bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hexahydroxytriphenylene/NiII MOF Compounds for Oxygen Reduction Reaction Catalysis
Authors: Moreau Florian , Tissot Antoine , Grimaud Alexis , Tarascon Jean Marie , Serre Christian 
Published: February 2020

Materials which show satisfying electrocatalytic activities for Hydrogen Evolution Reaction (HER) or Oxygen Reduction Reaction (ORR) for fuel cell energy storage are mainly based on Platinum which has a very limited abundancy. Although a few chalcogenides, such as MoS2 or MnO2 show promising catalytic activity, it is inherently limited by the accessible surface area of these materials. Over the last decade, hybrid porous materials (or Metal-Organic Frameworks) with intrinsic electronic conductivity have been reported.1 MOFs potential assets as electrocatalysts are mainly due to the combination of three factors: i) Their crystalline nature allows a fine control of the spatial layout of active sites over a long range order, and potentially the tuning of conductivity. ii) Their hybrid nature gives rise to a very versatile chemistry and thus permits the systematic investigation of how both organic and inorganic counterparts influence on the material properties. iii) Their porosity provides a high density of accessible active sites.
Among electrically conductive MOFs, 2D triphenylene-based frameworks are of particular interest owing to their large π-conjugated systems and the resulting large conductivities. 2-4 Indeed, a hexaimino-triphenylene/NiII MOF system (Ni-HITP) was recently reported to show great electrocatalytic activity towards ORR.5

Although a few tricatecholate MOFs based on 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and MII cations (Co, Ni, Cu) have been reported,4 none of these have been tested for ORR electrocatalysis. We thus decided to investigate this system and isolated a previously unreported phase: Ni-HHTP-S which consists solely of 2D layers stacked in a staggered manner with blocked porosity. Interestingly, when thermally treated, Ni-HHTP-S undergoes a phase transition towards Ni-HHTP-E with eclipsed layers and accessible porosity. Both materials show different and high electrocatalytic activities towards ORR. This system thus offers a great opportunity to investigate the modulation of conductivity and catalytic activity of a 2D MOF, not only by its primary structure, but also by the secondary arrangement of its layers.This communication will present the frameworks characterizations and discuss their electronic conductivities and ORR electrocatalytic activities.
[1] L. Sun et al., Angew.
Chem. Int. Ed.,
2016, 55, 3566-3579.
[2] D. Sheberla et al., J. Am. Chem. Soc., 2014, 136, 8859-8862.
[3] M. Campbell et al., Angew. Chem. Int. Ed.,
2015, 127, 4423-4426.
[4] M. Hmadeh et al., Chem. Mater., 2012, 24, 3511-3513.
[5] E. Miner et al, Nat. Commun., 2016, 7, 10942.
Sub-Zero Cell Reversal Tolerance in Polymer Electrolyte Membrane Fuel Cells
Authors: Bashyam Rajesh , Bellerive Julie , He Ping 
Published: February 2020

Polymer electrolyte membrane fuel cells (PEMFCs) have gained considerable attention in recent years for application in electric vehicles, portable devices, and cogeneration systems. Large scale commercialization of PEMFCs mainly requires addressing the high cost issues associated with the fuel cell stack in addition to the challenges associated in building H2 infrastructure. Though, significant amount of research has been carried out in developing low Pt loaded Membrane Electrode Assemblies to meet the 2020 DOE performance targets for automotive applications, there are still challenges associated in meeting durability requirements due to catalyst layer and membrane degradation. It is well documented voltage cycling during start-up/shutdown process leads to Pt dissolution and loss of electrochemical surface area of Pt and thereby affecting the durability. Fuel cells stacks need to be robust against both specific and non-specific failure modes. Specific failure modes of MEA can be predicted by operating conditions/parameters, however non-specific failure mode such as cell reversal is difficult to predict. Though, system level mitigation can be employed to minimize the impact of cell reversal, there is a potential cost trade-off associated with this approach. Ballard1 was first to develop and report the impact of cell reversal tolerance above sub-zero conditions with and without cell reversal tolerance catalyst in the MEA.
Cell reversals2 can occur mainly during reactant starvation and especially during H2 starvation under freeze start-up operation. This presentation will focus on evaluating the impact of operating parameters on cell reversal under sub-zero conditions and will highlight the mechanism and potential ways to improve cell reversal tolerance under sub-zero conditions. Figure 1 shows the impact of current density on cell reversal tolerance under sub-zero conditions3. As it can be seen, significant reduction in sub-zero reversal tolerance noticed with current density. To the best of our knowledge, we evaluated for the first time, the cell reversal tolerance under sub-zero conditions.
References

