bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Regular Dimpled Surface Morphology for the Oxygen Evolution Reaction
Authors: Taylor Audrey K. , Andreu Irene , Gates Byron D. 
Published: February 2020

Optimizing electrochemical reactions is essential to improving the energy efficiency of many renewable energy technologies, such as for increasing their competitive advantage across many sectors of the market. The oxygen evolution reaction (OER) is of particular importance for its applicability to chemical generation and energy storage, and its reliance on low cost materials, such as nickel based catalysts. Nickel electrodes with surface oxides (NiOx) are frequently used as anodes in these systems because they also offer reduced activation energies, exhibit sufficient catalytic activity, and durability under alkaline conditions. Persistent bubble accumulation on highly active electrodes can, however, result in blocked active sites and reduced system performance for these and other OER catalysts. The identification and development of surface morphologies that can effectively evolve and remove oxygen bubbles from the electrode surfaces could be a highly beneficial technology to further enhance the efficiency of the OER.
In this work, regular dimpled Ni surfaces were prepared using self-assembled poly(styrene) templates with a distinct diameter (e.g., 1 μm). The electrodeposition of Ni into these assembled templates was tuned to produce four types of dimpled surface textures. The electrochemical activity of these regular features were evaluated for the OER to investigate their influence on the mass transport properties. Enhancements to the OER efficiency were demonstrated for these systems when compared to flat Ni electrodes. The wettability of the dimpled Ni electrodes was characterized by contact angle measurements acquired both before and after electrochemical cycling. Theoretical wetting models were applied to the surface morphologies to correlate the results with adhesion of the oxygen bubbles and partial wetting with the electrolyte. The regular design of these micro- and nanostructured surfaces enables further correlation of structural morphologies in Ni based electrodes to their electrochemical performance.
(Invited) Techno-Economic Perspectives of Catalysts Development for Low Temperature Water Electrolysis
Authors: Xu Hui , Zhao Shuai , Mittelsteadt Cortney K 
Published: February 2020

Catalyst development for low temperature water electrolysis has been pursued in the electrochemistry community. Booming research and development in this area are due in part to near-commercialization of fuel cell vehicles and potential adoption of renewable electricity for water electrolysis. Two types of reactions, oxygen evolution reaction (OER) and hydrogen evolution reactions (HER) have been widely studied. Studies on the OER prevail in both acidic and basic media, while the HER studies are predominant in basic media. The increasing research interests have been reflected in this recurring symposium. At Giner Inc., we have developed a variety of highly active and durable catalysts (e.g, Ir nanotubes, Ir supported on titanium oxide, cobalt oxide on nanocarbon) for both proton and anion exchange membrane electrolysis.
This work aims to provide insightful guidance on the catalyst development from an industrial point of view. Compared to fuel cells, the catalyst cost in a water electrolyzer is less significant due to prohibitive cost of feedstock (electricity). Therefore, when regular (expensive) electricity is used for water electrolysis, the catalyst studies should be centered on the intrinsic activity improvement to lower the over-potential so as to increase the energy efficiency. On the other hand, when the renewable (low-price) electricity becomes available, the catalyst studies should be focused on the mass activity to lower the platinum-group metal (PGM) loading. Provided that the global supply of industry standard OER catalyst Ir is very limited, the development of non-PGM catalysts for both proton and anion exchange membrane electrolysis is very meaningful.
The second consideration is the catalyst performance in a real electrolyzer cell. The vast majority of research work is on the rotating disk electrodes (RDE) using liquid electrolyte. However, the RDE data may not be necessarily reproduced in real electrodes that use ionomer as an ion conductor. The interaction of the catalyst with other components (e.g., membrane, ionomer and gas diffusion media) determines electrode morphology and structure thus tremendously impacting the electrode performance.
The last consideration is the long-term durability of the catalysts, which is equal and even more important than the initial performance, from an industrial point of view. However, unlike the well-established durability benchmarks for fuel cells, the catalyst durability of water electrolyzer has not been thoroughly studied. Therefore, accelerated stress tests (AST) need to be implemented to evaluate the long-term durability of the catalysts.

