bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and Implementation of Catalysts and Membrane Electrode Assemblies Based on Extended Thin Film Electrocatalysts
Authors: Alia Shaun M , Neyerlin K.C. , Hurst Katherine , Zack Jason W. , Mauger Scott A , McNeary William W , Weimer Alan , Medlin Will , Shulda Sarah M , Ngo Chilan , Pylypenko Svitlana , Pivovar Bryan S 
Published: February 2020

Fuel cells (and hydrogen generation from renewable electrons) represent tremendous promise in pushing society towards a more sustainable energy system. One key barrier for such a future energy system is the need for platinum group metals for catalysis and the quantities required for efficient performance. It has been a long standing goal to continually increase performance and durability of electrochemical devices, and one promising approach has been the development and implementation of extended thin film electrocatalysts.1

Our team has extensively investigated extended surface catalysts as a novel platform for increased performance and durability at lower cost.2,3,4This presentation will highlight the advances of our team in the synthesis and implementation of extended surface electrocatalysts with a focus on PtNi nanowires (NWs) produced by atomic layer deposition (ALD) and spontaneous galvanic displacement (SGD), see Figure 1. While these materials have shown great promise in ex-situ (rotating disc electrode) studies, performance in-situ (fuel cell tests) has not yet fully reflected the performance potential seen in these ex-situ tests. In large part we attribute this to challenges in electrode fabrication and integration. This presentation will present results that focus on the differences between in-situ and ex-situ properties, quantification of performance losses in fuel cell tests, and our efforts to further improve performance and durability of such systems.
Figure 1. Polarization curves for PtNiNW based catalysts for catalysts synthesized by spontaneous galvanic displacement (SGD) and atomic layer deposition (ALD).
1. Mark K. Debe∗, Alison K. Schmoeckel, George D. Vernstrom, Radoslav Atanasoski, Journal of Power Sources 161 (2006) 1002–1011.
2. Shaun Alia, Svitlana Pylypenko, Arrelaine Dameron, KC Neyerlin, Shyam Kocha, Bryan Pivovar, J. Electrochem. Soc. 2016 163(3): F296-F301.
3. Shaun M. Alia, Svitlana Pylypenko, K.C. Neyerlin, Shyam S. Kocha, and Bryan S. Pivovar, J. Electrochem. Soc. 2015 162(12): F1299-F1304.
4. Shaun M. Alia, Svitlana Pylypenko, K.C. Neyerlin, David A. Cullen, Shyam S. Kocha, Bryan S. Pivovar, ACS Catalysis, 4, 2680, 2014.

Figure 1
Development of Electrocatalysts for PEFC By Encapsulating Pt Particles into Carbon Mesopores
Authors: Hayashi Akari , Fu Bo , Huang Ting-Wei , Noda Zhiyun , Sasaki Kazunari 
Published: February 2020

Electrocatalysts for PEFC are generally composed by Pt dispersed on carbon supports and have an important role to determine the performance of PEFC. Decrease in Pt active sites during the long-time use becomes a serious problem for practical use of PEFC. Pt particles have tendency to agglomerate, or dissolve and re-precipitate under the potential cycles, resulting in the growth of particles. In this study, suppressing such Pt particle growth has been focused on. So far, increasing the durability of electrocatalysts by encapsulating Pt into the nanochannnels of mesoporous carbon (MC) has been reported in our group.1 The basic idea comes from reducing Pt mobility on the curved carbon surface, which has also been supported by theoretical study.2 In this particular report, the effect of pore characteristics, such as pore diameter and pore volume, on PEFC performance are evaluated.
MCs were made from the self-organization formaldehyde/resorcinol and Pluronic F127,3 but the procedure was slightly modified for each kind of MCs. Then, electrocatalysts were synthesized from platinum(II) acetylacetonate as a precursor by depositing ca. 30 wt% Pt on MCs. These MC based materials were used for the cathode, and a standard Pt/Ketjen black catalyst (TEC10E50E, TKK Corp.) was used for the anode, in order to prepare membrane electrode assemblies (MEAs).
Current-voltage (IV) characteristics of MEAs were measured in this study. Then, ohmic loss, concentration loss, and overvoltage were further analyzed separately after ohmic resistance was found by impedance measurements. When three electrocatalyts, a standard Pt/MC, Pt/air-treated MC, and Pt/high pore volume-MC, are compared, the concentration overvoltage resulted in high with the order of a standard Pt/MC > Pt/high pore volume-MC > Pt/air-treated MC. Regarding to the activation overvoltage, it is reduced with the order of Pt/air-treated MC < a standard Pt/MC < Pt/high pore volume-MC. The correlation between the pore structure and the PEFC performance will be discussed.
References
[1] Y. Minamida et al., ECS Trans., 64(3), 137 (2014)
[2] A. Staykov et al., J. Phys. Chem. C, 118, 8907 (2014)
[3] A. Hayashi et al., Electrochim. Acta, 53(21), 6117 (2008)
Engineered Carbons Supports (ECSs) for Cathode Oxygen Reduction Reaction Electrocatalysts
Authors: Serov Alexey , Lubers Alia , McCool Geoff , McKinney Sam , Romero Henry , Zulevi Barr 
Published: February 2020

