bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of Fluorine Doped Tin Oxide (FTO) Coated Substrates Under Extreme Polarization Conditions
Authors: Korjenic Alen , Raja Krishnan S. 
Published: February 2020

Fluorine doped tin oxide (FTO) is a transparent conducting oxide which is widely used in different applications ranging from sensors, digital displays, smart window coatings, catalysts supports, and electrode substrates for various electrochemical applications. The FTO coated glass slides were evaluated for their chemical stability in different pH solutions at room temperature by carrying out potentiodynamic polarization and cyclic voltammetry (CV). Accelerated stress tests were carried out in 0.1 M HCl and 0.1 M NaOH solutions by scanning the potential from -2 V to 2 VRHE at a scan rate of 1 V/s. Ex-situ vibrational spectroscopy and in-situ photo absorption spectroscopy were carried out to evaluate the material degradation when electrochemically polarized.
The FTO was more stable in 0.1 M HNO3 and 0.1 M NaCl solutions under both anodic and cathodic polarization conditions. Oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) were the cathodic reactions observed during cathodic polarization of the FTO. The activity of FTO for HER was higher in the acidic solutions than that in the neutral or alkaline solutions. Cathodic polarization in 0.1 M HCl solution resulted in a reduction of SnO2 to lower valent species. The semiconductivity of FTO, which was n-type at low anodic potentials, was p-type at high anodic potentials possibly due to the formation of a SnO-type surface layer by the removal of lattice oxygen during the oxygen evolution reaction. Cyclic stability of the FTO was evaluated by conducting CV between -2.0 and vbn 2.0 VAg/AgCl at 1 V/s. Intergranular corrosion was observed and the stability was completely lost after 215 cycles in the 0.1 M HCl solution, as seen in Fig. 1. The stability of FTO was better in the 0.1 M NaOH solution, wherein the electro-catalytic activity degraded after 500 cycles, the electrical connectivity was maintained even after 4500 cycles.

Figure 1
Electro-Assisted Recycling of Lithium Ion Batteries
Authors: Diaz Luis A. , McNally Josh S. , Klaehn John R. , Gao Ningshengjie , Dufek Eric J. , Jones Michael , Adhikari Birendra , Lister Tedd E. 
Published: February 2020

The fast growth of the electric vehicle (EV) market is generating increasing anxiety regarding the sources and availability of minerals required to meet with a growing demand for lithium ion batteries (LIBs). Critical elements (lithium, cobalt, and graphite) are crucial to sustain the manufacturing of a growing EV market as well as thriving wireless demand. However, the geographical concentration of mining and refining of cobalt and graphite constitute a supply chain risk for the global production of LIBs. This is driving technical development, which in turn, is leading to a dynamic change in battery chemistry. Lithium sources are more diverse in nature and geographical distribution, and current lithium reserves are enough to cover projected scenarios within the next twenty years. Nevertheless, the main question is whether the extraction technologies can keep up with the pace of market growth for EV.
Interest in LIBs recycling is surging as a path to a circular battery economy and supply chain stabilization for critical materials on LIBs. Industrial processes for the recycling of LIBs are already operating around the world. However, these processes are almost exclusively focused on the recovery of Co, Ni and Mn from battery cathodes as the most valuable metals in the LIBs. Hydrometallurgical processes have been proposed for a comprehensive recovery that includes lithium and graphite, but the high operating costs and intensive chemical consumption do not support a cost-effective recovery of Li at industrial level.
To target this issue, an electro-assisted reduction technology, based on the use of electrons as green reagent, has been proposed for the extraction and recovery of critical materials from LIBs. Through this process, high extraction efficiencies (>98%) can be achieved at solid to liquid ratios up to 120 g/L and in a peroxide free environment. The process is suitable to different battery chemistries and allows for the recovery of graphite as bi-product. A description of the process, as well as a flowsheet, that describes a comprehensive recovery for different value streams will be discussed.
Tailored Catalyst Layer and Micro-Porous Layer Porosity and the Effect on the Performance and Water Content in PEMFC
Authors: Mohseninia Arezou , Kartouzian Dena , Wilhelm Florian , Markötter Henning , Scholta Joachim , Manke Ingo 
Published: February 2020

