bluuebunny/crossref_metadata_2025_split huggingface dataset:
CO2 Electrochemical Reduction to Hydrocarbon Fuels on Carbon-Supported Copper Nanoparticles: Support Effect
Authors: Lu Qin , Purdy Andrew , Dyatkin Boris , Gogotsi Yury , Baturina Olga A 
Published: February 2020

Previously, we reported activity and selectivity of Cu nanoparticles towards CO2 electroreduction to hydrocarbon fuels (CH4 and C2H4) on three different supports (Vulcan Carbon (VC), Ketjenblack (KB) and singled walled carbon nanotubes (SWCNT))1. We found that carbon materials not only serve as inert supports, but are actively involved in electrochemical CO2 reduction likely due to hydrogen spillover from the support to the surface of Cu nanoparticles. Here we explore the effect of carbon support on the product distribution in CO2 electroreduction reaction in more detail expanding the number of nanostructered supports to reduced graphene oxide (rGO), and onion-like carbon (OLC)3. These five carbon materials (VC, KB, SWCNT, rGO and OLC) have different surface area, electronic conductivity, morphology, and inherent size.
Cu nanoparticles of 15-25 nm diameters on different carbon supports were synthesized by the reduction of CuCl2 using NaBH4 in aqueous ethylene glycol solution (20% v/v). X-Ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) were used for nanoparticles ex-situ analysis. The catalytic activities and selectivity of supported Cu nanoparticles towards CO2 electrochemical reduction to hydrocarbon fuels were evaluated using a sealed rotating disk electrode (RDE) setup connected to a gas chromatograph1.
Cu nanoparticles supported on VC and OLC exhibited higher catalytic activity vs other catalysts towards CH4 and C2H4 generation, respectively, between -1.4 and -1.6 V (vs Ag/AgCl reference electrode). At a more negative potential of -1.6 V, all five Cu catalysts promoted generation of both CH4 and C2H4, with the higher selectivity in terms of Faradaic efficiencies towards C2H4 formation. The C2H4/CH4 ratio increased by almost an order of magnitude in the following order: Cu/VC (2.6:1) <Cu/KB (4.5:1) < Cu/SWNT (5.8:1) < Cu/GPO (10.8:1)< Cu/OLC (33:1). Cu/OLC showed both the lowest onset potential and the greatest selectivity towards C2H4 formation.
This presentation will discuss the reasoning behind the different catalytic activity and selectivity of supported Cu nanoparticles in catalyzing the CO2 electrochemical reduction reaction.
[1] O. A. Baturina, Q. Lu, M. A. Padilla, L. Xin, W. Li, A. Serov, K. Artyushkova, P. Atanassov, F. Xu, A. Epshteyn, T. Brintlinger, M. Schuette, and G. E. Collins, ACS Catal. 2014, 4, 3682.
[2] P. V. Kamat, J. Phys. Chem. Lett. 1 (2010), 520.
[3] J. K. McDonoug, Y Gogotsi,
Interface, 22 (2013), 61.
Exploring the Non-Innocence of Inorganic Complex Ligands in (photo-) Electrochemical CO2 Reductions
Authors: Saravanan Karthikeyan , Oyeyemi Victor B , Keith John A. 
Published: February 2020

Carbon neutral energy cycles necessitate the conversion of CO2 into other compounds.1 However, the unfavorable thermodynamics and slow kinetics of multiple proton and electron transfers makes CO2 conversion difficult. Improved insight into these processes would help elucidate reaction mechanisms that guide the development of improved and versatile photo- and electro-catalysts.2 Recent experiments have demonstrated that inorganic Ru complexes can catalyze the photo- and electro-chemical reduction of CO2 into methanol.3 These reactions involve aqueous phase aromatic N-heterocycles (ANH) in addition to complexes that contain ANH ligands themselves (e.g. phenanthroline). We previously developed4 a set of thermodynamic descriptors from quantum chemistry calculations to describe electrochemical conditions at which ANH molecules participate in energetically efficient proton and electron transfers. In this study, we report our latest efforts to provide insight into the mechanism of Ru catalyzed CO2 reduction using Pourbaix diagram descriptors. Although transition metal complexes are normally assumed to be electrochemically stable, our calculations indicate that certain environments may result in hydride transfers facilitated via the ligands of the inorganic complexes.
References:
1. Olah, G. A., Prakash, G. K. S. & Goeppert, A. Anthropogenic Chemical Carbon Cycle for a Sustainable Future. J. Am. Chem. Soc. 133, 12881–12898 (2011).
2. Qiao, J., Liu, Y., Hong, F. & Zhang, J. A review of catalysts for the electroreduction of carbon dioxide to produce low-carbon fuels. Chem. Soc. Rev. 43, 631–675 (2013).
3. Boston, D. J., Pachón, Y. M. F., Lezna, R. O., de Tacconi, N. R. & MacDonnell, F. M. Electrocatalytic and Photocatalytic Conversion of CO2 to Methanol using Ruthenium Complexes with Internal Pyridyl Cocatalysts. Inorg. Chem. 53, 6544–6553 (2014).
4. Marjolin, A. & Keith, J. A. Thermodynamic Descriptors for Molecules That Catalyze Efficient CO2 Electroreductions. ACS Catal. 5, 1123–1130 (2015).
Precise Viscosity Analysis of Alkali Metal Molten Salts at High Temperature
Authors: Kim Sun Woog , Uematsu Kazuyoshi , Toda Kenji , Sato Mineo 
Published: February 2020

