bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die Level Model for Electroplated Copper Pillars
Authors: Graham Gabe , Chua Lee Peng , Buckalew Bryan , Ponnnuswamy Thomas , Mayer Steve 
Published: February 2020

In wafer level packaging, within die Co-Planarity (CoP) of Cu Pillar (CuP) heights has always been critical for ensuring good electrical connections and low stresses in the final package. The recent market trend towards advanced packages imposes even more stringent CoP demands, thus warrants fundamental understanding of CoP drivers as well as innovations in plating technology.
The relatively large scale of CuP structures leads to sensitivities to mass transport during plating, especially for dies with multiple feature sizes and/or depths. Therefore a useful model for of CuP structures must include mass transport considerations. These models are typically computationally intensive and would not be feasible to solve at a die level.
In this work we develop a model which includes mass transport, but treats features as 1D elements. This approach enables solutions at a die level which may include many thousands of features. This model is validated by comparison to on-wafer data for two different die types.
Study of Se and Ge Solutions at Different Phs to Form Gese Via E-ALD
Authors: Howell Pauline , Stickney John Lewellen 
Published: February 2020

GeSe is a two-dimensional chalcogenide with ovonic threshold switching properties. Its properties strongly depend on the stoichiometry and the quality of the film.1 Electrochemical atomic layer deposition (E-ALD) is an electrochemical method that utilizes surface limited reactions to deposit materials layer by layer.2 Using E-ALD will allow growth of higher quality GeSe films. Before attempting deposition, cyclic voltammetry studies of the individual solutions were done to determine the best deposition potentials. Ge solutions made at different pHs show maximum deposition in more basic solutions, such as pH 9. Studies of Se solutions at pH 1.6, 3, 5, 7, and 9 were done to find complimentary deposition potentials to the basic Ge solution. By investigating the behavior of Se and Ge using cyclic voltammetry, better understanding of the chemistry was garnered for the development of an E-ALD cycle. Further research will evaluate the deposition patterns of Ge on Se and vice versa. Finally attempts at depositing a stoichiometric GeSe deposit will be made using E-ALD.
References:

Hu, Y.; Zhang, S.; Sun, S.; Xie, M.; Cai, B.; Zeng, H. Applied Physics Letters
2015, 107(12), 122107.

Stickney, J. Encyclopedia of Applied Electrochemistry
2014, 1947–1953.
Boosting the Hydrogen Evolution Performance of Transition Metal Phosphide Catalysts on 3D Electrode Supports
Authors: Sanchez Joel , Hellstern Thomas , King Laurie , Jaramillo Thomas F. 
Published: February 2020

To date, platinum-based catalysts have been employed for the hydrogen evolution reaction (HER) in PEM-electrolyzers.1 However, due to high costs and price volatility associated with Pt, there exists a need to investigate non-platinum-group metals (PGM) based catalysts. Tremendous efforts have been surmounted to develop non-noble metal catalysts that have the desirable properties of Pt during reaction without the associated costs, scarcity, and volatility.2 For non-PGM catalysts in various electrode configurations, an increase in performance is often accomplished by increasing the loading of the catalyst; while this strategy increases the density of active sites, it may lead to low mass activities, low utilization efficiencies, and potential suboptimal catalyst performance at excessive loadings.3,4 This motivates research into engineering catalyst support interactions to achieve highly active non-PGM catalysts at low-loadings.
To this end, utilizing various oxidation methods, the surface O/C ratio, and thus the hydrophilicity, is varied and is directly correlated to the cobalt phosphide dispersion onto the surface of the carbon electrode. The improved hydrophilicity (high O/C ratio) synergistically improves catalyst dispersion and yields electrodes with extraordinary performance as measured by low overpotentials (-51 mV at -10 mA cm-2), unprecedented mass activities (>800 A/g at -100 mV overpotential), high turnover frequencies (6.96 H2 s-1 at -100 mV overpotential), and promising stability (>8 hours at -10 mA cm-2) for a precious metal free catalyst at low loadings (~40-200 µg). Compared to reported HER catalysts, whether planar or 3D, in terms of mass activities and on a turnover frequency basis, our catalysts showed the highest values for non-PGM systems. Additionally, we show that the electrode fabrication process presented here is applicable to other phosphide catalysts (Ni and Fe phosphides) and can be used as a general methodology to reduce catalyst loading, improve overpotentials, mass activities, and TOFs.

