bluuebunny/crossref_metadata_2025_split huggingface dataset:
A M-N3/C Active Site Prepared through Terpyridine Motifs (M= Fe, Co, Mn, Ni, Sn) for the Oxygen Reduction Reaction
Authors: Fruehwald Holly M , Zenkina Olena V , Easton E. Bradley 
Published: May 2020

Non-noble catalysts for the oxygen reduction reaction (ORR) are in high demand for fuel cell technology due to their use of low cost and widely available starting materials. The development of these catalysts has been a constantly growing area. However, to the extent of our knowledge, there have only been a few literature reports that provide insights into the nature of the structure and geometry of the catalytically active sites formed in these materials.
In the current literature, the most commonly proposed catalytically active site(s) for ORR are active sites that correspond to Fe-N2+2/C geometry. These active sites are typically produced through a high-temperature pyrolysis step to obtain this desired configuration[1]. However, the pyrolysis step is very disadvantageous due to the production of a variety of nitrogen functional groups on the surface which can negatively affect the activity of the catalyst, since only nitrogen functionalities with specified geometry are considered to be the most active for ORR[2,3]. In addition, high-temperature treatments drastically increases the overall cost of production and can be quite energy demanding. Thus, high-temperature treatment makes it difficult to design a surface rich in a specific active site for the desired application.
We had previously developed a model of a catalyst rich in Fe-N3/C sites on a commercial Vulcan carbon. We showed that this site had high activity for the ORR reaction achieved by covalently functionalizing a carbon support with a nitrogen-rich terpyridine (tpy) ligand. The ligand geometry allowed for the formation of well-defined active sites on the carbon surface, leaving exposed N3 moities for the ORR. Metal-ligand coordination with Fe resulted in desired Fe-N3/C moieties on the surface. We demonstrated that this system can be prepared using mild reaction conditions and does not require high-temperature treatment for improved activity. On the contrary, the heat-treatment to this system was detrimental to the activity. Recently, we have been investigating the effect of other non-precious late transition metals for the activity of the novel N3/C sites. We present here the results of the M-N3/C site where M= Co, Sn, Ni, or Mn and show that these metals also show promising electrochemical activity in both acidic and basic media due to well-defined N3/C site for the ORR, showing generality of our initial results with iron and overall versatility and activity of an N3 site in combination with various non-precious metals for an ORR catalyst.
[1] M. Lefèvre, E. Proietti, F. Jaouen, J.-P. Dodelet, Science
2009, 324, 71-74.
[2] F. Charreteur, F. Jaouen, S. Ruggeri, J.-P. Dodelet, Electrochimica acta
2008, 53, 2925-2938.
[3] H. M. Fruehwald, I. I. Ebralidze, O. V. Zenkina, E. B. Easton, ChemElectroChem
2019, 6, 1350.

Figure 1
Novel Synthesis of Manganese Single Atom Oxygen Reduction Reaction Catalyst for Enhanced Stability in Polymer Electrolyte Membrane Fuel Cells
Authors: Stracensky Thomas Stephen , Yang Fan , Zhong Sichen , Jiao Li , Lattimer Judith , Jia Qingying , Mukerjee Sanjeev , Xu Hui 
Published: May 2020

In an effort to viably implement polymer electrolyte membrane fuel cells (PEMFCs) technology, there has been a drive for the development of platinum group metal free (PGM-free) oxygen reduction reaction (ORR) catalysts. To this end, iron based catalysts such as the single atom FeN4 catalyst have been identified as one of the most active species for the ORR in the PEMFCs . However, while initial activity of the catalyst is high, the stability of membrane and electrode assemblies (MEAs) is still poor upon extended operations. One degradation mechanism for Fe-based MEAs can be attributed to the Fenton reactions that produce highly reactive radicals capable of attacking the membrane of the PEMFCs. Therefore, alternative catalysts that can mitigate Fenton reactions have been investigated to enhance the MEA stability in PEMFCs.
Manganese single atom based catalysts have risen recent interest as a candidate to circumvent the issue of radical formation and provide a highly active and stable catalyst for the ORR in PEMFCs1. In this work we have developed a novel pyrolysis synthetic method to form the Mn single atom catalyst. It was found that the pyrolysis temperature and precursor selection are crucial factors for developing a highly active ORR catalyst. The developed pyrolysis leads to minimal aggregation and forms active sites on the exterior of the catalyst particle that become available to perform oxygen reduction. The active site of this catalysts was validated by x-ray absorption spectroscopy (XAS) and the catalyst showed good activity for the ORR in PEMFCs. The catalyst also demonstrated excellent stability upon voltage cycling under nitrogen where oxygen exposure is seen to decrease the activity. The mechanism of degradation due to oxygen exposure is investigated under storage and during operation by examining the structural changes to the Mn species via XAS. Here it was found that under storage in air the catalyst formed Mn(III) oxides and when the MEA was cycled under oxygen Mn(II) oxides formed.
Acknowledgements: This work is financially supported by the Department of Energy’s Fuel Cell Technology Office under the award# DE-EE0008075
(1) Liu, K.; Qiao, Z.; Hwang, S.; Liu, Z.; Zhang, H.; Su, D.; Xu, H.; Wu, G.; Wang, G. Mn- and N- Doped Carbon as Promising Catalysts for Oxygen Reduction Reaction_ Theoretical Prediction and Experimental Validation. Applied Catalysis B: Environmental, (243) p. 195-203, 2019.
Cobalt and Nitrogen Co-Doped Peat Derived Carbon Based Catalysts for Oxygen Reduction
Authors: Jäger Rutha , Teppor Patrick , Härk Eneli , Härmas Meelis , Adamson Anu , Paalo Maarja , Volobujeva Olga , Kikas Arvo , Kochovski Zdravko , Romann Tavo , Härmas Riinu , Lust Enn 
Published: May 2020