Recently, solar thermal energy has been attracted considerable attention as a renewable energy alternative to fossil fuels. The operation and efficiency of solar thermal energy plants employing thermal energy storage techniques have been proved at both experimental and commercial scales.1 In solar thermal energy plants, alkali metal molten salts have recently attracted as thermal storage media and heat transfer fluids, because these salts have a low melting point, high heat capacity, and moderate energy density.2 In addition, alkali metal molten salts are less expensive and more environmentally friendly than currently available high-temperature oils. However, many investigations are scarce focusing on thermophysical properties of molten salts at high temperature. In particular, the viscosity of alkali metal molten salts is few reported and the reported viscosities are shown larger difference by analysis method or other one. In this study, therefore, we are measured the viscosity of alkali metal molten salts at high temperature above 500 °C by rotation method using high temperature rheometer system (MCR 502, Anton Paar) and reliability of obtained viscosity values is evaluated.3

This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), "energy carrier" (Funding agency: JST).
References

Q. Peng, X. Yang, J. Ding, X. Wei, and J. Yang, Appl. Energy, 112 (2013) 682.

S.M. Flueckiger and S.V. Garimella, Sol. Energy, 86 (2012) 1631.

S.W. Kim, K. Uematsu, K. Toda, and M. Sato, J. Ceram. Soc. Jpn., (2015) in press.
Disorder and Ionic Transport in Pyrochlore/Defect Fluorite Oxide Thin Films
Authors: Kreller Cortney R , Holesinger Terry , Valdez James , Wang Yongqiang , Uberuaga Blas 
Published: February 2020

Numerous avenues are currently being explored to enhance ionic conductivity in solid oxide materials including dopants, nano-structuring, and strain engineering. Their effect on material properties, specifically mobile carrier concentration and mobility, needs to be understood and ultimately exploited to develop advanced functional materials. In this work, we seek to explore the relationship between intrinsic disorder and oxygen ion conduction. The pyrochlore compounds, A2B2O7, consist of both ordered cation and anion sublattices. The introduction of anti-site disorder, where the A and B cations switch positions, is accompanied by increasing disorder on the anion sublattice, and complete randomization of the A- and B-site cations results in the defect fluorite phase. Several workers have previously studied the influence of structural disorder on ionic conductivity by introducing disorder through dopants, temperature or pressure. In the present work, we are using irradiation as a tool to introduce, and control the extent of, structural disorder in pyrochlore oxide thin films. We have chosen to investigate the end members of the Gd2(ZrxTi1-x)2O7 system as Gd2Zr2O7 is an intrinsic fast-ion conductor that is also very rad tolerant whereas Gd2Ti2O7 is a comparatively poor ionic conductor that is much more susceptible to amorphization under irradiation than the zirconates. Electrochemical Impedance spectroscopy is used to measure the conductivity of materials with varying degrees of structural disorder in order to better understand how the underlying transport mechanisms depend on crystalline disorder.
Stress Engineering in Developing Mixed Conducting Si-Ge Solutions for Lithium Ion Batteries
Authors: Mishra Kuber , Geppert Mark , Zhou Xiao-Dong 
Published: February 2020

Despite having the highest theoretical specific capacity (3579 mAh/g), silicon has been known to undergo massive anisotropic volume expansion (~280%), and consequently, causing the fracture of the particles and loss of the specific capacity upon further cycling. Germanium has been reported to undergo isotropic expansion and observed in the in-situ studies to sustain lithiation induced fracture up to the particle size of ~680 nm. In this work, solid solution of Si and Ge of various compositions were synthesized. The formation of a single phase solid solution was confirmed by the X-ray diffraction and the electrode morphology were studied using Scanning electron microscopy. The solid solution of equimolar Si and Ge (Si0.5Ge0.5) displayed excellent electrochemical performance both in the cyclic stability as well as the total specific capacity.
Conjugate Analysis of Heat-Species-Charge Transport for Evaluating Effects of the Temperature Gradient on Cell Performance
Authors: Miyagawa Kiyofumi , Araki Takuto 
Published: February 2020