S.D.Knights, D.P.Wilkinson, S.A. Cambell, J.L.Taylor, J.M. Gascoyne and T.R. Ralph, Solid polymer fuel cell with improved voltage reversal tolerance. US Patent 6936370.

C. Qin, J. Wang, D. Yang, B. Li and C. Zhang, Proton Exchange Membrane Fuel Cell Reversal:A Review, Catalysts, 6, 2016, 197.

R.Bashyam, J.Bellerive, P.He, Fuel cell system and method of operating fuel cell system, German Patent application DE102016207786A1

Acknowledgement
We thank Volkswagen AG and Audi for funding this work.

Figure 1
Total Cost of Ownership of Fuel Cell Electric Vehicles Using Expert Assessments
Authors: Whiston Michael M. , Azevedo Inês , Litster Shawn , Whitefoot Kate , Samaras Constantine , Whitacre Jay 
Published: February 2020

We calculated the total cost of ownership (TCO) of fuel cell electric vehicles (FCEVs) in 2017, 2020, 2035, and 2050. Our TCO model incorporates proton exchange membrane fuel cell (PEMFC) cost and durability data that we obtained during our expert elicitation interviews [1]. Our assumptions, including hydrogen storage system and fuel costs, are consistent with those published by the U.S. Department of Energy [2, 3]. We characterized the uncertainty associated with FCEV life cycle costs, and we compared our FCEV projections to the DOE’s 2035 projections for internal combustion engine vehicles (ICEVs), battery electric vehicles (BEVs), hybrid-electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). In our sensitivity analyses, we studied the dependence of FCEV TCO on vehicle lifetime, hydrogen fuel cost, and hydrogen storage system cost. All monetary values are expressed in 2017 USD.
On median, we estimated the FCEV TCO to be $0.42/mile in 2017, $0.33/mile in 2020, $0.19/mile in 2035, and $0.18/mile in 2050 (Figure 1). Our 2017 and 2020 estimates ranged widely. Our 2017 estimates ranged from $0.40 to $0.75/mile and 2020 estimates ranged from $0.31 to $0.51/mile. By 2035, FCEVs could be competitive with ICEVs, BEVs, HEVs, and PHEVs, as long as the PEMFC stack lasts sufficiently long. If the FCEV’s lifetime falls below 11 yrs, FCEVs could become more expensive than competing vehicles. At about 11 yrs, the FCEV’s TCO exceeds that of the BEV. If stack durability remains a challenge, replacing the stack could be economical. Achieving a hydrogen fuel cost below $4/kg H2 and hydrogen system cost below $390/kg H2 could further improve FCEVs’ competitiveness.

References

[1] Whiston, M. M., Azevedo, I., Litster, S., Whitefoot, K. S., Samaras, C., and Whitacre, J. F. “Expert Assessments of the Cost and Expected Future Performance of Proton Exchange Membrane Fuel Cells for Vehicles.” Proceedings of the National Academy of Sciences of the United State of America. Manuscript submitted.
[2] Nguyen, T. and Ward, J. “Life-Cycle Cost of Mid-Size Light-Duty Vehicles.” Record No. 16009. U.S. DOE, Washington, D. C.
[3] U.S. DOE. “Multi-Year Research, Development, and Demonstration Plan.” U.S. DOE, Washington, D. C. Accessed April 3, 2018. Available at https://www.energy.gov/eere/fuelcells/downloads/fuel-cell-technologies-office-multi-year-research-development-and-22

Figure 1
Polynorbornene-Based Anion Exchange Membranes for Alkaline Fuel Cells
Authors: Huang Garrett , Mandal Mrinmay , Kim Yunbum , Kohl Paul A 
Published: February 2020