References:

(1) Vesborg, P. C. K.; Seger, B.; Chorkendorff, I. Recent Development in Hydrogen Evolution Reaction Catalysts and Their Practical Implementation. J. Phys. Chem. Lett.
2015, 6 (6), 951–957.
(2) Zou, X.; Zhang, Y. Noble Metal-Free Hydrogen Evolution Catalysts for Water Splitting. Chem. Soc. Rev.
2015, 44 (15), 5148–5180.
(3) Cheng, Y.; Liao, F.; Shen, W.; Liu, L.; Jiang, B.; Li, Y.; Shao, M. Carbon Cloth Supported Cobalt Phosphide as Multifunctional Catalysts for Efficient Overall Water Splitting and Zinc–air Batteries. Nanoscale
2017, 9 (47), 18977–18982.
(4) Ursua, A.; Gandia, L. M.; Sanchis, P. Hydrogen Production From Water Electrolysis: Current Status and Future Trends. Proc. IEEE
2012, 100 (2), 410–426.
Electrocatalysis of Ketjenblack-Supported Ru-Ir Cathode for the Electrohydrogenation of Toluene to Methylcyclohexane in the Organic Hydride System
Authors: Inami Yuta , Nagamatsu Shinichi , Asakura Kiyotaka , Iguchi Shoji , Yamanaka Ichiro 
Published: February 2020

Hydrogenation of toluene (TL) and dehydrogenation of methylcyclohexane (MCH) has been paid great attention for a highly efficient H2 storage technology [1,2]. At energy supply area, TL is hydrogenated to MCH by the catalytic hydrogenation using H2 produced by the water-electrolysis. We can easily transport and store MCH using the current infrastructures, because MCH is a component of petroleum and liquid state at ambient conditions. At energy demanding area, the catalytic dehydrogenation of MCH to TL and H2 (47.4 kg-H2/m3-MCH) is conducted. H2 can be used as an energy source, and TL is reused as the H2 carrier, repeatedly. To improve the H2 storage system to more efficient one, a direct electrohydrogenation of TL with water using a solid polymer electrolyte (SPE) electrolysis cell and 50 wt% Pt/Ketjenblack (KB) cathode has been proposed (Fig. 1) [3]. In those system, water is oxidized at the anode, and TL is electrochemically reduced to MCH at the cathode; however, the high loading of Pt is disadvantage from the viewpoints of system cost. For the efficient hydrogenation of TL, it is essential to reduce Pt or other precious metal loadings with keeping suppression of the competitive H2 evolution.
In this study, we found that Ru-Ir alloy supported on KB (Ru-Ir/KB) electrocatalyst showed superior electrocatalytic activity for the electrohydrogenation of TL to MCH under galvanostatic electrolysis conditions at 0.20 A cm-2. 5 wt% Ru-5 wt% Ir/KB loaded on a gas-diffusion layer (GDL) cathode (0.2 mgRu-Ir cm-2) showed a higher faradic efficiency of MCH formation than the 50 wt% Pt/KB loaded on the GDL cathode (1.0 mgPt cm-2), though the working potential of -0.183 V (SHE) at the former was slightly negative than that of -0.071 V (SHE) at the later. This indicated the significant reduction of amount of precious metals used for the electrohydrogenation of TL. Characterization studies for the Ru-Ir/KB electrocatalyst were conducted by using X-ray diffraction (XRD), transmission electron microscopy with energy dispersive spectroscopy (TEM-EDS) and X-ray absorption fine structure spectroscopy (XAFS), and a formation of hcp-structured Ru-Ir alloy was revealed. Based on the electrochemical and kinetic studies, synergy mechanisms of Ru and Ir for the electrohydrogenation of TL were proposed. To be concrete, a fast hydrogenation of TL to MCH on the Ru site, a fast electrocatalytic reduction of H+ to H-species on the Ir site, and a fast spillover of H-species from Ir to Ru, these three steps cooperate.
References
[1] J. Gretz, J. P. Baselt, O. Ullmann, H. Wendt, Int. J. Hydrogen Energy, 15, 419 (1990)
[2] Y. Okada, E. Sasaki, E. Watanabe, S. Hyodo, H. Nishijima, Int. J. Hydrogen Energy, 31, 1347 (2006)
[3] S. Mitsushima, Y. Takakuwa, K. Nagasawa, Y. Sawaguchi, Y. Kohno, K. Matsuzawa, Z. Awaludin, A. Kato, Y. Nishiki, Electrocatalysis, 7, 127 (2016)

