Nian Liu, Georgia Institute of Technology
Weiyang Li, Dartmouth College
Bin Liu, Nanyang Technological University
Karthish Manthiram, Massachusetts Institute of Technology
ET03.01: Electrocatalysis Perspectives, Fundamentals and Case Study of Water Splitting
Monday PM, November 26, 2018
Hynes, Level 3, Room 302
8:00 AM - ET03.01.01
Enhanced Stability and Oxygen Evolution Electrocatalysis Activity of Heterostructured Anodes with Nanoscopically Thin Degenerately Doped Stannate and Titanate Epitaxial Layers
John Baniecki1,Catalin Harnagea2,Dan Ricinschi3,Takashi Yamazaki4,Yoshihiko Imanaka4,Hiroyuki Aso1
Fujitsu Laboratories1,INRS - Énergie Matériaux et Télécommunications2,Tokyo Institute of Technology3,Fujitsu Laboratories Ltd.4Show Abstract
Fuel produced from the electrochemical splitting of water can be used to power a wide variety of technologies including information communication technologies infrastructure. The slow kinetics of the oxygen evolution reaction (OER) is one of the performance-limiting factors for hydrogen production through electrolysis. OER catalysts are often unstable in alkaline environments exhibiting deactivation and structural transformation causing a significant challenge for use in photoeletrochemical cells and water electrolyzers. Moreover, in nanoscopically thin catalyst layers, OER activity also decreases due to inefficient charge transfer to the electrolyte-catalyst interface. Epitaxial heterostructures are promising to solve these issues, though recent attempts yielded improved stability only at the expense of greatly reduced OER activity. In this presentation, we elucidate the competing factors for deactivation of LaxSr1-xCoO3 (LSCO) in nanoscopically thin layers supported on conducting perovskite substrates, and demonstrate heterostructured anodes with simultaneously high activity and stability during electrochemical water splitting in alkaline environments (pH = 13).
Epitaxial thin films of La1-xSrxCoO3, Ba1-xLaxSnO3, and Sr1-xLaxTiO3 were grown by pulsed laser epitaxy. Interface energetics were characterized using in situ X-ray and ultraviolet photoelectron spectroscopies. Scanning transmission electron microscopy and electron energy loss spectroscopy were used to resolve the atomic structures, and scanning nonlinear dielectric microscopy used to probe the nature of the charge carrier character on the heterostructured catalyst surface. Density functional theory calculations were used to assess the impact of the electronic structure of the heterostructured catalyst layers on the overpotential and OER catalytic activity.
While the LSCO undergoes dramatic structural and electronic changes during electrolysis, including leaching of La and Sr from the film to yield a layer of cobalt oxyhydroxide, the thickness dependence of the OER activity will be revealed to be due to inefficiency of charge carrier transport to active sites. We demonstrate engineering of depletion layers widths and chemical stability using heterostructures comprised of nanoscopically thin epitaxial layers of degenerately doped stannate and titanate perovskite structure oxides to yield low overpotentials ~ 300 mV at current densities (~10 mA/cm2) relevant for hydrogen production in electrolyzers and photo-electrochemical cells, at hundreds of hours operations in nanoscopically thin active layers. Implications of the results for applications of nanoscopically thin oxide heterostructures for designs of high activity and stable anodes for carbon neutral energy production via the electrochemical splitting of water will be discussed.
C.H. would like to thank the Japan Trust program of the National Institute of Information and Communication Technologies (NICT) for funding.
8:15 AM - ET03.01.02
OER Catalyst Stability Investigation Using RDE Technique—A Stability Measure or an Artifact?