The carbon precursor peat is one out of many mineral-rich resources of Estonia, which originally is a sediment of incompletely decomposed plant residues. The chemical properties of peat include the five basic elements: C, H, O, N and S [1]. Therefore, its composition is attractive and economically perspective not only for the synthesis of nonprecious catalysts for the oxygen reduction reaction (ORR), but also as a framework for batteries [2]. Generally, nonprecious metal and nitrogen co-doped catalysts have been synthesized using a metal salt, a nitrogen precursor and a carbon material via either one or multiple step preparation methods [3,4]. Herein, we introduce promising peat derived carbon (PDC) based cobalt and nitrogen co-doped catalysts (Co-N/PDCX) which demonstrate high catalytic activity towards ORR. The nanoporous carbon support was derived from peat via five different carbonization protocols (see Scheme). All the prepared PDCX and Co-N/PDCX catalysts were characterized by several physical characterization methods. The ORR activity of the synthesized PDCX and Co-N/PDCX catalysts were investigated in 0.1 M HClO4 solutions using rotating disc electrode method and the ORR activity of Co-N/PDCX shows significant dependence on the carbonization method used to derive a carbon support. The best catalyst was chosen for further testing in a fuel cell.

Acknowledgements

This work was supported by the EU through the European Regional Development Fund under project TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011), by the Estonian institutional research grant No. IUT20-13, NAMUR ”Nanomaterials - research and applications” (3.2.0304.12-0397) and LLTOM17351 “Activated carbon from peat” (01.07.2017-30.06.2020).

References

[1] Y. Uraki, Y. Tamai, M. Ogawa, S. Gaman, S. Tokura, BioResources, 2009, 4(1), 205-213.
[2] J. Ding, H. Wang, Z. Li, A. Kohandehghan, K. Cui, Z. Xu, B. Zahiri, X. Tan, E.M. Loftabad, B. Olsen, D. Mitlin, ACS Nano, 2013, 7(12), 11004-11015.
[3] F. Roncaroli, E.S. Dal Molin, F.A. Viva, M.M. Bruno, E.B. Halac, Electrochimica Acta, 2015, 174, 66–77.

Figure 1
Stability of Ionic-Covalently Cross-Linked PBI-Blended Membranes for so2 electrolysis at Elevated Temperatures
Authors: Peach Retha , Krieg Henning , Kruger Andries , Bessarabov Dmitri , Kerres Jochen A. 
Published: May 2020