In the development of PEMFC fuel cells main attention is mainly devoted to the "active" portion of the catalysts system, the precious metal nanoparticles. While this approach has led to great improvement in specific activity, existing catalysts are still not meeting the combination of performance and cost necessary for the commercialization of PEMFC.
A key limitation to catalysts today arises from reliance on carbon blacks (CBs) supports that is a matrix for the precious metal catalyst nanoparticles, but which corrode under certain operating conditions. Carbon support modifications that rely on "top-down" graphitization of CB's have so far improved resistance to carbon corrosion, but at the cost of reduced stabilization of precious metal dissolution.
Pajarito Powder developed a "bottom-up" approach where Engineered Carbon Supports (ECSs) are made from organic precursors that yield highly graphitic materials with controllable morphology and increased resistance to corrosion. This method which is based on technologies licensed from the University of New Mexico [1,2], Northeastern University, and Los Alamos National Laboratory allows manufacture of carbonaceous powders with controllable level of graphitization with reasonably high yields. The final chemical structure (doping with heteroatoms), morphology (pore size and modality) and surface area can be precisely controlled by selection of organic molecules and types of sacrificial supports.
Pt/C catalysts made using these Engineered Carbon Supports maintain performance under carbon corrosion test protocols and thus demonstrate their utility in achieving the performance/price balance needed for commercializing PEMFCs. The catalyst characteristics and performance, as well as economics of this approach will be presented and discussed. In addition, preliminary results in synthesis and performance testing of hybrid catalysts made using platinum group metal -free (PGM-free) oxygen reduction reaction (ORR) catalysts made using the VariPore™ platform with and without Pt nanoparticles added will be presented.
[1] S. Stariha, K. Artyushkova, M. J. Workman, A. Serov, S. McKinney, B. Halevi, P. Atanassov "PGM-free Fe-N-C catalysts for oxygen reduction reaction: Catalyst layer design" J. Power Sources 326 (2016) 43–49.
[2] A. Serov, M. J. Workman, K. Artyushkova, P. Atanassov, G. McCool, S. McKinney, H. Romero, B. Halevi, T. Stephenson "Highly stable precious metal-free cathode catalyst for fuel cell application", J. Power Sources 327 (2016) 557-564.

Figure 1
Pt Nanoparticles Supported on Reduced Graphene Oxide-Carbon Black Hybrids As Robust Electrocatalysts in Polymer Electrolyte Membrane Fuel Cells
Authors: Yarar Kaplan Begüm , Haghmoradi Navid , Biçer Emre , Alkan Gursel Selmiye 
Published: February 2020

Graphene has been utilized as an alternative catalyst support for new generation polymer electrolyte membrane fuel cell (PEMFC) with many outstanding properties which are associated with its 2 dimensional (D) structure [1]. However, restacking of individual graphene layers and the aggregation of platinum (Pt) nanoparticles result in low Pt utilization and low catalytic activity [2,3]. To overcome this problem, herein Pt nanoparticles supported on reduced garphene oxide-carbon black hybrids (rGO-CB) were synthesized by one-pot microwave-assisted synthesis (Figure 1.a). In this one step approach, not only restacking of graphene sheets was avoided by using CB but also Pt nanoparticles impregnated on both graphene and CB. By means of homogenous mixing of GO and CB, 3D CB was placed between the 2D graphene sheets. Therefore, the resultant hybrid possessed higher Pt utilization. In this study, hybrid catalysts were synthesized in varying ratios of GO:CB and optimum GO:CB ratio was selected. Structure of resultant catalysts were confirmed by Raman Spectroscopy, X-ray Diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and Transmission Electron Microscopy (TEM) techniques. The average diameter of the Pt nanoparticles was about 2-3 nm from TEM micrographs (Figure 1.b). Electrocatalytic activity of prepared catalysts towards fuel cell reactions (HOR and ORR) were investigated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The hybrid electrocatalyst was exhibited a much higher HOR and ORR catalytic activities than a Pt/rGO and Pt/CB electrocatalyst by enhanced utilization of Pt. Moreover, gas diffusion electrodes and membrane electrode assemblies were fabricated by using synthesized electrocatalysts and tested in the PEMFC. Pt/rGO-CB hybrid delivered a superior PEMFC performance with a maximum power density of 1091 mW cm-2 in comparison to those of Pt/rGO and Pt/CB.