Fuel cells based on alkaline exchange membranes (AEM) have garnered increased interest because of their inherent advantages over traditional proton exchange membranes (PEM). High pH operating conditions allow for more facile reaction kinetics, reduced platinum-group metal catalyst, and reduced fuel crossover issues. Moreover, these materials can be made from inexpensive precursors which can further drive down the cost of the membrane electrode assemblies (MEA) for fuel cells.
In this study, a variety of block copolymer AEMs based on based on vinyl addition and ring-opening metathesis polymerization of norbornenes was synthesized and characterized. Correlations were found between the ionic conductivity and mechanical properties and the polymer structure, channel size and phase separation. The AEMs were also used to construct MEAs for alkaline fuel cells and their performance was analyzed using electrochemical impedance spectroscopy.
Financial support provided by the ARPA-E IONICS program for G.H. and M.M. is gratefully acknowledged.
Self-Driven Strain Tuning in Transition Metal Nanocrystals for the Oxygen Reduction Reaction
Authors: Wang Lei , Zeng Zhenhua , Gao Wenpei , Maxson Tristan , Raciti David , Giroux Michael , Pan Xiaoqing , Wang Chao , Greeley Jeffrey 
Published: February 2020

The elucidation of governing principles of catalyst activity from fundamental research on well-defined model systems, combined with the advances in controlled synthesis of the transition metal nanocatalysts, have led to the rational design and development of advanced nanocatalysts. One principle is to tune surface strain and thereby modulate the surface electronic structure and catalytic reactivity. This approach has been employed to identify transition metal and (hydroxy)oxide catalysts for energy-relevant electrocatalytic reactions. For oxygen reduction reaction on platinum as an example, previous studies have indicated that a 1% compressive strain may improve the activity over 300%.
While strain tuning of catalysts is very promising for activity enhancement, two challenges continue to limit the performance of these materials. First, the effect of strain on high-surface-area nanoparticle catalysts is often convoluted with nanoparticle shape and by the presence of undercoordinated defects, while model catalysts, where high specific activities is achievable by strain tuning, have prohibitively small mass activities and are therefore of limited practical interest. Thus, there is an urgent need to develop strain tuning strategies for nanomaterials that preserve the structural simplicity and high specific activity of single crystals while simultaneously possessing high surface areas and mass activities. In addition, strain in catalyst overlayers is often imposed by heterosubstrates, which may lead to interfacial reconstructions and strain release.
In this talk, in combination DFT calculations, electrochemical tests and TEM characterization, we will present a strategy to resolve these problems through self-driven strain tuning in transition metal nanocrystals with the characteristics of low-index single-crystal surfaces. As we demonstrate for the oxygen reduction reaction in alkaline fuel cells, this relationship could be exploited to enhance reaction rates by orders of magnitude in comparison with nanoparticle catalysts, suggesting that this self-driven tuning mechanism in transition metal nanocrystals can be a powerful strategy for the design and development of advanced catalytic materials.
(Invited) Gold Nanoparticles Modified with Platinum and Palladium As Electrocatalysts for Ethanol Oxidation Reactions
Authors: Shao Minhua , Xing Zelong , Chen Huimei 
Published: February 2020

Electrooxidation of ethanol on noble metals, such as Pt in acidic and Pd in alkaline solutions is of particular interest due to its potential application in low-temperature direct ethanol fuel cells (DEFCs). The slow, incomplete oxidation of ethanol as well as the high price of Pt and Pd has impeded the wide application of DEFCs. In response to these challenges, several resembling core-shell electrocatalysts using Au nanoparticles were synthesized and evaluated for ethanol oxidation reaction (EOR).
It was found that the Pd shell is not uniform consisting of tiny Pd clusters with a coverage of 0.5-0.6. The EOR activity of this kind of structure is much higher than Pd/C in an alkaline solution. The forward peak current density of was 5 times higher than that of Pd/C. Furthermore, the onset potential for EOR of the former was ~100 mV more negative. An interesting particle size dependent EOR activity was also observed. With increasing the Au particle size (2.9 to 5.8 and 6.5 nm), the EOR activity increases. The strain and ligand effects from the Au core, together with the bifunctional mechanism from the core and shell can explain the observed activity trend. Similar core-shell catalysts with a Pt shell were also synthesized and evaluated for EOR in acidic electrolytes. In a further study, the core-shell particles were modified with Ru and SnO2, which showed enhanced activities. In situ spectroscopic studies were conducted to reveal the reaction intermediates and products of various catalysts to give more insights into the reaction pathway and activity enhancement mechanisms.
A Novel IrOx-Based Composite Material with High Oxygen Evolution Reaction Performance in Acidic Media
Authors: Cheng Junfang , Yang Jun , Kitano Sho , Cui Xuedong , Yamauchi Miho , Nakashima Naotoshi 
Published: February 2020

