bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of the Catalyst Metal Content on PEMFC Durability
Authors: Li Dongguo , Pan Yung-Tin , Wang Xiaojing , Wang Chenyu , Kim Yu Seung , Spendelow Jacob S 
Published: February 2020

The sluggish oxygen reduction reaction (ORR) continues to limit proton exchange membrane fuel cell (PEMFC) performance, while degradation of ORR catalysts contributes to poor durability. So far, carbon supported Pt (Pt/C) and Pt based alloy catalysts are the most effective for electrocatalysis of ORR. In addition to the metal particle properties, the metal to carbon ratio and type of carbon support also affect the performance and durability. Therefore, it is necessary to single out these factors and evaluate each of them while keeping other parameters consistent.
In this work, we systematically investigated the effect of cathode catalysts on the PEMFC activity and durability using a single cell membrane electrode assembly (MEA). By screening commercial Pt/C catalysts supplied by Tanaka, we were able to establish that both metal to carbon ratio (from 5% to 50% wt.) and the type of carbon support (Vulcan XC-72 and high surface area) influence the MEA performance and durability. The Vulcan XC-72 carbon catalysts (VC) showed inferior initial mass activity at 0.90 V and lower electrochemically active surface area (ECSA) but similar power density at 0.67 V compared with the high surface area carbon catalyst (HSC). Moreover, the degradation of Pt/VC was more severe than that of Pt/HSC after accelerated stress testing (AST, 30000 cycles between 0.60 V and 0.95 V). This may be related to Pt particles distribution on the surface of carbon as opposed to those in the pores. The Pt particle distribution on the HSC was also probed by the carbon monoxide (CO) stripping under different relative humidity, which further indicated that Pt particles became more accessible after AST. On the other hand, the HSC with lower metal carbon ratio (10%, 20% wt.) demonstrate better durability, which may be attributed to the higher inter-particle distance. All the data will be presented and discussed for implication in practical PEMFC operation.
Novel Pt-Co Catalyst Concept to Boost the Oxygen Reduction Reaction for Acidic and Alkaline Polymer Electrolyte Fuel Cells
Authors: Weber Philipp , Weber Daniel Jochen , Janssen Marek , Oezaslan Mehtap 
Published: February 2020

Polymer electrolyte fuel cells (PEFCs) play a critical role in clean and sustainable energy conversion technology in the near future. However, the widespread application of PEFCs is currently limited by their high loadings of costly and rare platinum group metals (PGM) and insufficient long-term durability. In the last 20 years, Pt-M alloys (M = Cu, Co, Ni) have been emerged as one of the promising catalyst materials to accelerate the sluggish kinetics of oxygen reduction reaction (ORR).[1-2] The superior ORR activity originates from ligand effects and geometric effects (lattice mismatch).[3]
In our work, we present a novel catalyst concept to efficiently modify PtxCo1-x (1<x<0) alloy nanoparticles for the ORR in acidic and alkaline media. The chemical composition and structure of the Pt-Co nanoparticles are controlled by variation of the synthetic parameters during the industrial relevant wet impregnation method.
Our catalyst concept is based on the surface rearrangement of the Pt-Co alloy nanoparticles to form core-shell or inverse core-shell structures by tuning the electrochemical parameters. Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and CO chemisorption were used to understand the different stages of the surface rearrangement of Pt-Co alloy nanoparticles. In fact, 12 to 30 – fold increases in Pt surface area-based specific activity and 6 to 11 – fold higher Pt mass-based activities are achieved with our catalyst concept compared to commercial Pt/C. The simple switching between core-shell and inverse core-shell nanoparticles creates an efficient bifunctional catalyst to tune the reactivity and selectivity for the ORR in acidic and alkaline media. The observed activity improvement allows to reduce the Pt loading by a factor of at least 6, thus exceeding the DOE targets from ~0.4 to below 0.1 mg cm-2 of PGM loading for ORR.[4]
Based on our results, we present a novel Pt-Co catalyst concept to boost the electroreduction of oxygen for alkaline and acidic PEFCs.
References:
[1] T. Toda, H. Igarashi and M. Watanabe, Journal of The Electrochemical Society, 1998, 145, 4185-4188.
[2] M. Oezaslan, F. Hasché and P. Strasser, The Journal of Physical Chemistry Letters, 2013, 4, 3273-3291.
[3] B. Hammer and J. K. Norskov, Advances in Catalysis, 2000, 45, 71-129.
[4] https://www.energy.gov/eere/fuelcells/downloads/fuel-cell-technologies-office-multi-year-research-development-and-22.
Preparation of Various Platinum Rare Earth Metal Alloy Nanoparticles and Their ORR Performance
Authors: Brandes Benedikt Axel , Hu Yang , Cleemann Lars Nilausen , Li Qingfeng , Jensen Jens Oluf 
Published: February 2020