Acknowledgement: The financial support is from the Department of Energy under the Contract Grant DE-SC0007471.
IrO2 Decorated Self-Doped TiO2 Nanotube Arrays: A Binder-Free and More Stable Electrode for Oxygen Evolution Reaction in Acid Condition
Authors: Shi Yan , Lu Zhuoxin , Wang Zhida , Guo Lili , Tan Hongyi , Guo Changqing , Yan Changfeng 
Published: February 2020

The effective, stable and low cost anodic catalyst or electrode for OER is still a big challenge for water electrolysis in acid condition. Many efforts were devoted to develop suitable supports for depositing Ir and Ru metal or oxides to obtain an enhanced activity or stability for OER.
In this work, self-doped TiO2 nanotube arrays (sTNTA) which has a higher electrical conductivity than TNTA was chosen as the support, it was fabricated by a simple electrochemical reduction of TNTA in neutral electrolyte. Then IrO2 nano particles were deposited on it by electrochemical pulse deposition method to form an OER electrode. The cyclic voltammetric behavior, electrical conductivity and micro structure of sTNTA prepared under different reduction potential were characterized to obtain an optimal performance for depositing IrO2, the OER activity and stability of new electrode were also determined. The obtained sTNTA shows an increased current in CV test than TNTA, which is due to the increased carrier density. As the reduction potential move to more negative level (from -1.5V to -1.9V vs. Ag/AgCl), the carrier density was found increased for 3 order of magnitudes, and XPS characterization confirm the existence of Ti3+ which formed in electrochemical reduction process, and sTNTA prepared under -1.9V shows the best electrochemical performance. After depositing IrO2, IrO2/sTNTA exhibited higher OER activity than IrO2/TNTA, according to the CV and EIS test, this can be ascribed to the enhanced electrical conductivity of support, which results in more active sites and lower charge transfer resistance of the electrode. The OER stability of IrO2/sTNTA was tested under constant current of 5mA/cm2, IrO2/TNTA and IrO2/Ti which prepared by electrochemical deposition on Ti foil were also tested for comparison. A higher stability of IrO2/sTNTA electrode was observed than the other two electrodes, and this may be due to the interaction between the IrO2 and sTNTA. XPS studies show a clear peak shift of Ir4f in IrO2/sTNTA, indicating a possible lower valence of Iridium, and such lower oxidation state of Iridium may be response for the enhanced OER stability.
In summary, our studies have demonstrated the possibility of self-doped TNTA as a potential anodic support for OER. Comparing with the TNTA, the high electrical conductivity of sTNTA facilitate the charge transfer rate and thus improve the OER activity. Additionally, a higher OER stability was observed for IrO2/sTNTA electrode, and this may be due to possible catalyst-support interactions between IrO2 and self-doped TNTA.

Figure 1
Cobalt Platinum Bronze for an Active and Durable Oer Electrocatalyst of PEM Electrolysis without Ir or Ru
Authors: Kamitaka Yuji , Morimoto Yu 
Published: February 2020

Water electrolysis is an essential technology for realizing the renewable energy society. PEM electrolysis, in particular, is promising because of its high power density despite its high cost per unit active area. Its OER catalyst often contains Ir or Ru (or both) because of their high OER activities and durabilities. Although the current prices of these two metals are not extremely high compared with other precious metals because of their relatively low demand, Ir and Ru are, however, ones of the scarcest elements on earth and this extreme scarcity could be a major obstacle for wide distribution of PEM electrolysis technology.
Recently we have started fundamental studies on mixed oxides of platinum so called "platinum bronze" (Bronze in this context means mixed oxides with metallic sheen) consisting of platinum, oxygen and other metal ions (such as Li, Na, Mg, Ca, Zn, Cd, Co, Ni [1]) as a versatile electrocatalyst for ORR, OER and HOR.
Co-Pt bronze was prepared according to the literature [1] with some modifications. Platinum oxide and Co(NO3)2·6H2O powders were mixed and heat-treated under air conditions at 650 ºC for 5 hours. The obtained powder was washed with heated (80 °C) aqua regia for 3 times and the remaining powder was then thoroughly rinsed with pure water.
The electronic conductivity of the bronze measured with a compression cell was compared in Fig. 1 with those of Vulcan XC-72 (a typical conductive carbon black), IrO2 (a typical OER catalyst) and PtO2. The Co-Pt bronze showed a comparable conductivity with XC-72 and IrO2, which is much higher than that of PtO2, an insulator.
OER activities were measured by potential sweep and potential hold experiments. The electrodes were prepared by depositing the catalysts on a glassy carbon disk electrode. Fig. 2 a) and b) show that the Co-Pt bronze has a similarly active and stable OER activity with IrO2 not like Pt black and Pt/Vulcan, which show rapid decay of OER current due to formation of PtO2.
This study is financially support by the New Energy and Industrial Technology Development Organization.
References
[1] R.D. Shannon, et al., Inorg. Chem., 21, 3372 (1982)

