bluuebunny/crossref_metadata_2025_split huggingface dataset:
Engineering PGM-Free Electrodes to Facilitate Improved Performance for the Oxygen Reduction Reaction in Polymer Electrolyte Fuel Cells
Authors: Osmieri Luigi , Wang Guanxiong , Neyerlin K C 
Published: February 2020

With the aiming of reducing stack cost, the investigation of platinum group metal (PGM)-free catalysts for oxygen reduction reaction (ORR) has gained a lot of interest in the recent decades,1 with the majority of focus on improved electrocatalysis via various precursors and synthesis methods. The most promising PGM-free catalysts in terms of activity are carbon-based materials doped with nitrogen and active transition metals (like Fe, Co, and Mn), obtained by high temperature pyrolysis.2

The literature regarding synthesis, characterization, and rotating disk electrode (RDE) performance of this class of PGM-free materials is abundant, with many works reporting beginning of life performance testing in PEFC. Relative to the extensive literature on electrocatalyst fabrication, a less extensive and rigorous examination of PGM-free electrode design has been performed.
A number of variables like ionomer content, catalyst deposition method (e.g. spray coating, blade coating, hand painting), ink concentration, ink solvent composition and ink evaporation rate may influence PEFC performance. All of these process variables, along with the properties of the electrocatalyst itself, can alter the electrode ionomer distribution,3 resulting is significant differences in gas transport and electrode proton conductivity.3–5

In this work, we examine the impact of ionomer content, ink deposition method, and ink solvent composition on the PEFC performance of a commercially available PGM-free catalyst (Pajarito Powder LLC). Electrode properties will be assessed using different electrochemical diagnostics techniques. The viability of H2 limiting current will be discussed as a means to extract the pressure dependent and independent mass transport resistance of the electrode layer.6,7 Cyclic voltammetry and electrochemical impedance spectroscopy will be used to determine electrode capacitance and subsequently related to ionomer coverage and proton conductivity8,9 and contrasted with SEM images of MEA cross sections.
Through this methodology we will demonstrate how the electrode fabrication process plays a crucial role in electrode properties and the absolute performance.

References:

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H. K. Lee, J. H. Park, D. Y. Kim, and T. H. Lee, J. Power Sources, 131, 200–206 (2004).

T. T. Ngo, T. L. Yu, and H. L. Lin, J. Power Sources, 238, 1–10 (2013).

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T. Schuler et al., J. Electrochem. Soc., 166, F3020–F3031 (2019).

G. Wang, A. G. Star, L. Osmieri, and K. C. Neyerlin, in 235th ECS Meeting Abstract, (2019).

K. C. Neyerlin, W. Gu, J. Jorne, A. Clark, and H. A. Gasteiger, J. Electrochem. Soc., 154, B279 (2007).

R. Makharia, M. F. Mathias, and D. R. Baker, J. Electrochem. Soc., 152, A970 (2005).
A Synthetic Route for the Preparation of PtRu-Ni Core-Shell Nanoparticles Using Polydopmaine Protective Coating for a CO Tolerant Electrocatalyst
Authors: Lee Hojin , Kim Hansung 
Published: February 2020

Carbon supported PtRu-Ni/C catalysts with a Ni-rich core structure are prepared through high temperature treatment of as-prepared polyol PtRu/C catalysts. It is well acknowledged that in conventional PtRu alloys, Ru prevents the adsorption of carbon monoxide on Pt surface via bifunctional mechanism. Also, the ligand effect of Ni is known to alter the electron structure of Pt for increased methanol oxidation reaction (MOR). In this work, the optimal Ni amount is determined for enhanced MOR and high resistance to carbon monoxide poisoning. The diffusion of Ni into the core of the catalysts is conducted by controlling the temperature during heat treatment. The as-prepared polyol PtRu/C catalysts have carbonized polydopamine layer on the surface, which prevents particle segregation during high temperature heat treatment. The carbon layer also partakes the role of transferring Ni particles into the core of the catalyst. When compared to using the polyol method to directly fabricate PtRu-Ni/C catalysts, this method is far more superior. Because Ni has a very low reducing power, most of it is lost during polyol process, and the final product has an extremely low Ni content.
In this study, Energy-dispersive X-ray spectroscopic line scan profile and X-ray photoelectron spectroscopic analysis confirm that the PtRu-Ni/C catalyst has a Ni-rich core and PtRu-rich shell structure. From Cyclic voltammograms for methanol oxidation and polymer electrolyte membrane fuel cell tests using CO containing H2 gas, the core-shell structured PtRu-Ni/C alloy formed by high-temperature annealing is demonstrated to have higher tolerance to CO poisoning than PtRu/C catalysts synthesized by co-deposition via the polyol method.
On the Activity of Electrospun Tantalum Doped SnO2 for Durable ultra-Low PGM Fuel Cell Cathodes
Authors: Haidar Fatima , Jimenez Morales Ignacio , Cavaliere Sara , Jones Deborah J. , Rozière Jacques 
Published: February 2020

