bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) accelerating Polymer Discovery for Multifunctional Polymer Thin Films: High-Throughput Characterization
Authors: Quinn Harley J , Wang Wenlu , Werner Joerg G , Brown Keith A 
Published: September 2023

Identifying new formulations of polymers that have multiple highly tuned properties is a grand challenge of materials development. This is especially important in polymer thin film devices where several distinct transport properties must be controlled. For instance, solid-state battery electrolyte materials must be conductive to ions, but remain electronically insulating. In order to achieve the materials advances needed to transform the use of such polymer thin films, new paradigms of accelerated materials development are needed.
In this talk, we discuss our recent efforts to accelerate the development of advanced polymer thin film materials for energy applications. A crucial feature of accelerating the discovery of high performing formulations and processing conditions is a rapid means to assess the properties of polymer films with spatial resolution commensurate with nanoscopic defects and throughput that can accommodate macroscopic devices. We initially focus on the challenge of verifying that films are electrically insulating. Maintaining electrical insulation across large films is a particularly insidious challenge as small “pin-hole” defects can result in an entire device failing. We explore an optical method to detect and characterize conductive defects based upon the electrochemiluminescence of luminol. In particular, when a voltage is applied to a conductive surface that is protected by a nominally insulating film, regions where the film is not present or is electrically conductive will result in the local generation of light. A major virtue of this approach is that the minimum detectable feature is not directly determined by the wavelength of light or the optical magnification in use, but rather the intensity of light generated per unit area on the surface. To explore this approach, we conduct an extensive series of optimization experiments to maximize the intensity of light generated by electrochemiluminescence by adjusting the timing, voltage, and solution properties. The result of this optimization is that lines narrower than 100 nm are readily detectable using this method. Finally, we present efforts to use this approach to screen centimeter-square areas to find and characterize nanoscale defects.
Looking beyond the important task of characterizing films at high throughput, we conclude the talk with a discussion of how this approach fits in a broader materials discovery pipeline. In particular, recent years have seen a number of examples of autonomous experimentation systems that combine automation to perform experiments and machine learning to select experiments to vastly increased the speed at which knowledge is gained. The reported high-throughput analytical process is anticipated to form an important link in this process by providing a path to rapidly and effectively screening films for electrical properties.
(Invited) nanoengineered Surfaces for Modulating Cell-Surface Interaction and Sensing Applications
Authors: Bachhuka Akash 
Published: September 2023

The greatest challenge in the field of biomaterials is the understanding and prediction of long-term biological responses in patients receiving implantable materials. Reconstructing and detailing these mechanisms may allow for more targeted approaches and highlights how immune processes are amenable to manipulation by synthetic biomaterials. Surface nanotopography and chemistry are critical factors in integrating implanted devices into tissues and in the satisfactory resolution of the wound healing process. However, how the interplay between surface chemistry and nanotopography may influence inflammatory and wound-healing pathways remains unanswered. To address this gap, 2D and 3D surfaces with nanotopography of controlled height (16, 38, and 68 nm) and lateral spacing with uniform outermost surface chemistry tailored with plasma polymerized amines (NH2), carboxyl (COOH-) and hydrocarbon (CH3-) functionalities were fabricated. These surfaces were employed to study cellular responses responsible for implant encapsulation, wound healing, and tissue regeneration. The data shows that the right combination of chemistry and nanotopography can modulate cellular adhesion, proliferation, self-differentiation, collagen deposition, and the expression of anti and pro-inflammatory signals.
Furthermore, our surface engineering expertise was utilized to fabricate metal ion sensors and biosensors based on nanoporous anodic alumina (NAA) and gold nanoclusters (AuNCs). We anticipate that future explorations in this field of research will facilitate the rational design of biomedical implants and devices with physicochemical surface characteristics tailored at the nanoscale that will enhance utility and function and improve clinical outcomes.
Optimization of Time-of-Flight Secondary Ion Mass Spectrometry for Analysis of Porous Transport Layers
Authors: Stelmacovich Genevieve , van Eijk Lonneke , Walker Michael , Cullen David A. , Ware Sam , Young James L. , Bender Guido , Pylypenko Svitlana 
Published: September 2023

