bluuebunny/crossref_metadata_2025_split huggingface dataset:
Manufacturing Process of Electrode Films
Authors: Banas Charles Joseph , Aponte Bryan , Pasaogullari Ugur 
Published: December 2020

Rotating disk electrode experiments form a key experimental characterization technique for measuring electrocatalyst performance and durability. Numerous studies have been performed to gauge catalyst performance and suitability for polymer electrolyte fuel cells. However, those studies can show for a wide range of performance measurements for the same catalyst.1

Standard rotating disk electrode testing protocols have been documented, and used repeatedly in available literature.1 Little research has been devoted to the catalyst film preparation however. Catalyst films are formed from the drying of a catalyst solution consisting of a catalyst-water-ethanol-Nafion solution on a glassy carbon working electrode surface.
Experiments within our group show large variation in catalyst performance characterization for catalyst films dried under ambient conditions, which result from inconsistent and non-uniform catalyst distribution on the electrode surface. To promote consistent film production, a controlled environmental chamber was constructed. The objective of this chamber was to establish conditions for equalizing water and alcohol evaporation in the catalyst solution by controlling relative humidity. Catalyst film quality was shown to improve when using the chamber, improving film catalyst distribution uniformity, along with electrochemical catalyst performance. This paper will detail the construction and the environmental control chamber, and the effect of environmental conditions on the catalyst film quality and electrochemical measurements.
Reference
1. S. Kocha et al., “Best Practices and Testing Protocols for Benchmarking ORR Activities of Fuel Cell Electrocatalysts Using Rotating Disk Electrode,” Electrocatalysis, vol. 8, no. 4, pp. 366–374, Jul. 2017, doi: 10.1007/s12678-017-0378-6.

Figure 1
Influence of Quaternary Ammonium Cation Chemistry on Interfacial Morphology of Anion-Conducting Block Copolymers at a Silver Interface
Authors: Buggy Nora Catherine , Du Yifeng , Kuo Mei-Chen , Coughlin E. Bryan , Herring Andrew M. 
Published: December 2020

The heterogeneous microstructure of the electrode in polymer electrolyte-based electrochemical devices features a complex mixture of interacting species, including ionomer, catalyst particles, and typically a conductive carbon support. The triple-phase boundary which forms between these three components significantly impacts the transport of water, ions, and reactant and product species to and from reaction sites. Hence, overall performance of the electrochemical device is significantly impacted by the structures that form in the electrode, which are driven by interactions between the ionomer and catalyst components. It is known that interactions at the ionomer-catalyst interface can facilitate restructuring of the ionomer morphology, ultimately affecting transport networks. Therefore, a more fundamental understanding of ionomer-catalyst interactions can aid in the development of ionomer chemistries that result in desirable interfacial morphologies and electrode structures.
Since alkaline systems can leverage the ORR capabilities of non-noble metal catalysts beyond Pt, this work focuses on interactions with silver, which has been shown to have ORR activity akin to Pt catalysts. Our previous work has shown that the quaternary ammonium cations trimethylammonium (TMA) and methylpiperidinium (MPRD) both interact with silver and can affect bulk properties of the ionomer, including crystallinity and water uptake. To continue this study, a set of tunable block copolymers, post-functionalized with either TMA or MPRD, are used to investigate how cation chemistry influences the resulting interfacial morphology of the ionomer. Model interfaces between ionomer thin films and silver surfaces are fabricated and studied using a combination of environmental GISAXS and AFM to assess morphological characteristics such as domain size and orientation under relevant electrochemical device conditions. These efforts will lead to a better understanding of the ionomer-catalyst interface and will provide key insight toward rationally designing block copolymers for the alkaline electrochemical devices.
Single Site Substitution in 2D Molybdenum Carbide: Applications in Electrocatalysis
Authors: Kuznetsov Denis A. , Chen Zixuan , Kumar Priyank V. , Abdala Paula M. , Fedorov Alexey , Müller Christoph R. 
Published: December 2020

