bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toward a Fundamental Understanding of Strain Generation and Strain Tuning for ORR: DFT Insights
Authors: Zeng Zhenhua , Liu Guangdong , Deng Huiqiu , Greeley Jeffrey 
Published: December 2020

The development of industrial electrocatalysts with improved ORR performance strongly relies on the fundamental understanding of governing principles of catalysis from fundamental research on well-defined model systems. One particularly successful strategy has been to tune surface strain and thereby modulate the surface electronic structure and energetics of reaction intermediates, leading to a fundamental understanding and identification of catalysts with improved activity. For the well-known example of the ORR on platinum, previous studies indicated that a 1% compressive strain could improve the activity by more than 300%.
While the concept of tailoring the reactivity of metal catalysts through surface strain has been discussed over two decades, fundamental challenges remain regarding both strain generation and strain tuning. In the present talk, we will share our recent progress on these topics, including [1] tunable intrinsic strain in two-dimensional transition metal electrocatalysts, [2] tunable intrinsic strain in stepped transition metal electrocatalysts, and [3] strain tuning of supported transition metal overlayers. We will demonstrate [1] how these fundamental understanding can be used to understand terrace-width dependent ORR activity of stepped Pt surfaces that have puzzled the community over a decase; and [2] how they pave the way toward developing both model electrocatalysts and industrial electrocatalysts with significantly improved performance toward the oxygen reduction reaction.
References

Wang, Z. Zeng, W. Gao, T. Maxson, D. Raciti, M. Giroux, X. Pan, C. Wang, J. Greeley,. Science
363, 870-874 (2019).

Zeng, J. Greeley, Nano Energy 29 (2016) 369.
Development of in situ A-SAXS and XAS Measurements of Pt Catalyst under Controlled Electrochemical Condition Using Channel Flow Electrode Cell
Authors: Watanabe Takeshi , Kawamoto Teppei , Suda Kohei , Pondchanok Chinapong , Hiraoka Yuji , Hirosawa Ichiro , Inukai Junji 
Published: December 2020

Understanding of the structural and the chemical properties of Pt catalysts in polymer electrolyte fuel cells (PEFCs) is necessary to improve the activity for the durability of the catalysts. The small-angle X-ray scattering (SAXS) and the X-ray absorption spectroscopy (XAS) measurements are widely used to investigate these properties. Recently, we developed a measurement system of SAXS and fluorescence-yield (FY)XAS in the same observed area to investigate the structural and the chemical properties of low-concentrated catalysts. [1] As the results, the diameter size, distributions, and chemical state of catalysis were successfully characterized. Our measurement system also found to be easy to combine the electrochemical cell. In this study, we newly developed a channel flow cell to control the electrochemical conditions during SAXS and FYXAS measurement in the same observed area.
All experiments were carried out at SPring-8 BL19B2. Electrochemical measurements were conducted using a newly developed channel flow cell. Using the flow system, the electrolyte solution with a controlled temperature was continuously supplied to the cell during the in-situ measurements. A commercial Pt/carbon black catalyst(TEC10E50E, Tanaka Kikinzoku Kogyo) was used as the sample in this experiment. In situ SAXS and FYXAS measurement was conducted while holding the potential at 0.4 V, 1.0 V, and 1.5 V vs. the reversible hydrogen electrode (RHE). For the XAS measurements, the Pt LⅢ edge was used. The ionization chamber and a single-element Ge solid state detector were used to obtain the FYXAS spectra. For the SAXS measurements, the X-ray energy was set to 11.5 keV and 11.55 keV, which are below and near to the Pt LIII absorption edge, respectively. The scattered X-ray was detected using an area detector (PILATUS 2M).
As the result, we could estimate the diameter size, distributions, and chemical state of Pt catalysis under controlling the electrochemical conditions. We will discuss the degradation mechanism of the Pt nanoparticle catalyst from both SAXS and FYXAS data.
Takeshi Watanabe, et al., ECS 236th I01D-1593, (2019) Atlanta, USA.
Preparation of Unique Flower-like Pt-Ni Alloy Catalysts As the Cathode of a PEMFC By Electrodeposition Technique
Authors: Huang Jen-Hui , Yeh Tsung-Kuang , Wang Mei-Ya 
Published: December 2020