Despite the advances in the development of Proton Exchange Membrane Fuel Cells (PEMFCs), some locks still need to be lifted before they are deployed on a large scale:

i) Reduce the amount of platinum group metals (PGM) used in the electrodes by increasing the mass activity of the supported catalyst.

ii) Improve durability of the electrodes by replace the conventional carbon support

In particular, for the cathode side, carbon blacks (e.g. Vulcan XC-72) are conventionally used as a support materials for Pt and Pt-alloy nanoparticles. These materials exhibit high electric conductivity, controlled chemical properties, and high surface area that are of interest in PEMFCs application as electrocatalyst supports. However, carbon blacks are oxidized at the high voltage experienced at the cathode side (e.g. in stop/start conditions) leading to PEMFC major failure due to support corrosion leading to catalyst particles sintering or detachment [1,2].
Alternative supports based on tin oxide have attracted research interest due to their high corrosion resistance and promotion of activity for oxygen reduction reaction (ORR)[3]. The drawback is their low electrical conductivity, that in this work was tackled by doping with tantalum. Ta-doped SnO2 conducting fibers were synthetized by electrospinning followed by calcination [4] (Figure 1). This support was catalyzed with platinum nanoparticles prepared by a microwave-assisted polyol method and characterized for their physico-chemical and electrocatalytic properties towards ORR. In particular, stability to voltage cycling at high potential was evaluated by ex situ electrochemical analysis. A very significant mass activity of 470 A / gPt has been reached with 7.4wt.% of Pt homogenously deposited onto Ta-doped SnO2 nanofibers [5,6]. In addition, improved electrochemical stability was demonstrated with the retention of 70 % of the mass activity up to 10000 cycles from 1 to 1.6 V/RHE.

Figure 1:

SEM micrograph of 1%at. Ta-doped SnO2 nanofibers.

References

C. Meier, C. Galeano, I. Katsounaros, A. a. Topalov, A. Kostka, F. Schüth, K. J. J. Mayrhofer, ACS Catal. 2012, 2, 832–843.

Yu, H. Li, H. Wang, X.-Z. Yuan, G. Wang, M. Pan, J. Power Sources 2012, 205, 10–23.

Savych, S. Subianto, Y. Nabil, S. Cavaliere, D. Jones and J. Rozière, Chem. Chem. Phys. 2015, 17, 16970-16976
.

Cavaliere, I. Jiménez-Morales, G. Ercolano, I. Savych, D. Jones and J. Rozière, ChemElectroChem 2015, 2, 1966-1973.

Senoo, K. Taniguchi, K. Kakinuma, M. Uchida, H. Uchida, S. Deki, and M. Watanabe, ElectroChem. Commun. 2015, 51, 37–40.

Jiménez-Morales, S. Cavaliere, D. Jones, and J. Rozière, Phys. Chem. Chem. Phys. 2018, 20, 8765–8772
.

Figure 1
Synthesis of Pt-Rare Earth Metal Alloy Nanocatalysts
Authors: Hu Yang , Jensen Jens Oluf , Cleemann Lars Nilausen , Brandes Benedikt Axel , Li Qingfeng 
Published: February 2020

Further enhanced performance of platinum nanocatalysts towards the oxygen reduction reaction (ORR) in fuel cells can be achieved by alloying platinum with a secondary metallic element, typically late transition metals such as Ni and Co.(1-4) Recent theoretical and experimental studies have shown that Pt- Rare earth (RE) metal alloys exhibit remarkable ORR activities, among the highest of all ORR catalysts ever reported. (5-7) Due to the substantial difference of standard reduction potentials between Pt and RE metals as well as the extremely high oxophilicity of RE metals, alloying of the two metals as nanoparticles meets great challenges by usual chemical routes.
Here we report a simple method of synthesizing Pt-RE alloy catalysts by one-step heat-treatment of common precursors. A long series of Pt-RE alloy catalysts with single alloy phases, e.g., Pt3Y, Pt2Gd, Pt2Sm, Pt5Ce, or Pt5La, have been successfully synthesized, which exhibit narrow particle size distributions and excellent ORR performance. The highest ORR activities, achieved as far, are around 6 times (by Pt surface area) and 3 times (by Pt mass) higher than the start-of-the-art Pt/C catalysts. Several alloy catalysts such as Pt5Ce/C and Pt5La/C have showed also excellent stabilities by the standard accelerated stability tests. Furthermore, the synthesis mechanism has been clarified by investigation of intermediate products of the synthesis. The synthesis scale has been increased to 5-10 per batch for specific catalysts. As such, fuel cell tests with this type of catalysts become feasible, which have yielded promising results.

