bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanoporous-Based Sensors for Electrical Detection of Gaseous Pollutants
Authors: Schindelholz Mara , Small Leo J. , Henkelis Susan , Krumhansl James , Nenoff Tina M 
Published: December 2020

The advanced in situ detection of gaseous pollutants, such as NOx or SOx, is of great interest in many applications, such as the automotive and coal industries. Here, we leverage the previous successful development of impedance spectroscopy-based sensors for the detection of gaseous I2 to develop a novel sensor for the detection of these gaseous pollutants. During initial development of an I2 sensor, a metal-organic framework (MOF ZIF-8) material was utilized as an adsorbent layer deposited onto Pt interdigitated electrodes. The MOF was demonstrated to selectively adsorb I2, irreversibly, from a complex gas stream with a (>105x) change in measured impedance across the electrodes1. Further studies aimed at developing a robust sensor examined other materials, including zeolites2 and additional MOFs. It was demonstrated that utilizing MFM-300(X) (X= Al, Fe, In or Sc metal center) active materials enabled a reversible electrical response via gas adsorption/desorption3. The current work is focused on exploring these same nanoporous phases (MOFs, zeolites, etc.) for the real-time detection of NOx. The down-selection of candidate materials from bulk synthesis and gas selectivity testing will be discussed. Methods for deposition of these materials onto the Pt interdigitated electrodes and initial sensor performance during controlled gas exposures will be presented.

Acknowledgements

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

References

1) Small, L.J and Nenoff, T.M., ACS Appl. Mater. Interfaces, 2017, 9 (51), 44649-44655.
2) Small, L.J.; Krumhansl, J.L.; Rademacher, D.X.; Nenoff, T.M. Micro. Meso. Mater., 2019, 280, 82-87.
3) Small, L.J.; Hill, R. C.; Krumhansl, J. L.; Schindelholz, M. E.; Chen, Z.; Chapman, K.W.; Zhang, X.; Yang, S.; Schroder, M.; Nenoff, T.M., ACS Applied Materials and Interfaces, 2019, 11(31), 27982-27988.
Coordinated Molecule-Modulated Magnetic Phase with Metamagnetism in Metal–Organic Frameworks
Authors: Oh Hyunchul 
Published: December 2020

Metal Organic Frameworks (MOFs) are a very prominent research topic because of their potential uses in applications such as molecular devices, gas storage systems, and especially single chain magnet (SCM) materials. Among these MOFs, those that feature open metal sites (Ni2+) inherently possess spin states that are tunable via organic molecular coordination. They have demonstrated the potential of SCM materials, exhibiting the possibilities for the spin-canting, magnetic phase transition, and field-induced spin slow dynamics behavior.
In this paper, we experimentally and theoretically investigated the magnetic properties of a MOF possessing an open metal site, and its derivatives. It exhibits a magnetic ordered state at low temperatures, which can be altered by altering its imidazole (IM) coordination. Our results show that coordinated IM clearly influences the spin state of Ni(II) ions with orbital geometries, resulting in shifts in critical temperature and field. These obtained results imply that the magnetic behavior in MOFs with IM reveals the coexistence of spin-canting, metamagnetism, magnetic phase transitions, and field-induced spin slow dynamics.
To the best of our knowledge, this is the first example of a MOF exhibiting the influence of the spin state of Ni(II) ions with orbital geometries via organic molecular coordination, which shows the coexistence of spin-canting, metamagnetism, magnetic phase transition, and field-induced spin slow dynamics.
(Invited) Investigation on Coloring/Self-Bleaching Mechanism in Photochromic Device Using Raman Spectroscopy
Authors: Chun So Yeon , Park SungHyeok , Lee Seok In , Hong Sungjun , Han Chi-Hwan , Cho Minhaeng , Kwak Kyungwon , Choi Han-Kyu 
Published: December 2020

Smart windows have been of great interest for a wide variety of energy saving application to control the penetration of solar energy into buildings by switching between a coloring and bleaching states. For dynamic transmittance control, various smart devices are developed, such as electrochromic (EC), photochromic (PC), and photoelectrochromic (PEC) devices. Although, the coloring/bleaching mechanisms of EC and PEC devices are well-known to achieve better smart window performance, it is still lacking information about coloration/decoloration mechanism in PC device. In this regards, unrevelling photochromic mechanism during coloring/self-bleaching could help to improve their performance to advance smart window application.
In this talk, we investigate the coloring/self-bleaching mechanism using Raman spectroscopy. The Raman spectroscopy help to understand the photochromic mechanism upon light irradiation and self-bleaching stage. Our approach is based on the PC device, which is composed of the tungsten oxide (WO3) and titanium oxide (TiO2), and 5-methyl salicylic acid (5-MSA) as a cost effective ligand. The Raman spectroscopy allows us to understand the correlation between coloring/bleaching process and intercalation/deintercalation of Li ion.