Hany El-Sayed1,Alexandra Weiß1,Lorenz Olbrich1,Garin Pratomo1,Hubert Gasteiger1
Technical University of Munich1Show Abstract
The development of OER catalysts for PEM water electrolysis requires both activity and stability testing methods. The OER catalyst activity can be estimated by using rotating disk electrode (RDE), flow-channel methods, or in an electrolyzer. The evaluation of catalyst stability is realized using accelerated tests as testing over the whole lifetime (5-10 years) under realistic conditions is not practical.1, 2 A protocol for the OER catalyst stability using RDE was proposed by the JCAP group and is now used by other researchers. In this protocol, a constant current is applied in a half-cell configuration and the change in potential is monitored until a sudden increase in potential indicates complete catalyst degradation.3 It was shown recently that the measured catalyst life-time depends on the nature of the electrode substrate onto which the catalyst powder is being supported. Based on this, it was recommended that Au and boron-doped diamond be used as they show better stability of the catalyst under investigation, while glassy carbon and fluorine doped tin oxide electrodes were deemed unsuitable in such stability test (St. T.).2
Here we present a careful examination of the use of RDE for investigating OER catalyst stability. Although the increase in potential in an RDE St. T. is thought to be due to catalyst degradation (dissolution), our findings provide a clear evidence that the change in potential is rather due to an experimental artifact. The source of this artifact are nano- and micro-bubbles formed within the pores of the catalyst layer during the OER that cannot be removed by electrode rotation. These bubbles accumulate and block the OER active sites, resulting in a potential increase, which is mistakenly interpreted as catalyst degradation. Our findings indicate that almost no catalyst degradation takes place at the first phase of the St. T., which can last for several hours. In this phase, the bubbles accumulate and block the active sites, resulting in an artificial increase in the potential. The second phase of the St. T. starts once a threshold potential is realized, where a rapid potential increase is observed, due to catalyst dissolution at high potentials. Gas bubbles accumulation is responsible for the increase in potential, and ultimately resulting in the full degradation of the catalyst layer. A proper St. T. using RDE technique should avoid the accumulation of oxygen bubbles, which is currently under investigation and preliminary results will be also presented.
1. H.-S. Oh, H. N. Nong, T. Reier, A. Bergmann, M. Gliech, J. Ferreira de Araújo, E. Willinger, R. Schlögl, D. Teschner and P. Strasser, J. Am. Chem. Soc., 138(38), 12552–12563 (2016).
2. S. Geiger, O. Kasian, A. M. Mingers, S. S. Nicley, K. Haenen, K. J. J. Mayrhofer and S. Cherevko, ChemSusChem, 41, 15 (2017).
3. C. C. L. McCrory, S. Jung, J. C. Peters and T. F. Jaramillo, Journal of the American Chemical Society, 135(45), 16977–16987 (2013).
8:30 AM - *ET03.01.03
Nature Catalysis’ Views on the Electrochemical Conversion and Storage of Energy
Nature Catalysis1Show Abstract
Modern societies face the challenge of supplying a continuously increasing energy demand. Intensive research is being conducted all around the globe to ensure that these needs can be satisfied while minimizing carbon emissions and other environmental threats. Electrochemistry holds promise to satisfy this requirement, either by using renewable energy to obtain fuels or store electricity or by converting fuels into electricity. Here catalysis research is pivotal, providing key advances in electrolyzers, fuel cells, and metal-air batteries.
Nature Catalysis, a new journal from the Nature Research group launched in January 2018, provides coverage of top research from the area of electrocatalysis, as well as all other areas of catalysis. Our broad scope, drawing from the work of scientists, engineers and researchers in industry and academia, ensures that published work reaches the widest possible audience. Nature Catalysis brings together researchers from across all chemistry and related fields, publishing work on homogeneous, heterogeneous, and biocatalysis, incorporating both fundamental and applied studies that advance our knowledge and inform the development of sustainable industries and processes.
9:00 AM - *ET03.01.04
Catalyst and Electrode Development for Proton and Anion Exchange Membrane-Based Electrolyze
Prasanna Mani1,Katherine Ayers1,Chris Capuano1,Luke Dalton1
Proton OnSite1Show Abstract
The need for a sustainable source of hydrogen has been widely recognized, not just as a potential transportation fueling vehicles, but to limit CO2 production and fossil fuel consumption from existing industrial processes such as ammonia generation. Currently over 95% of hydrogen is made from fossil fuels through natural gas reforming or coal gasification. However, significant growth has occurred in recent years in water electrolysis research, especially in catalyst research for the hydrogen (HER) and oxygen (OER) evolution reactions. Proton exchange membrane (PEM)-based systems are relatively mature in that the technology has been commercialized, but further research and development can achieve significant impact; for example, order of magnitude reductions in catalyst loading. Anion exchange membranes based systems are still under development, with membrane and ionomer stability in the operating environment being a critical issue. In both the AEM and PEM case, there are complex interactions at the electrode level which need to be considered in catalyst and membrane development. First, the liquid electrolyte environment used for catalyst activity screening, where all of the catalyst surface is accessible to the reactant is often not comparable to a complex, 3-dimensional, ionomer-based electrode. Also, similar to automotive fuel cells, the operating environment is highly important and should be considered when claiming improvements over state of the art. For example, catalyst performance at very low current densities may indicate inherent activity but may not represent capability at typical device operating currents. Similarly, a membrane which cannot operate at differential pressure may be highly limited in utility even if more efficient than current commercial solutions. This talk will describe some of the complex interactions that need to be considered, typical operating requirements, and stages of development where relevant conditions should be introduced.