References:

1) A.K. Geim and K.S. Novoselov. Nat Mater, 6,183-91 (2007)
2) L.T. Soo, K.S. Loh, A.B. Abu Bakar Mohamad , W.R.W. Daud, and W.Y.Wong. Appl Catal A, 497, 198–210 (2015)
3) S.H. Cho, H.N. Yang, D.C. Lee, S.H. Park, and W.J. Kim. J Power Sources, 225, 200-6 (2013)

Figure 1
Functionalized TiO2 Supported Pt Nanocatalysts for Oxygen Reduction Reaction in PEMFCs
Authors: Hwang Bing Joe , Su Wei-Nien , Shieh Bing-Jen , Tsai Mon-Che 
Published: February 2020

The activity and durability of the catalysts used for the oxygen reduction reaction (ORR) are crucial to the commercialization of polymer electrolyte membrane fuel cells (PEMFCs). Pt is still the most common catalytic material for the PEMFCs. Many factors, such as the catalyst’s composition, size, shape, support, and adsorbates, are related to the catalyst’s performance; such matters have been extensively studied over the past several decades in pursuit of high ORR activity, long term stability, and reduced Pt consumption. Titanium oxidebased materials compared to traditional carbon supports have been seen as promising supports for nanosized catalysts in electrochemical applications because of their low cost, nontoxicity, and high stability in acidic and oxidative environments1,2. In this presentation, dual doping of anatase TiO2, used as a Pt catalyst support, both augments resistance against the carbon corrosion that commonly occurs in oxygen reduction reaction (ORR) Pt/C catalysts and promotes the generation of oxygen vacancies that allow better electron transfer from the nanosupport to Pt, thereby facilitating the oxygen dissociation reaction. The effects of the oxygen vacancies within the doped TiO2 nanosupport on ORR activity and stability are investigated both experimentally and by density functional theory analysis. The mass activity of Pt supported doped anatase TiO2 is shown to be 9.1 times higher than that of a commercial standard Pt/C catalyst after hydrogen reduction3. The oxidesupported nanocatalysts also show improved stability against Pt sintering under during cycling, because of strong metal−support interactions (SMSI).
References
1. VTT Ho, BJ Hwang et al., “Nanostructure Ti0.7Mo0.3O2 Support Enhances Electron Transfer to Pt:
Used as High Performance Catalyst for Oxygen Reduction Reaction”, 2011, J. Amer. Chem. Soc., 133,
11716–11724.
2. CJ Pan, BJ Hwang et al., “Tuning/exploiting Strong MetalSupport Interaction (SMSI) in Heterogeneous Catalysis”, 2017, J. Taiwan Inst. Chem. Eng., DOI.org/10.1016/j.jtice.2017.02.012.
3. MC Tsai, BJ Hwang et al., “Interplay between Molybdenum Dopant and Oxygen Vacancies in a TiO2
Support Enhances the Oxygen Reduction Reaction”, 2016, ACS Catalysis, 6 (10), 6551–6559.
Pt-Ni/WC Alloy Nanorods Arrays as ORR Catalyst for PEM Fuel Cells
Authors: Begum Mahbuba , Yurukcu Mesut , Yurtsever Fatma , Ergul Busra , Kariuki Nancy , Myers Deborah J , Karabacak Tansel 
Published: February 2020