Figure 1
Development of Targets for Heavy Duty Fuel Cell Vehicles with Application-Driven System Modelling
Authors: Padgett Elliot , Kleen Gregory J , Mukundan Rangachary , Wang Xiaohua , Ahluwalia Rajesh , Papageorgopoulos Dimitrios C 
Published: December 2020

Hydrogen fuel cells are an attractive technology to power zero-emissions heavy-duty vehicles, including road vehicles, such as trucks and buses, as well as marine, rail, and mining applications. Hydrogen fuel cell powertrains can offer several advantages over incumbent technologies, such as diesel engines, including higher efficiency, reduced emissions, higher torque, and no noise pollution. Additionally, they offer fast fueling and adequate fuel storage for applications demanding longer range. In comparison to light duty fuel cell vehicles, which have begun early commercialization, fuel cell systems for heavy duty applications have important differences in their requirements and typical operation. Heavy duty fuel cell systems must offer high durability and efficiency to provide a competitive total cost of ownership considering capital costs, fuel costs, and lifetime. Furthermore, load-hauling applications, such as trucks, rail locomotives, and mining vehicles, must provide higher average and peak power while meeting heat rejection and onboard packaging constraints.
Efforts to develop effective fuel cell materials, components, stacks, and systems for heavy duty applications must be guided by new targets and testing protocols. Fuel cell system modeling is essential to determine how application requirements translate to specific demands for the fuel cell system and components.
The Department of Energy has set system-level targets for long-haul class 8 fuel cell trucks at 25,000 hour lifetime, 68% peak efficiency, and $80/kWnet fuel cell system cost by 2030 and ultimate targets of 30,000 hour lifetime, 72% peak efficiency, and $60/kWnet fuel cell system cost.[1] This presentation will discuss the system-level targets as well as the development of new targets and testing protocols for heavy duty fuel cell components and materials. This includes specific performance tests for different operational requirements, accelerated stress tests, and targets combining durability, performance, efficiency, and cost. We will also discuss differing needs between heavy duty applications, each of which presents unique requirements for fuel cell systems. It is desirable to address these unique requirements with standardized, cross-platform fuel cell stacks and components to enable high volume, low cost manufacturing, which requires the development of suitable cross-platform targets.

[1] U.S. Department of Energy. “Hydrogen Class 8 Long Haul Truck Targets”. DOE Hydrogen and Fuel Cell Technologies Program Record. December 12, 2019: https://www.hydrogen.energy.gov/pdfs/19006_hydrogen_class8_long_haul_truck_targets.pdf
Cumulative Damage Modeling of Fuel Cell Membranes
Authors: Khattra Narinder , Bhattacharya Sandeep , Kjeang Erik , Lauritzen Michael Victor 
Published: December 2020

The strongly varying humid environment under which fuel cell membranes operate introduces detrimental mechanical stresses that inflict damage to the membrane1. The damage incurred by the membrane during each humidity cycle when accumulated over time may lead the membrane to fatigue failure. The residual fatigue life of the membrane is determined here by using a cumulative-damage model2. A time-temperature-humidity dependent constitutive model and a multi-physics fuel cell finite element model are first developed to characterize the material properties and estimate the coupled mechano-hygral-thermal stress field in the membrane. Using this multi-level modeling approach, and with the aid of experimentally obtained fatigue data, fail-safe regions (see Figure) are identified for the case of accelerated stress test loading. For general loads simulating fuel cell operation, the distribution of stress-reversals is calculated for the load history using rain-flow counting algorithm. The regions of membrane that are more susceptible to fatigue damage are identified. It is also found that high amplitude stress cycles with low occurrence percentage are more detrimental than high occurrence low-amplitude cycles.
This work was supported by Natural Sciences and Engineering Research Council of Canada, Simon Fraser University Community Trust Endowment Fund, Canada Research Chairs, Mitacs through the Mitacs Accelerate program, and Ballard Power Systems.