As we move towards commercialization of the proton exchange membrane water electrolyzers (PEMWEs), fundamental understandings of individual components and their integration with focus on material composition and its correlation to performance and lifetime of electrolysis cell operation is of significant importance. Porous Transport Layers (PTLs) increase overpotential of the cell when the titanium passivates, i.e. develops a titanium oxide surface layer of a certain thickness. To prevent this passivation, platinum group metal coatings are typically applied to the PTL, but this adds significant costs.
This presentation will cover recent developments in characterization of PTL coatings and PTL-coating interfaces using Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) in correlation with Scanning Transmission Electron Microscopy and Energy Dispersive X-ray Spectroscopy (STEM-EDS) analysis. Although this technique is extremely beneficial, ToF-SIMS is typically applied to flat substrates and therefore has been mainly utilized in other scientific fields such as the thin film industry. This talk will discuss method validation and optimization that has been conducted for PTL analysis to allow its characterization by ToF-SIMS. Topics include understanding parameters and limitation of using SIMS on these morphologically challenging samples, as well as looking at elemental and species identification, and applying depth profiling to gauge information on coating and oxide thickness and their consistency. Correlations between real and flat substrates prepared under similar conditions are made, allowing standardization of depth profiling for future analysis of a wider variety of samples.
Gas Crossover and Supersaturation in Advanced Alkaline Water Electrolysis
Authors: Lira Garcia Barros Rodrigo , Kraakman Joost , de Groot Thijs Theodorus , van der Schaaf John 
Published: September 2023

Conventional alkaline water electrolyzers operate with a finite-gap between the cathode and anode [1]. The ohmic resistance induced by this finite-gap results in energy losses. Therefore, the zero-gap assembly is considered an attractive configuration to perform advanced alkaline water electrolysis. However, gas crossover is enhanced in the zero-gap configuration by supersaturated hydrogen concentrations in the vicinity of the electrode. To avoid excessive gas crossover there is a limiting minimal operational current density.
Different transport mechanisms can contribute to gas crossover through the porous separator, namely diffusion, convection, and electrolyte mixing. For well-balanced pressures and industrial flow rates, diffusion is the main contributor to gas crossover [2].
Local supersaturation at the diaphragm interface significantly contributes to gas crossover [2]. To confirm this hypothesis, in-situ gas analysis experiments were conducted in an electrolysis setup equipped with in-line gas chromatography that could be operated with negligible influence of convective transport mechanisms to evaluate the diffusive transport in both zero- and finite-gap configurations.
There is a clear distinction in gas crossover between zero- and finite-gap designs. In Figure 1 is shown that for the zero-gap assembly, hydrogen crossover rates were found to increase with current density, evidencing that supersaturation at the diaphragm interface plays an important role on gas crossover. In contrast, using a finite-gap configuration, gas crossover was significantly reduced and approached equilibrium diffusion rates, proving that gas crossover is mainly driven by diffusive hydrogen transport. Therefore, advanced alkaline electrolysis could be operated at higher current densities by applying a zero-gap configuration and reducing diaphragm thickness, but gas crossover leads to higher hydrogen in oxygen levels at low power load.
[1] J. Brauns, T. Turek. “Alkaline water electrolysis powered by renewable energy: A review”. Processes, vol. 8, no. 2 (2020).
[2] M. T. de Groot, J. Kraakman, R. Lira Garcia Barros. “Optimal operating parameters for advanced alkaline water electrolysis”. International Journal of Hydrogen Energy, vol. 47, no. 82 (2022) 34773-34783.

Figure 1
Electrochemical Analysis of Anion Exchange Membrane Water Electrolyzers (AEMWE)
Authors: Nuggehalli Sampathkumar Suhas , Ferriday Thomas B. , Middleton Peter Hugh , Van herle Jan 
Published: September 2023