Polymer electrolyte hydrogen fuel cells and their application can contribute to a sustainable future energy landscape. A significant contribution to their costs originates from the platinum-based catalyst. To this date platinum cobalt alloy nanoparticles are the industry standard catalysts to facilitate the sluggish Oxygen reduction reaction (ORR). It has been demonstrated that platinum rare earth metal alloy nanoparticles have high ORR activities which is retained during accelerated stress tests (AST) [1].
The very negative reduction potential of the rare earth metals (-2.0 V to -2.5 V) pose great challenges on the synthesis of its respective platinum alloys with the right properties such as alloy phase and particle size distribution [2].
Last year we showed the successful synthesis of small Pt3Y alloy nanoparticles using potassium vapor as the reducing agent at mild temperatures around 400 °C. Herein we demonstrate the synthesis of platinum alloy nanoparticles of gadolinium, cerium and lanthanum using the same method. Furthermore, we investigated the phase stability of different alloys towards acid leaching and the ORR performance before and after AST.
The Pt3Y alloy phase appears to be stable against acid leaching, in contrast to Pt2Y and all of the synthesized alloy phases of Gd, Ce and La. However, a lattice strain (shown by XRD) and traces of the respective rare earth element in the catalyst surface (shown by XPS) in combination with promising ORR results justify further investigation into these catalysts.
[1] Hernandez-Fernandez, P., Masini, F., McCarthy, D. N., Strebel, C. E., Friebel, D., Deiana, D., ... Chorkendorff, I. (2014). Mass-selected nanoparticles of PtxY as model catalysts for oxygen electroreduction. Nature Chemistry, 6(8), 732–738. https://doi.org/10.1038/nchem.2001
[2] Knudsen, B. P. (2016). Synthesis of Platinum Rare Earth Alloy Catalysts for Fuel Cells.
Study of Alkaline Durability and Anion Conductivity Using New Expanded Pyridinium Polymer with Self-Assembly Ability
Authors: Motoishi Yuki , Fujigaya Tsuyohiko 
Published: February 2020

Polymer electrolyte fuel cells (PEFCs) are promising for practical use as the next generation clean power source. Since the anion exchange membrane fuel cell (AEMFC) operates in a basic environment, cost reduction is possible because non-platinum catalysts such as iron can be used. In addition, since the activation overpotential of oxygen reduction is smaller than that of a proton exchange membrane fuel cell (PEMFC), it is attracting attention as an alternative to PEMFC [1]. However, for practical use, further improvement of the anion conductivity and alkaline durability of the anion exchange membrane (AEM), in which a hydroxide ion (OH-) acts as an anion conductor is required. General strategy to promote anion conduction has been to move cation side chain freely, however problem is that the decomposition reaction occurs due to the attack from the OH-.
In this research, a new strategy of “self-organizing cation units to form channel structure” is studied to improve alkaline durability and anion conductivity at the same time. It is considered that this self-assembly strategy can achieve both the low mobility of cation to suppress from OH- attack and the anion conduction path. To realize this concept, an extended pyridinium monomer was newly designed with reference to extended pyridinium, one of the heteropolycyclic aromatic cation. Since strong π-π interactions have been reported between extended pyridiniums, introducing an extended pyridinium into the polymer will suppress the molecular motion of the anion conduction site and will induce the formation of self-assembled channels.
A new extended pyridinium monomer (TVP) was synthesized according to the synthesis method of the extended pyridinium salt of Katrizky et al [2]. Synthesized TVP was obtained as a pale yellow powder. From the 1H-NMR spectrum, vinyl group and aromatic peaks were observed, and it was confirmed that the monomer possessed high purity. The homopolymer (PTVP) was synthesized by free radical solution polymerization of TVP. Synthesized PTVP was obtained as a yellow solid. In 1H-NMR measurement, vinyl peaks were disappeared and the broadening of aromatic ring peaks were observed, suggesting that the free radical polymerization was taken place. Since PTVP is brittle and difficult to use as a film probably due to its rigid molecular structure, the introduction of a copolymer monomer was examined. When styrene and isoprene reported as an anion exchange membrane were examined as a copolymerization monomer, copolymer of PTVP-styrene and PTVP-isoprene were obtained, respectively. Although a PTVP-styrene copolymer film was brittle, a PTVP-isoprene copolymer film was obtained as a free standing film. Alkaline stability and anion conductivity of the films will be discussed.
[1] G. Merle; M. Wessling; K. Nijmeijer, J. Membr. Sci, 2011, 377, 1-35.
[2] A. R. Katritzky; Z. Zakarial; E. Lunt; P. G. Jones; O. Kennard, J. Chem. Soc., Chem. Commun., 1979, 6, 268-269.
Comparison of Direct Sodium Borohydride Fuel Cells with Cation and Anion Exchange Membranes
Authors: Swider-Lyons Karen , Garsany Y , Hjelm R. M. E. 
Published: February 2020

