bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gravitational Effects on the Initial Stage of Cu Electrodeposition
Authors: Inari Hirofumi , Konishi Yoko , Alkire Richard , Homma Takayuki , Fukunaka Yasuhiro 
Published: February 2020

The electrochemical processing has been favorably reviewed in the microelectronics industry. It is essential to control the nucleation and crystal growth in the initial stages of electrodeposition process. For this purpose many effects of additive have been examined. However, few quantitative examinations has been reported on the coupling phenomena of ionic mass transfer rate and microstructural/morphological variations through nucleation and crystal growth.
This work discusses various gravitational levels as new parameters into the nonequilibrium electrochemical processing in order to create or tailor the unique physical properties in micrometer space field. It is fruitful in terms of not only physical chemistry but also industrial applications to comprehensively understand the coupling phenomena. In fact, it has been confirmed that the gravitational levels as well as the magnetic field introduce the intensive effects to the coupling behavior different from that under 1 G normal environment.
Here is a report to analyze the effect of gravitational level on the initial stages of Cu electrodeposition on TaN or TiN substrate installed in a cavity-type electrolytic cell. In case of Cu on TaN substrate, cathode, anode and reference electrode are TaN substrate, copper sheet and copper wire, respectively. Electrolyte solution is 0.05 M CuSO4 – 0.05 M H2SO4. Two kinds of electrolytic cell configuration are used; one is a cathode facing downward over anode horizontally (C/A), and another is an anode over a cathode (A/C). A centrifugal field is applied to introduce a high gravitational field.
Time dependence of nucleus number density shows that the nucleation of Cu on TaN is “progressive” nucleation. Under 1 G, saturated nucleus number density (N0) increases and mean diameter (dmean) becomes smaller as the electrode potential decreases. At any potential, N0 in A/C configuration is higher and dmean is smaller than C/A. The current transient shows the difference caused by two cell configurations and macroscopic natural convection due to the concentration difference should be inevitably induced with time progressed in a cavity in the A/C configuration. The image analysis indicates the nucleus distribution is considerably deviate from the Poisson distribution as long as the nearest-neighbor distance concerns. The existence of “exclusion zone” around the growing nuclei in nucleation phenomena has been found. Under high G level field, N0 becomes slightly increased and is saturated as G level increases. The effect of G level on the current transient is quite large. It is almost saturated under G level over 100 G. It is moreover found that the nucleation is saturated under high G level earlier than under low G level. The effect of ionic mass transfer rate due to the concentration difference becomes significant to enhance the nucleation rate knN0.
Demonstration of a Reactive Hydrogen Pump Using Methanol
Authors: Fane Brian , Zawodzinski Thomas A. , Goenaga Gabriel A. 
Published: February 2020

Polymer electrolyte membrane (PEM) fuel cells are an attractive energy conversion device because of the potential for extremely high efficiency and low emissions. Hydrogen is an ideal fuel for PEM fuel cells but it is energy intensive to produce.
Currently the main method of producing hydrogen is steam reforming of natural gas. This is a break from the renewable energy future promised by hydrogen fuel cells. The most obvious method of producing hydrogen is water electrolysis but that is highly energy intensive since the electrolysis requires greater than the theoretical voltage of 1.23 V and thus is somewhat inefficient. To fulfill the promise of fuel cells, less energy intensive methods of producing hydrogen must be found.
Here we describe some initial exploration of the concept of replacing water in the anode electrolyzer feed with a feedstock from which hydrogen can be stripped and purified in a combined electrochemical reactor. As a first step in testing this concept, we use methanol as the feed. Oxidation of methanol to hydrogen takes place at a theoretical voltage of .03 V. This is a significantly lower over-potential than water electrolysis and since most of the operating cost is energy, it has the potential to be significantly cheaper. Of course, the methanol oxidation reaction requires substantial overpotential because of sluggish kinetics but this is only an initial study.
We constructed a methanol water electrolyzer based the conventional direct methanol fuel cell architecture as shown in Figure 1. The electrolysis cell uses a Pt-Ru black catalyst in the anode and a Pt cathode with a Nafion 117 membrane. We examined the effects of several different catalyst loadings, back-pressures, temperatures, and humidity levels. Finally, we utilized electrochemical impedance spectroscopy (EIS) and a dynamic hydrogen electrode (DHE) to more accurately determine the effectiveness of the catalysis and sources of voltage loss.
Figure 2 shows an initial polarization curve obtained with this cell. Hydrogen was chosen for the working electrode and methanol for the counter electrode. The counter electrode potential stays fairly steady as does the ASR, while the working and cell potentials depend somewhat on the current being drawn. Increasing polarization of the working electrode begins to have a negative effect on cell current after .6V vs DHE.