The increase in deployment of renewable electricity has made green hydrogen production an attractive solution for decarbonizing energy systems. The prominent technologies currently deployed are the proton exchange membrane water electrolyzers (PEMWE) and alkaline water electrolyzers (AWE). The PEMWE technology uses platinum group material (PGM) catalysts, coated onto fluorinated Nafion® polymer membranes and needs specially treated titanium bipolar plates, reaching current densities of greater than 2 A cm-2. The AWE technology, in contrast, uses cheaper materials with a porous diaphragm separator, but the operating current density reaches only <0.5 Acm-2. The anion exchange membrane water electrolyzers (AEMWE) combine the advantages of both the PEMWE and AWE by using hydroxide (OH-) conducting, functionalized styrene-based membranes with non-PGM electrocatalysts, reaching current densities of >1 Acm-2.
In this study, a membrane electrode assembly (MEA) consisting of Sustainion® X37-50 Grade RT membranes and non-PGM hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts are fabricated and analyzed for performance. NiFe2O4 (Merk) was chosen as the OER electrocatalyst and spray-coated on the sintered 316L stainless steel fibre (dioxide materials). On the counter side, NiFeCo (USnano) as HER electrocatalyst was spray coated on the molded graphite layer 370 (MGL370- fuelcellstore) porous transport layer. A catalyst loading of 3 mg cm-2 is obtained for both HER and OER electrodes.
The fabricated MEA of 1x1cm2 is firstly tested for performance in a inhouse setup, using current density-voltage scans (j-V) using Zahner Zennium X electrochemical workstation. Consequently, electrochemical impedance spectroscopy (EIS) is performed in pseudo-galvanostatic mode. The perturbation amplitude is adjusted such that a linear region of the j-V curve is probed. The fuel electrode and air electrode contributions to the overall MEA performance are distinguishable due to the twin reference electrode configuration. The half cell-MEA contributions are further analyzed by performing parallel impedance measurements between the i) Reference electrode – cathode, ii) Reference electrode - Anode and iii) full-cell operation at predetermined current-density biases. These type of investigation gives deeper insight to the fuel electrode and the air electrode processes. The quality of the EIS spectra is analyzed using Kramers Krönig residual tests.
A sensitivity analysis on the MEA is performed by changing impedance-effecting parameters such as temperature, operating current density and potassium hydroxide (KOH) concentration. Further, post-test characterization of the electrode substrates is performed to identify affected parameters through XPS, Raman spectroscopy, SEM-EDX and XRD techniques. The parallel impedance measurements confirms the presence of anodic, cathodic and low-frequency diffusion processes in real time.
(Invited) Advancing Hydrogen Generation Technologies Assisted by a Solid International Benchmarking Effort
Authors: Carmo Marcelo , Ayers Katherine E. , Bender Guido , Bensmann Boris , Gago Aldo , Gottschalk Torben , Gross Karl , Hanke-Rauschenbach Richard , Jensen Jens Oluf , Kraglund Mikkel Rykær , Marina Olga A , Roberts George , Metz Sebastian , Smolinka Tom , Stechel Ellen B , Turek Thomas , Xiang Chengxiang("CX") 
Published: September 2023

Water electrolyzers are today of worldwide strategic importance for the deployment of green hydrogen as an energy carrier, and the ultimate integration of stochastic renewable energies into the electrical grid at scale. Targets for the total cost of ownership of hydrogen have been constantly revised, but values around $1 to $2 per kilogram of H2 are generally accepted to reach parity with other energy conversion and storage strategies. However, further advancement of electrolyzers while maintaining durability and robustness of its cell/stack components is still needed. This can only be accomplished through focused research and development efforts that address efficiency, degradation, and cost aspects of the technology.
A growing number of research groups are starting to participate in this development with key contributions in the form of fundamental and material advances. However, the high deviation of reported results as well as the complex history the tests performed, and components used have shown that this growth creates challenges that hinder the development of trust in the test results generated. Moreover, such lack of trust ends up hampering the overall progress and leads to wasted allocated resources. Contributors to the HydroGEN Advanced water splitting Materials, Energy Materials Network; and H2-New programs funded by the Department of Energy in the USA; aligned with efforts by the International Energy Agency (IEA) within the Electrolysis Annex 30 are conducting a benchmarking effort: 1) to develop methods to identify reference hardware, cell components, and materials; and 2) to harmonize testing protocols and enable the meaningful comparison of performance across the community.
In this presentation, the latest results of this effort will be presented. The talk will also include updates on current strategies among the different teams, round robin testing results, protocol development and fine tuning of test parameters and material specifications. This effort should finally lead to the creation, validation, dissemination, and adoption of accelerated test protocols that can ultimately contribute to conducting collaborative studies on cell and stack degradation.
(Invited) Proton Exchange Membrane Electrolyzers Based on Sub-Micron Thick Membranes
Authors: Esposito Daniel V. , Yim Kyungmin , Fraga Alvarez Daniela V. , Cohen Lucas , Jin Jingjing , West Alan C. , Weimer Matthew S , Moulton Staci , Dameron Arrelaine A , Ayers Katherine E. , Capuano Christopher , Fortiner Serafina , Hawkes Justin , Glenn Jennifer 
Published: September 2023