In this study, the effect of the catalyst layer (CL) and the cathode microporous layer (MPL-C) porosity on the performance and water content of the polymer electrolyte membrane (PEMFC) is investigated. Monodispersed polystyrene (PS) particles are used as pore formers to fabricate CL and MPL with different degrees of porosities. Specially developed miniature Single single cells for neutron imaging experiments with an active area of 8 cm² are implemented with the in-house made catalyst coated membranes and cathode MPLs. The cathode MPLs were coated on a 29 BA substrate, and commercial 29 BC SGL were used on the anode side as the gas diffusion layers (GDLs). Neutron tomography is used to investigate the water content and distribution inside the operating fuel cells. The quantitative analysis of the water thickness under the channels of the cells at RH=120% and I=1 A.cm-2 is shown in figure 1.a.
It is observed that the water content has decreased for cell 3 ( CL: 10 wt.% PS, MPL: 10 Vol.% PS) compared to cell 2 ( CL: 5wt.% PS, MPL:10 Vol.% PS) and cell 1 (Reference CL and MPL (without PS)). Polarisation curves for these three cells are provided in Figure 1.b. At current densities higher than I=1 A.cm-2 performance has increased for cell 2 and 3 where the components had higher porosity degree compared to the cell 1 which has a reference CL and reference cathode MPL. The results show that addition of macropores could facilitate the transport of gases and the removal of water at the mass transport regions. This method is currently under investigation by the authors. Further results will be provided in the presentation.

Figure 1
Carbon Effect on the Synthesis and MEA Performances of L10 CoPt Intermetallic Catalysts
Authors: Wang Chenyu , Li Dongguo , Kim Yu Seung , Spendelow Jacob S 
Published: February 2020

Incorporation of base metals to carbon supported Pt catalysts is known to enhance oxygen reduction reaction (ORR) activity. Therefore, Pt-base metals random alloys, such as Pt-Co, are often applied as cathode catalysts in proton exchange membrane fuel cells (PEMFCs). However, poor stability of Co under oxidative and acidic conditions makes the enhancement limited during long-term fuel cell testing. Recently, we have developed a robust method to prepare L10 ordered CoPt catalysts that exhibit superior fuel cell performances compared with the random alloy counterpart. In this systematic study, we observed that carbon supports impose strong effects not only on the growth of CoPt L10 intermetallic nanoparticles but also on the fuel cell performances.
Solid carbons, including Vulcan other highly graphitized carbons, have moderate surface areas and relatively higher degree of graphitization. CoPt L10 intermetallic particles prepared such type of carbons usually have a large size distribution. But their fuel cell performances are still desirable, showing high current densities at low voltages and less carbon corrosion. Moreover, we found that surface functionalization can improve the size distribution and dispersion of nanoparticles, thus improving the fuel cell performances. In parallel, porous carbons of high surface areas were also applied as the supports for depositing CoPt L10 intermetallic nanoparticles. Different from the particles on surface of solid carbons, a large number of nanoparticles are located in the micropores of porous carbons. These nanoparticles can maintain their small particle size and a narrow size distribution after heat treatment. CoPt L10 intermetallic nanoparticles on porous supports exhibit excellent performances at high voltage end in fuel cell testing.
Computational Analysis of Relative Graphene Layer Orientations Around FeN2+2 Sites for ORR
Authors: Gallenkamp Charlotte , Ni Lingmei , Krewald Vera , Kramm Ulrike Ingrid 
Published: February 2020