Polymer electrolyte membrane fuel cells (PEMFCs) among the other types of fuel cells technology are attractive power sources especially for electric vehicle applications. Even though there is ongoing progress and plausible prospects of PEMFCs, there are several challenges that need to be overcome to make them successfully and economically viable. One of the most important concerns in a PEMFC is the sluggish kinetics of the cathodic oxygen reduction reaction (ORR) that requires an expensive platinum (Pt) catalyst with high weight loadings (~0.3 mg/cm2) to meet the power requirements, which is mostly responsible for the high cost of PEMFCs. Therefore, reduction in the major cost of the system can be achieved by increasing the ORR kinetics of platinum-based catalyst and by more efficient utilization of the Pt component. In addition, carbon support used in conventional Pt/C catalyst present problems including oxidation of carbon, formation of peroxide species causing degradation of polymeric membrane, and separation from the ionomer over time leading to loss of catalyst effectiveness. For this purpose, we developed vertically aligned nanorod arrays of tungsten carbide (WC) as a support and coated them with platinum-nickel (Pt-Ni) alloy shell. A glancing angle deposition (GLAD) technique was used to fabricate the WC nanorod arrays and the shell comprised of different atomic ratios of Pt:Ni prepared by a small angel deposition (SAD) technique for conformal thin film coating. We utilized a multi-source sputter deposition unit that is capable of performing GLAD and SAD in the same chamber. In our design, WC nanorods offer advantages including higher electron conductivity, thermal and chemically stability, compared to the conventional carbon support. In addition, GLAD WC nanorods are coated with SAD Pt-Ni thin film in the same deposition unit without breaking the vacuum allowing to minimize surface oxidation resulting in decreased contact resistance between Pt-Ni and WC. Moreover, Pt-Ni alloy shell can achieve superior ORR activity due to expected electronic and geometric effects. Pt-Ni/WC nanorods were deposited on glassy carbon electrodes and as well as on silicon substrates for evaluation of their electrocatalytic ORR activity and physical properties. Cyclic voltammetry and rotating disk electrode experiments were performed in a 0.1 M HClO4 electrolyte at room temperature to characterize the ORR activity and activity stability of Pt-Ni/WC nanorods. Scanning electron microscopy and X-ray diffraction methods were utilized to study morphology and crystallographic properties, respectively.
Imidazolium-Functionalized Polymer Membranes for Fuel Cells and Electrolyzers
Authors: Pellerite Mark , Kaplun Marina , Hartmann-Thompson Claire , Lewinski Krzysztof A. , Kunz Nancy , Gregar Travis , Baetzold John , Lutz Dale , Quast Matthew , Liu Zengcai , Yang Hongzhou , Sajjad Syed D. , Gao Yan , Masel Rich 
Published: February 2020

Imidazolium-functionalized styrenic copolymers have been widely studied as candidates for use as anion exchange membranes in carbon dioxide and water electrolysis systems. Recent new developments in catalytic electrode materials suggest that electrolyzers based on this technology will be commercially viable. Nevertheless, important aspects of the physicochemical behavior of these membrane materials, especially transformations occurring upon activation in strongly alkaline media, remain incompletely understood. We will discuss results from 1- and 2-D NMR, IR, IEC, and DSC studies of imidazolium-functional styrenic copolymer membrane materials recovered after activation by exposure to 1M KOH solution and reacidification in HCl. The work sheds some new light on such aspects as chemical reactions and polymer crosslinking processes occurring in strong base, although mechanistic questions remain.
Anion Conducting Block Copolymers with Partial Fluorination and Long Side Chains
Authors: Mandal Mrinmay , Liu Lisha , Ahlfield John M. , Kohl Paul A 
Published: February 2020

Anion Exchange Membranes (AEM) can be used in fuel cells and electrolyzers. The benefits include lowering the amount of platinum catalysts, simplifying water management, and improving electrochemical kinetics at the air cathode. However, the performance of AEMs is not as high as that of proton exchange membranes partially because of factors such as low ionic conductivity, poor stability at high pH, and high water uptake.
A series of multiblock copolymers including poly(arylene ether)s and poly(norbornenes) with long head-group tethers were synthesized for use in AEM fuel cells and electrolyzers. In this study, the number of head-groups per block and resulting conductivity, domain size and water uptake was studied. The improvement in performance (increased conductivity and reduced water uptake) was correlated with domain size, bound and unbound water content, and ion channel configuration.
Financial support for L.L. and J.M.A. from US Office of the Deputy Assistant Secretary of the Army for Defense Exports and Cooperation (DASA-DE&C) is gratefully acknowledged. Financial support for M.M. from ARPA-E Ionics program is gratefully acknowledged.
Synthesis and Characterization of Perfluorinated Anion Exchange Membranes
Authors: Park Andrew Michael , Owczarczyk Zbyslaw R. , Garner L. E. , Yang-Neyerlin Ami C. , Long Hai , Antunes C. M. , Sturgeon Matthew R , Lindell M. J. , Hamrock Steven J , Yandrasits Michael , Pivovar Bryan S 
Published: February 2020