Significant decreases in the price of electricity from solar photovoltaics and wind are enabling concurrent decreases in the cost of clean hydrogen production by water electrolysis. However, to meet the US Department of Energy’s Hydrogen Shot Initiative target for levelized cost of hydrogen production of < $1 per kg of hydrogen by the year 2030,[1] it will also be necessary to drive down the capital costs of water electrolyzers. Reducing capital costs is especially important for scenarios where close to 100% of the electricity is provided by variable renewable energy generators, which greatly limits the capacity factor of the electrolyzer.[2] Towards this end, our team is exploring a proton exchange membrane (PEM) electrolyzer architecture based on ultrathin (< 1 micron) membranes. Modeling is used to show that defect-free membranes possessing appropriate proton and hydrogen transport properties present opportunities to decrease membrane resistances < 80% relative to conventional Nafion membranes, which can subsequently allow for operation at > 4 A cm-2 while maintaining the same efficiencies achieved by today’s commercialized PEM electrolyzers operated at < 2 A cm-2. Additionally, this talk will describe modeling and experimental efforts that address the viability of using sub-micron thick membranes that can operate with H2 crossover rates < 1%.
References
[1] US DOE Hydrogen Shot Initiative: https://www.energy.gov/eere/fuelcells/hydrogen-shot
[2] D.V. Esposito, Joule, 1, 1-8, 2017.
Poly(carbazole)-Based Anion Exchange Membranes Developed by Grafting Alkyl Ammonium Group
Authors: Adhikari Santosh , Klein Jeffrey Michael , Matanovic Ivana , Kim Yu Seung 
Published: September 2023

AEM water electrolysis offers several advantages over proton exchange membrane water electrolysis such as the potential use of non-precious metal catalysts and less expensive bipolar plates. Therefore, there is a great demand for reliable, high-performing, durable, and low-cost AEMs for the technologies.1 In this presentation, we report polycarbazole-based AEMs by acid-catalyzed Friedel Craft’s polycondensation reaction followed by grafting with an alkyl ammonium group.2 Two AEMs, PDPC-3QA (IEC=1.25 meq./g) and PDPC-6QA (IEC=1.74 meq./g), were synthesized by grafting 3-bromo-N,N,N-trimethylpropan-1-aminium bromide (3-BrQA) and 6-bromo-N,N,N-trimethylhexan-1-aminium bromide (6-BrQA), respectively on the precursor polymer. While 100% grafting was achieved with 6-BrQA, only 60% of grafting was achieved with 3-BrQA due to the competition between the elimination and substitution reaction on 3-BrQA because of the higher acidity of β-hydrogen resulted from the proximity of the bromide and ammonium groups. With high OH- conductivity (103 mS/cm at 80 °C) and excellent alkaline stability (< 3% conductivity loss after 500 hours in 1 M NaOH at 80 °C), PDPC-6QA exhibits promising water electrolyzer performance.
References:

E. J. Park, C. G. Arges, H. Xu, Y.S. Kim, Membrane Strategies for Water Electrolysis, ACS Energy Letters, 7, 3447-3457 (2022).