9:30 AM - ET03.01.05
Highly Enhanced Electrochemical Water Oxidation Reaction Over Hyperfine β-FeOOH(Cl):Ni Nanorod Electrode by Modification with Amorphous Ni(OH)2
Tomiko Suzuki1,Takamasa Nonaka1,Kosuke Kitazumi1,Naoko Takahashi1,Satoru Kosaka1,Yoriko Matsuoka1,Keita Sekizawa1,Akihiko Suda1,Takeshi Morikawa1
Toyota Central R&D Labs Inc1Show Abstract
The catalytic oxygen evolution reaction (OER) to extract electrons from water molecules is important for the artificial photosynthesis to generate useful chemicals such as hydrogen and organic compounds [1, 2]. In terms of elements strategy, utilization of abundant element for OER catalysts is remarkably advantageous for future low-costly artificial photosynthetic system. Fe-based OER catalysts, based on the fourth most earth-abundant element, are attractive, but are known to suffer from low OER activity due to limited electrical conductivity and non-ideal electronic structures near the surfaces of these catalysts.
Here, we report a highly crystalline, 10 nm-sized red rust OER catalyst composed of pure β-phase FeOOH(Cl) nanorods (ca. 3 × 13 nm) doped with Ni ions (β-FeOOH(Cl):Ni)  and surface-modified with amorphous Ni(OH)2 (a-Ni(OH)2, at a Ni to Fe ratio of 22 at.%), which shows the highest level of performance among Fe-rich oxides and oxyhydroxides. This catalyst can be synthesized by a facile one-pot process at room temperature, and colloidal aqueous solutions of the β-FeOOH(Cl)Ni/a-Ni(OH)2 nanorods are very stable, with no apparent precipitation over a time span of at least one month.
Electrochemical measurements for β-FeOOH:Ni/a-Ni(OH)2 stacked nanorod anodes deposited on carbon paper (CP) were performed in a 3-electrode configuration using a Ag/AgCl reference electrode and a Pt wire counter electrode. The overpotential during the electrochemical OER over the anodes was 170 mV, and an OER current of 10 mA/cm2 was obtained at an overpotential of 430 mV(+1.66 V vs. RHE) in 0.1 M KOH (without subtracting the iR drop). It is suggested that the surface modification with the a-Ni(OH)2 lowered the OER overpotential of β-FeOOH(Cl):Ni, resulting in the very high current density at low potential compared with Fe-rich oxide and oxyhydroxide electrodes reported previously. Mössbauer spectroscopy also suggested electronic interaction between Fe and Ni species, which may be crucial evidence for the enhanced activity in the Fe-rich OER system .
The present cost-effective Fe-based OER catalysts can be widely applied to construct artificial photosynthetic systems for solar fuel generation by combination with CO2 reduction catalysts.
 T. R. Cook, et al., Chem. Rev., 110 (2010) 6474.  C. C. L. McCrory, et al., J. Am. Chem. Soc., 136 (2013) 16977.  T. M. Suzuki, T. Morikawa, et al., Sustainable Energy Fuels, 1 (2017) 636.  T. M. Suzuki, T. Morikawa, et al., Bull. Chem. Soc. Jpn., 91 (2018) 778.