The hydrogen economy can play an important role in the low-carbon economy, and fuel cells technology is an essential part of the hydrogen economy. The proton exchange membrane fuel cell (PEMFC) is one kind of electrochemical reaction device with the advantages of low temperature operation, high conversion efficiency and noiseless, which is expected to widely utilizes in public transportations.
The oxygen reduction reaction (ORR) at the cathode is the rate-determining step in PEMFC. To enhance the ORR activity at the cathode, the unique flower-like platinum-nickel binary alloy catalysts were electrodeposited on the commercial carbon cloth by potentiostatic electrodeposition technique, the PtNi alloy effectively improved the oxygen adsorption and desorption paths on the surface. The PtNi alloy catalysts with shorter lattice distance and effects of high-index facets would increase the electrochemical surface area (ECSA) of the catalysts and power density of fuel cell. The samples of the pure platinum and commercial Pt/C catalyst were also prepared as comparison.
Morphology, particle size and elemental composition were characterized by SEM, XRD and ICP-MS. In addition, the electrochemical characteristics of the PtNi catalysts were investigated via cyclic voltammetry (CV) and linear sweep voltammetry (LSV) analysis in 0.1 M perchloric acid solution with rotating disk electrode (RDE). In single cell test, the maximum peak power density of PEMFC with homemade PtNi alloy catalyst as the cathode reached 1031 mW/cm2, enhancing about 12% power density, compared to the commercial Pt/C.

Figure 1
Advanced Thermal Conductivity Characterization with Implications for Thermal Control Strategies during Fast Charging
Authors: Steinhardt Marco , Gillich Elisabeth Irene , Stiegler Maximilian , Jossen Andreas 
Published: December 2020

Extreme fast charging lithium ion batteries require aggressive thermal management, which keeps the maximum cell temperature below abusive thresholds without derating the charging power. The importance of thermal management is further increased for many new cell designs with improved energy density which often brings along weaker thermal performance. For instance, reducing the volume fraction of electrochemically inactive materials like the current collectors reduces the thermal conductivity and increases the heat generation. Aggressive cooling is achieved by increasing the heat convection coefficients between the cell surface and the heat transfer medium. With high heat convection coefficients, the internal thermal conductivity of the electrode-separator-composite determines the maximum cell temperature. Consequently, the thermal conductivity needs to be characterized accurately for fast charging investigations, which includes dependencies on parameters like temperature or compression load at the cell surface. Therefore, this work presents thermal conductivity measurements at different cell temperatures and compression loads with their impact on fast charging.
The thermal conductivity of a large-format NMC-111 graphite cell with a flat-wound jelly roll and prismatic PHEV2 hardcase made of aluminum alloy is measured at temperatures between -10 and 50 °C and at external compression loads between 37 and 74 kPa. This compression range is defined by the manufacturer at the largest cell surfaces to counter swelling of the jelly roll. Based on the guarded heater principle, a precise thermal conductivity test bench is designed and validated by a stainless steel reference material. For deriving the thermal conductivity of the electrode-separator-composite from the full-cell measurements, the thermal conductivity of the hardcase has to be compensated. For this purpose, a fast and simple technique for measuring the thermal conductivity of the hardcase by using electrical resistance measurements and applying theories like the law of Wiedemann–Franz is introduced.
According to the measurement result, the thermal conductivity increases by 13.6% at 20 °C when the compression load rises from 37 to 74 kPa, which is mainly attributed to reduced thermal contact resistances between the cell layers. At constant compression and rising mean temperature, the thermal conductivity decreases by more than -1% per °C compared to the value at 20 °C. Both findings affect the cell internal temperature rise during aggressive cooling and therefore the power-derating events due to overheating. Based on these findings, implications for thermal control strategies during fast charging are discussed.
Figure: Thermal conductivity of NMC-G electrode-separator-composite in through-plane direction at different cell temperatures and compression loads at the two largest surfaces of a prismatic PHEV2 cell.

Figure 1
Study of Cathode Catalyst Layers for Anion Exchange Membrane Fuel Cells Using Fe-N-C Catalyst and a Novel Polymer Electrolyte
Authors: Otsuji Kanji , Yokota Naoki , Tryk Donald A. , Kakinuma Katsuyoshi , Miyatake Kenji , Uchida Makoto 
Published: December 2020