Figure 1
(Invited) Engineering Advanced Transition-Metal Based Electrocatalysts for Oxygen Evolution Reaction
Authors: Song Junhua , Fu Shaofang , Shi Qiurong , Zhu Chengzhou , Du Dan , Lin Yuehe 
Published: February 2020

Increasing energy demands and environment awareness have promoted extensive research on the development of alternative energy conversion and storage technologies with high efficiency and environmental friendliness. Among them, electrochemical water splitting is very appealing, and is receiving more and more attention. Essential to the water splitting is the kinetically sluggish oxygen evolution reaction (OER), which demands efficient electrocatalysts. To make the water splitting process more energy-efficient and economical, developing high-performance noble metal-free catalysts, i.e., transition-metal-based nanomaterials, has aroused great attention due to their distinct advantages, such as relatively low cost, low toxicity, great flexibility in terms of structure and morphology, and satisfying electrochemical performance. We focus on the rational design of porous nanostructures with tunable composition and other favorable synergistic factors, aiming at increasing the number of the active sites and enhancing the reactivity of the active sites. Taking advantage of these favorable structural and compositional parameters, the resultant nanostructures exhibited excellent OER activity and stability, holding great promise in water splitting.
References:

Song, C. Zhu, B. Xu, S. Fu, M. Engelhard, R. Ye, D. Du, S. Beckman, Y. Lin. Bimetallic Cobalt-Based Phosphide Zeolitic Imidazolate Framework: CoPx Phase-Dependent Electrical Conductivity and Hydrogen Atom Adsorption Energy for Efficient Overall Water Splitting. Advanced Energy Materials 7, 2017, 1601555

S Fu, C Zhu, J Song, M Engelhard, X Li, D Du, Y Lin. Highly Ordered Mesoporous Bimetallic Phosphides as Efficient Oxygen Evolution Electrocatalysts. 2016, 1, 792-796

Zhu, S. Fu, D. Du, Y. Lin. Facilely tuning porous NiCo2O4 nanosheets with metal valence states alteration and abundant oxygen vacancies as robust electrocatalysts towards water splitting. Chemistry European J. 2016, 22, 4000-4007

Fu, J. Song, C. Zhu, G. Xu, K. Amine, C. Sun, X. Li; M. H Engelhard, D. Du, Y. Lin. Ultrafine and highly disordered Ni2Fe1 Nanofoams Enabled Highly Efficient Oxygen Evolution Reaction in Alkaline Electrolyte. Nano Energy. Submitted
In Situ Scanning Probe Microscopy of Li-Ion Battery Cathode Materials
Authors: Baghgar Bostan Abad Mina , Ignatova Tetyana , Turvey Mackenzie W. , Collins Philip G. 
Published: February 2020

Designing the next generation of high performance energy storage devices requires a deeper understanding of structural degradation. To this end, a wide variety of scanning probe microscopy techniques can help characterize charge transport and aging mechanisms in Li-ion battery materials and their interfaces. For example, we use in-situ probe microscopy and Kelvin probe force microscopy (KPFM) to investigate the mechanical and potentiostatic changes in MnO2 cathodes as they undergo charge cycling. Topography monitors mechanical expansion during charging, and the dependence of expansion on scan rate reveals the separate roles of Mn3+/4+ redox pseudocapacitance and faster, double-layer surface capacitance. On the same electrodes, KPFM observes the evolution of surface potentials with lateral resolution as low as 40 nm. At this length scale, inhomogeneous lithiation is clearly observed as a highly nonuniform, fractal growth or shrinkage of Mn3+ and Mn4+ phases. Via surface potential, KPFM also reveals "dead" zones that do not participate in charging, "hot" zones that charge or discharge most readily, and the evolution of each type as an electrode is repeatedly cycled.
This work was supported as part of the Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science.
The Role of Cathode Architecture in Conversion Reaction Chemistries
Authors: Tozier Dylan , Giordani Vincent , Uddin Jasim , Tan Hongjin , Chase Gregory V , Addison Dan , Greer Julia R 
Published: February 2020