1 Borup, R., et al., Scientific aspects of polymer electrolyte fuel cell durability and degradation. Chemical Reviews, 2007. 107(10): p. 3904-3951.

2 Fatemi, A. and L. Yang, Cumulative fatigue damage and life prediction theories: a survey of the state of the art for homogeneous materials. International Journal of Fatigue, 1998. 20(1): p. 9-34.

Figure 1
Measurement of Proton Conductivity and Water Diffusivity of Nafion Membrane at Subzero Temperatures
Authors: Tajiri Kazuya , Shrivastava Udit , Verma Saumitra 
Published: December 2020

Water management is critical for the high performance of proton exchange membrane fuel cells (PEMFCs). The knowledge of PEM properties such as water content, proton conductivity, and water diffusivity is necessary for water management. In literature, PEM properties are very well documented at temperatures above room temperatures but at subzero temperatures PEM properties are scarcely reported. The acquisition of PEM properties at sub-zero temperatures is very important to the quick start-up of fuel cell electric vehicles in below freezing conditions.
The objective of this study is to obtain the water transport characteristics of a membrane at subzero temperatures for automotive applications. In this study, three different properties of a Nafion membrane are quantified: water content, proton conductivity, and water diffusivity.
In sub-zero condition at different RHs, the membrane water content and proton conductivity were quantified from gravimetric and electrochemical measurements. A novel measurement technique using segmented cell and methodology were established to estimate water diffusion coefficient as a function of water content and temperature (see figure below). Further, particular to the Nafion membrane, an empirical relationship between water diffusivity and water content in temperature range of 243K to 303K was developed.

Figure 1
Electrocatalytic Activity and Durability of Pt–Ni Nanowires for Oxygen Reduction
Authors: Kato Masaru , Iguchi Yoshimi , Li Tianchi , Zhuang Yu , Nakahoshiba Ryota , Yagi Ichizo 
Published: December 2020

Oxygen reduction reaction (ORR) is a key reaction in future energy generation devices such as polymer electrolyte fuel cells (PEFCs) and metal–air batteries. To drive the ORR in PEFCs, Pt–M alloy nanoparticles (M = Ni) on carbon supports have been used as catalysts. Under electrocatalytic conditions, these electrocatalysts are known to degrade involving particle detachment, agglomeration and metal dissolution.[1] These phenomena can be suppressed by increase metal/support interactions: using heteroatom-doped carbon supports[2] and/or nanostructured Pt–M alloy catalysts.[3]

Herein, we report synthesis, activity and durability of Pt–Ni nanowires (NWs) for the ORR in acidic media. The Pt–Ni NWs showed higher ORR electrocatalytic activity than Pt/C. The Pt–Ni NWs showed almost no activity loss even after 50,000 potential cycles in acidic media. Physicochemical measurements including in situ Pt L3-edge X-ray absorption spectroscopy [4] revealed that the Pt surface oxide formation under potential control was suppressed after potential cycles, relative to the initial state. This finding suggests that potential cycles could induce strong metal/support interactions, resulting in the formation of highly durable NW catalysts.
References.
[1] N. Hodnik, G. Dehm, K.J.J. Mayrhofer, Acc. Chem. Res., 49, 2015–2022 (2016).
[2] M. Kato, K. Ogura, S. Nakagawa, S. Tokuda, K. Takahashi, T. Nakamura, I. Yagi, ACS Omega, 3, 9052–9059 (2018).
[3] J. Li et al., Science, 354, 1414–1417 (2016).
[4] K. Nagasawa et al., J. Am. Chem. Soc., 137, 12856 (2015).
Acknowledgements.
This work was supported by NEDO.
Effect of Global Fuel Starvation on Reversal Tolerant Anode Materials – Pulsed Versus Continuous Cell Reversal Events
Authors: Maric Robert , Gebauer Christian , Hasché Frédéric , Strasser Peter 
Published: December 2020