Two-dimensional carbides and nitrides (MXenes) represent an excellent platform for the fundamental catalysis studies due to their well-defined and tunable structure and theoretically predicted high activity in numerous catalytic reactions.1 However, the scope of metals capable of forming thermodynamically stable MXenes is limited mostly to early transition metals, making the investigation of properties inherent to mid or late transition metal carbides/nitrides challenging. Here, we present the synthesis and structural characterization of the Mo2CTx
:M phases (M = Co, Fe; Tx
= O, OH, F surface terminations), where M substituents occupy molybdenum positions in the Mo2CTx
lattice, providing isolated Co/Fe sites. Our experimental and DFT studies demonstrate that metal M substitution renders Mo2CTx
:M carbides active catalysts for the hydrogen evolution reaction. Overall, our work expands the compositional space of the MXene family by introducing materials with isolated metal sites incorporated into the matrix of Mo2CTx
. The results discussed here highlight the general applicability of the developed synthetic approach and illustrate that tailoring the properties of MXenes for a specific application can be achieved via targeted substitution of the host metal.
(1) Anasori, B.; Lukatskaya, M. R.; Gogotsi, Y., Nat. Rev. Mater.
2017,
2, 16098.
Catalyst Assessments and Device Incorporation in Low Temperature Electrolysis
Authors: Alia Shaun M , Reeves Kimberly Shawn , Ha Mai-Anh , Larsen Ross E , Cullen David A. 
Published: December 2020

Although hydrogen has a significant role in transportation and agriculture, its use in energy consumption overall has been limited, particularly when produced through electrochemical water splitting. With decreasing electricity prices, electrolysis cost reductions can be achieved and allow for an opportunity for greater use.(1) While load following renewable power sources can reduce feedstock cost, further cost reductions rely on minimizing the capital cost by reducing the platinum group metal (PGM) content.(2) Efforts are needed to understand and mitigate electrolyzer degradation, particularly when accounting for lower PGM loadings and intermittent operation.
Previous efforts have developed accelerated stress tests focused on catalyst layer and interfacial loss with standard material sets. (3) Expanded studies have incorporated advanced materials, including higher surface areas, different oxide compositions, supports, and multicomponents. Kinetic improvements were found to lessen load requirements and can mitigate catalyst loss. Cell performance loss during extended operation, however, tended to qualitatively correspond to ex-situ dissolution rates of less stable materials leading to accelerated catalyst layer thinning, migration into the membrane, and interfacial tearing, as determined in post-mortem electron microscopy analysis.
While individual components dictate cell-level performance and durability, how components are integrated into membrane electrode assemblies was found to have an impact on catalyst layer properties and electrolyzer performance/durability. Catalyst layers were modified using an ultrasonic spray approach due to the number of variables that could be tuned. While changes to these variables affect several properties and loss mechanisms, trends were found with regards to how catalyst-ionomer integration and catalyst layer uniformity affected performance nonidealities and how losses grew during extended operation. These approaches are useful in diagnostics, to identify and mitigate lower performance and durability. Understanding catalyst layer formation and the relationship between catalyst layer properties and electrolyzer performance/durability is critical to establishing baselines and better informing catalyst development and fabrication efforts.
[1] B. Pivovar, N. Rustagi and S. Satyapal, The Electrochemical Society Interface, 27, 47 (2018).
[2] K. Ayers, N. Danilovic, R. Ouimet, M. Carmo, B. Pivovar and M. Bornstein, Annual Review of Chemical and Biomolecular Engineering, 10, 219 (2019).
[3] S. M. Alia, S. Stariha and R. L. Borup, J. Electrochem. Soc., 166, F1164 (2019).
Interface Engineering: On the Impact of Micro-Porous Layers on Polymer Electrolyte Water Electrolysis Performance
Authors: Schuler Tobias , Schmidt Thomas J. , Buechi Felix N. 
Published: December 2020