State of the art commercial lithium ion batteries use cathodes such as lithium cobalt oxide which rely on insertion and removal of lithium ions from a host material. However, insertion cathode materials are limited in their capacity, and replacing them with a cathode that employs growth and dissolution of new phases could significantly increase a battery’s energy density. For example, oxygen and sulfur cathodes have been widely researched to this end, with both cases involving the growth of a lithium-rich compound on a current collector/catalyst support.
Consider a similar phase-forming conversion chemistry[1], whereby a molten nitrate salt serves as both an active material and the electrolyte. Molten nitrate salts have been previously studied as an active material in a primary lithium battery where lithium oxide irreversibly forms as nitrate reduces to nitrite. We will describe how the use of a nanoparticle heterogeneous catalyst allows the reversible growth and dissolution of large (several micron) lithium oxide crystals in this system, as substantiated by SEM, XRD, and TEM.
After introducing this molten salt lithium battery, we address the effect of cathode geometry on the electrochemical performance of this model system. In particular, we note that the growth of such large, solid phase species on the surface of the catalyst support imposes new design restrictions when optimizing a cathode for energy density. For instance, it is not just the surface area of the catalyst support that determines the discharge capacity, but also the amount of usable pore volume which can accommodate this solid phase discharge product. As a proof of concept, we design and implement an architected electrode with large pore volume and relatively small surface area, comparing it with the more typical geometries of thin films and nanoparticles. These electrode design principles can be extended to other phase-forming conversion chemistries.
[1] Addison, D.; Bryantsev, V.; Chase, G. V.; Giordani, V.; Uddin, J.; Walker, W Rechargeable Batteries Employing Catalyzed Molten Nitrate Positive Electrodes. US Patent 2016/0204418, August 8, 2013.
Optimization of Li-O2 Batteries Using Bi Compartment Cells to Separate and Improve Each Electrode Condition
Authors: Kim Hun , Sun Yang-Kook 
Published: February 2020

Despite theoretically high energy density of Li-O2 batteries, low energy efficiency, poor cycle life and Li-metal safety issues make the use of them yet impractical. Therefore, efforts are made to protect/block the lithium metal anode in these cells, in order to mitigate side reactions. However, new approach1-3 is required in order to solve the problems mentioned above, especially the irreversible reactions of the redox mediators which are mandatory to these systems with the Li anode.
Here, optimized bi compartment cells are proposed, in which detrimental crossover between the cathode and anode is completely avoided. The Li metal anode is cycled in electrolyte solution containing fluorinated ethylene carbonate, in which its cycling efficiency is excellent. The cathode compartment contains ethereal solution with redox mediator that enables oxidation of Li2O2 at low potentials. The electrodes are separated by a solid electrolyte membrane, allowing free transport of Li ions. This approach increases cycle life of lithium oxygen cells and their energy efficiency.1

References

W.-J. Kwak, H.-G. Jung, D. Aurbach, and Y.-K. Sun, Adv. Energy Mater. 2017, 7, 1701232

S. H. Lee, J.-B. Park, H.-S. Lim, and Y.-K. Sun, Adv. Energy Mater. 2017
, 7, 1602417

W.-J. Kwak, S.-J. Park, H.-G. Jung, and Y.-K. Sun, Adv. Energy Mater. 2017, 7, 1702258
A Simple Metallic Coating on Separator for Lithium Dendrite Suppression
Authors: Lee Hongkyung , Ren Xiaodi , Niu Chaojiang , Yu Lu , Engelhard Mark H , Liu Jun , Xu Wu , Zhang Ji-Guang 
Published: February 2020