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Molecular-Level Design and Synthesis of M-N-C Non-Precious Metal Catalysts Derived from Transition Metal-Coordinated Bis(imino)-Pyridine Based Polymers for Highly Efficient Oxygen Reduction
Authors: Tian ZhiQun 
Published: February 2020

Molecular-Level Design and Synthesis of M-N-C Non-Precious Metal Catalysts Derived from Transition Metal-Coordinated Bis(imino)-Pyridine Based Polymers for Highly Efficient Oxygen Reduction
Zhi Qun Tian*, Xiaoran Zhang, Dandan Lyu, and Pei Kang Shen
Collaborative Innovation Center of Sustainable Energy Materials, Guangxi Key Laboratory of Electrochemical Energy Materials, State Key Laboratory of Processing for Non-ferrous Metal and Featured Materials, Guangxi University, Nanning，53004, China.
（E-mail:tianzhiqun@gxu.edu.cn）
Abstract: Transition-nitrogen-carbon (M-N-C) materials as the most promising non-precious metal catalysts for oxygen reduction reaction (ORR) to replace Pt-based catalysts are in high demand for large scale application of fuel cells. However, their activity and durability are still critical issues. Development of M/N/C-containing precursors is a straightforward strategy for obtaining advanced M-N-C ORR catalysts to address these issues. Herein, we report a new strategy for synthesizing a highly efficient and robust M-N-C catalyst for oxygen reduction reaction (ORR) via the pyrolysis of bis(imino)-pyridine metal-ligand based polymers. A series of Fe-N-C, Co-N-C and Mn-N-C catalysts prepared by the new presucors displays an excellent electrochemical performance for ORR with onset and half-wave potentials of >0.95 V, 0.84 V vs. RHE, respectively, in acidic media, and >1.0 V, 0.9 V vs. RHE, respectively, in alkaline media. These values are comparable to commercial Pt/C catalyst in acidic media and even more superior to commercial Pt/C in alkaline media. And a low H2O2 yield (< 2%) in the diffusion-limiting current region and a high electron transfer number (3.97-3.99) were achieved in our catalysts, indicating the occurance of direct 4 e- process for ORR. Meanwhile, the catalyst shows remarkable cycle stability at high potential range of 0.6-1.35V both in alkaline and acidic media, outperforming Fe-N-C catalysts reported previously, which is important for practical application of ORR catalysts in fuel cells. This feature makes it among most efficient non-precious catalysts in alkaline/acidic media for ORR. We believe this novel approach may open a new way of synthesizing highly efficient and robust noble metal-free catalysts for ORR.
References
[1]X. Zhang, Y. B. Mollamahale, D. Lyu, L. Liang, F. Yu, M. Qing, Y. Du, X. Zhang, Z. Q. Tian and P. K. Shen, J. Cata. 2019,372, 245-257.
[2]D. Lyu, Y. B. Mollamahale, S. Huang, P. Zhu , X. Zhang, Y. Du, S. Wang, M. Qing, Z. Q. Tian and P. K. Shen, J. Cata. 2018, 368, 279-290.
[3]X. Zhang, D. Lyu, Y.B. Mollamahale, F. Yu, M. Qing, S. Yin, Z. Q. Tian, and Shen, PK, Electrochim. Acta 2018, 281, 502-509
Recent Advances in Low and Pt-Free Loading in Anion Exchange Membrane Fuel Cells
Authors: Neyerlin Ami , Strasser Derek , Antunes Christopher M , Owczarczyk Zbyslaw R. , Meek Kelly M , Pivovar Bryan S. 
Published: February 2020