In this study, the effect of component composition on the chemical stability of the developed ionic-covalently cross-linked PBI-blended membrane concept from earlier studies for application in SO2 electrolysis at elevated temperatures (>100 °C) is further investigated. Three different acid-base ratios were studied by blending a partially fluorinated sulfonated arylene main-chain polymer (SFS) with polybenzimidazole (F6PBI) and a partially or non-fluorinated bromo-methylated polymer (BrPAE). In addition two different alkylated imidazoles (EMIm and TMIm) were included as quaternization agents. Accordingly, twelve different PBI-blended membranes were used in this study. The suitability of these membranes for SO2 electrolysis at elevated temperatures was determined in terms of i) the H2SO4 stability (80 wt% H2SO4 at 100 °C for 120 hours), (ii) the oxidative stability (Fenton’s test, FT) and (iii) the organic solvent stability (extraction in N,N-Dimethylacetamide). Membranes were characterized in terms of the percentage weight, the ion exchange capacity (IEC) and the thermal stability (TGA-FTIR) changes, before and after the various treatments. Although all blended membrane types were sufficiently stable during H2SO4 treatment, proton conductivity measurements indicated that the blends containing only partially fluorinated blend components displayed superior stability (better compatibility) as well as conductivity. Cell voltages showed an improvement of up to 190 mV for operations at 120 °C compared to earlier studies conducted at 80 °C for similar PBI-blended membranes. It was established that both chemically stable and conductive PBI-blended membranes, suitable for SO2 electrolysis above 100 °C, could be obtained by varying the composition of selected polymer components.
Figure 1: Schematic of the ionic-covalently cross-linking concept for the blend membranes (black – BrPAE, purple – F6PBI, blue – EMIm, and brown - sPPSU).

Figure 1
Effect of Microporous Layer (MPL) and Carbon Fiber Paper (CFP) Properties on PEMFC High Current Density Performance
Authors: Niangar Ely , Vora Mehul , Koestner Roland John , Kumaraguru Swami 
Published: May 2020

The effect of microporous layer (MPL) and carbon fiber paper (CFP) properties on high current density cell performance is investigated in this work. Two types of carbon black (Denka Li-400 and Soltex AB50-HC) were used with the same MPL ink formulation using FEP as hydrophobic agent, and the inks were coated on two types of wetproofed CFP substrates. The resulting GDLs (CFP + MPL) have different, contrasting through-plane thermal conductivities – for the MPLs coated on Toray TGP-H-060, k = 0.310 – 0.390 W/mK but for those coated on Freudenberg H2312, k = 0.170 – 0.210 W/mK (under 2 MPa compression).
The MPL coatings were characterized by mercury porosimetry and scanning electron microscopy (SEM) (top-down and cross-section). The two MPLs show contrasting peak pore sizes – the AB50-HC MPL peak pore size is at 60 nm while the Li-400 MPL peak pore size is at 300 nm, consistent with recent MPL studies using Li-400 in the MPL [1]. Single cell membrane electrode assemblies (MEAs) were made in a catalyst-coated membrane (CCM) configuration at both 5 cm2 (for testing under differential flow conditions) and 38 cm2 (non-differential cell) active areas. Polarization curves at different operating conditions were obtained in addition to limiting current experiments (on 5 cm2 differential cells) to determine the total oxygen transport resistance.
At dry operating conditions (Tcell = 80°C, RH = 32%, pabs = 150 kPa), the cell performance of all four (4) samples (2 MPLs coated on 2 different CFP substrates) are comparable, but under wet operating conditions, (Tcell = 80°C, RH = 100%, pabs = 150 kPa), the 2 MPLs (AB50-HC and Li-400) coated on TGP-H-060 have significantly lower cell performance (38 cm2 non-differential cells, but the same trends were observed when testing under differential flow conditions (5 cm2 CCM MEAs)). These results reiterate the importance of GDL through-plane thermal conductivity as the main GDL property that influences water management and controls cell performance at high current densities (> 2.0 A/cm2) [2].

References

1. C Simon, H Gasteiger et. al., Impact of Microporous Layer Pore Properties on Liquid Water Transport in PEM Fue Cells: Carbon Black Type and Perforation, J. Electrochem. Soc., 2017, 164 (14), F1697- F1711
2. J Owejan, M Mathias et. al., Water Transport Mechanisms in PEMFC Gas Diffusion Layers, J. Electrochem. Soc., 2010, 157 (10), B1456- B1464

Figure 1
Surface Treatment of Titanium for Fuel Cell Bipolar Plates
Authors: Sato Haruka , Imamura Junko , Nose Koichi 
Published: May 2020

PEFC (polymer electrolyte fuel cell) metallic bipolar plates have attracted much attention because of their thermal and electrical conductivity, gas impermeability, mechanical strength, and ease of manufacturing compared to high-density graphite. Titanium also exhibits these properties but the electrical conductivity is decreased in fuel cell environment due to the growth of surface passive film.
Generally, metal bipolar plate surface is coated by a noble metal, carbon or another material. However, these are high cost due to using expensive materials or process. This study introduces a low cost production method of a high performance titanium bipolar plate. The method consists of pickling and heat treatment and enables to produce bipolar plate with a specific thin film on the surface.
The film formed on the titanium sheet was investigated by transmission electron microscope. The electrical conductivity was measured by contact resistance with carbon paper after endurance test in simulated fuel cell environment.
These results indicate that the material produced by our method exhibits both high conductivity and corrosion resistant. It is expected to be utilized as a bipolar plate for PEFC.
Investigation on Electrochemical Properties of Low-Temperature Ionic Liquid-Based Electrolytes for MET Sensor
Authors: Lin Wendy Jessica , Xu Yifei , MacDonald Shaun , Dai Lenore L. 
Published: May 2020

