble explosion provides huge pressure and energy for a chemical reaction if the bubble size reached the critical point under ultrasound irradiation.[4] In addition, ultrasound has a micro jet effect, which has ability to clean a substrate and coat nanoparticles on it.[5] In our study, ultrasound applied to form a catalyst layer and the we adopted it for fabricating MEA (Membrane Electrode Assembly) of single cell. The MEAs were compared with MEA fabricated by a conventional method with Pt/C catalyst.
To verify a formation of nanoparticle via a cavitation effect of ultrasound, we used UV-visible spectroscopy and observed spectrum change nearby 450 nm which is known for Pt4+ after ultrasound’s irradiation.[6] To coat Pt nanoparticles on the carbon paper, we prepared carbon papers fixed at an acrylic frame in platinum precursor solution with reducing agent. Ultrasound was irradiated at various conditions. For example, time and power of irradiation, concentrations of the precursor and the reducing agent were changed to find an optimum condition for a sonochemical coating. As shown in Figure 1, images of the carbon papers acquired by FE-SEM (Field Emission Scanning Electron Microscope) and EDS (Energy Dispersive Spectroscopy) were used for checking platinum distribution. Cathode’s catalyst layer of MEAs was prepared by sonochemical method and anode’s catalyst layer was formed by spraying Pt/C on carbon paper. The MEAs were fabricated using hot-pressing without ionomer. Figure 2 shows I-V curve of the MEAs made at the 12 W of ultrasound power for 120 min and 90 min. To figure out experiment condition effect, we are still carrying out single tests and perform a characterization of MEA to elucidate the difference between MEAs. All the results investigated in the study will be presented with in-depth discussion.

Figure 1
CFD Analysis of a Fuel Cell Stack Package Using LNG for a Ship
Authors: Roh Gill-Tae , Ahn Jong-Woo , Song Jong-Chun , Lee Jae-Hoon 
Published: February 2020

One of the key issues to ensure the safety of a ship in the case of a gas leakage is the condition of air flow inside a fuel cell stack package. Unstable air flow increases the explosion risk by allowing the accumulation of leaked gas in one place. Therefore, a place for installing a ventilating fan and its capacity should be properly selected in order to make the air flow smoothly inside the package. Furthermore, an alarm unit and gas detector should be installed at the proper place for detecting leaked gas.
This paper studied the characteristics of air flow inside the stack package using CFD techniques (FLUENT flow analysis) in order to ensure safety in the case of a gas leak for the 300kW MCFC stack package model for ships. The analysis of a leaked gas accumulation is to decide for the installing sites of the alarm unit, gas detector, and ventilating fan, as well as its capacity. As a subsequent, a model for flow field including a fuel cell stack module, BOP and various pipes was prepared.
With the developed stack package model, a temperature flow analyzation was performed for the heating conditions of each component or pipe to study where the temperature was evenly distributed inside the package and the temperature rise at the outlet of the model. Using the analytical model for the gas leakage that may occur in the valve, analysis of the gas distribution inside the package was also conducted.
Durablility of Methane Steam Reforming Catalysts Prepared By Exsolution and Infiltration
Authors: Lim Ye Sol , Bang Wan-Keun , Hwang Hae Jin 
Published: February 2020

Methane steam reforming reaction is the most important chemical process to produce hydrogen or synthesis gas. Hydrogen is heavily consumed for ammonia production, the cryogenics industry and methanol production. Recently, the hydrogen demand is expected to increase as fuel cells become more widely accepted and are used more in the near future. For effective production of hydrogen or synthesis gas, the role of the reforming catalyst becomes more significant. Especially, highly active and stable catalyst is necessary for an on-site reformer for fuel cell systems.
In conventional technology, the methane steam reforming reaction is conducted on supported noble metals- (Pt, Pd, Rh, Ru, and Ir) or nickel-based catalysts at temperature up to 700~800°C and steam to methane rations between 2 and 4. However, these catalysts suffer from the deactivation by agglomeration and carbon deposition. Noble metal-based catalysts are less sensitive to carbon deposition than nickel-based catalyst. However, high cost and limited availability are major concern.
In this study, nickel-based nanocomposite catalysts were fabricated by exolution process. The exsolution means the process to precipitate particles from solid solution by means of the heat treatment in a specially-controlled atmosphere. This process is distinguished from the infiltration in which particles are precipitated from solutions by evaporation. First, Mg1-xNixO solid solution powders were synthesized from aqueous magnesium and nickel nitrate solution by precipitation technique and then the powder was heat-treated in reducing atmosphere at 600 to 900°C. SEM and TEM images revealed that the nano-sized nickel particles were homogeneously dispersed in the Mg1-xNixO solid solution matrix and the size and morphology of nano nickel particles can be controlled by the heat-treatment condition. Catalytic activity for the methane steam reforming or methane particle oxidation reaction and durability of the Ni/Mg1-xNixO was investigated in terms of nickel contents and sizes.
Numerical Simulation of PEMFC Performance Considering Striped Wettability Distribution of GDL
Authors: Takaya Koji , Araki Takuto 
Published: February 2020