Figure 1
Electrolyzer Components and Coatings: Methods for Ex-Situ Accelerated Stress Testing
Authors: Callahan Will , Guerrero Trent , Klein Ellis , Vidal Judith C , Bender Guido , Young James L. 
Published: February 2020

Lowering electrolyzer capital costs and increasing material durability are key efforts toward furthering the commercial penetration of PEM electrolysis technology. This work focuses on bipolar plate and porous transport media materials, typically consisting of a titanium alloy coated with a protective thin-film of Pt, Au, or Ir. The titanium alloy serves as a corrosion-resistant base material and the coating material is selected with the purpose of delaying titanium oxidation that leads to increasing contact resistance and performance decline during operation. Potential alternative, lower-cost materials and coatings exist and/or could be developed. To avoid time, equipment, and labor intensive in-situ durability testing, accelerated high-throughput screening methods are desirable and explored in this work..
The explored ex-situ testing methodologies involve the preparation of coated material samples which are used as oxygen evolution electrodes. The materials are submersed in liquid electrolyte and degradation stressors such as temperature, pH, and potential are directly controlled. By varying each stressor independently, the influence that each has on the rate of degradation can be quantified. Such an approach may ultimately be useful in translating ex-situ results toward predicting in-situ performance. Periodic measurement of contact resistance and coating thickness during durability testing are also used toward this end. We further developed the use of time-lapse microscopy monitoring and analysis for our ex-situ testing setup. This technique allows identification and comparison of distinct corrosion modes and enables visual observations to be related to electrochemical durability data, which can improve its interpretation.
We will first present results that have guided our methodology development, in which electrode surface preparation and mounting variants were evaluated using a model system of sputtered Pt coatings on Ti coupons. With improved electrode preparation, we then evaluate some common Pt deposition techniques that include evaporation, sputtering, and electrodeposition. We also make a direct comparison between sputtered Pt and Ir coatings while using time-lapse microscopy to identify the corrosion modes of each. Coatings of Pt show a progression of yellowing, blistering, and peeling while Ir corrodes via darkening and dissolution. By processing the time-lapse microscopy to determine the change in apparent active area with time, we show that performance decline trends closely with the loss of active area. Some discrepancy at the beginning and end of the durability test have yet to be explained and additional analyses of the time-lapse data are ongoing. We will also present results of work in progress that includes investigation of Pt and Ir coating thickness, adhesion layers, and post-deposition annealing.
Effect of NH3 Etching on Fe-N-C Catalyst for Oxygen Reduction Reaction in Direct Methanol Fuel Cell
Authors: Luo Zhijun , Hou Chenjun , Zhang Xuelin , Zhang Yufeng , Liu Xiaowei 
Published: February 2020

Globally, because of the consumption of fossil fuel, the proton exchange membrane fuel cells (PEMFC) have received great attention. Direct methanol fuel cells(DMFC) have been applied into many fields, such as computers, global positioning systems(GPS) and portable devices. Platinum catalysts are considered as one of the most efficient catalysts for the oxygen reduction reaction(ORR),which is one of the most essential process for the DMFC. However, due to the high cost, the development of the DMFC calls for the non-precious metal catalyst, such as the Fe-N-C catalyst.
We report a process to synthesize a Fe-N-C catalyst. Firstly, 80 ml 1.5M HCl, 2 ml aniline, 3 ml cyanamide, and 3 g ferric chloride were fixed and stirred for 20 min, with 5 g (NH4)2S2O8 dissolved into 80 ml 1.5M HCl dropped slowly. The mixture after being stirred for 4 h was mixed with the BP2000 carbon black dissolved into 80 ml 1.5M HCl for 40 min. Secondly,the mixture was heated at 80 degrees and stirred at 300rpm until dried. After being boiled in 2M H2SO4 for 5 h at 90 ℃ and milled at 400rpm for 3h, the sample was filtered and dried. Finally, half of the precursor was calcined for 2.5 h in N2, and 0.5 h in NH3 at 900℃, and the others were calcined in N2 for 3 h. After being heated for 5 h in 0.5 M H2SO4 at 90℃, and calcined for 3 h in N2 at 900℃ to gain the catalyst. The catalysts were named Fe-N-C00 and Fe-N-C30 separately.
For RDE and RRDE tests on the Fe-N-C catalyst, the ink was prepared by mixing 15mg catalyst dissolved into 525µl ethanol and 145µl Nafion, which was stirred for 40min to achieve a good dispersion. 7µl ink was coated on the surface of RDE, making the loading of the catalyst 800µg cm-2. The staircase voltammetry(SCV) tests were conducted at the speed of 1600rpm in O2-saturated 0.5M H2SO4 solution. The half-wave of the potential of Fe-N-C00 catalysts were about 20mV lower than Fe-N-C30(0.685V vs 0.705V). According to the Koutecky-Levich equation, we calculated the electron transfer number was 3.97, and the productivity of H2O2 was 1.3%, which proved a four-electrons transfer process.
The Fe-N-C catalyst used as the cathodic catalyst,which was sprayed onto a carbon paper gas diffusion(GDL,SGL 29BC), was applied into a single DMFC. A Nafion® 117 membrane from Dupont worked as the electrolyte. The membrane was pre-treated following a standard procedure before use. A commercial Pt-Ru (30% Pt-Ru/C)catalyst was used as anodic catalyst.The anode gas diffusion electrode (GDE), the cathode GDE and the membrane were put together in sequence and hot-pressed by 135℃and 5MPa for 5 min to form a MEA separately. The loading of the catalysts including Fe-N-C and Nafion was 4mg cm-2,and the ratio of the Fe-N-C catalyst was 55%. The polarization curve of the DMFC with the different MEA was tested to reflect the effect of Fe-N-C00 and Fe-N-C30 catalyst on DMFC.