Acknowledgements

We gratefully acknowledge the support of the Office of Naval Research for this activity.
References
C. Cloutier and D. Wilkinson, International Journal of Hydrogen Energy., 35,9,(2010)
S. Thomas, X. Ren, S. Gottesfeld and P. Zelenay, Electrochimica Acta., 47 (2002)
Laboratory-Scale Apparatus for Semi-Continuous Electrokinetic Dewatering of Phosphatic Clay Suspensions
Authors: Huang Yuelong , Orazem Mark E. , Kong Rui , Yu Dazhi , Lai Han , Moghaddam Saeed , Bloomquist David , Cleveland Christopher 
Published: February 2020

The by-products of phosphatic clay suspensions are a major waste product of the phosphate mining industry. The phosphate clay suspensions produced from beneficiation are about 130,000 gallons per minute (GPM) at about a solids content of 2 wt%. After flocculation the settled clay suspensions at 10% solids content are pumped into the clay settling areas (CSAs) for natural settling. This natural clay settling process takes as much as 25 years to reach the demanded value of 40 wt% solids content. Therefore, the CSAs are frequently constructed on the unmined land and currently cover an area of over 100,000 acres in Florida. Disposal of the phosphatic clay suspensions has become the phosphate mining industry’s major challenge. Thus, it is necessary to develop a technique to increase the solids content of the effluent of phosphate clay suspensions from a phosphate mining beneficiation plant and thereby can save the land used for CSAs and recycling water.
A semi-continuous electrokinetic dewatering apparatus for phosphatic clay suspensions has been designed and its performance has been evaluated. A 23 factorial design was applied to determine the optimum process parameters. The results show that the electric field was found to have the greatest positive influence on the solids content. The maximum change in solids content reached a plateau as a function of operating time at a given electric field. Moreover, the plateau occurred earlier at larger electric fields, indicating that for the maximum solids content the optimum parameters of the electric field and the operating time can be determined. The CEDA had lower energy consumption and continuously produced the thickened clay which had the highest solid content of about 33 wt%. The CEDA can be operated to cope with dilute initial solids content (3-10%) from a phosphate mining beneficiation plant. The CEDA has potential to replace existing thickening equipment.
Graphene Supported Platinum-Cobalt Nanocomposites As Electrocatalysts for Borohydride Oxidation
Authors: Tamasauskaite-Tamasiunaite Loreta , Radomskis Algimantas , Antanaviciute Kornelija , Jablonskiene Jolita , Balciunaite Aldona , Zieliene Albina , Naruskevicius Leonas , Vaiciuniene Jurate , Kondrotas Rokas , Norkus Eugenijus , Jagminiene Aldona 
Published: February 2020

In relation to other types of fuel cells direct borohydride fuel cells (DBFCs) are of particular value for their high theoretical capacity and specific energy density, i.e. 5.6 Ah/g and 9.3 Wh/g for NaBH4, respectively. For reducing the amount of Pt, transition metals such as Ni, Co, Fe, Cu have been added as alloy metals to the Pt-based catalysts. Recently, graphene as catalyst support has incurred intense interest in fuel cell applications due to its unique, outstanding physicochemical properties, such as an extremely high specific surface area (2600 m2g–1).
A rapid microwave heating method was used to prepare the graphene supported PtCo catalysts with the Pt:Co molar ratio 1:7, 1:22 and 1:44. TEM and ICP-OES were employed to characterize the morphology and composition of catalysts. The electrocatalytic activity of the synthesized catalysts towards the oxidation of borohydride was investigated by means of the cyclic voltammetry and chronoamperometry. The kinetics of the catalytic hydrolysis of NaBH4 in the presence of the synthesized catalysts was also investigated.
It was found that Pt nanoparticles of about 1-3 nm in size were successively deposited onto the surface of graphene nanosheets. Pt nanoparticles were uniform and well dispersed on the surface of graphene. The EDX spectra confirm the presence of Pt and Co nanoparticles in the investigated PtCo/GR catalysts.
The Pt loadings were 0.125 mg Pt cm–2 in the Pt/GR and 0.165, 0.144 and 0.125 mg Pt cm–2 in the synthesized PtCo/GR having the Pt:Co molar ratio 1:7, 1:22 and 1:44, respectively. It has been determined that the synthesized graphene supported PtCo catalysts show an enhanced electrocatalytic activity towards the oxidation of H2 generated by catalytic hydrolysis of BH4
– and direct oxidation of BH4
– ions comparing with the graphene supported bare Pt and Co catalysts. The graphene supported PtCo catalyst having the Pt:Co molar ratio 1:44 exhibits the highest electrocatalytic activity for the both oxidation reactions of H2 and BH4
– ions.