For optimizing the performance of proton exchange membrane fuel cells (PEMFCs), proper water management in the cell is one of the most important issues because liquid water in PEMFCs have a significant impact on the cell performance. If excessive water accumulate in the cell, including that produced by chemical reactions and the humidification of supplied gases, power generation performance will decrease since the transport of the fuel gas will be blocked by the liquid water that has accumulated in the void of a gas diffusion layer (GDL) or a gas flow channel. On the other hand, the drying of the polymer electrolyte membrane (PEM) causes not only a performance decrement due to an increased proton transport resistance, but also a degradation of membrane. Therefore it is very important to understand the water transport in PEMFCs. Some researchers have investigated the water transport phenomena and mass transfer characteristics in the GDL. Utaka and Koresawa have been proposed a novel GDL (Hybrid type GDL, Fig. 1) which has two different wettability to improve the oxygen diffusivity by controlling the water distributions and movement in the GDL, and have examined the effects of the wettability distribution and PTFE content in the hydrophobic region of the GDL on efficient oxygen diffusivity [1]. Additionally, they also have been proposed a novel gas channel with micro-grooves [2]. The cell performance of PEMFC that combined the hybrid GDL and the gas channel with micro-grooves were experimentally investigated in an attempt to improve the power generation of PEMFC. Figure 2 shows the effects of hybrid GDL and novel gas channel on cell performance, and from this figure, the PEMFC combined the hybrid GDL and gas channel with micro-grooves could enhanced the performance under high current density.
A three-dimensional numerical model, which includes the gas channels with micro-grooves, GDLs, catalyst layers in both cathode and anode side and PEM, has been developed to investigate the water transport and power generating characteristics. In addition, we investigate the effectiveness of the hybrid GDL to mitigate liquid water saturation under flooding conditions by using our comprehensive model, and compared with experimental results.
Numerical result of liquid water distribution at two different wettability region in GDL shown in Fig. 3. Liquid water distribution biased to hydrophilic regions due to the drawing the water from the hydrophobic region into the hydrophilic region. Furthermore, the performance of PEMFC improved by combined the hybrid GDL and novel gas channel with micro-grooves, and discussed quantitatively.
Reference
[1] R. Koreaswa and Y. Utaka, J. Power Sources, 271, 16 (2014).
[2] Y. Utaka, A. Okabe and Y. Omori, J. Power Sources, 279, 533 (2015).

Figure 1
Preferential Horizontal Growth of WS2 Nanoplate on Porous Carbon: A Highly Efficient Electrocatalyst for the Hydrogen Evolution Reaction
Authors: Seo Bora , Jung Gwan Yeong , Kim Jae Hyung , Kwak Sang Kyu , Joo Sang Hoon 
Published: February 2020