1. Introduction
Management of water in the PEMFC is very important to improve the cell performance. However, the water transport mechanism in the PEMFC is complicated and it is difficult to understand by only experimental methods because of the thinness of the components of the PEMFC. Thus, numerical analyses are very useful methods.
The two-dimensional analytical model considering distributions of temperature, spices and reaction in components of the PEMFC is developed to estimate the unsteady performance of the PEMFC. The absolute value of the temperature of the cell impacts on the cell performance. However, the gradient of temperature has also great impacts on the cell performance. Moreover, temperature, chemical reaction and transport phenomena have interaction, for example the phase change and impeding the transport of the reactant gases by liquid water. So, it is important to consider not only temperature but also water transport. MPL was reported to moisturize CL and PEM and at the same time MPL enhances liquid water drainage to Channel. However, the detailed mechanism how MPL works on the cell performance is yet unclear. Finally, in this study, the effects of the gradient of temperature are investigated, and the models with MPL and without MPL are compared to validate the work of MPL.
2. Analytical methods
The unsteady cell performance has been studied with two-dimensional analytical model considered heat, species and charge transport in components of the PEMFC, such as GDL, MPL, CL and PEM. The impact of temperature gradients has been investigated by comparison of non-isothermal and isothermal condition at 72 deg. C.
3. Results and discussions
In Fig. 1, the distribution of temperature was shown. From this, the temperature of the area nearby CL and PEM was the highest and the value was 72 deg. C. And the temperature around separators was lowest and the value was 70 deg. C. The difference of temperature is only 2 deg. C, however, the current density had more than 5 times difference between non-isothermal and isothermal condition as shown in Fig. 2. The distributions of the liquid water saturation of each condition were shown in Fig. 3 and Fig. 4, respectively. Under isothermal condition, the value of liquid water saturation in CL was about approximately s=1, on the other hand, there is little liquid water in CL under non-isothermal condition. Then, current density drastically decreased from 40 s under isothermal condition with the liquid water accumulation in the CL.

Figure 1
Correlating Site Density and Catalytic Activity for Non-Precious ORR Electrocatalysts
Authors: Strasser Peter , Ranjbar Nastaran , Steinberg Julian , Kramm Ulrike 
Published: February 2020

Carbon materials doped with iron and nitrogen (Fe-N-C) are highly active, precious metal-free catalysts for the electrochemical conversion of molecular oxygen in fuel cells, metal air batteries, and electrolytic processes1-4. However, accurate measurement of their intrinsic turn-over-frequency (TOF) and active site density based on metal centers in bulk and surface has remained difficult to date, which has hampered a more rational catalyst design. Here, we report a successful quantification of bulk and surface-based active site density and associated TOF values of mono- and bimetallic Fe/N-doped carbons using a combination of chemisorption, desorption, and 57Fe Mößbauer spectroscopy techniques. Our general approach yields novel experimental descriptors for intrinsic activity and active site utilization, aiding in the catalyst development process and enabling a previously unachieved level of understanding of reactivity trends owing to a deconvolution of site density and intrinsic activity.

1. Wu, G.; Zelenay, P., Nanostructured Nonprecious Metal Catalysts for Oxygen Reduction Reaction. Acc. Chem. Res. 2013, 46, 1878-1889.
2. Sahraie, N. R.; Paraknowitsch, J. P.; Göbel, C.; Thomas, A.; Strasser, P., Noble-Metal-Free Electrocatalysts with Enhanced ORR Performance by Task-Specific Functionalization of Carbon using Ionic Liquid Precursor Systems. J. Am. Chem. Soc. 2014, 136, 14486-14497.
3. Chung, H. T.; Won, J. H.; Zelenay, P., Active and stable carbon nanotube/nanoparticle composite electrocatalyst for oxygen reduction. Nature Communications 2013, 4.
4. Wu, G.; More, K. L.; Johnston, C. M.; Zelenay, P., High-Performance Electrocatalysts for Oxygen Reduction Derived from Polyaniline, Iron, and Cobalt. Science 2011, 332, 443-447.
Synthesis of Non-PGM ORR Catalysts: Control of Chemical, Morphological and Catalytic Properties
Authors: Serov Alexey , Stariha Sarah , Artyushkova Kateryna , Andersen Nalin , Atanassov Plamen 
Published: February 2020