Proton exchange fuel cells (PEFCs) are a promising technology for energy conversion, but are not yet commercialized due to highly expensive platinum as state-of-the-art catalyst for the cathodic oxygen reduction reaction (ORR). As low-cost materials with earth abundant metals, non-precious metal and nitrogen doped carbon catalysts (Me-N-C) have become a viable alternative for platinum. Encouraging results were especially achieved with the use of iron as the metal center.[1]
Me-N-C catalysts are obtained from pyrolysis of different metal, nitrogen and carbon precursors, which results in highly amorphous structures. The latter causes difficulties for the spectroscopic characterization of the active sites. Thus the exact chemical nature of the active center and the oxygen reduction reaction (ORR) mechanism are still being debated. [2]
So far, three sites were proposed as possible contributors to the ORR activity. In Mössbauer spectroscopy they give rise to the D1, D2 and D3 doublets. They are all assigned to some type of FeN4 centers that are either integrated in graphene layers (D1: FeN4) or situated between two graphene layers (D2 and D3: FeN2+2). [3] While in the case of the D1 doublet, FeN4 macrocycles seem to work well as a model system, in the case of the FeN2+2 sites it is difficult to find suitable molecular model systems as references for the interpretation of the Mössbauer data. Furthermore, in the literature this site is often displayed as a flat structure. However, it remains unclear to what extent the graphene layers could possibly be tilted against each other.
In this contribution, we will use density functional theory calculations to determine structure-property relationships of FeN2+2 site models with different Fe coordination environments – in particular the angle between adjacent graphene layers – with respect to relative energy, preferred spin state, Mössbauer spectroscopic parameters, and likely reaction intermediates for ORR.
[1] Szakacs, C.E. et al., Phys. Chem. Chem. Phys., 2014, 16, 13654.
[2] Kramm, U.I. et al., Adv. Mater., 2019, 1805623.
[3] Kramm, U.I. et al., Phys. Chem. Chem. Phys., 2012, 14, 11673–11688.
Sulphur-Doped Ordered Mesoporous Carbon Hollow Spheres with High Catalytic Activity for the Oxygen Reduction Reaction and Exceptional Electrochemical Stability
Authors: Carrillo-Rodríguez J.C. , Alonso-Lemus Ivonne Liliana , de la Torre Saenz Luis , Escobar-Morales Beatriz , Garay-Tapia A.M. , Rodríguez-Varela F.J. 
Published: February 2020

We reported the synthesis and characterization of the novel and less explored methanol-functionalized Sulphur-Doped Ordered Mesoporous Carbon Hollow Spheres (S-HWf) as metal-free electrocatalyst for the Oxygen Reduction Reaction (ORR) in alkaline media. The S-HWf was synthetized by the silica template-based method, using resorcinol and formaldehyde as carbon source. The doping was made in situ using 2-thiophenemethanol as sulphur source. The functionalization was carried out with methanol solution (0.5 mol L-1) with the aid of intermittent microwave heating. The catalytic activity of S-HWf was compared with that of non-doped Ordered Mesoporous Carbon Hollow Spheres (HW) synthetized by the same method.
The morphology of S-HWf and HW analyzed in a Field Emission-Scanning Electron Microscope (FE-SEM) resulted in rough hollow spheres. The diameter and wall thickness were ~304 and ~90 nm for HW, while for S-HWf were ~248 and ~50 nm, respectively. The use of 2-thiophenemethanol as dopant, had an important effect in the morphology. The chemical surface composition determined by X-ray Photoelectron Spectroscopy (XPS) included the presence of C, O, and Si for HW. In addition to these elements, S was also detected at S-HWf (0.4 at. %). The textural properties were determined by N2 adsorption/desorption measurements. S-HWf and HW showed a surface area of 1007 and 505 m2 g-1, respectively, with micro-mesoporosity. Analysis of the electrocatalysts by X-Ray Diffraction (XRD) showed their amorphous structure with low-intensity crystalline phases. Meanwhile, from Raman spectroscopy S-HWf exhibited better ordering in its structure due to a lower value in ID/IG the intensity ratio compared to HW. The catalytic activity of the electrocatalysts for the ORR was evaluated by Rotating-Ring Disc Electrode (RRDE) technique. S-HWf showed a higher performance than HW, with an onset potential of 0.88 V half-wave potential 0.81 V and a current density (j) of -1.49 mA cm-2 at 0.8 V (all potentials vs. RHE). Moreover, its electron transfer number was n= 3.9 with a H2O2 production of ~3%. Furthermore, after accelerated degradation tests (3000 cycles, between 0.6 and 1.0 V), S-HWf showed an improvement in catalytic activity with onset potential of 0.88 V, half-wave potential of 0.82 V and j= -1.69 mA cm-2 at 0.8 V. Also, its n was 3.9 with a production of H2O2 of ~2%.
In this study it was found that doping with sulphur and functionalizing with methanol have a positive effect on the catalytic activity for the ORR and the electrochemical stability of Ordered Mesoporous Carbon Hollow Spheres. The electrochemical behavior of the S-HWf electrocatalyst indicated that it is a potential candidate for Anion Exchange Membrane Fuel Cells (AEMFC) cathode applications.
Highly Active Binder Free Plasma Sprayed Non-Noble Metal Electrodes for Anion Exchange Membrane Electrolysis at Different Reduced KOH Concentrations
Authors: Razmjooei Fatemeh , Reißner Regine , Gago Aldo Saul , Ansar Asif 
Published: February 2020