In this work, we examined the cell performance of membrane-electrode assemblies (MEAs), for anion exchange membrane fuel cells (AEMFCs), using a non-noble metal catalyst and a novel polymer electrolyte. The chemical structure of quaternized poly(arylene perfluoroalkylene), i.e., QPAF-4 (ion exchange capacity: IEC = 2.1 meq g-1) developed in this laboratory1 is shown in Figure 1. Since this ionomer is soluble in lower alcohols such as methanol, it is also suitable for use as an electrode binder. The non-precious metal catalyst cell was loaded with 0.45 mg cm-2 Fe-N-C catalyst supplied by Pajarito Powder on the cathode and 0.45 mg cm-2 platinum catalyst on the anode, respectively. Pt loaded on carbon black (Pt/CB, TEC10E50E), supplied from TKK Japan, was used as the platinum electrocatalyst.
Figure 2 shows the results of current-voltage (I-V) measurements of the cell using the Fe-N-C catalyst under back pressures from 0 to 100 kPag (same pressure on both sides) at 60 oC, 100% RH; anode H2 (100 mL min-1); cathode O2 (100 mL min-1). The cell using the Fe-N-C catalyst showed hysteresis in the I-V curves between increasing and decreasing current. The degree of hysteresis decreased with increasing the back pressure. Figure 3 shows the results obtained when the back pressure of the anode was 100 kPag and the back pressure of the cathode was varied. The hysteresis decreased as the cathode back pressure increased. At the present stage, the loading amount of Fe-N-C catalyst, ionomer content, and porosity of the catalyst layer have not yet been optimized.
By increasing the back pressure, liquid water would be generated more easily which is advantageous since cathodic reaction in AEMFCs requires water. We found that supplying liquid water to the cathode lead to decrease of the hysteresis when using the QPAF-4 polymer and Fe-N-C catalyst as the cathode.

Acknowledgements

This project was partly supported by NEDO Japan through funds for the “Advanced Research Program for Energy and Environmental Technologies” and the Japan Society for the Promotion of Science (JSPS) and the Swiss National Science Foundation (SNSF) under the Joint Research Projects (JRPs) program.

Reference

Ono, T. Kimura, A. Takano, K. Asazawa, J. Miyake, J. Inukai, K. Miyatake, J. Mater. Chem. A, 5, 24804 (2017).

Figure 1
A New Method for Producing Hydrogen Carrier Using Renewable Energy -Direct MCH–
Authors: Nagatsuka Tomomi , Takamura Toru , Misu Yoshitatsu , Miyoshi Kota , Matsuoka Koji , Sato Yasushi 
Published: December 2020

New energy sources with lower environmental impact are the focus of increasing attention to enable the sustainable growth of human societies. There is an urgent need for technologies that enable conversion of renewable energy (RE) to a transportable energy carrier and recovery of that energy for later use. We have focused on organic hydrides, specifically the toluene (TOL) / methylcyclohexane (MCH) system, and have been working on a one-step process for producing MCH from TOL via electrochemical hydrogenation. We named this new method “Direct MCHTM”.
The equipment needed for Direct MCH is basically the same in structure as that already used for water electrolysis. An electrolyzer with a membrane-electrode-assembly (MEA), similar to those used for polymer electrolyte water electrolysis (PEWE), can be used. The cathode consists of a carbon-supported Pt-Ru alloy catalyst with a high specific surface area and a proton-conductive ionomer. The cathode shows good electron conductivity and high diffusivity of protons and TOL, and provides a three-dimensional network of active sites. On the cathode catalyst, TOL from the diffusion layer is converted directly to MCH via electrochemical hydrogenation by protons coming from the anode through the electrolyte membrane. (Fig. 1)
For process commercialization, it will be necessary to get the electrolysis voltage closer to the theoretical voltage and achieve current densities as high as those seen in alkaline water electrolysis. We also looked at how the toluene concentration affects Direct MCHTM. It has been shown that as electrolysis proceeds and the TOL concentration drops, the current density falls because it is a diffusion-limited reaction. But from the standpoint of transport efficiency, the MCH conversion rate needs to be 95% or higher, and the average current density during electrolysis to reach this rate should be comparable to that of water electrolysis, which is 0.4 A/cm2. By studying the catalyst compositions, we have made it so the percolating water through with the protons from the anode drains more easily from the cathode catalyst layer. Moreover, we obtained a cathode catalyst with high TOL diffusivity. (Fig. 2)
Finally, we conducted a demonstration of the Direct MCHTM process in Queensland, Australia that was powered only by renewable energy, using electricity generated by photovoltaic cells. Over four liters of MCH obtained via Direct MCHTM was brought to Japan, showing that it is possible to transport CO2-free energy from Australia to Japan. Then, so-called "green hydrogen" was generated via dehydrogenation of the MCH and used to run a miniature car equipped with a fuel cell.