The molecular electronic transducer (MET) sensor that operates based on an electrochemical principle provides an alternative approach for motion sensing applications and seismic investigations. As the liquid state proof mass responds to detected seismic waves, the electroactive species, iodide and triiodide, are brought to the electrodes by the induced fluid motions. At the cathode, the triiodide reduction currents are generated correspondingly and serve as a record of the detected ground activities. Compared to the conventional motion sensor and seismometer with solid state mass-spring system, by utilizing a liquid state electrolyte as the proof mass, the MET sensor presents advantages such as installation angle independence, superior shock tolerance, low mass, and low power consumption. The abovementioned characteristics have made MET sensor an appealing candidate for seismic investigations in space explorations, especially on planetary objects with deployment challenges.
For potential seismic studies on icy ocean worlds, such as Europa, Titanic, and Enceladus where the extremely low temperatures can be challenging for liquid state electrolytes, our group has developed several ionic liquid-based electrolyte systems with broad liquidus range down to -120 ˚C. While enhancements in thermal and transport properties of the electrolyte systems via optimization of intermolecular interactions were validated, we have yet to fully explore their electrochemical properties at low temperatures that are critical for the MET sensor functionality. In this work, we present investigations on electrochemical properties of the developed electrolyte systems over a broad temperature range. Using electrochemical impedance spectroscopy, we observed effects of tailored intermolecular interactions between ionic liquid and incorporated molecular solvents on conductivity evolution from room temperature to -75 ˚C. Specifically, the resulting bulk conductivity of the overall system was governed by an interplay between ion mobility and ion disassociation, and its temperature dependence can be depicted by the Vogel-Fulcher-Tammann model. Furthermore, we also investigated kinetics of the targeted iodide/triiodide redox reactions via cyclic voltammetry for the MET sensing technology. The electrochemical reversibility of triiodide reduction for signal generation was correlated to the employed molecular solvents and their interactions with the electroactive species. Lastly, the electrochemical windows were also identified for respective electrolyte systems at various temperatures as references for future MET sensor operations. Discoveries of the presented work disclose effects of intermolecular interactions on electrochemical properties and contribute to applications of the MET sensing technology at room temperature and low temperatures.
A Raman Spectroscopic Study of Radiation-Grafted Anion-Exchange Membranes Containing Different Anions
Authors: Bance-Soualhi Rachida , Crean Carol , Herman Henryk , Islania Saima , Lai Cheuk Ying , Tencheva Mariya , Varcoe John R. , Whelligan Daniel 
Published: May 2020

Anion exchange membranes (AEM) are being developed for use in a variety of electrochemical energy systems, such as alkaline membrane fuel cells, AEM-based electrolysers, reverse electrodialysis (RED), and redox flow batteries (RFB). The AEMs used will contain a variety of anions, depending on the application. For fuel cells and electrolysers (H2 generating or CO2 conversion), then alkaline anions such as OH-, CO3
2-, and HCO3
- are important. For RED cells and RFBs, non-alkali anions such as Cl-, HSO4
-, and SO4
2- are more relevant. If an AEM is synthesised using a methyl iodide reaction, then monitoring the ion-exchange of the resulting "as-synthesised" I- forms to other forms, such as Cl-, is important as it is well known that it can be difficult to completely ion-exchange soft anions such as I- out of AEMs (particularly those containing aromatic cationic groups).
This presentation will highlight some initial results obtained from an on-going Raman spectroscopic study of radiation-grafted AEMs (RG-AEM). This study was initiated to see if Raman spectro-microscopy can be used to identify the anion form of a RG-AEM by looking at the shifts and intensity changes of Raman peaks as a function of anion. The RG-AEMs will be made from either the grafting of vinylbenzyl chloride onto ETFE (followed by reaction with amines such as trimethylamine, imidazole and pyridine) or the grafting of alternative monomers such as vinylpyridine onto ETFE (followed by reaction with methyl iodide).
The below Figure shows Raman spectra (Renishaw inVia Raman microscope: 785 nm laser, 1800 lines mm-1 grating, and x20 objective giving a Airy spot diameter of ca. 3 μm) of a RG-AEM made from the grafting of vinylpyridine onto ETFE films (with a final methyl iodide reaction) in both the I- and Cl- forms (three spectra each):
.