Direct sodium borohydride fuel cells (DBFCs) present challenging electrochemistry due to the complexity of the electrocatalytic reactions at the cathode and anode plus the lack of a suitable membrane. The complex 8-electron oxidation reaction for sodium borohydride (NaBH4) to borate (BO2) at the anode is most efficient in alkaline electrolyte. However, the reduction of peroxide (H2O2) at the cathode is best carried out in acid electrolyte. The selection of whether to use an acidic or alkaline membrane has not been clear. Most researchers have used a perfluorosulfonic acid proton exchange membrane (PEM) as the membrane separator in the cells, but this becomes highly resistive when it becomes exchanged with sodium ions from the NaBH4, serving as a cation exchange membrane (CEM). The standard membrane for DBFCs has been Nafion 117, which is 7-mils thick. This relatively thick membrane has been chosen by DBFC researchers to improve the separation between the acidic cathode electrolyte and the alkaline anode electrolyte. We determine herein how H2O2-DBFCs performance is improved when made with a commercial 0.8-mil-thick anion exchange membrane (AEM) or a 0.8-.mil-thick CEM, in comparison to cells with 7-mil-thick CEMs.
The H2O2-DBFCs design is based on a well-characterized flow-cell design (1). Both the anode and cathode catalyst layers are prepared with carbon-black supported Pt electrocatalyst (Pt/CB, 50 wt. % Pt). The compartments are separated by either a Na-exchanged CEM (Nafion® 117 or Nafion HP) or AEM (Fumasep FAA-3-20). The electrochemical performance of the cell and its impedance are measured at an operating cell temperatures of 25 and 60 ° C.
H2O2-DBFCs with the 0.8-mil-thick AEM have a marked improvement of the current density of the standard cells with the 7-mil-thick Nafion 117 membrane below 0.8 V at 25 ° C (Figure 1a). There is also a performance gain over the cell with the Nafion 117 membrane when the0.8-mil-thick Nafion HP is used, suggesting that the standard cells are highly limited by the resistance of the membranes. The trend changes at the more relevant operation condition of 60 ° C (Figure 1b). The H2O2-DBFCs with the Nafion HP membrane are the best performers with a maximum power density of ~600 mW cm-2, followed by the cells with the AEM (~500 mW cm-2), and then the Nafion 117 (~360 mW cm-2).
The presentation will discuss these results, in combination with electrochemical impedance spectroscopy results, to reconcile how the thinner membranes improve cell performance and also affect the charge-transfer reactions at the electrodes.
References:

M. E. Hjelm, Y. Garsany, R. W. Atkinson III, R. O. Stroman, K. E. Swider-Lyons, C. Lafforgue and M. Chatenet, ECS Trans, 80, 1033 (2017).

Figure 1
(Invited) Large Scale PEM Electrolysis for Industrial Applications
Authors: Lettenmeier Philipp 
Published: February 2020