9:45 AM - ET03.01.06
WITHDRAWAL: 11/23/18 (ET03.01.06) Unprecedented Impact of Charge on Electrochemical Reactions of Two-Dimensional Materials
Yuanyue Liu1,Donghoon Kim1,Jianjian Shi1
The University of Texas at Austin1Show Abstract
Two-dimensional (2D) materials have attracted great interest in catalyzing electrochemical reactions such as water splitting, oxygen reduction, and carbon dioxide reduction. Quantum mechanical simulations have been extensively employed to study the catalytic mechanisms. However, these calculations typically assume that the catalyst has a zero/constant charge for computational simplicity, while in reality, the catalyst usually has a varying charge as the reaction proceeds due to the match between its Fermi level and the applied electrode potential. These contradictions urge an evaluation of the charge effects.
Here using grand canonical density functional theory calculations, we show that the charge on 2D materials can have a much stronger impact on the electrochemical reaction than the charge on 3D metals, which arises from the unique electronic properties of 2D materials. Our work calls for reconsideration of some of the previously suggested electrocatalytic mechanisms of 2D materials by incorporating the charge effects. 
 Donghoon Kim, Jianjian Shi, Yuanyue Liu, submitted
10:30 AM - *ET03.01.07
Hydroxide Exchange Membrane Electrolyzers (HEMELs) for Hydrogen Production
University of Delaware1Show Abstract
One of the grand challenges facing humanity today is the development of an alternative energy system that is safe, clean, and sustainable and where combustion of fossil fuels no longer dominates. A distributed renewable electrochemical energy and mobility system (DREEMS) based on cheap renewable electricity could meet this challenge. At the foundation of this new energy system, we have chosen to study a number of electrochemical devices including fuel cells, electrolyzers, and flow batteries. We have been working on the development of hydroxide exchange membrane fuel cells (HEMFCs) and electrolyzers (HEMELs) which can work with nonprecious metal catalysts and inexpensive hydrocarbon polymer membranes. We have developed roadmaps for HEMFCs and HEMELs, the most chemically stable membranes, and the most active nonprecious metal catalysts. We have also studied why hydrogen oxidation and evolution reactions (HOR/HER) are slower in base than in acid for precious metal catalysts. For flow batteries we have developed novel designs, chemistries and cost models e.g., double-membrane aqueous flow batteries with high voltages (i.e., 3 V), single-element-mimic redox pairs, and user friendly physics-based analytical cost models. In this presentation, I will focus on our HEMEL work highlighting a new class of membranes, nonprecious metal catalysts and base/salt-free HEMEL cells for hydrogen production.
11:30 AM - ET03.01.09
Ultrathin Pinhole-Free Molecular Wires-Embedded SiO2 Membrane Connecting Incompatible Redox Reactions for Scalable Artificial Photosynthesis
Won Jun Jo1,Georgios Katsoukis1,Heinz Frei1
Lawrence Berkeley National Laboratory1Show Abstract
Replacing fossil fuels with renewable resources to meet the global need requires a technology that is scalable to the unprecedented level of several terawatts. Natural photosynthesis is the sole existing technology that produces energy dense chemicals on the terawatt scale (> 100 TW). Its key design feature is the closed cycle of H2O oxidation and formation of the primary reduction products on the shortest possible length scale, the nanometer scale, while separating the incompatible redox environments by an ultrathin membrane. This offers the advantage of minimizing efficiency-degrading mass transport processes and unwanted side reactions.
To incorporate the key feature into artificial photosystems, we assembled ultrathin (2 nm), pinhole-free, molecular wires-embedded SiO2 membrane on planar and nanotube constructs. This membrane system spatially separates the H2O oxidation CO2 reduction, but enables (photo-)electrochemical communication between the incompatible redox reactions by transmitting protons and electrons in a precisely controlled manner, while preventing O2 transport causing unwanted reverse reactions. This unique mass-transport behavior on planar and nanotube configurations was systematically studied via cyclic voltammetry, electrochemical impedance spectroscopy, and visible light-sensitized short circuit current experiments. The embedded molecular wires’ integrity before and after the mass-transport process was confirmed by time-resolved optical spectroscopy and grazing angle ATR-FT-IR or IRRAS characterization.