A broad scientific consensus exists that anthropogenic emissions are major factors fueling global warming and its potential impacts on the earth’s ecosystem. On the way to a sustainable and decarbonized energy supply, "green" hydrogen is an emission-free alternative to conventional energy carriers. In this context, proton exchange membrane fuel cells (PEMFCs) offer promising properties for the electromobility by a simple scalability of the performance through the modular design of fuel cell stacks, a refueling time and range comparable with conventional combustion engines and zero emissions if "green" hydrogen is used. Despite all scientific work on this field – performance, cost and durability issues still hamper the wide commercialization of PEMFCs.
Concerning the durability, global fuel starvation causes destructive and irreversible degradation at the anode catalyst. A lack of fuel supply leads to the anode potential being raised to levels where the oxygen evolution reaction (OER) and carbon oxidation reaction (COR) take place instead of the hydrogen oxidation reaction (HOR). Thus, the overall cell voltage reverses compared to normal operation. In consequence, the widely employed carbon-supported anode catalyst corrodes and the overall cell performance is reduced if appropriate mitigation strategies are absent [1]. Among other remedies, incorporating a second catalyst component with an enhanced OER activity, such as IrO2 [2], is a promising material-specific strategy. Within this study we present a technical approach on single cell level (50 cm2
geo) to investigate and evaluate the impact of short-pulsed versus long-lasting fuel starvation events on the degradation of a reversal-tolerant anode catalyst layer comprising Pt/C and IrO2 [3]. By utilizing an on-line mass spectrometer, the anode exhaust gas stream is examined in terms of O2- and CO2-amounts to reveal the origin of the degrading effect.
References:
[1] T. Ioroi and K. Yasuda, J. Power Sources, 450, 227656 (2020).
[2] K. H. Lim, W. H. Lee, Y. Jeong, and H. Kim, J. Electrochem. Soc., 164, F1580 (2017).
[3] R. Marić, C. Gebauer, M. Nesselberger, F. Hasché, and P. Strasser, to be submitted.
Fuel Cell Automotive Drive-Cycle Cathode Catalyst (Pt/C) Layer Durability: Dependence on Low Vs. High Carbon Supports and Ionomer-to-Carbon-Ratio
Authors: Rice Cynthia A. 
Published: December 2020

The typical urban automotive drive-cycle for proton exchange membrane fuel cells (PEMFC) consists of frequent idle-to-peak power cathode voltage transients, with extremes ranging from 1.2 V to 0.6 V, respectively. Understanding the platinum electrochemical surface area (ECSA) loss mechanisms dependence on material and operational conditions have been extensively investigated with the objective of minimizing performance losses over the lifetime of PEMFC powered automobiles. Commonly, automotive accelerated stress tests (AST) are performed ex-situ on thin catalyst films. The standard catalyst consists of carbon supported platinum nanoparticles (Pt/C). This study compares triangle waveform (TW) ASTs monitoring ECSA loss for ex-situ (thin film in 0.1 HClO4) and in-situ (catalyst layers bond with ionomeric electrolyte in a complete membrane electrode assembly (MEA)). The ionomer-to-carbon ratios (I/C) of the MEAs is varied from 0.6 to 1.5 on either low surface area carbon (LSAC) or high surface area carbon (HSAC) supports. The AST profiles included 25k cycles at 10 sec intervals, between the upper potential limit of either 0.9 V or 1.2 V and the lower potential limit of 0.6V, with intermediate ECSA evaluations from the H-desorption current (0.02 V → 0.4 V).
The electrolyte environment alters, liquid vs. ionomer, the dominant AST decay mechanism, Figure 1A. The decay in the liquid electrolyte is most sever upon initiation of the AST and the rate of decay decrease after the first 2000 cycles. While the MEA decay is less initial, but maintains the same rate of initial decay over 5000 cycles resulting in a higher overall loss of ECSA. ECSA decay is exacerbated at temperatures of 70°C. Increasing the I/C increases the interfacial acidity at the surface of the Pt/C and results in exacerbated ECSA loss, Figure 1B. In accordance with the Pourbaix diagram for Pt, it is less stable in a more acidic environment. The relative rate of ECSA loss is reduced on HSAC supports.