Polymer electrolyte membrane (PEM) based water electrolysis for hydrogen production is widely considered as a key technology to decarbonize our fossil-based energy system. Due to its highly dynamic behavior PEM electrolyzer systems accomplish the requirements to be operated with renewable energy-based electricity such as wind or PV power. The production of chemical energy carrier such as hydrogen enables the integration of renewable energy into industrial processes and mobility and therefore sector coupling.
Changes need to be made in energy production to achieve the long-term goal of the Paris agreement, to keep global warming below 2°C [1], and to reach the CO2 target by 2050 whereas hydrogen could make up to 20% of the abatement [2]. Reaching this target, a transition of the fossil-based hydrogen production towards green hydrogen produced by electrolysis is an essential factor. Therefore, PEM electrolyzer systems have to reach industrial relevant sizes and significant cost reduction.
Siemens Hydrogen Solution has released its next generation of PEM electrolyzer system Silyzer 300 in 2018. By choosing a highly modular concept, Siemens AG is offering hydrogen generation plants from 10 to 100 MW based on PEM technology. It allows the full utilization of economy of scale effects also for customized solutions. However, in order to achieve the expansion targets that are published in various studies of several hundreds of Megawatts per year, it is essential to achieve further progress in regards to cost reduction, efficiency increase and overall hydrogen production plant optimization.
Together with our partners in H2Future, an FCH JU funded project, a demonstration plant is currently being built and will be operated at the largest steel production site of voestalpine Group in Linz, Austria. In a nutshell, the fundamental goal of H2Future is to demonstrate that an industrially integrated PEM electrolyzer system is able to produce green hydrogen and provides grid services at the same time.
[1] https://ec.europa.eu/clima/policies/international/negotiations/paris_de
[2] Hydrogen Council, Hydrogen Scaling up: A sustainable pathway for the global energy transmission, Nov. 2017

Figure 1
(Amazon Catalyst at ECS Grant Winner)
Carbon Catalysts for Cost-Efficient Hydrogen Production in PEM Electrolyzers
Authors: Das Rajib Kumar , Vasilyeva Svetlana V , Zhao Chong , Rinzler Andrew G. 
Published: February 2020

Exposure of single-walled carbon nanotubes (CNTs), as well as other lower cost layered graphitic carbons (LGCs), to acidic intercalants, in combination with low voltage electrochemical cycling, induces in these materials hydrogen evolution activity that initiates at near zero overpotential and is on par with that of platinum catalysts.1 These results encouraged the further development and testing of the CNT catalyst in a PEM water splitting electrolyzer prototype. Once activated, the CNT cathode demonstrated 1 A/cm2 of HER current at 1.64 V, comparable to a similarly tested commercial Pt-loaded cathode. While carbon nanotubes are not intrinsically scarce, the single wall nanotubes used in these electrode tests remain relatively expensive. Commercial significance would benefit from a demonstration of comparable performance from activated lower cost layered graphitic carbons in a PEM electrolyzer prototype.
The following LGC materials, having a combination of high electrical conductivity, large pore volumes, and high specific surface areas, were tested in terms of their ability to achieve low HER overpotential during the activation process: microcrystalline graphitic particles, Vulcan XC-72 carbon, highly graphitized stacked-cup tubular carbon nanofibers (CNFs), and carbon needle felt. CNF electrodes demonstrated slightly higher mass basis activity than that of the other tested LGCs in acid electrolyte in a standard three-terminal electrochemical cell.
Here we report excellent performance from activated CNF cathodes, prepared by a scalable spray-coating method, in our PEM electrolyzer prototype (IrRuOx as anode catalyst). As anticipated, a control MEA, based on the non-activated CNF cathode and tested in PEM electrolyzer under identical conditions, showed poor performance, indicating a low electrocatalytic HER activity of the electrode.
The activated CNF cathode-based PEM electrolyzer achieved 1 A/cm2 at 1.78 V, while a control commercial MEA with Pt-loaded cathode/IrRuOx anode (a high Pt catalyst loading of 3 mg/cm2 cathode, Fuel Cells Etc) tested in the same PEM electrolyzer cell demonstrated 1 A/cm2 at 1.7 V.
Acknowledgements.
This work is supported by Amazon through ECS Amazon Catalyst Program.
References:

R. K. Das, Y. Wang, S. V. Vasilyeva, E. Donoghue, I. Pucher, G. Kamenov, H.-P. Cheng, A. G. Rinzler, ACS Nano, 2014, 8 (8), 8447–8456.
Activity and Stability of Iron-Based Spinel Oxides for Oxygen Evolution Reaction
Authors: Jiang Wulv , Liu Weiyan , Tang Fei , Gan Lin 
Published: February 2020