Figure 1
Supported Transition Metal Phosphides: Activity Survey for HER, ORR, OER, and Corrosion Resistance in Acid and Alkaline Electrolytes
Authors: Parra-Puerto Andres , NG Kai Ling , Fahy Kieran F. , Goode Angela E , Ryan Mary P. , Kucernak Anthony 
Published: December 2020

One of the main bottle necks for the introduction of fuel cell technology in the market, is their dependency on precious metals as catalyst. Focusing on the electrochemical reactions involved, the most sluggish is the Oxygen Reduction Reaction (ORR). Significant research has been performed to optimize for the amount of the precious metal used, whilst keeping the same activity. On the other hand, many investigations have been carried out to find non-precious metal catalysts with the same performance for ORR, Oxygen Evolution Reaction (OER), Hydrogen Evolution Reaction (HER) and Hydrogen Oxidation Reaction (HOR) [1]. One of those candidates are the metal phosphides [2], however, these catalysts nowadays only are active for ORR, HER, OER and they have very poor activity towards the HOR [3]. Here we present the work done related to the simple synthesis of different MP catalysts (M = Ni, Co, W, Cr and Mo) [4]; their catalytic activity towards H2 and O2 reactions; and their corrosion resistance in acidic and alkaline electrolytes. Co2P was found to have a very interesting ORR catalytic behaviour and peroxide generation under alkaline and acidic conditions respectively. To understand the activity of Co2P, an HRTEM analysis was done to understand the changes in the morphology before and after the ORR reaction.

References

[1] M. S. Faber and S. Jin, “Earth-abundant inorganic electrocatalysts and their nanostructures for energy conversion applications,” Energy Environ. Sci., vol. 7, no. 11, pp. 3519–3542, Oct. 2014, doi: 10.1039/C4EE01760A.
[2] A.-M. Alexander et al., “Alternative catalytic materials: carbides, nitrides, phosphides and amorphous boron alloys,” Chem. Soc. Rev., vol. 39, no. 11, pp. 4388–4401, Oct. 2010, doi: 10.1039/b916787k.
[3] R. Prins and M. E. Bussell, “Metal Phosphides: Preparation, Characterization and Catalytic Reactivity,” Catal. Letters, vol. 142, no. 12, pp. 1413–1436, Dec. 2012, doi: 10.1007/s10562-012-0929-7.
[4] A. Parra-Puerto, K. L. Ng, K. Fahy, A. E. Goode, M. P. Ryan, and A. Kucernak, “Supported Transition Metal Phosphides: Activity Survey for HER, ORR, OER, and Corrosion Resistance in Acid and Alkaline Electrolytes,” ACS Catal., vol. 9, pp. 11515–11529, Nov. 2019, doi: 10.1021/acscatal.9b03359.

Figure 1
Highly Active Fe-N/C Oxygen Electrocatalysts Based on Silicon Carbide Derived Carbon
Authors: Teppor Patrick , Jäger Rutha , Hints Johanna , Volobujeva Olga , Valk Peeter , Koppel Miriam , Lust Enn 
Published: December 2020

Extensive research is currently being conducted in the field of non-platinum group metal oxygen reduction catalysts for low-temperature fuel cells1,2. Many of the synthesis methods used to produce these novel materials involve grinding the precursors in a planetary ball mill3,4. Consequently, more information is needed to understand how this procedure affects the physical properties of the resulting carbon-based materials. Additionally, it is crucially important to investigate the influence of the physical properties on the electrochemical performance of the electrocatalysts.
In this work, several Fe-N/C type electrocatalysts were synthesized from silicon carbide derived carbon via ball milling. A number of parameters, such as grinding mode and ball diameter, were changed in order to study their effect on both the physical and electrochemical properties of the Fe-N/C catalysts. The main characterization methods used in this study were N2-sorption and laser diffraction, which provide insight into the pore and particle size distributions of the materials, respectively.
From the rotating disc electrode measurements it is clear that highly active Fe-N/C catalysts can be successfully synthesized using a facile two-step process involving ball milling and pyrolyzing. Changing the ball milling parameters has a considerable effect on both the surface morphology as well as particle size distributions of the studied Fe-N/C catalysts. As a final step, the importance of these changes in the physical properties was studied in a single cell experimental setup.

B.-Y. Song, M.-J. Li, Y.-W. Yang, and Y.-L. He, J. Clean. Prod., 249, 119314 (2020) http://www.sciencedirect.com/science/article/pii/S0959652619341848.