Development of non-platinum catalysts for both the anode [1] and cathode [2] attracts significant attention from researchers around the globe. Catalysts consisting of transition metal, nitrogen and carbon (M-N-C) where M=Fe, Co, Ni etc)framework possess reasonable stability and activity in both acidic and alkaline media. The use of inexpensive organic precursors doped with low molecular weight metal salts is proposed in the present research to provide a high surface area framework consisting of C-N decorated with M species.
All catalysts presented in this work were synthesized using a modified sacrificial silica support method which has been widely adopted in our research group [4]. Appropriate amounts of metal precursor (iron nitrate or cobalt nitrate) and nitrogen-containing, precursors (e.g. polyethyleneimine (PEI)) were deposited on the surface of fumed silica (surface area ~380 m-2 g-1) by Mechanochemical approach. The composite material was pyrolyzed in a nitrogen atmosphere at various temperatures, to form the M-N-C-SiO2framework. The pyrolysis conditions were determined from a MS-TGA analysis, where MS was used to identify the precursor’s decomposition products as a function of thermal treatment. After heat treatment, the fumed silica was removed by etching in HF acid and washed appropriately, revealing a high surface area M-N-C matrix
The catalysts were comprehensively characterized by BET, SEM, TEM, XRD and XPS. Catalytic activity for ORR was measured in acidic media (0.5M H2SO4) using the RRDE method and fuel cell test.

Figure 1. Mechanochemical synthesis
The broad XRD peak for Fe indicates small metallic iron particles exist on the order of several nanometers (Fig. 1). It can be assumed that the homogeneous distribution of precursors on the high surface of fumed silica prevents metal particles from agglomeration.
Analysis of material morphology by SEM reveals that the Fe-DAAPyr catalyst yields a highly porous surface structure. BET analysis of the adsorption isotherm reveals a surface area of ~700m-2 g-1.
Synthesized materials were found to be active in ORR in both RRDE and MEA fuel cell tests conditions.
We would like to acknowledge funding support from DOE-EERE Fuel Cell Technology Program: “Development of Novel Non Pt Group Metal Electrocatalysts for PEM Fuel Cell Applications” (S. Mukerjee, NEU, PI).

References:

M. Min, C. Park, H. Kim, C. Kwak, A. A. Serov, H. Kweon, S. Lee, Electrochimica Acta, 52, (2006) 1670-1675.

A. Serov, K. Artyushkova, P. Atanassov, Adv. Energy Mater., 4: 1301735 (2014). doi: 10.1002/aenm.201301735..

U. Tylus, Q. Jia, K. Strickland, N. Ramaswamy, A. Serov, P. Atanassov, S. Mukerjee, J. Phys. Chem. C, 118 (17) (2014) pp 8999–9008.

A. Serov,A. Aziznia, P. H. Benhangi, K. Artyushkova, P. Atanassov, E. Gyenge J. Mater. Chem. A 1 (2013) 14384-14391.

Figure 1
Nafion Nanothin Films
Authors: Karan Kunal 
Published: February 2020

In the conventional catalyst layer of polymer electrolyte fuel cells, the ionomer (e.g. Nafion) exists as an ultra-thin film (4-10 nm thick) coating the Pt/C catalyst aggregates. Recent studies [1-12], including those from our group, have begun to investigate the properties and structure of such thin ionomer films. Thickness-dependent properties including proton conduction (7, 11), wettability of free-surface(5), water uptake (2, 6) and water diffusivity (9) of such ultra-thin ionomer films have been observed. The influence of substrate and processing method has also been observed (12). A number of the properties of the thin ionomer films differ significantly from the much thicker counterpart, i.e. the free film or bulk ionomer membrane. The nanostructure of these films are less understood. And, although indirect methods such as x-ray reflectivity (1) and grazing incidence (2) small angle x-ray scattering (GISAXS) have been employed a clear picture of the nanostructure of these thin films has not emerged.
The presentation will summarize the current understanding of ionomer thin film structure and properties. Results of recent and ongoing work on direct imaging of thin Nafion films to probe the nano-features of the phase-segregated morphology will be presented. Results of thermal behavior of thin films investigated using in-situ thermal ellipsometry will also be presented.
Reference:

A. Dura et al., Macromolecules 42 (2009), 4769-4774.

M.A. Modestino et al., Macromolecules 2013, 46 (3), pp 867–873, 2013

M. Bass et al., Macromolecules 44 (2011), 2893–2899.

Dishari, K. S.; Hickner, A. M. ACS Macro Lett., 1 (2012), 291-295.