Figure 1
Efficient Electroreduction of CO2 in an Ultra-Slim Pressurized Electrolyzer
Authors: Edwards Jonathan P. , Xu Yi , Gabardo Christine M. , Dinh Cao-Thang , Li Jun , Qi ZhenBang , Sargent Edward H. , Sinton David 
Published: February 2020

Society’s consumption of fossil fuels has caused a surge in atmospheric carbon dioxide (CO2) concentrations which, if left unchecked, will have tremendous implications for all life on our planet. Consequently, new approaches are being investigated to utilize CO2 instead of releasing it into the atmosphere. One of these approaches is the electrochemical CO2 reduction reaction (CO2RR) which can store intermittent renewable energy in the form of valuable chemicals and fuels.
To encourage the implementation of industrial CO2RR systems, such systems must demonstrate economic benefits in conjunction with environmental benefits. To make such systems economical, electricity inputs, the single largest operating cost in these systems, must be minimized. A great deal of recent work has been devoted to optimizing the cathode catalyst and electrolyte to attain high selectivity towards specific products at low overpotentials. However, few studies optimize the full cell design, which includes the cathode, anode, ion exchange membranes, and electrolytes to demonstrate an efficient CO2RR process. These additional full cell elements require some consideration when designing industrial systems as improved cathode energetics may be overshadowed by increased losses in other areas of the system resulting from the cathode optimization.
Here we present an ultra-slim pressurized electrolyzer whose membrane-free operation with minimized electrode spacing yields negligible cell resistances. To showcase this cell design, we employ a silver catalyst for carbon monoxide (CO) generation at the cathode coupled with a nickel anode for oxygen evolution on the anode. In conjunction with the low cell resistances, we demonstrate further improvements in the uncorrected full cell energetic efficiency. First, we show that operation at elevated pressures, up to 51 bar, offers benefits to the reaction rates and helps to maintain high CO selectivities, resulting in energetic efficiency improvements. We then couple these high pressures with high alkalinity to demonstrate even greater improvements in energetic efficiencies due to improved kinetics. The system presented demonstrates substantial improvements in full cell energetic efficiency, enabling efficiencies > 65% to be attained while operating at industrially relevant current densities above 100 mA/cm2.
(Invited) Nanohybrids for Manipulating Solar Energy
Authors: Yurtsever Aycan , Ma Dongling 
Published: February 2020