In polymer electrolyte water electrolysis (PEWE), operational cost represents the main cost fraction. Losses induced by kinetic, ohmic as well as mass transport overpotentials limit cell efficiency and in turn lead to lower volumetric power density and higher energy consumption.
The interplay of porous transport layer bulk/surface properties1,2, providing thermal and electrical conductivity as well as fluid management between bipolar plates and catalyst layer, and cell efficiency is a disputed question in literature. Governing design parameters for porous transport layers, as well as fundamental limiting process haven’t been addressed so far This study aims to close the gap between fundamentals and highly efficient PTL microstructure design.
A series of four different PTL materials with different MPL types was analysed3. Structural properties, characterized by X-ray tomographic microscopy (XTM) were correlated to in-depth electrochemical analysis. Performance of the novel PTLs was probed by comparison to state-of-the-art PTL materials and stack technology. The superior surface properties of the microporous-layer enables the use of thin membranes with Ti PTLs for the first time.

References

S. A. Grigoriev, P. Millet, S. A. Volobuev and V. N. Fateev, International Journal of Hydrogen Energy, 2009, 34, 4968-4973.

T. Schuler, R. De Bruycker, T. J. Schmidt and F. N. Büchi, Journal of The Electrochemical Society, 2019, 166, F270-F281.

T. Schuler, J.M. Ciccone, B. Krentscher, F. Marone, C. Peter, T.J. Schmidt, and F.N. Büchi, Hierarchically Structured Porous Transport Layers for Polymer Electrolyte Water Electrolysis, Advanced Energy Materials, 2020, 10, 1903216.

Figure 1
Iron Contamination and Local Distribution within a 50 Cm Single-Channel Proton Exchange Membrane Water Electrolysis Cell
Authors: Immerz Christoph , Singer Matthias , Hasché Frédéric , Bensmann Boris , Suermann Michel , Hanke-Rauschenbach Richard , Oezaslan Mehtap 
Published: December 2020

Proton exchange membrane water electrolysis (PEMWE) will play a major role in the clean and versatile energy conversion in the near future.[1] Offering scalable solutions of PEMWE are of high industrial interest and have to provide a sufficient durability and reliability.[2] To achieve this, a better understanding of the impact of contamination on the PEMWE performance is very crucial. In this context, the membrane electrode assembly (MEA) is susceptible to several degradation processes like metallic cations (Fe3+/2+ stemmed from tubing). In particular, soluble and reduced iron species forming by Fenton reaction might attack via radicals the MEA.[3,4] Hence, analyzing impurities and their resulting impacts on e.g. the proton transport resistance and degradation mechanisms at different length scales and local distributions are of large interest.
In this work, the influence of spatially resolved iron contamination in MEAs on the cell performance has been investigated using a 50 cm single-channel PEMWE cell equipped with local current density measurement setup.[5] Adding defined amounts of FeSO4 via the anode inlet feed, the changes on the three main regimes of overpotentials, i.e. kinetic, ohmic and mass transport, is correlated with the current density mapping as well as local and global electrochemical impedance spectroscopy (EIS) measurements. Ex-situ scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) are used to detect the distribution and agglomeration of iron species within the MEA.
With this combined approach of electrochemical and ex-situ physical methods, the contamination pathways and their effects of (spatially resolved) iron contamination on the overall performance of MEA are investigated as a function of degree of contamination and operating conditions. Especially, the (spatially resolved) overpotential-specific degradation processes along the 0.5 m channel, which mimic a technically relevant stack size, allow us to conclude on the optimum design of MEA, targeting use of mitigation strategies and development of accelerated stress test protocols.
[1] M.A. Pellow, C.J.M. Emmott, C.J. Barnhart, S.M. Benson, Energy Environ. Sci. 8 (2015) 1938-1952.
[2] P.K. Shen, C.-Y. Wang, S.P. Jiang, X. Sun, J. Zhang, Electrochemical Energy: Advanced Materials and Technologies, CRC Press, 2015.
[3] X. Wang, L. Zhang, G. Li, G. Zhang, Z.-G. Shao, B. Yi, Electrochim. Acta 158
(2015) 253-257.
[4] C. Rozain, P. Millet, Electrochim. Acta 131 (2014) 160e167.
[5] C. Immerz, B. Bensmann, P. Trinke, M. Suermann, R. Hanke-Rauschenbach, JECS 165 (16) (2018)
Manufacturing Challenges and Opportunities for PEM Electrolysis
Authors: Capuano Christopher , Ayers Kathy , Manco Judith , Wiles Luke , Keane Alex , Dalton Luke 
Published: December 2020