D.K Paul et al., Macromolecules, 46 (2013), 3461–3475

A. Kongkanand J. Phys. Chem. C, 115 (2011) 11318–11325.

D.K. Paul, D. K Electrochem. Comm., 13 (2011), 774-777.

A. Modestino et al., Macromolecules, 45 (2012), 4681–4688.

S.A. Eastman, Macromolecules, 45 (2012), 7920−7930.

D.K. Paul and K. Karan J. Phys. Chem. C, 118 (2014), 1828–1835.

D.K. Paul et al., J. Electrochem. Soc., 161 (2014), F1395-F1402

A. Kusoglu et al
Adv. Funct. Mater. 2014, 24 (30), 4763-4774
Enhanced Durability with Cu-Containing Chemically Ordered Pt-Alloy Catalyst for Oxygen Reduction Reaction in Polymer Electrolyte Fuel Cell
Authors: Arumugam Balamurugan , Tamaki Takanori , Yamaguchi Takeo 
Published: February 2020

Large-scale commercialization of polymer electrolyte fuel cells (PEFCs) requires great improvement in activity and durability of the cathode catalyst [1]. We have reported enhanced activity and durability of the Pt-based intermetallics, Pt2FeCo/C, with L10 ordered face-centered tetragonal (fct) structure both in acidic solution [2] and as the cathode catalyst of a membrane-electrode assembly [3]. In this work, Cu with higher standard reduction potential was employed to form ordered fct-Pt2FeCu/C, and its activity of oxygen reduction reaction (ORR) and durability were compared with its counterpart bimetallic catalyst, fct-PtFe/C, and the commercial catalyst from Tanaka Kikinzoku Kogyo (TKK-Pt/C).
Pt2FeCu/C and PtFe/C were fabricated by the heat treatment of the mixture of metallic precursors and carbon black at 800 °C under 20% H2 in N2 for 2 h. The metal content of the catalyst was around 40 wt%. ORR activity of the catalysts was evaluated in 0.1 M HClO4solution using the rotating disk electrode technique. The durability of the catalysts was examined in the same solution at 60 °C by applying square wave potential cycling, 0.6 V for 3 s and 1.0 V for 3 s, according to load cycle durability testing protocol recommended by the Fuel Cell Commercialization Conference of Japan (FCCJ).
XRD patterns of Pt2FeCu/C and PtFe/C showed the formation of chemically ordered fct structures. Both the fct catalysts initially showed high mass activity above 0.5 A/mg-Pt. Figure 1 shows the change in electrochemical surface area (ECSA) and mass activity during load-cycle durability test at 60 °C. Cu-containing fct-Pt2FeCu/C retained more than 70% of mass activity and ECSA at 10K durability cycles, while fct-PtFe/C and TKK-Pt/C catalysts showed a significant loss of activity and ECSA: retention was about 50% for TKK-Pt/C and 40% for fct-PtFe/C. The mass activity of fct-Pt2FeCu/C catalyst was enhanced by more than twice with respect to TKK-Pt/C catalyst, both at the initial state and after 10K durability cycles. STEM-EDX line-scans of the catalysts before and after durability cycles showed that dissolution of Fe and Cu was much less in fct-Pt2FeCu/C than in fct-PtFe/C. The enhancement in the durability of the fct-Pt2FeCu/C catalyst may be ascribed to the synergistic effects of the presence of Cu with higher redox potential and the ordered structure of catalyst.
References
[1] M.K. Debe, Nature,
486, 43–51 (2012).
[2] B. Arumugam, B. A. Kakade, T. Tamaki, M. Arao, H. Imai, T. Yamaguchi, RSC Advances, 4, 27510–27517 (2014)
[3] T. Tamaki, A. Minagawa, B. Arumugam, B.A. Kakade, T. Yamaguchi, J. Power Sources, 271, 346–353 (2014)

Figure 1
Making Economical MOF-Based Precious-Metal Free Oxygen Reduction Reaction Catalysts
Authors: McCool Geoff , Li Jingkun , De Castro Emory , Mukerjee Sanjeev , Halevi Barr 
Published: February 2020

The performance and promise of precious metal free catalysts for the Oxygen reduction Reaction (ORR) has increased steadily with several synthesis methods approaches developed. Catalysts based on Metal-Organic-Framework(MOF) precursors have been at the forefront of non-Precious Metal Catalyst development, with a number of groups having demonstrated well performing catalysts. A key limitation to these catalysts is the high cost of commercial MOF precursors. In an effort to reduce the cost of MOF-based ORR catalysts several groups have developed low-cost MOF synthesis.
In this presentation, we describe the scale-up and engineering for air operations of inexpensive MOF-based ORR catalysts as developed by Northesastern University and scaled to 50x by Pajarito Powder.