Lithium (Li) metal has been considered as a very promising anode material for next-generation batteries because of its low electronegativity (-3.04 V), low gravimetric density (0.53 g cc-1) and ultrahigh specific capacity (3860 mAh g-1). The recent simulations forecast that the rechargeable Li metal batteries (LMBs) coupled with the conventional transient metal oxide cathodes and the Li metal anode can deliver a high gravimetric energy density of up to 500 Wh kg-1.[1] However, major challenges including low Coulombic eﬃciency (CE), short cycle life, and safety concerns have plagued the practical applications of Li metal as anode in recharge batteries.[2]
Here we present a simple approach to suppress dendritic Li metal growth by introducing a multifunctional Janus-faced separator. This separator is designed by coating metallic copper (Cu) thin film (CuTF) onto one side surface of conventional polyethylene (PE) membrane via simple sputtering technique. The CuTF of the obtained Janus separator (PE/CuTF) plays a crucial role of an additional conducting agent for facile Li metal deposition/stripping. Furthermore, its electrically conductive nature can guide the backside plating of Li metal and electrochemical Li metal merging, resulting in less dendritic Li metal deposition (Figure 1). The lifetime of Li metal anode is enhanced by preventing short circuit failures even under extensive Li metal deposition. LMBs with the PE/CuTF separator exhibit stable cycling performances and enhanced CE during extended cycles. Moreover, the CuTF coating can suppress the thermal shrinkage of the polymer separators and enable a current collector-less cell configuration for high energy density.

K.G. Gallagher, S. Goebel, T. Greszler, M. Mathias, W. Oelerich, D. Eroglu, V. Srinivasan, Energy Environ. Sci.
7, 1555 (2014).

Xu, J. Wang, F. Ding, X. Chen, E. Nasybulin, Y. Zhang, J.-G. Zhang, Energy Environ. Sci.
7, 513 (2014).

Figure 1. Proposed working principle on Li dendrite suppression by using Janus-faced separator; (A) conventional PE separator and (B) Cu metal thin film (CuTF) coated Janus (PE/CuTF) separator.

Figure 1
Advanced Characterization and Quantification of Fuel Cell Electrodes Using Electron and X-Ray Microscopy Techniques
Authors: Jankovic Jasna , Susac Darija , Putz Andreas Michael Vincent , Kneer Alexander , Zhang Shawn 
Published: February 2020

Performance and durability of proton exchange membrane fuel cells (PEMFC) very much depend on the composition, microstructure and spatial distribution of all components in the fuel cell electrodes, especially the metal catalyst, carbon support, ionomer and pores in the catalyst layer. This dependence is even more enhanced in the case of low Pt loading fuel cells, where high performance losses occur due to increased oxygen transport resistance [1, 2], and the design of the catalyst layer is of utmost importance. Understanding the electrode microstructure and component distribution at the beginning of life (BOL), as well as their change at the end of life (EOL), after running the cells at various operating conditions, is crucial for further development of fuel cells. Conventional imaging techniques offer limited information and can often be misleading. Novel and advanced methods for spatial structural characterization and component quantification are being developed, enabled by the rapid advancement of the microscopy techniques and computational power, offering a new level of understanding for processes in fuel cells.
This talk will give an overview of some of the advanced approaches reported in the literature, as well as describe novel fuel cell material characterization and quantification methods developed in our team. The topics will cover:

3D imaging and quantification of catalyst powders and resulting catalyst layers on a nano-scale using an electron tomography (ET) approach that enables spatial distribution of all phases, ionomer included, for the first time.

3D multi-scale imaging and quantification of membrane electrode assemblies (MEAs) correlatively utilizing ET, focused ion beam-scanning electron microscopy (FIB-SEM), and 3D X-ray microscopy (3D XRM), coupled with effective property simulation.

Applying a novel (all-in-one) approach to visualize and quantify a number of catalyst layer parameters in BOL and EOL samples, such as Pt loading, loss and distribution, ionomer loading and I/C ratio, as well as layer porosity using transmission electron microscopy with energy dispersive spectroscopy (TEM-EDX).

These advanced characterization approaches, coupled with targeted experimental testing and mathematical modeling, are key for further understanding and improving the performance and durability of fuel cells, bringing them closer to mass commercialization.

A. Kongkanand and M. F. Mathias, J. Phys. Chem. Lett., 2016, 7 (7), pp 1127–1137

P. Gazdzicki, J. Mitzel, A.M. Dreizler, M. Schulze, K. A. Friedrich, Fuel Cells, 2017, 17 (5)

Figure 1