The production of hydrogen by the water electrolysis technique to provide a fossil fuel alternative energy source has attracted a plethora of attention among the other different methods in the context of sustainability, renewable energy source utilization and green technology.[1] Conventional alkaline water electrolyzer (AWE) offers many advantages compared with other systems. One of the major advantages of AWE over proton exchange membrane water electrolyser (PEMWE) is the replacement of conventional noble metal electrocatalysts with active, stable and relatively low-cost transition metal catalysts. However, AWE electrolyzers suffer from lower operational current density compared with their PEMWE counterpart. Like AWE, anion exchange membrane (AEM) electrolyzer does not require noble metal catalysts, which makes this technology much less expensive than PEMWE, while possessing the advantage of PEMWE. However, the electrochemical water splitting performance of AEM water electrolysis is still much lower than that of PEMWE. Focusing on this issue, the presented work aims at improving the performance of AWE and AEM electrolysers by developing cost effective non-noble electrodes on macro-porous transport layer (MPL) using the air plasma spray deposition method.[2] MPLs were fabricated by depositing Ni-graphite on porous substrates. Graphite was removed during particle in-flight forming a controlled porous layer. Electrodes were developed by plasma spraying of NiMoAl for cathode and NiAl for anode on top of the MPL followed by activation in which Al was partially leached out from layers of both electrodes using an alkaline solution. Electrochemical tests were conducted on half-cell in 6M KOH solution and then in the full cells for AWE and AEM in 6M and 0.3M KOH, respectively. The electrochemical performance is recorded via over-potential measurements, electrochemical impedance spectroscopy (EIS), cyclic voltammetery and polarization curve. With optimal combination of MPL and electrodes, current density of 0.5 Acm-2 at 1.80 V was recorded as the initial performance in 6M solutions for AWE using Zirfon separator and the current density of 0.31 Acm-2 at 1.80 V was recorded for AEM electrolyzer with more dilute KOH solution (0.3M) using an anion exchange membrane. 64 days of abusive testing was conducted for the AWE without measurable degradation in the performance in 6M KOH. The catalysts developed in this work will be promising in supporting the pursuit of cheap, affordable and ideal eco-friendly hydrogen fuel.
[1] F. Razmjooei, K.P. Singh, D.S. Yang, et al., Acs Catalysis, 2017, 7, 2381-2391.
[2] A.S. Gago, S.A. Ansar, B. Saruhan, et al., J Power Sources, 2016, 307, 815-825.
Quantifying the Effect of Ruthenium Contamination on the ORR Activity of DMFC Cathode Catalyst
Authors: Olewsky Chen , Ripenbein Tania , Keinan Liz , Ben Yehuda Ohad , Shviro Meital , Kaplan Dmitri , Peled Emanuel 
Published: February 2020