Acknowledgement

This research was funded by a Grant (No. ATE-08/2012) from the Research Council of Lithuania.
Comparative Study of Electrocatalytic Activity Towards Borohydride Oxidation on Gold- or Platinum-Metal (Cu, Co, Ni) Deposited on the Titanium Surface Via Galvanic Displacement
Authors: Tamasauskaite-Tamasiunaite Loreta , Balciunaite Aldona , Zabielaite Ausrine , Stankeviciene Ina , Jagminiene Aldona , Kepeniene Virginija , Selskis Algirdas , Juskenas Remigijus , Norkus Eugenijus 
Published: February 2020

Here we present comparative study of electrocatalytic activity of gold- or platinum-metal (Cu, Co, Ni) catalysts deposited on the titanium surface towards the oxidation of borohydride in alkaline medium. A simple and cost-effective galvanic displacement technique was used for preparation of nanostructured catalysts [1-4]. The morphology, structure and composition of the prepared nanostructured catalysts were examined using Field emission scanning electron microscopy, Energy dispersive X-ray spectroscopy, X-ray diffraction and inductively coupled optical emission spectroscopy. The borohydride oxidation kinetic was studied on the as-prepared catalysts by cyclic voltammetry and chronoamperometry. The electrocatalytic activity of catalysts was compared with that of bulk Au or Pt electrodes.
Well-adherent gold- or platinum-coated metal (Cu, Co, Ni) films with nm-scaled particles were formed on the surface of titanium. The electrocatalytic activity of the as-prepared nanostructured catalysts was compared on the basis of electrochemical data. It was found that the nanostructured gold- or platinum-metal (Cu, Co, Ni) catalysts deposited on the titanium surface via galvanic displacement exhibits an enhanced electrochemical activity towards the oxidation of borohydride as compared to that of bulk Au or Pt electrodes and seem to be promising anodic materials for direct borohydride fuel cells.

Acknowledgments

This research was funded by a Grant (No. ATE-08/2012) from the Research Council of Lithuania.

References

[1] L. Tamašauskaitë-Tamašiûnaitë, A. Balèiûnaitë, D. Šimkûnaitë, A. Selskis. J. Power Sources 202 (2012) 85-91.
[2] L. Tamašauskaitë-Tamašiûnaitë, A. Balèiûnaitë, R. Èekavièiûtë, A. Selskis. J. Electrochem. Soc. 159 (2012) B611-B618.
[3] L. Tamašauskaitë-Tamašiûnaitë, A. Balèiûnaitë, A. Zabielaitë, I. Stankevièienë, V. Kepenienë, A. Selskis, R. Juškënas, E. Norkus. J. Electroanal. Chem. 700 (2013) 1-7.
[4] L. Tamašauskaitë-Tamašiûnaitë, A. Jagminienë, A. Balèiûnaitë, A. Zabielaitë, J. Vaièiûnienë, A. Selskis, R. Juškënas, E. Norkus. Int. J. Hydrogen Energy 38 (2013) 14232-14241.
ECS Energy Technology Division Supramaniam Srinivasan Young Investigator Award Advanced Electrocatalysts for Oxygen Reduction Reaction
Authors: Shao Minhua 
Published: February 2020