11:45 AM - ET03.01.10
Interesting Proton Conduction Environment within Thin Films of Fluorocarbon based Ionomers with Single or Multi-Acid Side Chains
University of Nebraska--Lincoln1Show Abstract
Polymer-catalyst interfaces control the energy efficiency of many energy conversion and storage device. The interfacial polymer layers are very thin (typically less than one micron thick). Many interesting structural, mechanical and transport properties in such thin ion containing polymer (ionomer) layers evolve as a result of complex multimodal interfacial interactions, unusual hydration behavior and confinement. Especially ion conductivity at the interface can be drastically different from that in the bulk membranes and the route to this poor ion conduction behavior is not well-understood. It is thus highly needed to systematically study how the ion conduction environment and water uptake change with the change in ionomer structure and film thickness. In this work, three potential fluorocarbon based hydrogen fuel cell ionomers (Nafion, 3M PFIA, 3M PFSA) having single/multiple acids at side chain were studied in sub-micron thick films. All three ionomers have fluorocarbon (PTFE) backbones. The difference between Nafion and 3M PFSA is in the side chain structure, but both has single acid group at the side chains. On the other hand, 3M PFIA has bis(sulfonyl)imide group in addition to perfluorosulfonic acid which makes the polymer more acidic. By tracking the fluorescence response of photoacid dye HPTS incorporated within hydrated ionomer thin films, very interesting trends were obtained regarding the extent of proton transfer. The results, when combined with the information on nanoscale structure and water sorption, clearly indicated that there are many factors controlling the proton conduction behavior in thin ionomer films, in addition to water uptake.
ET03.02: Battery Fundamentals, Characterization and Modeling
Monday PM, November 26, 2018
Hynes, Level 3, Room 302
2:00 PM - *ET03.02.02
Nanoscale Characterizations and Material Designs for Rechargeable Lithium Batteries
Columbia University1Show Abstract
Nanoscale transport and materials are critical to electrochemical energy storage, such as power density, cycling life and safety. In this talk, I will present two examples on advanced tools and fabrication to understand nanoscale transport phenomena and designing of nanoscale materials. The first one is based on an emerging Stimulated Raman Scattering Microscopy, which is three orders of magnitude faster than traditional Raman microscopy. Therefore it can clearly track ion transport in electrolyte together with lithium dendrite, to illustrate their correlations. A positive feedback mechanism has been visualized, which guide methods to suppress lithium dendrite. The second example is through designing nanoscale modification of interfaces between battery electrodes and solid electrolyte. Therefore, the stability between electrodes and electrolyte and the cycling life of corresponding full cells are significantly improved.
2:30 PM - ET03.02.03
Mechanistic Understanding of Phase Transformation Behavior during Lithiation of MoS2 using Density Functional Theory Calculations
Avinash Dongare1,Jin Wang2,Arthur Dobley3,C Carter1,4
University of Connecticut1,University of Pennsylvania2,Eaglepicher Technologies3,Sandia National Laboratories4Show Abstract
The design/discovery of layered materials for applicability in next-generation battery technologies requires a fundamental understanding of the links between the atomic-scale structure, chemistry and the mechanisms and energetics of intercalation and de-intercalation reactions, and a consideration of other solid-state reactions that might compete. The goal of our research is to design/discover layered material microstructures as alternatives to graphite using an innovative combination of atomic-scale modeling, experimental in-situ characterization of the microstructural evolution during (de)intercalation reactions. Density functional theory (DFT) simulations are carried out to investigate the structural accommodation of the layered material during insertion and exertion of the intercalating species (energy barriers, volumetric expansion, and phase transformations). The structural stability of the 2H and 1T phases of MoS2 during lithiation suggests that a phase transformation of the 2H phase of MoS2 to the 1T phase may occur when MoS2 is reacted with Li; the computational study allows different dosages of Lithium ion to be assessed with the aim of testing these the validity of these models using in-situ characterization of the solid-state reactions between Li and MoS2 in the transmission electron microscope (TEM). The mechanisms of strain relaxation and the energetics of Li intercalation-induced phase transformations in MoS2 at the atomic scales will be presented. This work is supported by NSF grant No. 1820565.