The alkaline membrane fuel cell (AMFC) field continues to expand in interest. Membrane chemical stability is approaching the level required for commercial application (1), and membrane-electrode assembly (MEA) power output has reached and even surpassed 1 W/cm2 (2). In this presentation, work at NREL in the AMFC field regarding the synthesis of PFAEM and its implementation into MEAs will be summarized.
For example, our ‘Generation 2’ PFAEM, based on sulfonamide-linked hexyl trimethyl ammonium, retains greater than 90% of its ion exchange capacity (IEC) after 14 days of exposure to 2 M KOH at 80°C. Well over 200g of this material has been synthesized and is readily processed into solutions (for membrane fabrication) and dispersions (for electrode ionomer use). MEAs employing PFAEM membranes and ionomers outperform commercial AEM materials from Tokuyama with equivalent catalyst loadings (see figure). Further improvements have been attained with MEAs comprising PFAEM membranes and advanced electrodes where ~1 W/cm2 peak power and >500 hr durability in H2/O2 at 60°C were demonstrated. Performance and durability across different electrode architectures and compositions were studied via impedance, RH dependence, and cyclic voltammetry. Comparisons will be presented along with insights gained into the relative contributions of electrodes and membranes to durability and performance of AMFCs.
References
1. W.-H. Lee, Y. S. Kim and C. Bae, ACS Macro Lett., 4, 814 (2015).
2. L. Wang, E. Magliocca, E. L. Cunningham, W. E. Mustain, S. D. Poynton, R. Escudero-Cid, M. M. Nasef, J. Ponce-Gonzalez, R. Bance-Souahli, R. C. T. Slade, D. K. Whelligan and J. R. Varcoe, Green Chemistry, 19, 831 (2017).
Figure 1. Comparison between all-PFAEM and all-Tokuyama AMFC MEAs. Cell conditions comprised H2/O2 gas flows at 0.2 slpm, 60°C, 121 kpa absolute, and 100RH. Catalysts were 46% Pt/HSC for each electrode and loadings for all were 0.4 mg/cm2.

Figure 1
Quantification of Active Sites at Spinel Type Metal Oxide Catalysts by Surface Interrogation Scanning Electrochemical Microscopy
Authors: Behnken Julian , Deng Xiaohui , Tüysüz Harun , Dyck Alexander , Wittstock Gunther 
Published: February 2020

Nanostructured spinel type metal oxides are promising catalysts for the oxygen reduction reaction (ORR) in fuel cells as well as for the oxygen evolution reaction (OER) in electrolysers under alkaline conditions [1]. For a more comprehensive understanding of the oxygen electrochemistry the enlightenment of the interaction between catalyst structure and occurring surface reaction will be a major step [2]. Therefore, new experimental approaches are needed to identify material patterns that determine the electrocatalytic activity. Especially, following the oxidation states of metal atoms as function of potential and time will provide new insights into the ORR and OER mechanisms.
A versatile and powerful method in the assessment of electrocatalysts is scanning electrochemical microscopy (SECM). The spatial activity and selectivity of a catalytic material is immediately visualized by analyzing the current response of a movable probe electrode [3]. Recently, Rodríguez-López et al. [4] described a surface interrogation mode of SECM that allows the detection of adsorbates depending on time and substrate potential. This method is based on a transient feedback of a redox mediator with which a coulometric titration is performed. By integrating the current response at the tip electrode the quantification of active catalytic sites is accessible.
In this study, we apply the surface interrogation mode to detect the amount of active sites at spinel type metal oxide catalyst under alkaline fuel cell conditions. Therefore, the catalyst powder is supplied in cavity-microelectrodes which were prepared by electrochemical etching of a metal wire [5]. Through the quantification of active sites and the examination of their reactivity new insights to the ORR of alkaline fuel cells are achieved. The results will be compared to a commercial carbon-supported platinum fuel cell catalyst.
1. X. Deng and H. Tüysüz, ACS Catal., 4, 3701 (2014).
2. I. Katsounaros, S. Cherevko, A. R. Zeradjanin and K. J. J. Mayrhofer, Angew. Chem. Int. Ed., 53, 102 (2014).
3. G. Wittstock, M. Burchardt, S. E. Pust, Y. Shen and C. Zhao, Angew. Chem. Int. Ed., 46, 1584 (2007).
4. J. Rodríguez-López, M. A. Alpuche-Avilés and A. J. Bard, J. Am. Chem. Soc., 130, 16985 (2008).
5. A. Minguzzi, C. Locatelli, O. Lugaresi, A. Vertova and S. Rondinini, Electrochim. Acta, 114, 637 (2013).