Two-dimensional layered transition metal dichalcogenides (2D TMDs) have been of tremendous recent interests. Understanding their growth behavior on specific substrate or support can provide critical insights for designing the TMDs with desirable structure and functionality for targeted applications. Particularly for the electrocatalytic hydrogen evolution reaction (HER), where porous carbons are predominantly used as conductive supports, revealing the growth behavior of TMDs on porous carbon materials can suggest rational design concept for the TMD-based HER catalysts. With an aim to investigate the growth orientation on porous carbon support, we synthesized MS2 (M = W or Mo) nanoplates embedded on porous carbon nanorod arrays by limiting their growth space at the nanoscale. We found that the horizontal growth is preferred in WS2 giving rise to monolayer nanoplates, which is contrast to the growth of MoS2 that favors vertical stacking to generate multilayer structure. Density functional theory calculations of adhesion energy of TMDs on porous carbons and their stacking energies revealed that WS2 favor the basal plane bonding with carbon support and horizontal growth, wheareas the edge bonding and vertical growth is favored for MoS2, supporting experimental results. The orientation-controlled WS2 monolayer NPs embedded in mesoporous carbon exhibited highly efficient electrocatalytic activity for the HER with a low overpotential of 179 mV (vs RHE) at ‒10 mA cm-2 and low Tafel slope of 63 mV sec-1.
Electrochemical Fabrication of Ag and Au Foams for Electrochemical Conversion of CO2
Authors: Lee Hyunju , Kim Hoyoung , Park Hyanjoo , Kim Junhyeong , Kim Hyunki , Hwang Eunkyoung , Kim Soo-Kil , Ahn Sang Hyun 
Published: February 2020

In recent, huge efforts have been conducted to relieve the global warming problem by the electrochemical conversion of CO2 into useful chemicals. Particularly, it has been reported that the Ag and Au are highly active materials to produce the CO with high selectivity. However, the cost problem originated from use of noble metal catalysts limits their practical applications.
In this study, the Ag and Au foam structures were electrochemically fabricated as a catalyst for CO2 reduction to produce CO. As a first step, the Cu foam was prepared on Ti foil substrate by galvanostatic pulse deposition which consisted of low current for continuous Cu film and following high current for porous Cu. The pore size (22 ~ 56 μm) and wall thickness (14 ~ 42 μm) were controlled by concentration of Cu precursor and applied deposition currents. Then, the Cu foams were immersed in the electrolyte which contained noble metal precursors and additives, in order to minimize the noble metal usage as well as to increase the electrochemical surface area. The coverage and morphology of noble metals on the surface of Cu form were affected by the precursor and additives concentrations in displacement step. The catalytic activity of fabricated noble metal foams were examined for electrochemical CO2 reduction. As a result, it was revealed that the CO Faradaic efficiency was significantly related to the morphology and composition of noble metal foams.
Mechanical Response of Thin Nafion Films during Hydration Cycles
Authors: Frieberg Bradley R. , Graybill Joshua R. , Page Kirt A. , Stafford Gery R. , Soles Christopher L. , Stafford Christopher M. 
Published: February 2020

Proton exchange membrane (PEM)-based fuel cells are being aggressively targeted as an alternative energy source for transportation and stationary power due to their high charge density and low operating temperatures. While the structure, transport and mechanical properties of bulk PEMs have been extensively studied, there is increasing interest on the behavior of these materials at interfaces and under confinement, since there exist many heterogeneous interfaces within an actual fuel cell assembly. One could argue that the performance and ultimate failure of the membrane electrode assembly is greatly impacted by the structure and transport of ionomers confined to extremely small length-scales.
At the heart of the PEM fuel cell is the polymer membrane that must transport protons but not electrons, while also acting as a barrier to the reactant gases (H2 and O2). The most widely studied material for this purpose is perfluorosulfonic acid (PFSA) ionomers such as Nafion. Over its service life, the polymer membrane undergoes hundreds if not thousands of cycles between wet and dry conditions, which leads to swelling and shrinking of the membrane material. This can ultimately lead to mechanical failure in the membrane. This mechanical fatigue is of particular importance in the catalyst layer where the PFSA ionomers, often used as an ionically conductive binder, are confined in domains on the order of tens of nanometers in thickness. A further understanding of the swelling-induced stresses experienced in both the catalyst layer as well as the PEM is necessary.
In this talk, we will describe our efforts to develop and implement a cantilever bending technique1 in order to investigate the swelling induced stresses in Nafion thin films. By monitoring the deflection of a cantilever beam coated with a thin Nafion film as it is exposed to varying humidity environments, the swelling induced stresses of the polymer film can be measured. Using this technique, we have measured the mechanical response to humidity cycling of thin Nafion films as a function of film thickness and thermal annealing, as well as hygrothermal aging.