2:45 PM - ET03.02.04
Mechanistic Understanding of Lithiation in MoS2 by Atomic Scale Characterization
C Carter1,2,Shalini Tripathi1,Matthew Janish1,William Moyer Mook2,Katherine Jungjohann2,Avinash Dongare1,Arthur Dobley3
University of Connecticut1,Sandia National Laboratories2,EaglePicher Technologies LLC3Show Abstract
Understanding the structure and phase changes associated with two-dimensional (2D) layered transition metal dichalcogenides (TMDs) is critical in optimizing performance in lithium-ion batteries. The large interlayer spacing in MoS2 (∼0.65nm) accommodates species such as alkali metal ions (Li+/Na+/K+) during intercalation. Intercalation is reported to change the electronic structure of the host molecule, resulting in variations in their electrical and optical properties. In this work, we examine the solid-state reactions between Li and MoS2. Li+ ions can be inserted into vdW gap; the reaction is still unclear. Plan-view imaging has been extensively used, however, it is essential to visualize the process with the electron beam being parallel to the basal planes of the layer material to understand the reaction process. Lattice-fringe images have been discussed for several systems but relying on microtoming or simply using curved thin layers, the orientation of the specimen was less than ideally uncontrolled. Here, TEM specimens are made using FIB, and oriented for detailed study of the intercalation process. This study of TMDs uses a Tecnai F30 and a Cs/image-corrected Titan equipped with a direct electron detector camera, K2. This camera has two major advantages: the electron dose can be minimized and quick changes during reactions are recorded; both instruments have EELS and XEDS capabilities. DFT calculations are used to probe the structure and bonding changes during these reactions. Volumetric expansion, energy barriers, phase transformations and the role of doping, defects and interfaces can be modeled. The dynamics of the structural response are modeled using ab initio MD simulations. Electrochemical aspects can be monitored in situ in real-time and at atomic scale to provide understanding of lithium-ion storage mechanisms in these solid-state reactions and thus to test the modeling-based results.
In plan-view specimen, variations normal to the basal plane are not seen. Defects associated with the reactions were monitored real-time. As the reaction between MoS2 and Li proceeds, white-line defects were observed under high-resolution imaging by TEM. Lower-magnification images show that the defects are not equally spaced and do not correspond to ‘stage’ development. These defects can cross several basal planes in the MoS2 (either forwards or backwards) but maintain essentially the same width after the step; they are not completely constrained to the vdW gap.
This work is funded by NSF grant No. 1820565. MTJ is at LANL. TEM is at CINT, an Office of Science User Facility operated for the U.S. DOE. Sandia NL is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE’s NNSA under contract DE-NA-0003525. The views expressed in the abstract do not necessarily represent the views of the U.S. DOE or the U.S. Government.
3:30 PM - ET03.02.05
Gate-Tunable Electrochemical Kinetics on Back-Gated 2D Materials
Yan Wang1,Daniel Frisbie1
University of Minnesota1Show Abstract
Electrochemical processes at electrode/electrolyte interfaces (e.g. electric double layer charging, heterogeneous charge transfer and surface binding of reaction species on the electrode) are of vital importance to energy conversion and storage systems including batteries, supercapacitors and electrocatalytic production of fuels. It has been widely acknowledged that the kinetics of the interfacial electrochemical processes are largely determined by the electronic structure (e.g. density of states and electronic occupation) at the electrode/electrolyte interface. We have developed a back-gated electrode structure that utilizes electrostatic charging (induced by a gate bias) to control electrochemical kinetics on ultrathin or 2D materials (5-nm-thick ZnO, monolayer MoS2 and graphene).1,2 Such back-gated electrodes are fabricated with nanometer-thick semiconductors on SiO2/degenerate Si substrates, analogous to the metal–oxide–semiconductor stack in the CMOS technology. Due to the extreme thinness of the electrode materials, the alignment of electronic bands as well as the electronic occupation, at the electrode/electrolyte interface, can be dramatically altered by the gate-induced charge carriers. Thus, real-time, continuous and efficient modulation of reaction kinetics can be achieved on 2D materials by varying the gate bias.
In this presentation, we will use back-gated monolayer MoS2 as an example to demonstrate how the applied gate bias affects the kinetics of heterogeneous charge transfer and surface binding processes. Specifically, the standard charge transfer rate constant between MoS2 and ferrocene/ferrocenium redox couple can be tuned by over two orders of magnitude and the catalytic overpotential of hydrogen evolution reaction on 2H-MoS2 can be reduced by more than 150 mV. Overall, the approach introduced here is generally applicable to investigation and optimization of interfacial electrochemical phenomena in a wide range of electrochemical systems. With the ability to control the band alignment and electronic occupation independent of the electrode potential, the back-gated 2D electrodes will provide new insights to rational design of electrode materials.