Hydrogen generation via electrolysis has gained much attention internationally as not only a sustainable source of fuel for the transportation, but as a carrier of energy to capture stranded renewable due to the carbon-free chemical cycle and response characteristics of the technology. The barrier to entry preventing this technology from being widely adopted is the overall cost associated with both the upfront capital expense as well as the operating cost incurred over the product life. The majority of this cost is driven by 1) low electrical efficiencies due to the high ohmic resistance of thicker membranes required by electrolysis systems to electrochemically compress generated hydrogen for storage and the overpotential associated with the water splitting oxygen evolution reaction (OER) catalysts typically used, 2) high cost of system and cell stack materials, which need to be durable for up to 100,000hrs at a potential of 2V in both reducing and oxidizing environments, and 3) the lack of a robust supply chain for high volume manufacturing to further drive down cost through economies of scale.
With 95% of hydrogen currently being produced through the reformation of cheap natural gas, significant cost reductions are necessary for electrolysis to become a viable alternative to the incumbent. Commercial proton exchange membrane (PEM)-based electrolysis has reached scales of several hundred kg/day, providing a relevant pathway for industrial scale hydrogen generation with tremendous opportunity for continuing cost reduction by leveraging system and manufacturing scaling laws by leveraging advancements in PEM fuel cell materials, manufacturing, and analysis tools. Order of magnitude improvements in some of the highest cost elements are easily achievable and with more research funding being directed towards hydrogen production, the realization of these reductions are occurring at a faster rate. While many improvements in stack design and materials of construction have been identified and implemented, there are still numerous opportunities to explore that would move electrolysis towards a viable, cost-effective alternative to natural gas reformation. This talk will describe some of the areas of success, where research is still needed, and ultimately how each of these improvements translate into cost and the path to reformation parity.
The Relationship between Activity and Durability of Surface Area and Catalyst Loading of IrOx Anode Catalyst in Proton Exchange Membrane Water Electrolysis (PEMWE)
Authors: Fujita Mitsuharu , Arima Ikkei , Goto Hiroki , Konaka Saki , Tada Tomoyuki 
Published: December 2020

The R&D of highly active and durable anode catalysts for the oxygen evolution reaction (OER) is very important for high efficiency Proton Exchange Membrane Water Electrolysis (PEMWE). The reason is that the high overpotential of OER reaction is the main factor of the energy loss. At present, the use of highly active and durable iridium catalyst is one of the resolutions for reducing overpotential. From the perspective of iridium production, not only is limited the producing area, but production amount is limited because iridium is by-product of PGM mine in South Africa. Therefore, in order to popularize hydrogen production by large-scale PEMWE, it is necessary to to achieve the high performance with the minimum amount of iridium material. In this study, we report the activity and durability of catalysts coated membranes (CCMs) based on the IrOx catalyst surface area and loadings.
High surface area IrOx catalyst (SA100) and a low surface area IrOx catalyst (SA5) from Tanaka Kikinzoku Kogyo K.K. were used for OER catalysts in this study. These catalysts were characterized by ICP-AES analysis, powder XRD, N2-BET, and SEM images. CCMs were prepared by spray-coating and hot-press with IrOx catalysts at the anode and carbon supported platinum at the cathode (TEC10E50E, Tanaka Kikinzoku Kogyo K.K.). Single cell electrochemical analysis including initial polarization curves, cyclic voltammetry, and durability tests (at 50℃, 2A/cm2) and SEM cross section images was studied for all CCMs.
The SEM images of the CCMs microstructure near the catalyst layer were shown in Figure 1-A and 1-B. The particle size of IrOx (SA100) was found to be ca.5nm. For IrOx (SA5), the particle size was less than 2nm. The cell voltages focused on the iridium loadings were confirmed in Figure 2-A and 2-B. Although there was significant difference in SEM cross section images of catalyst layers, the trend obtained for the SA100 was consistent with the trend in the SA5. The IrOx loaded from 0.1 to 0.3 mg/cm2 range exhibited a gradual increase in cell potential. Furthermore, the catalytic durability and CV studies using single cells at 2A/cm2, 50℃ will be discussed. This report will be one of the valuable source of information for CCM design for general PEMWE.