Low temperature fuel cells have great potential for both stationary and transportation applications and are expected to help address the energy and environmental problems that have become prevalent in our society. Despite their great promise, commercialization has been hindered by lower than predicted efficiencies and the high cost of Pt-based electrocatalysts in the electrodes. For more than five decades, the predominant work has being focused on the development of novel catalysts for the cathodic reaction (oxygen reduction reaction. ORR), which has sluggish kinetics and is responsible for the high overpotentials.1 One way to address the high cost and low activity problem associated with the conventional Pt catalysts is to increase the activity by optimizing the shape of constituent nanoparticles and thus maximizing the expression of facets most reactive towards ORR reaction.2 Another approach is to increase the utilization of expensive noble metal atoms by developing core-shell catalysts.3

In this talk, recent progress in developing advanced materials for ORR in my group will be presented, with an emphasis on core-shell catalysts4-8 and shape-controlled nanocrystals.9-11 The structural dependence of ORR activity on Pd and PtNi nanocrystals were investigated. The mechanisms for activity enhancement of these materials will also be discussed based on the results of density functional theory (DFT) calculations. Finally, the issues associated with the mass production of core-shell catalysts were analyzed.
References

Electrocatalysis in Fuel Cells: A Non- and Low- Platinum Approach; Shao, M., Ed.; Springer: London, 2013.

V. R. Stamenkovic, B. Fowler, B. S. Mun, G. Wang, P. N. Ross, C. A. Lucas and N. M. Markovic, Science 2007, 315, 493.

Adzic, R. R.; Zhang, J.; Sasaki, K.; Vukmirovic, M. B.; Shao, M.; Wang, J. X.; Nilekar, A. U.; Mavrikakis, M.; Valerio, J. A.; Uribe, F. Topics in Catalysis 2007, 46, (3-4), 249.

Shao, M. H.; Shoemaker, K.; Peles, A.; Kaneko, K.; Protsailo, L. J. Am. Chem. Soc. 2010, 132, (27), 9253.

Shao, M. H., et al. J. Phys. Chem. Lett. 2011, 2, 67

Humbert, M.; Smith, B.; Wang, Q.; Ehrlich, S.; Shao, M., Electrocatalysis 2012, 3 (3-4), 298.

Shao, M. H., et al. Chem. Commun. 2013, 49, 4030.

Shao, M. H., et al. Phys. Chem. Chem. Phys. 2013, 15, 15078.

Shao, M.; Yu, T.; Odell, J.; Jin, M.; Xia, Y. Chem
.
Commun. 2011, 47, 6566.

Shao, M.; Odell, J.; Humbert M.; Yu, T.; Xia, Y. J. Phys. Chem. C 2013, 117, 4172.

Choi, S-I.; Shao, M. H., et al., Nano Lett. 2013, 13, 3420.
Perovskites As Electrocatalysts for Alkaline Water Electrolysis
Authors: Nikiforov Aleksey Valerievich , Puebla Ana Raquel de la Osa , Jensen Jens Oluf , Petrushina Irina Michailovna , Bjerrum Niels Janniksen 
Published: February 2020

Water electrolysis is a promising technology for the production of hydrogen as a sustainable energy storage source, combined with solar or wind power.
In this work various electrocatalysts for the Oxygen Evolution Reaction (OER) electrode were synthesized and characterized by several techniques such as X-ray diffraction, electrical conductivity, scanning electron microscopy (SEM), energy dispersive microscopy (EDX) and rotating disk electrode.
The perovskites tested in this work were both produced by a ball-milling technique and by an auto-combustion synthesis, which appeared to be a fast and robust method for synthesis of perovskites with various chemical compositions1.
The electrochemical performance of the materials was tested through pellet pressing of the perovskite powders. This involved in some case a time consuming preparation process. Furthermore the technique should show the adequate reproducibility.2

In this work we show the development of the method, which was further used to compare the activity of various electrocatalysts (Figures 1,2).
The electrocatalytic activity of all prepared perovskites was tested in 1M KOH at 80 °C, using an ink consisting of potassium exchanged Nafion®. All tests were performed in the potential window 0-700 mV on a glassy carbon electrode. All the tested perovskites were characterized by their overpotential , measured current at 650 mV, obtained kinetic current and Tafel slopes.
It was also shown that this technique do not depend on the initial powder electric conductivity which varied by several orders of magnitude, as shown on Figure 3.