(1) Kim, C.-H.; Frisbie, C. D. Field Effect Modulation of Outer-Sphere Electrochemistry at Back-Gated, Ultrathin ZnO Electrodes. J. Am. Chem. Soc. 2016, 138 (23), 7220–7223.
(2) Wang, Y.; Kim, C.-H.; Yoo, Y.; Johns, J. E.; Frisbie, C. D. Field Effect Modulation of Heterogeneous Charge Transfer Kinetics at Back-Gated Two-Dimensional MoS2 Electrodes. Nano Lett. 2017, 17 (12), 7586–7592.
3:45 PM - ET03.02.06
Nanoscale Characterization of Interfacial Phenomena in Battery Materials—New Insights from Correlative Electron Microscopy and Secondary Ion Mass Spectrometry Imaging
Santhana Eswara1,Alisa Pshenova1,Venkata Siva Varun Sarbada2,Lluís Yedra1,Andrew Kercher3,Kenneth Takeuchi4,Amy Marschilok4,5,Esther Takeuchi4,5,Nancy Dudney3,Tom Wirtz1,Robert Hull2
Luxembourg Institute of Science and Technology1,Rensselaer Polytechnic Institute2,Oak Ridge National Laboratory3,Stony Brook University, The State University of New York4,Brookhaven National Laboratory5Show Abstract
The performance of electrochemical energy materials depends crucially on the underlying nanoscale processes. The charge-discharge cycles of batteries result in gradual changes in nanoscale structure and chemistry of the different electrode layers with often detrimental consequences for the electrochemical properties . To understand the nanoscale mechanisms causing the degradation of the battery materials and to develop strategies to counteract, high resolution imaging and analysis techniques are indispensable. While high-resolution Transmission Electron Microscopy (TEM) enables imaging of the nanostructures down to atomic resolution, analysis of light elements (Z < 6) and low concentrations (< 0.1 at. %) are difficult using typing analytical tools in a TEM such as Energy Dispersive X-ray Spectroscopy. In comparison, Secondary Ion Mass Spectrometry (SIMS) has an excellent sensitivity (can be as low as ppm range) and all the elements (including isotopes) of the periodic table can be analysed. However, the SIMS image resolution is limited to ~ 50 nm in most commercial SIMS instruments (except some new developments  where resolution < 20 nm has been demonstrated). Nevertheless, the resolution is still more than 2 orders of magnitude poorer than TEM imaging. To complement the strengths of TEM and SIMS in the same instrument, we developed an in-situ correlative microscopy technique combining TEM-SIMS [3, 4]. In this presentation, we will demonstrate the application of this new nanoscale characterization technique to elucidate the structural and chemical changes occurring in Li ion battery cathodes containing LiV3O8 thin film with different initial microstructures obtained by thermal annealing. Bright-Field TEM and corresponding SIMS images (e.g. Li+ and V+ maps) from uncycled and cycled samples were obtained to investigate the underlying materials phenomena (such as vanadium dissolution) in the cycled cathodes and to correlate the nanoscale processes with macroscopic electrochemical performance .
 Q. Zhang et al, Journal of The Electrochemical Society, 164 (7) A1503-A1513 (2017)
 D. Dowsett, T. Wirtz, Anal. Chem. 89 (2017) 8957-8965
 T. Wirtz, P. Philipp, J.-N. Audinot, D. Dowsett, S. Eswara, Nanotechnology, Vol. 26, 434001, 2015.
 L. Yedra, S. Eswara, D. Dowsett, T. Wirtz, Sci. Rep. 6, 28705, 2016
 Acknowledgements: LVO cathode samples are synthesized as part of the Center for Mesoscale Transport Properties, an Energy Frontier Research Center supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under award #DE-SC0012673.