D. Banham, J.-Y. Choi, T. Kishimoto, and S. Ye, Adv. Mater., 31, 1804846 (2019) https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.201804846.

S. Ratso et al., ACS Appl. Energy Mater., 2, 7952–7962 (2019) https://doi.org/10.1021/acsaem.9b01430.

M. J. Workman et al., J. Power Sources, 348, 30–39 (2017) http://www.sciencedirect.com/science/article/pii/S0378775317302410.

Figure 1
Rationalizing Effect of Metal Substitution in Ruthenium Pyrochlores on the Lattice Oxygen Binding and Oxygen Evolution Activity
Authors: Kuznetsov Denis A. , Naeem Muhammad A. , Kumar Priyank V. , Abdala Paula M. , Fedorov Alexey , Müller Christoph R. 
Published: December 2020

Ruthenium pyrochlores, i.e. oxides of composition A2Ru2O7
−
δ, are known as advanced catalysts for the oxygen evolution reaction (OER) in acidic conditions.1 In this work, we discuss a direct correlation between the OER activity of Y1.8M0.2Ru2O7
−
δ pyrochlores (M = Y, Fe, Co, Ni, Cu), the lattice oxygen binding strength/lability and the formation enthalpy of the binary MOx oxide, i.e. metals M with highter enthalpies of formation for the respective oxide weaken the oxygen binding on the surface of Y1.8M0.2Ru2O7
−
δ pyrochlores that results in enhanced OER activity. DFT studies captured changes in the electronic structure of the Y1.8M0.2Ru2O7
−
δ oxides induced by M substitution and revealed trends in the electronic band structure that govern the OER performance of the Y1.8M0.2Ru2O7
−
δ catalysts. Specifically, an increase in the density of oxygen vacancy (VO) sites and the OER activity in Y1.8M0.2Ru2O7
−
δ is attributed to the shift of the O 2p band center closer to the Fermi level. Our work introduces Y1.8Cu0.2Ru2O7
−
δ as a novel OER catalyst with enhanced OER activity and, more fundamentally, emphasizes the underexplored role that substituents can play in regulating the OER activity of complex oxides, i.e. by influencing the surface oxygen binding strength. Our results can be utilized for the rational design of new compositions for oxygen electrocatalysis and other applications that involve lattice oxygen sites.
(1) Kim, J.; Shih, P.-C.; Tsao, K.-C.; Pan, Y.-T.; Yin, X.; Sun, C.-J.; Yang, H., J. Am. Chem. Soc.
2017,
139, 12076-12083.
Investigation of Anodic Porous Transport Electrode for Anion Exchange Membrane Electrolyzers
Authors: Wang Ruixiang , Ishida Masayoshi , Ohashi Masato , Ito Hiroshi 
Published: December 2020

As global warming and the exhaustion of fossil fuels deepen, major countries are trying to promote the spread of renewable energy such as solar and wind power. Hydrogen with high energy density, no harmful emissions and various transportation, storage methods is regarded as the optimal energy carrier for renewable energy. Water electrolysis technology is usually used for the transformation of renewable resources to hydrogen. In the development of water electrolysis technology, proton exchange membrane (PEM) water electrolysis used a PEM with high mechanical/chemical stability and a membrane electrode assembly (MEA) with a zero-gap structure of electrodes has excellent variability to power fluctuation and a better electrolysis efficiency. However, due to the acidic electrolyte, cell components materials of PEM water electrolysis are limited to precious metal such as iridium (Ir) based catalysts on anode and platinum-group metals (PGMs) catalyst on cathode.
In contrast, in the anion exchange membrane (AEM) water electrolysis, alkaline membrane can be used as electrolyte which means, compared with PEM water electrolysis, widely available non-precious metal catalysts and stainless components can be used. However, different from proton exchange ionomer (PEI), typical models of anion exchange ionomer (AEI) tend to lack mechanical and chemical stabilities and are difficult to apply to the binder for anode catalyst layer [1]. Therefore, we have adopted a different electrode structure for each of the two electrodes in the MEA, that is, catalyst-coated-membrane (CCM) for the cathode and porous transport electrode (PTE) for the anode.
In this study, various types of PTE were fabricated and applied for the anode. The effect of each property of PTE (catalyst lading, porosity, thickness, and pore diameter) on the electrolysis performance was examined experimentally.
Acknowledgement
Part of the experiments reported here are supported by the New Energy and Industrial Technology Development Organization (NEDO).
Reference
[1] H. Ito et al. J. Appl. Electrochem., 48, 305 (2018)