1 H. Nijjar, J. Lamonier, O. Mentr´e, J. Giraudon, H. Batis, Appl. Catal. B, 106, 149–159, 2011
2 J.O’M. Bockris and T. Otagawa J. Phys. Chem. 87:2960-2971, 1983.
ECS Research Award of the Energy Technology Division Membrane Electrode Assembly Fabrication from Membranes of the DOE High Temperature Membrane Working Group
Authors: Fenton James M. , Mohajeri Nahid , Rodgers Marianne P. , Brooker R. Paul , Slattery Darlene K. , Bonville Leonard J. , Kunz H. Russell 
Published: February 2020

The Florida Solar Energy Center (FSEC) has led the U.S. Department of Energy (DOE) High Temperature Membrane Working Group (HTMWG) since 2006. The HTMWG investigates membrane performance at elevated temperature/low relative humidity conditions. For the final three years of the project, FSEC has worked with six teams to develop membrane electrode assembly (MEA) fabrication methods for their respective membranes. This presentation details the challenges associated with MEA fabrication of various membrane types, along with the performance results from several HTMWG membranes.
The MEA fabrication technique utilized by FSEC is to suspend the membrane vertically in front of a heated plate, and then spray catalyst-ink slurry onto the membrane. Following electrode application, the CCM is hot pressed to ensure good interfacial contact. Through these procedures, several challenges were identified. First, during electrode application, the membrane can swell due to the high solvent content in the ink and shrink due to the heat from the plate. These combined effects were shown to cause significant internal stresses in a hydrocarbon-based membrane with Teflon support. A second challenge was the ductility (either too high or low) of the membrane, leading to poor mechanical stability. Too high ductility rendered spraying ineffective, while too low ductility led to crack formation, either during spraying or hot pressing. An example is given of a membrane showing a series of pressure-induced cracks after hot pressing. A third challenge relates to the compatibility of the ionomer in the electrode with that in the membrane. For the majority of the teams, the same ionomer was utilized in the electrode, to provide consistency across the tests. However, due to differences in the membrane, the cell performance changed, even though the electrodes were the same. This suggests a performance limiting mechanism is operating at the membrane/catalyst interface.
Notwithstanding these challenges, several cells showed significant progress towards DOE performance and durability targets, including a hydrocarbon-based membrane. One team was able to develop a membrane that exhibited several times-lower fluoride release than NRE 211. Another team’s fuel cell performance exceeded DOE targets, with further optimization possible. These results will be presented.
Surface Fermi Energy and Activity of Atomically Layered Pt/Ru Catalyst
Authors: Takmeel Qanit , Moghaddam Saeed 
Published: February 2020

The development of bimetallic catalysts has played a significant role in the development of technologies such as catalytic reforming, fuel cell electrocatalysis, hydrodesulfurization, partial alkene oxidation, etc. The interest in the development of bimetallic catalysis for direct methanol fuel cells (DMFCs) has been over a four-decade-old exercise. Platinum has generally been alloyed with a plethora of other metals such as tin, cobalt, ruthenium etc. in order to attain better methanol deprotonation and reduced carbon monoxide poisoning of the catalyst. Here, to better understand the role of ruthenium in a bilayered Pt/Ru catalyst, we demonstrate its effect on the surface Fermi energy level and catalytic activity.
Using the atomic layer deposition (ALD) process, a number of samples were prepared and the effect of atomic layering of platinum on ruthenium on the surface catalytic activity was studied. The thickness of Pt was monitored by varying the number of Pt ALD cycles and catalytic activity was determined by cyclic voltammetry. In addition, copper underpotential deposition (Cu-UPD) was used to estimate the fractional coverage of Pt on the surface of Ru at different Pt ALD cycles. This is key to the understanding since it ensures that the studied surface involves only one metal. We found that for 10 ALD cycles of Pt, the surface of Ru was completely coated with Pt. Work function of the catalyst surface was estimated by Kelvin probe. A large variation in work function values for the sample with 5 Pt ALD layers suggests that there is significant islanding of Pt on Ru corroborating well with Cu-UPD results.
Our results show that by manipulating Fermi energy of Pt catalysts, optimum activity can be obtained. In addition, it is suggested that the common 50/50% alloying of metals is an unnecessary enterprise and comparable activity can be achieved by careful engineering of catalysts involving lower Pt loading.