Figure 1
Surface and Grain Boundary Effect in the Local Ionic Transport of (La,Sr)(Co,Fe)O3 Observed By in Situ Scanning Probe Microscopy
Authors: Kang Hung-Sen , Barkhordarian Orbel , Lee Min Hwan 
Published: December 2020

Ionic transport in solid oxides lays the fundamentals of solid-state electrochemical energy and sensor devices. The transport is understood as a thermally activated hopping of point defects (i.e. oxygen vacancies), and its kinetics is highly dependent upon the bonding state of the ionic species with their surrounding lattice environment. While the heterogeneous ionic transport in polycrystalline oxides has been studied for decades, the exact role of interfaces and surfaces in the transport is still an open question.
In this presentation, we report our recent effort to directly observe the ionic transport in (La,Sr)(Co,Fe)O3 (LSCF), the most widely used cathode material for intermediate temperature solid oxide fuel cells, by the use of Kelvin probe force microscopy (KPFM) and conductive atomic force microscopy (CAFM). By providing a positive bias to the tip-LSCF contact in a CAFM mode, oxygen vacancies are generated via oxygen evolution reaction and the amount of newly formed oxygen vacancies are quantified by measuring the total charge transferred during the bias application. Subsequently, the evolution of charge distribution (and thus the distribution of oxygen vacancies) are observed by KPFM at various temperatures. The resulting KPFM maps were analyzed to gauge the heterogeneous ionic transport, in particular, around the grain boundary (GB) areas, and the effective ionic diffusivity within each grain and across GBs were to quantified. From this practice, a direct observation of charge transport was made to confirm the ionic diffusion across GBs is indeed much slower than those within each GB, and the effective resistance in ionic transport through GB was quantified.
In addition, 3D KPFM maps were also acquired by an in situ etching with a diamond-coated tip, providing the charge distribution map with depth. From this, it was directly observed that the ionic transport along the surface (~5 nm) is significantly higher than the transport through the interior of a grain. In combination with a simplified Monte Carlo simulation, the ionic diffusivity and its activation energy were quantified for both surface and bulk diffusion, respectively.
The authors acknowledge the support by U.S. National Science Foundation CAREER Award (DMR 1753383).
(Invited) Switching on Electrocatalytic Activity for Synthetic Fuel Production
Authors: Irvine John T.S. 
Published: December 2020

The greatest challenge facing Solid oxide cells (SOC), in both fuel and electrolysis cell modes (i.e SOFCs and SOECs) is to deliver high, long-lasting electrocatalytic activity while ensuring cost and time-efficient electrode manufacture. Ultimately, this can best be achieved by growing appropriate nanoarchitectures under operationally relevant conditions, rather than through intricate ex situ procedures.
In our approach, metal particles are grown directly from the oxide support though in situ redox exsolution. We demonstrated that by understanding and manipulating the surface chemistry of an oxide support with adequately designed bulk (non)stoichiometry, one can control the size, distribution and surface coverage of produced particles. We also revealed that the emergent particles are generally epitaxially socketed in the parent perovskite which appears to be the underlying origin of their remarkable stability, including unique resistance of metal particles to agglomeration and to hydrocarbon coking, whilst retaining catalytic activit.
Operando redox treatments yield emergent nanomaterials at potentials in excess of 2V. Here we apply this technique to drive steam, CO2 and coelectrolysis processes at emergent metals and alloy particles.