In order to reduce the overpotential of oxygen evolution reaction (OER) and improve energy utilization efficiency of water splitting, spinel oxides have attracted considerable interests in OER electrocatalysis due to their potentially both high activity and high stability. Inspired from highly active Fe sites identified in Fe-contained (oxy)hydroxides, there are particular interests in developing Fe-based spinel oxides, yet correlations between their surface structures and OER activities still remain elusive. In addition, the electrochemical stability of spinel oxides has not received adequate concerns as usually deemed stable in alkaline solution. Recent studies have shown a substantial metal ion dissolution (e.g. Fe dissolution in Fe-containing metal oxides) during OER electrocatalysis, yet a fundamental insight into the metal dissolution process, its effect on the OER stability, and an efficient way to control the metal dissolution remain largely unaddressed.
Herein, we reveal the atomic and electronic structures (particularly the metal-oxygen hybridization) of a series of Fe-based spinel oxide nanoparticles (XFe2O4, X=Mn2+, Fe2+, Co2+, and Ni2+) by using aberration-corrected scanning transmission electron microscope, electron energy loss near edge spectroscopy, in-situ Raman spectroscopy combined with density functional theory (DFT) calculations. We show that substituting different divalent cations in the octahedral sites results in increasing metal-oxygen hybridization and thereby increasing activity in the order of Mn2+<Fe2+<Co2+<Ni2+, with the most active Ni-Fe spinel oxide even superior to a benchmark IrO2 catalyst. DFT calculations suggest that the divalent cation X2+ in the octahedral sites dominantly contributes to the metal-oxygen hybridization, suggesting that it is the divalent cation rather than the trivalent Fe3+ that constitutes the active site of the Fe-based spinel oxides.
We further compared the electrocatalytic stability of the Fe-based spinel oxide by using combined microscopic and spectroscopic methods by using in-situ electrochemical quartz crystal microbalance (EQCM) and identical-location transmission electron microscopy (IL-TEM). Distinctly different extents of metal dissolution were observed in the four spinel catalysts, showing significant metal dissolution (Mn/Fe) in MnFe2O4 and Fe3O4 whereas much less metal dissolution (Fe) in CoFe2O4 and NiFe2O4. Moreover, the Fe dissolution under potential-dynamic condition in the spinel oxides also shows quite different potential dependences, contributing to their different catalytic stabilities. Based on these results, we further developed a robust strategy to suppress Fe dissolution and thus improve the stability of the Fe-based spinels by intentionally adding Fe ions in the electrolyte.
Rational Design of Perovskite Oxide Nanofibers As Electrocatalysts for Oxygen Evolution Reaction
Authors: Zhao Bote , Liu Meilin 
Published: February 2020

Oxygen evolution reaction (OER) is a necessary reaction for several promising energy storage and conversion technologies such as metal-air batteries, reversible fuel cells, water splitting for hydrogen production, and carbon dioxide reduction. Since the kinetics of the four-electron transfer process is notoriously sluggish, the development of highly efficient OER electrocatalysts is urgently needed. In this presentation, we will report our recent progress in design, synthesis, and characterization of perovskite oxides as highly efficient and robust electrocatalysts for OER, including double perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+
δ (PBSCF),[1] single perovskite La0.6Sr0.4Co1–xFexO3–δ
[2] nanofibers, and surface-modified perovskite nanofibers. The remarkable electrocatalytic activity of PBSCF with A/B site co-doping is attributed to the Fe site, as rationalized by theoretical computations and confirmed by experimental measurements. Further, the nanofibers of these materials (with a diameter of ~20 nm) demonstrate a significant enhancement in intrinsic activity while maintaining excellent durability, achieving performance superior to those of the commercial IrO2 catalyst. Moreover, a unique surface-modification strategy has been developed recently, resulting in more than two orders of magnitude enhancement in intrinsic activity of PBSCF nanofibers, which is more than three orders of magnitude higher than that of IrO2.
[1] Zhao, B. T., Zhang, L., Zhen, D. X., Yoo, S., Ding, Y., Chen, D. C., Chen, Y., Zhang, Q. B., Doyle, B., Xiong, X. H., Liu, M. L. A tailored double perovskite nanofiber catalyst enables ultrafast oxygen evolution. Nat. Commun.
8, 14586 (2017).
[2] Zhen, D. X., Zhao, B. T., Shin, H. C., Bu, Y. F., Ding, Y., He, G. H., Liu, M. L. Electrospun porous perovskite La0.6Sr0.4Co1–xFexO3–δ nanoﬁbers for efﬁcient oxygen evolution reaction, Adv. Mater. Interfaces
4, 1700146 (2017).