Figure 1
Depth-Profiling Buried Interfaces within Polymer Electrolyte Membranes
Authors: Korzeniewski Carol , Bukola Saheed , Creager Stephen E , Harris Joel M. 
Published: May 2020

Confocal Raman microscopy is being adapted to probe interfaces within bipolar membranes and ionomer-graphene composites of interest for use in fuel cell and related electrochemical devices [1-2]. Although versatile and adaptable to in-situ measurements, confocal Raman microscopy depth-profiling has pitfalls when applied to bulk membranes. Optical aberration and sensitivity to light scattering from sample regions outside the probe beam focus limit depth resolution. With these constraints in mind, initial studies focused on detecting single layer graphene (SLG) as a barrier between two Nafion membranes (Nafion 211, 25 µm thickness). These graphene-sandwich membranes have shown high selectivity for proton transport across electrochemical cells [2]. Using a microscope equipped with oil-immersion optics to provide refractive index matching, the graphene layer was easily detected in confocal Raman microscopy depth-profiles. Spectra were sensitive to defects and stress within the buried graphene layer. Building on the ability to probe membrane-supported SLG, SLG adsorbed to a glass microscope coverslip (SLG/SiO2) was adapted as a platform for confocal aperture alignment and probe volume characterization [1]. Using SLG/SiO2to estimate the limiting axial spatial resolution, the junction separating the AEM/CEM (anion exchange membrane / cation exchange membrane) phases of bipolar polymer membrane (Fumasep FBM) was probed and shown to be consistent with roughness at the boundary on the order of a few micrometers (~3 µm). Continuing efforts are aimed at developing 2-dimensional (x-, y-direction) Raman spatial maps of buried polymer membrane interfaces and model AEM/CEM interfaces for high spatial resolution (< 10 nm) neutron reflectometry depth profiling.
1. Korzeniewski, C.; Kitt, J.P.; Bukola, S.; Creager, S.E.; Minteer, S.D.; Harris, J.M. ”Single layer graphene for estimation of axial spatial resolution in confocal Raman microscopy depth profiling” Anal. Chem.2019, 91, 1049 (DOI:10.1021/acs.analchem.8b04390).
2. Bukola, S.; Liang, Y.; Korzeniewski, C.; Harris, J.M.; Creager, S.E. “Selective proton / deuteron transport through Nafion | graphene | Nafion sandwich structures at very high current density” J. Am. Chem. Soc. 2018, 140, 1743. (DOI: 10.1021/jacs.7b10853)
Investigation of Glucose Oxidation on Gold Nanocrystallites Modified Cobalt and Cobalt-Boron Coatings
Authors: Šimkūnaitė Dijana , Upskuvienė Daina , Sukackienė Zita , Balčiūnaitė Aldona , Kepenienė Virginija , Šimkūnaitė-Stanynienė Birutė , Tamašauskaitė-Tamašiūnaitė Loreta , Norkus Eugenijus 
Published: May 2020

Herein, the electrochemical oxidation of glucose has been investigated on the Co and CoB alloy coatings, which were deposited on the copper substrate (Cu) and subsequently modified with a small amount of Au nanocrystallites (termed as the AuCo/Cu and AuCoB/Cu catalysts), with the aim to use them as the anode catalysts for direct glucose fuel cells (DGFCs). The catalysts have been prepared via a simple electroless Co deposition method followed by a spontaneous Au galvanic displacement from the Au(III)-containing solution. The activity of the prepared catalysts for the oxidation of glucose in an alkaline medium has been examined by cyclic voltammetry and chrono-techniques.
In conclusion, the Co and CoB alloy coatings, which were modified with a small amount of Au nanocrystallites in the range from 11 to 14 µg Au cm–2, exhibit a significantly higher activity for the oxidation of glucose as compared to that of bare Au, Co and CoB alloy catalysts. Furthermore, the process of glucose oxidation has been significantly shifted to more negative potential domain at the both AuCo/Cu and AuCoB/Cu catalysts, indicating the higher activity of the latter catalysts as compared to that of the unmodified Co/Cu and CoB/Cu catalysts and the bare Au electrode. In addition, approximately 22 and even 67 times higher glucose oxidation current density values have been obtained at the AuCo/Cu and AuCoB/Cu catalysts, respectively, as compared to those for the unmodified CoB/Cu and Co/Cu. The prepared AuCo/Cu and AuCoB/Cu catalysts, which have been prepared with very small amount of Au nanocrystallites, seem to be a promising anode material for DGFCs.