Direct methanol fuel cell (DMFC) technology is a promising energy source for portable, stationary and light transportation applications in the range of several watts and up to a few kW. Currently, one of the main drawbacks preventing widespread commercialization of DMFCs is their relatively short lifetime, up to a few thousands of hours at best. Usually a DMFC lifetime is not defined by a complete failure of the cell but by a slow and continuous degradation of the performance, up to the point when the delivered power is too low for the intended application. Several different degradation mechanisms contribute to this degradation [i], one of them is ruthenium contamination of the cathode catalyst [ii] following ruthenium dissolution from the anode PtRu catalyst and its cross-over to the cathode [iii].
The aim of our research is to quantitatively measure the effect of ruthenium contamination on the ORR performance of the cathode catalyst. For this purpose, different amounts of ruthenium (equivalent of 0.15-3 monolayers) were deposited on commercial Pt/C nanopowder to simulate ruthenium deposition on the cathode during a DMFC operation. The ruthenium-contaminated Pt/C powders were prepared using electroless polyol reduction method with methanol as the reducing agent. Johnson Matthey HiSPEC 8000 50%Pt/C was chosen to simulate a DMFC cathode catalyst. The composition, particles size and structure of these RuPt/C powders were verified by TGA, SEM-EDS, XPS, HR-TEM and STEM-EDS. Electrochemical characterization was performed with the use of cyclic-voltammetry and rotating–disk–electrode (RDE) techniques and compared to that of HiSPEC 8000. It was found that already at 0.25 equivalent monolayer of ruthenium (EDS %At Pt92Ru8, XPS %At Pt90Ru10) there is a massive, more that 25%, decrease in ORR specific activity of the commercial Pt/C catalyst. This decrease grows rapidly up to a complete inhibition of ORR at approximately 1 equivalent monolayer of ruthenium (EDS %At Pt64Ru36, XPS %At Pt50Ru50). The obtained results quantitatively show that ruthenium contamination indeed has a major role in the performance degradation of DMFCs.
[i] A. Mehmood, M. A. Scibioh, J. Prabhuram, M. G. An, H.Y. Ha, Journal of Power Sources, 2015, 297,224–241
[ii] L. Gancs, B. N. Hult, N. Hakim, S. Mukerjee, Electrochem. Solid-State Lett., 2007, 10, 9, B150
[iii] P. Piela, C. Eickes, E. Brosha, F. Garzon, P. Zelenay, Journal of The Electrochemical Society, 2004, 151 (12), A2053–A2059
Molecular Dynamics Simulation on Quaternized Ammonium Poly (ether ether ketone) for Anion-Exchange Membrane Fuel Cells
Authors: Chen Sian , Wang Haining , Zhang Jin , Lu Shanfu , Xiang Yan 
Published: February 2020