With unique physical and chemical properties, and high potential for many important applications, nanomaterials have attracted extensive attention in the past two decades. For instance, due to their unique, size- and shape-tunable surface plasmon resonance, plasmonic nanostructures have recently been explored for increasing the efficiency of solar cells and photocatalysis. Essentially they enhance and/or broaden solar photon harvesting via improved light scattering, strong near field effect and/or hot electron injection. Combination of different nanomaterials into a single architecture leads to greatly enhanced properties, or even better, promising, multifunctional nanomaterials. In this talk, I will present our recent work on the synthesis of hybrid nanomaterials (the assemblies of different types of nanoscale materials) as well as their applications in smart windows, solar cells, solar fuel, photocatalysis, etc. [1-8]. Rational design of hybrid nanomaterials, which is the key to maximize the benefits from respective nano-components, is highlighted.
References: 1. Am. Chem. Soc., 2013, 135, 9616; 2. Adv. Energy Mater. 2018, 1703658; 3. Adv. Funct. Mater. 2018, 1706235; 4. ACS Catalysis, 2017, 7, 6225; 5. Adv. Funct. Mater, 2015, 25, 2950; 6. Adv. Funct. Mater. 2015, 25, 6650; 7. Adv. Funct. Mater., 2012, 22, 3914; 8. Adv. Mater., 2012, 24, 6289.
First-Principles Simulations of Stability, Optical and Electronic Properties of Competing Phases in Chalcopyrite-Based Photoelectrodes
Authors: Varley Joel Basile , Sharan Abhishek , Ogitsu Tadashi , Janotti Anderson , DeAngelis Alexander D , Gaillard Nicolas 
Published: February 2020

Photoelectrochemical (PEC) hydrogen production is one promising approach to economically generating renewable fuels, yet the widescale deployment of leading photoelectrodes (e.g. GaInP-based devices) has been hampered by issues with durability, efficiency and cost. Chalcopyrite-based tandem photoelectrodes are attractive alternatives in that they offer a great flexibility in the choice of component materials necessary that drive the reactions for different device designs, offering ways to reduce the cost and to improve the performance. The synthesis of low-band gap chalcopyrites like CuInSe2 and alloys with CuGaSe2 (CIGSe) are known to exhibit a variety of Cu-poor phases (ordered-vacancy compounds or OVCs) that can greatly influence the resulting properties of fabricated devices, while the existence and properties of these phases in wider-band gap chalcopyrite compounds and alloys remains largely unexplored. Using hybrid functional calculations, we discuss the stability, optical and electrical properties of OVCs in a number of other chalcopyrite chemistries beyond CIGSe. We discuss the influence of such phases on the resulting absorption and band offsets that would result upon their formation, which have implications in device design. We additionally discuss experimental fingerprints that could be used to identify the existence of such phases in synthesized material.
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the HydroGEN Consortium within the Department of Energy Office of Energy Efficiency & Renewable Energy (EERE) and Fuel Cell Technologies Office.
Electroreduction of CO2 to High-Value Products Using Selenide Based Electrocatalysts
Authors: Saxena Apurv , Masud Jahangir , Nath Manashi 
Published: February 2020

Electrochemical conversion of carbon dioxide (CO2) to useful chemicals presents both the potential for advantageous processes to the industry and for environmental benefits. Anthropogenic gas emissions has increased to a new level (413 ppm) in past few years. Concerns are high about impacts on climate due to high CO2 gas levels. Intergovernmental Panel on Climate Change (IPCC) report has indicated a strong risk of crisis as early as 2040 which includes worsening food shortages and wildfires, and a mass die-off of coral reefs.3 Fossil fuels has been predicted to last only for 100 years. Also the common renewable resources like wind energy or solar energy depends on the whim of weather. CO2 has been believed to cause the rise in temperature of earth’s atmosphere by 1°C. If we can use CO2 to produce energy then it can prove an everlasting energy source. Copper based catalysts are mostly active for the electrochemical reduction of CO2. Cu nanocrystals when used for CO2 electrochemical reduction give some C2 products which contain a C-C bond. Cu nanowires also reduced CO2 to CO with a faradaic efficiency of ∼50% at a moderate overpotential of 490 mV. Electrochemical reduction of CO2 if incorporated in the modern day energy resources can serve two purpose: make environment clean and provide energy too.
In this work we have shown for the first time, electrocatalytic activity of Cu2Se for CO2 electroreduction to value-added chemicals. The Cu­2Se catalyst was synthesized hydrothermally and was dropcasted on Carbon Fiber paper substrate (CFP) using very low quantity of nafion as binder. The Cu2Se modified CFP served as the working electrode for CO2 electroreduction and the electrochemical measurement was measured in KHCO3 electrolyte under flowing CO2 using a two-compartment electrochemical cell. The electrocatalyst was characterized by XRD, XPS, SEM, TEM, and EDS for morphology, and elemental chemical compositions. It was observed that the reduction products could be controlled by tuning the reduction potential, and a highly selective formate production was obtained at a higher potential with a high total current density approximately 30 mA cm-2. C2 products such as ethanol and acetic acid were obtained as reduction products. The details of catalyst synthesis, characterization and activity will be presented in the meeting.