S. Adhikari, I. Matanovic, D. Leonard, J. M. Klein, T. Agrawal, Y.S. Kim, Alkyl Ammonium Group Grafted Poly(carbazole)s for Anion Ex-change Membranes, Submitted (2022).
(Invited) Impact of Phenyl Adsorption of Various Ionomers on the Performance of Anion Exchange Membrane Water Electrolyzers
Authors: Klein Jeffrey Michael , Matanovic Ivana , Lehmann Michelle , Saito Tomonori , Kim Yu Seung 
Published: September 2023

In this presentation, design principals of ionomeric binders for anion exchange membrane water electrolysis (AEMWE) will be discussed. The crucial impact of phenyl adsorption on AEMWE performance is highlighted with poly(terphenylene), poly(fluorene), poly(aryl piperidinium), or polynorbonene ionomers. Adsorption energies to hydrogen oxidation catalyst surfaces, calculated by density functional theory, demonstrate the utility in the phenyl free ionomer structure wherein lower adsorption energies yield improved AEMWE performance.1,2 Polarization curves with higher adsorption energy ionomers show a nonlinear transition to mass transport limited behavior at cell potentials above 1.68 V. Alternatively, mass transport limitations are absent when using the phenyl free ionomer, polynorbonene.3 Furthermore, polarization curves in 1 M NaOH of all studied systems begin to overlap suggesting that the phenyl oxidation on the oxygen evolution catalyst may be a primary influence on the transition to mass transport limits in AEMWE. Recent progress in both ionomer and AEM development at LANL for improved performance and durability of AEMWE, specifically with regard to limiting phenyl oxidation, will be discussed.
1 Matanovic, I. et al. Adsorption of Polyaromatic Backbone Impacts the Performance of Anion Exchange Membrane Fuel Cells. Chemistry of Materials
31, 4195-4204, doi:10.1021/acs.chemmater.9b01092 (2019).
2 Motz, A. R. et al. Performance and durability of anion exchange membrane water electrolyzers using down-selected polymer electrolytes. Journal of Materials Chemistry A
9, 22670-22683, doi:10.1039/D1TA06869E (2021).
3 Huang, G. et al. Ionomer Optimization for Water Uptake and Swelling in Anion Exchange Membrane Electrolyzer: Oxygen Evolution Electrode. Journal of The Electrochemical Society
167, 164514, doi:10.1149/1945-7111/abcde3 (2020).
Design Principles for Hydroxide Exchange Membrane Water Electrolyzers
Authors: Tricker Andrew W. , Lee Jason Keonhag , Shin Jason R. , Weber Adam Z. , Peng Xiong 
Published: September 2023

Green hydrogen, produced by via water splitting using renewable electricity, will play a crucial role as a renewable energy carrier and in decarbonizing hard-to-decarbonize sectors in the future.1 Hydroxide-exchange-membrane water electrolyzers (HEMWE) have the potential to be more cost effective compared to the incumbent technology, proton-exchange-membrane water electrolyzers (PEMWE), through the use of cheaper catalysts and cell component materials.2 However, HEMWE are at much earlier stage of development compared to PEMWE and, in part, generally operate at lower efficiencies due to a lack of established guiding design and operating principles. Herein, we study how membrane electrode assembly (MEA) component design and cell operating conditions influence the performance of HEMWE. A custom design three-electrode MEA is used to breakdown the overpotential contributions from the anode and cathode, showing that anode OER still dominates the kinetic loss while cathode mass transport limitations is more severe compared to anode. A significant improvement in cell performance is observed for more porous anode porous transport electrode (PTE) compared to dense ones, due to a higher anode catalyst utilization. On the cathode, the use of a hydrophobic gas diffusion layer (GDL) improves performance at high current densities by facilitating the removal of hydrogen gas. The impact of feed configurations including electrolyte fed to both sides, anode fed only, and cathode fed only, on HEMWE performance is thoroughly investigated. In various electrolytes including KOH, KHCO3, K2CO3 and DI water, HEMWEs perform the best with anode fed only, signifying that back diffusion of water through the membrane is sufficient to supply enough reactant to the cathode. These learned principles were used to assemble a completely PGM-free HEMWE that reached 1.6 A cm-2 at 2 V in 1 M KOH, and exhibited stable performance in 0.1 M KOH at 1.5 A cm-2 for over 500 h.
Acknowledgements
This work was funded under the HydroGEN Consortium by the Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office, of the U. S. Department of Energy under contract number DE-AC02-05CH11231.
References

B. Pivovar, N. Rustagi and S. Satyapal, The Electrochemical Society Interface, 27, 47 (2018).

K. Ayers, N. Danilovic, R. Ouimet, M. Carmo, B. Pivovar and M. Bornstein, Annual review of chemical and biomolecular engineering, 10, 219 (2019).