Poly (ether ether ketone) (PEEK) is a robust engineering plastic with good thermal and chemical stability. The quaternized ammonium (QA) functionalized PEEK provides anion transfer capacity for anion-exchange membrane fuel cells (AEMFC), because the introduction of hydrophilic QA groups or QA-based side chains. QA-PEEK membrane has been a promising solution for AEMFC in recent years thanks to the improvement of synthesis method1-3 and the abundance of grafting groups4,5. The divergence of hydrophilicity between backbones and side chains of QA-PEEK could result in microphase separation due to the spontaneous aggregation. In our previous work5, we reported the ions conductivity of two QA groups functionalized PEEK (GQ-PEEK, Fig.(a)) is higher than that of one QA groups (SQ-PEEK, Fig.(a)) under same grafting degree (GD). However, the mechanism of the improved conductivity still needs more investigation because various parameters could affect the ions conductivity, for example, ion exchange capacity (IEC), micro-phase separation, as well as effective ions diffusion coefficient.
Generally, the micro-structure of the membrane and ions transportation process could be effectively investigated by molecular dynamics simulations6,7. In the present work, we carried out molecular dynamics simulation to investigate the microphase separation and transportation process (H2O and OH-) of SQ-PEEK and GQ-PEEK respectively. The calculated structure factor (Fig.(b)) reveals the possible microphase separation in both membrane. The cluster size of GQ-PEEK (~3.69 nm) is slightly larger than that of SQ-PEEK (~3.24 nm), which is in consistent with the TEM results (Fig.(c)). Meanwhile, the self-diffusion coefficients (Fig.(d)) of both H2O and OH- in GQ-PEEK have no obvious difference than those in SQ-PEEK. Therefore, the increased conductivity of GQ-PEEK should attribute to the increased IEC in comparison to SQ-PEEK. This work provides a deeper understanding of anion-exchange membrane for fuel cells.

Reference

(1) Jasti, A.; Prakash, S.; Shahi, V. K. Journal of Membrane Science
2013, 428, 470.
(2) Han, J.; Peng, H.; Pan, J.; Wei, L.; Li, G.; Chen, C.; Xiao, L.; Lu, J.; Zhuang, L. Acs Applied Materials & Interfaces
2013, 5, 13405.
(3) Yan, X.; He, G.; Gu, S.; Wu, X.; Du, L.; Zhang, H. Journal of Membrane Science
2011, 375, 204.
(4) Si, J.; Wang, H.; Lu, S.; Xu, X.; Peng, S.; Xiang, Y. Journal of Materials Chemistry A
2017, 5, 4003.
(5) Si, J.; Lu, S.; Xu, X.; Peng, S.; Xiu, R.; Xiang, Y. Chemsuschem
2014, 7, 3389.
(6) Pan, J.; Chen, C.; Li, Y.; Wang, L.; Tan, L. S.; Li, G. W.; Tang, X.; Xiao, L.; Lu, J. T.; Zhuang, L. Energy & Environmental Science
2014, 7, 354.
(7) Lyu, K.; Peng, Y.; Xiao, L.; Lu, J.; Zhuang, L. Journal of Energy Chemistry
2018.

Figure 1
Hydroxide and Carbon Dioxide Transport Properties in High Performance Poly(norbornene) Anion Exchange Membranes
Authors: Huang Garrett , Mandal Mrinmay , Kohl Paul A 
Published: February 2020

Alkaline exchange membrane (AEM) fuel cells are an alternative to more conventional proton exchange membrane (PEM) fuel cells and electrolyzers. In recent years, anion conducting polymer membranes have achieved stability and ionic conductivity competitive with Nafion. Lightly cross-linked AEMs based on vinyl addition polymerized norbornene have record-high hydroxide conductivity (212 mS/cm) with <1% performance degradation over 1,200 hours in 1 M NaOH at 80 °C. Composite versions of these AEMs have also been used to construct membrane electrode assemblies for alkaline fuel cells with a peak power density of 3.4 W/cm2, 70% higher than the previous record for this type of system to date.
The presence of carbon dioxide in air, or carbonate in the electrolyzer water feed impacts device performance because of the high pH of the membrane. Carbon dioxide in the fuel cell air stream poses a practical limitation for large scale deployment of alkaline fuel cells. AEM fuel cell tests are often operated with oxygen or CO2-free air to avoid the complications of carbonate formation, which inherently lowers conductivity and the overall fuel cell performance. The focus of this talk is on the transport of hydroxide, bicarbonate and carbonate in poly(norbornene) membranes. The transport properties of CO2 have been characterized and relationships between the diffusivity and solubility of CO2­ in the polymer membrane in parallel with the in situ flux of carbonate ions through the AEM have been studied.
Financial support provided by the ARPA-E IONICS program for G.H. and M.M. is gratefully acknowledged.