Anion exchange membrane (AEM) fuel cells have seen tremendous advances in recent years.[1] Power densities have now been obtained reaching over 3 W/cm2.[2] The advances in the field have been enabled by new AEM materials that have improved properties and durability as well as advances in electrode processing and performance. While the potential advantages of AEM fuel cells have been widely reported to be around the area of enabling non-precious electrocatalysis (and lower cost system materials), most of the results reported to date have focused on Pt containing electrocatalysts, often with high loadings to improve power density.[1] Now that exceptionally high-power densities have been achieved, it has become more important to focus on the performance and durability of AEM fuel cells at low loadings.
At the National Renewable Energy Laboratory (NREL), we have investigated a number of different polymer systems and have demonstrated the ability to greatly improve performance through electrode processing techniques. We have also demonstrated durability greater than 500 hours with a wide range of different membrane compositions. We have found that electrodes play a much more critical role in determining performance and durability. Recently, we have demonstrated the ability to achieve high performance with a variety of different ionomeric electrode materials. Most of our initial work had focused on Pt at high loadings, but we have also explored low Pt and Pt-free catalysts. In this talk we will discuss the role of different polymers, different electrode fabrication techniques, and the impact of loading on observed fuel cell performance and durability. With the issue of power density largely demonstrated our efforts have focused on areas including increased robustness (operating under dynamic conditions particularly at different RH), low Pt group metal loading, impacts of carbon dioxide exposure, and durability.

References

[1] D. Dekel, J. Power Sources, 375 (2018) 158-169.
[2] G. Huang, M. Mandal, X. Peng, A. Yang-Neyerlin, B. Pivovar, W. Mustain, and P. Kohl, Achieving 3.4 W/cm2 Alkaline Polymer Fuel Cell: Composite Cross-linked Poly(norbornene) Anion Conducting Membranes for High Power, Durability and Water Management, submitted.
Electrochemical Behavior of Plutonium in Molten Fluoride Medium
Authors: Claquesin Julien , Lemoine Olivier , Massot Laurent , Gibilaro Mathieu , Bourges Gilles , Chamelot Pierre 
Published: February 2020

A pyrochemical process for slag recycling containing trapped actinide particles into a CaF2-CaO matrix is currently in progress. Since the process requires to melt the slag (melting point above 1300°C), an additional amount of CaCl2 must be used to decrease the operating temperature below 1000°C. Then, a reducing agent (calcium) is added into the molten medium to remove the actinides in a stable metallic form after decantation. The clean salt product meets the radiological requirements to be discarded to the dedicated way (ANDRA).
However, the extraction process is operated in a molten chloro-fluoride salt which is complex and quite unknown. Pu investigation in simplified media, chloride and fluoride, must lead to understand the mechanism of Pu reduction in chloro-fluoride media. Pu behavior has already been investigated in molten chloride media via electrochemical techniques by J. Serp et al. [1], O. Shirai et al. [2] and Lambertin et al. [3]. Nevertheless, data regarding this actinide behavior in molten fluoride media are incomplete [4].
Consequently, a detailed electrochemical study was carried out on plutonium in fluoride salt. The selected solvent is a mixture of two well-known salts, LiF and CaF2, melted in a crucible made of vitreous carbon in an oxygen free atmosphere (argon). Plutonium ions were introduced into the melt in the form of PuF4 powder. The setup consisted of a three electrodes assembly: tungsten as working electrode, vitreous carbon as auxiliary electrode and the potentials were referred to a platinum electrode. Cyclic voltammetry, square wave voltammetry and chronopotentiometry were coupled with thermodynamic calculations (potential-oxoacidity diagram) to investigate the electrochemical system. The acquired data will be used for a better understanding of Pu extraction from the melt.
[1] J. Serp, R.J.M. Konings, R. Malmbeck, J. Rebizant, C. Scheppler, J.-P. Glatz, Electrochemical behaviour of plutonium ion in LiCl-KCl eutectic melts, J. Electroanal. Chem., 561 (2004) 143.
[2] O. Shirai, T. Iwai, Y. Suzuki, Y. Sakamura, H. Tanaka, Electrochemical behavior of actinide ions in LiCl-KCl eutectic melts, J. Alloys Compd., 271-273 (1998) 685.
[3] D. Lambertin, S. Ched’homme, G. Bourgès, S. Sanchez, G. Picard, Plutonium chemical properties in NaCl-KCl and CaCl2 at 1073 K, J. Nucl. Mater., 341 (2005) 124.
[4] C. Hamel, Séparation actinides-lanthanides (neodyme) par extraction électrolytique en milieux fluorures fondus, vol. 3, 2005. Thesis, Toulouse.
Decentralized Electrochemical Production of H2O2: A Focus on Catalysis and Single-Atom Catalysts
Authors: Yang Sungeun , Xi Jiangbo , Colic Viktor , Stephens Ifan , Silvioli Luca , Rossmeisl Jan , Kibsgaard Jakob , Wang Shuai , Chorkendorff Ib 
Published: February 2020