With excellent oxygen evolution reaction (OER) activity and stability in acidic media, IrOx-based materials are regarded as the most suitable catalysts to fulﬁl the technological requirements in acidic conditions. However, because of the high cost of Iridium, it is crucial to reduce the Ir consumption without compromising catalytic activity[1
-
3].
In this study, we synthesized a novel IrOx-based composite catalyst by low temperature processes, and the obtained catalyst showed an outstanding OER performance in acidic media. The detail synthesis method, micromorphology and performance of the catalyst will be presented at the meeting.

References

[1] N. Mamaca, E. Mayousse, S. Arrii-Clacens, et al., Applied Catalysis B: Environmental, 2012, 111-112, 376– 380.
[2] H. Nong, H. Oh, T. Reier, E. Willinger, M. Willinger, V. Petkov, D. Teschner, P. Strasser, Angew. Chem. Int. Ed. 2015, 54, 2975–2979.
[3] E. Oakton, D, Lebedev, M. Povia, D. Abbott, E. Fabbri, A. Fedorov, M. Nachtegaal, C. Copéret, T. Schmidt, ACS Catal. 2017, 7, 2346−2352.
Palladium Nanoparticles on Nickel for Direct Methanol Solid Oxide Fuel Cell Catalyst
Authors: Koo Junmo , Jang Dong Young , Choi Hyeon Rak , Kim Jun Woo , Shim Joon Hyung 
Published: February 2020

Direct Methanol Solid Oxide Fuel Cell (DMSOFCs) has been drawn comparable attentions in fuel cell society for its fuel flexibility and high energy density of methanol compared to that of hydrogen. However, carbon coking and carbon monoxide poisoning occur due to usage of methanol as fuel, which hinder electrode kinetics and eventually cause performance degradation. Therefore, demand of high performance catalyst with excellent stability has been risen for the widespread usage of DMSOFC. To these days, bimetallic Pt-Ru is known as the best DMSOFC catalyst for its superior methanol oxidation capability. However, high scarcity of Pt and Ru hinders the widespread commercialization of DMSOFC for its expensive price. Recently, Ni has been considered as promising alternative for Pt-Ru. Price of Ni is far lower than that of Pt or Ru, and Ni has respectable methanol oxidation ability. During electrochemical oxidation of methanol, however, carbon tends to deposited on the surface of Ni, which leads performance and stability degradation of Ni catalyst.
In this study, we deposited the palladium nanoparticles on the surface of Ni in order to obtain bimetallic Pd/Ni catalyst for DMSOFC application. Pd nanoparticles were deposited by DC magnetron sputtering and atomic layer deposition. DMSOFC with Pd/Ni catalyst were analyzed by current-voltage measurement and electrochemical impedance spectroscopy at the temperature range of 300 - 450 ºC. Pd/Ni catalyst showed enhanced performance and stability compared to bare Ni catalyst. Detailed analysis of experiment will be discussed in the presentation.
Surface Ligands As Atomic Valves for Growth of Nanocrystal Quantum Dots
Authors: Lee Doh C 
Published: February 2020

Growth of monodisperse quantum dots (QDs) is a pressing requirement in the context of commercial application as well as academic study, as the size uniformity is directly related to color purity in display products which have been commercialized. In the growth, surface ligands serve not only as a protection layer for QD surface but also controller for reaction kinetics. I will present our recent findings pertaining to these issues on the basis of different material examples.
Our study on the colloidal synthesis of InP QDs in the presence of Zn precursors will be discussed, in which size uniformity is markedly enhanced as compared to the case of InP QDs synthesized without Zn precursors. In the presence of zinc carboxylate, intermediate species containing Zn-P bonding appears. The Zn-P intermediate complex with P(SiMe3)3 exhibits lower reactivity than In-P complex. The formation of stable Zn-P intermediate complex results in lower reactivity, hence monodisperse QDs. Insights from the experimental and theoretical studies advance the mechanistic understanding and controlling of nucleation and growth of InP QDs.