Figure 1
Co3O4/CeO2/C As Electrocatalyst for Ethylene Glycol Oxidation Reaction
Authors: Kepeniene Virginija , Ruškytė Linora , Stagniūnaitė Raminta , Drabavičius Audrius , Tamašauskaitė-Tamašiūnaitė Loreta , Norkus Eugenijus 
Published: December 2020

In recent decades, alkaline direct alcohol fuel cells have been interested due to their advantages over hydrogen fuel cell. Alcohols such as methanol and ethanol are the most common types of fuel used in direct liquid-feed fuel cells however alternative alcohols are increasingly being investigated. One of the choices for alkaline alcohol fuel cell is ethylene glycol. Ethylene glycol in an alkaline medium generates, as intermediates, oxalates, glyoxylate, glycolate, glycolaldehyde, glyoxal and carbon dioxide and it is considered an energy carrier for fuel cells. The importance of this fuel is attributed to several factors: low molecular weight, biomass origin, high energy density, high boiling point and lower toxicity than methanol.
One more challenge is to find the most efficient electrocatalysts for various fuel oxidation reaction which could replace platinum in fuel cell anode materials in relation to its limited resources and high price.
Lately, the most research is based on the development of different, new, rare earth metals and metal oxides compositions, the improvement of known materials such as carbon with various additives with the aim to reduce or completely refuse of noble metal and to find low cost, higher efficient and great performance catalysts.
In this study, the Co3O4 was deposited onto the CeO2/C substrates prepared by two different ways. The substrates were prepared as follow: a) dry powder of CeO2 was mixed with carbon powder (mass ratio being 1:1) in a 2-propanol solution by ultrasonication for 30 min with further drying of the mixture (CeO2/C-1); b) CeCO3 were precipitated onto the carbon surface using the appropriate concentrations of CeCl3 and Na2CO3 solutions with stirring on a magnetic stirrer, followed by drying the mixture (CeO2/C-2). Then Co3O4 was deposited onto the CeO2/C-1 and CeO2/C-2 substrates using microwave irradiation and β–cyclodextrin as reducing agent. The synthesized Co3O4/CeO2/C-1 and Co3O4/CeO2/C-2 catalysts were characterized by Inductively Coupled Plasma Optical Emission Spectroscopy, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy and X-ray Diffraction. Electrocatalytic activity of the prepared catalysts was evaluated towards ethylene glycol oxidation reaction in an alkaline medium using cyclic voltammetry and chrono-techniques.
It has been found, that the Co3O4 supported catalysts showed higher electrocatalytic activity for the ethylene glycol oxidation reaction than the pure CeO2/C substrates. Moreover, the preparation way of the substrate has had the influence on the electrocatalytic activity of prepared catalysts. It has been found that Co3O4/CeO2/C-2 catalyst where CeO2/C substrate was obtained from CeCl3 salt solution showed higher electrocatalytic activity towards ethylene glycol oxidation reaction than Co3O4/CeO2/C-1 catalyst where CeO2 was directly mixed with carbon powder.
(PEFC&E 2nd Place Best Poster Winner) Investigation on Methanol Tolerance of Pt/C Cathode Catalyst with Heteroatom-Doped Carbon Layer for Direct Methanol Fuel Cell
Authors: Choi Jung-goo , Ham Kahyun , Lee Jaeyoung 
Published: December 2020

Direct methanol fuel cell (DMFC) is one of the most commercialized technology in direct liquid fuel cells due to various advantages of rapid refueling and high energy density, which are crucial characteristics for portable applications. DMFC consists of methanol oxidation reaction at anode and oxygen reduction reaction (ORR) at cathode on PtRu-based and Pt-based catalyst, respectively. Most challenging problem toward DMFC is methanol crossover. Methanol at the anode permeates the cathode and reacts with cathode catalyst, resulting in voltage drop. Pt/C is an excellent catalyst, but it actively reacts with methanol at the cathode. Thus, it is crucial to design a methanol-tolerant Pt-based catalyst to increase the ORR selectivity at the cathode.
In this study, we synthesized Pt/C with heteroatom-doped carbon layer. Heteroatom-doped Pt/C showed both lower activity in the methanol oxidation reaction and higher activity in ORR than pristine Pt/C. The origin of selectivity will be investigated with electrochemical tests such as CO stripping voltammetry and XPS in aspects of oxophilicity and Pt electronic structure. Finally, we will apply heteroatom-doped Pt/C on the cathode and confirm selectivity compared with pristine Pt/C. This approach suggests the way to design a Pt catalyst for ORR to improve performance in DMFC.
References
[1] Strmcnik, D., et al. Nat. chem., 2013, 5, 300-306.
[2] Wang, Y., et al. Energy Environ. Sci., 2015, 8, 177-181.
[3] Uhm, S., et al. ChemPhysChem, 2008, 9(10), 1425-1429.