K. A. Page, J. W. Shin, S. A. Eastman, B. W. Rowe, S. Kim, A. Kusoglu, K. G. Yager, and G. R. Stafford. In Situ Method for Measuring the Mechanical Properties of Nafion Thin Films during Hydration Cycles, ACS Applied Materials and Interfaces, 7, 17874-17883 (2015).
Pyrolyzed Stable Ferrocene-Co-Corrole N4 As a Promising Non-Precious Electrocatalyst for Oxygen Reduction Reaction
Authors: Samireddi Satyanarayana , Shown Indrajit , Wong Ken-Tsung , Chen Li-Chyong , Chen Kuei-Hsien 
Published: February 2020

The limited natural abundance, high cost and carbon monoxide deactivation of Pt and other noble metals possess a major barrier in its applications for hydrogen or methanol fuel cells and therefore; development of alternative electrocatalytic materials based on non-precious metal-N4 is a key challenge in the current growing demand for the clean-energy fuel cell research. In this regard, in our group, a new cobalt-corrole molecule functionalized with ferrocene has been successfully synthesized and its structural characterization was done by UV-Vis, NMR and HR-Mass spectroscopic studies. The molecular structure of the complex was also confirmed by single crystal X-ray diffraction and explained with structural orientation of the atoms and attached moieties. Furthermore, this molecule mixed with activated carbon was pyrolyzed at different temperatures and among the resulting electrocatalysts, particularly at 500 °C was shown to be performed as promising ORR active catalyst for the PEM Fuel-Cell application. The unique Co-corrole integrated with mono substituted peripheral Fe complex with its pyrolyzed form of low symmetric structure provides a bimetallic (Co and Fe) active centre and facilitates the oxygen reduction reaction (ORR) via a 4-electron pathway. The prepared carbon black supported catalyst at 500 °C pyrolyzed temperature exhibits higher electron transfer number 3.96 for ORR in acidic medium with better stability, which is superior to the previously reported pyrolyzed Co-corroles. The enhancement of the ORR activity of the well characterized Co-corrole with peripheral Fe-metallocene bimetallic N4 macrocyclic complex provides a new prospect for the next-generation of non-precious metal-N4 electrocatalysts for fuel cell application. In this presentation, I will talk more in details of the electrochemical experimental process of the catalyst and its characterization using different analytical techniques.

Key words: N4-macrocyclic, corrole, oxygen reduction reaction, electrocatalysts, fuel cell
Power Generation Characteristics of the Direct Formic Acid Fuel Cell Using Silica Containing Carbon Nanofiber as the Anode Supports
Authors: Tsujiguchi Takuya , Mohamed Aslam Norraihanah , Onishi Ryo , Matsuoka Fumihiko , Yamazaki Nozomi , Osaka Yugo , Kodama Akio 
Published: February 2020

Direct formic acid fuel cells, DFAFCs, have received considerable attention due to their higher power density in the direct liquid fuel cells. Recently, 550 mW/cm2 of power density at 30 oC was reported by Chan et al. using Pd–Ni2 P/C catalyst for DFAFC anode [1]. In order to obtain the higher power density, the operation temperature of DFAFC should be elevated since anode and cathode reaction kinetics increases with the increasing operation temperature, however, it has been known that the power density of DFAFC above 50 oC showed plateau with the increasing temperature. As a reason of the plateau in the power desnity above 50 oC, the increase of the mass transport loss was considered [2]. Therefore, controlling the mass transport in the catalyst layer is one of the key factor to obtain high power density. In this context, the silica embedded carbon nanofiber, SECNF, support for DFAFC anode have been suggested in this study. By using SECNF as a catalyst support, both of the high porosity catalyst layer which can enhance the mass transport rate in the catalyst layer and the high catalystic activity due to the support metal effect of the silica have been expected. It was found that the formic acid oxidation reaction activity significantly increased by using SECNF as a support of Pd comparing to conventional Pd/CNF and Pd/C due to the support effect of the SiO2. Moreover, the high porosity anode electrode could be successfully fabricated by using Pd/SECNF. On the other hand, the power density of DFAFC was not enhanced due to thick catalyst layer. In the presentation, the effect of the porosity and thickness of catalyst layer on the anode mass transport loss and power generation characteristics will be discussed in detail.
Reference
[1] J. Chang, L. Feng, C. Liu, W. Xing, and X. Hu, Angew. Chemie Int. Ed., 53, 122–126 (2014).
[2] T. Tsujiguchi, F. Matsuoka, Y. Hokari, Y. Osaka, and A. Kodama, Electrochim. Acta, 197, 32–38 (2016)