We investigated diffusion of active species monomers through ligand layers using CdSe nanorods (NRs) as a model system. Colloidal NRs are of special interest for optoelectronic applications because its shape anisotropy leads to unique optical and physical characteristics, expandable with morphological and structural deviation. I present a new answer for detailed growth mechanism of colloidal semiconductor NRs. For this, we developed dual-diameter nanorod (DDNR) structure via colloidal synthesis, where two sections along the long axis in each NR have different diameters at a few nanometer scale. The vivid segmentation is an ideal platform for monitoring the growth process of NRs, presenting important determinants in the reactivity of distinguishable NR facets. By controlling the discovered factors, single-diameter NRs with controllable core position also became available. I will put the findings in perspective by outlining the effect of diffusion of monomers and surface growth reactions.
On the Assumption-Free Determination of Single-Ion Gibbs Energies of Transfer
Authors: Radtke Valentin , Ermantraut Andreas , Krossing Ingo 
Published: February 2020

Since about 100 years, the quest on the determination of Gibbs energies of transfer of single-ions exists. While some consider that the chemical potential of single-ions is physically senseless, other determined Gibbs solvation energies or Gibbs transfer energies of single-ions with the help of extra-thermodynamic assumptions (e.g. TATB-assumption, ferrocene-assumption and others), thereby introducing an error of the respective quantity of insufficiently assessable magnitude.[1]

We suggest a procedure for the thermodynamically rigorous, experimental determination of the Gibbs energy of transfer of single-ions Δtr
G°(i, S1--> S2). The method is based on potential difference measurements between two electrochemical half-cells with different solvents (solvation cells) connected by an ideal ionic liquid salt bridge (ILSB).[2] We point out the specific requirements for the IL with regard to the procedure, thus ensuring that those parts of liquid junction potentials (LJP) at both ends of the ILSB cancel which depend on the redox system used. The remaining parts of the LJPs can be determined by separate electromotive force measurements, the knowledge of the ionic transference numbers and Gibbs energies of transfer of the used salts is mandatory. No extra-thermodynamic assumptions are necessary for this procedure. The accuracy of the target quantity is an inherent part of the measurements and depends, amongst others, on the ideality of the IL used. We present results concerning the crucial steps a) and b) of the methodology exemplarily for Ag+ and Cl− with S1 being water and S2 being acetonitrile as an important intermediate goal to evaluate our concept for the assumption-free determination of single-ion Gibbs transfer energies Δtr
G°(i, S1--> S2).[3] The used IL, [N2225]+[NTf2]−, shows nearly ideal behavior, that is, nearly identical diffusion of anion and cation, in the pure IL, but also in water and acetonitrile solution. Electromotive force measurements of solvation cells between S1 and S2 demonstrate Nernstian behavior for Ag+ concentration cells and constant like cell potentials for solutions with five tested Ag+ counterions.
The Gibbs transfer energies can be utilized to collect data for the unified scales of acidity pHabs and reducity and peabs and for their two dimensional plot, the Protoeletric Potential Map (PPM), enabling the possibility to easily compare acidities and redox potentials between different media.[4]

Literature:
[1] P. Hünenberger, M. Reif, Single-Ion Solvation. Experimental and Theoretical Approaches to Elusive Thermodynamic Quantities, The Royal Society of Chemistry, Cambridge, 2011.
[2] V. Radtke, A. Ermantraut, D. Himmel, T. Koslowski, I. Leito, I. Krossing, Angew. Chem. Int. Ed. 2018, 57, 2344.
[3] A. Ermantraut, V. Radtke, N. Gebel, D. Himmel, T. Koslowski, I. Leito, I. Krossing, Angew. Chem. Int. Ed. 2018, 57, 2348.
[4] D. Himmel, V. Radtke, B. Butschke, I. Krossing, Angew. Chem. Int. Ed., 2018, doi:10.1002/anie.201709057.