Electrochemical production of hydrogen peroxide, H2O2, holds promise for small-scale, on spot, and safe production of green oxidizer. Electrochemical process requires small electrochemical device that can replace large and centralized current infrastructure using anthraquinone method. Optimizing cathode catalyst that can reduce oxygen to hydrogen peroxide with high activity and high selectivity will make such a system reality.
We focus on the catalysis of electrochemical oxygen reduction to hydrogen peroxide. Electronic effect and geometric effect are the two important factors determining activity and selectivity of catalysts. Beyond these well-known effects, pH and mass transport of product can profoundly change the activity and the selectivity of catalyst. Activity and selectivity of Pt-Hg, Ag-Hg, Ag, and glassy carbon electrode abruptly changed by pH of reaction environment. We also highlight the importance of mass transport on benchmarking the selectivity by comparing three different systems with different mass transport phenomena, rotating ring disk electrode, stagnant electrode, and membrane electrode assembly.
We propose single-atom catalyst as a promising type of catalyst for H2O2 production. Single-atom catalysts exhibit intriguing catalytic properties due to its geometric arrangement where active atoms are well separated with each other, and each individual atom directly interact with support atoms. Single-atom catalyst can satisfy both electronic and geometric effect for the optimized performance. Near hundred percent noble metal utilization led to high mass activity for electrochemical H2O2 production.
In Situ Raman Microscopy for Redox Mechanism of Cathode Materials
Authors: Ri Vitalii , Jeon Cheolho , Kim Chunjoong , Moon Joonhee 
Published: February 2020

Raman spectroscopy has been used to study structural information is a vibrational technique which is very sensitive to the metallic oxidation state, and it is very suitable for electrode materials due to several characteristics; fast, nondestructive method, measurement of the same electrode and even on the same spot with various laser, and analysis using another techniques. Moreover, the Raman imaging technique is powerful tool to study the charge of structure, surface morphology, and phase transition accompanying crack propagation.
Here, we introduce Raman micro-spectroscopy installed at Advanced Nano-Surface Research Group in KBSI which is especially set up in glove box to measure various materials without air exposure, which can exhibit a sample from another surface contamination when exposure to atmosphere. Additionally, we designed and fabricated two types of electrochemical cells (plane cell and cross cell) developed for in situ Raman micro-spectroscopy for studying electrode materials in operating battery during battery operation. This approach simultaneously characterizes phase transition and facilitates uncovering the relationships between surface structure and activity during battery operation. This result provides a method for visualizing chemical structure of phase transition and the changed surface morphology.
Nano-Scale Confinement for Efficient Multi-Step Reaction Cascades
Authors: Chavan Kanchan Suklal , Calabrese Barton Scott 
Published: February 2020

Strategic operation of multi-step reaction cascades for energy conversion/storage applications such as biofuel cells is a necessary step to increase process efficiency [1]. Beyond maximizing catalytic activity, efficient transport of reaction intermediates between active sites with minimal diffusion loss into the bulk is critical. Therefore, implementation of intermediate channeling mechanisms, many of which exist in nature, to multi-step energy cascades is a critical aspect of an overall design strategy.
Molecular tunneling is one mechanism of substrate channeling that minimizes intermediate diffusional losses into the bulk by confining intermediate pathway [2].In this work, we studied intermediate transport between two active sites confined by single-walled carbon nanotube (SWCNT) using continuum and molecular dynamics (MD) approaches [3]. MD was performed using model intermediates (oxalate and ethanol) inside SWCNTs with diameter 1 nm to 4 nm. Due to water molecule orientation inside the SWCNT, the intermediates experienced a constrained environment that resulted in Knudsen diffusion and decreased diffusion coefficient [4].
In order to increase intermediate residence time inside the nanotube, SWCNT termini were modified with varying numbers of negatively-charged carboxylate groups. Due to attractive-repulsive electrostatic interactions, ethanol, which is uncharged but polar, was retained for a longer time inside the SWCNT. Like-charged intermediates such as oxalate were less affected. This approach represents one possible technique to enhance confinement and therefore increase reaction efficiency.
References:
(1) Wheeldon, I. et al., Nat. Chem. 2016 p299.
(2) Dunn, M. F. et al., Trends Biochem. Sci. 2008 p254.
(4) Chavan, K. S. and Calabrese Barton, S., J. Phys. Chem. C 2018, p14474.
(3) Striolo, A., Nano Lett. 2006, p633.