4:00 PM - ET03.02.07
Simulation of Charge Transfer Reactions at Graphite and Electrolyte Solution Interfaces with Density Functional and Implicit Solvation Theory
Minoru Otani1,Jun Haruyama1
National Institute of Advanced Industrial Science and Technology1Show Abstract
Development of a stable energy-storage device is a fundamental approach to solve energy-related issues. Lithium-ion batteries (LIBs) are one of the most promising candidates because of their high energy density and long cycle life. From electrochemical impedance spectroscopic measurements, the cell resistance of conventional LIB is dominated by charge transfer resistance at electrode/electrolyte interfaces. [1,2] Therefore, we investigate the charge transfer process, i.e. Li insertion/desorption process, at the interface between a graphite anode and 1 M LiPF6EC electrolyte. The density functional theory (DFT) with effective screening medium (ESM) method  combined with the reference interaction site model (RISM), called ESM-RISM, is employed to simulate the Li insertion/desorption process.  In this method, the graphite surface (LixC6slab and additional Li+) and liquid solution (1 M LiPF6EC) are represented as quantum mechanical and implicit classical solvation, respectively. The energy landscapes of reaction are revealed under constant electron chemical potential conditions at the interface. Across the transition state where the Li forms a half solvation shell, the reacting Li inside the electrode changes to a full solvation structure in the solution accompanied by electron transfer. The activation energies at the equilibrium potentials of the charge transfer reaction are approximately 0.6 eV,  which is consistent with the electrochemical impedance spectroscopy measurements. In the presentation, we explain the details of the ESM-RISM simulation and introduce the energy profiles of the Li insertion/desorption path at the LiC6/EC LiPF6interface.
 T. Abe, H. Fukuda, Y. Iriyama, and Z. Ogumi, J. Electrochem. Soc. 151, A1120 (2004).
 K. Xu, A. von Cresce, and U. Lee, Langmuir 26, 11538 (2010).
 M. Otani and O. Sugino, Phys. Rev. B 73, 115407 (2006).
 S. Nishihara and M. Otani, Phys. Rev. B 96, 115429 (2017).
 J. Haruyama, T. Ikeshoji, and M. Otani, J. Phys. Chem. C 122, 9804 (2018).
4:15 PM - ET03.02.08
Measurement of Mechanical Properties and Assessment of Mechanical Degradation of Solid Electrolyte Interphase (SEI) Formed with Carbonate-Based Electrolytes
Brown University1Show Abstract
Rapidly increasing demand for low-cost, high energy density energy storage motivates researchers to develop advanced and reliable anode materials. Lithium alloying anodes such as Si, Sn, or Ge has three to ten times of charge capacity compared to the traditional graphite electrodes, and thus gathered enormous research interest. One of the major challenges associated with the lithium alloying anodes originates from de/lithiation-induced large volume change (~300%). Such volume change applies excessive cyclic strain on solid electrolyte interphase (SEI) to cause its mechanical failure and continued formation, resulting in poor cycle life. Several electrolyte additives such as fluoroethylene carbonate (FEC) or vinylene carbonate (VC) have been investigated and demonstrated to improve cyclic performance of Si electrodes. However, quantitative evaluation on influence of the additives on mechanical properties of SEI is still challenged.
With this background, we have developed an experimental approach to characterize elastic modulus, yield stress, inelastic deformation behavior, and crack density evolution of SEI formed with carbonate-based electrolytes. An SEI (~100nm) is prepared by lithium thin film - electrolyte (1.2M LiPF6 in ethylene carbonate) reactions on a rectangular free-standing polydimethylsyloxane (PDMS) membrane (~300 - 400nm in thickness). The prepared sample is subjected to bulge testing in an inert environment; various level of controlled pressure is applied to the SEI/PDMS membrane and the corresponding deflection is measured by the atomic force microscopy (AFM). The plane strain elastic modulus and the yield stress of SEI are evaluated from the pressure-deflection relation from the bulge testing. Moreover, a careful observation of SEI surface topography yields the evolution of crack density as a function of applied strain. The experiment is repeated using FEC added electrolytes to investigate the influence of the FEC additive on mechanical stability of SEI.
4:30 PM - ET03.02.09
Developing an Understanding of Solid-Electrolyte Interphase Formation in Multivalent Ion Batteries Using First Principles Calculations
Joshua Young1,Manuel Smeu1
Binghamton University1Show Abstract
Multivalent ion batteries (MVIB), or those utilizing Mg, Ca, Zn, and Al, are garnering increasing attention as alternatives to Li-ion batteries in applications where portability is not an issue owing to their high energy density, cost efficiency, and abundance. However, the lack of suitable electrolytes allowing for the reversible plating of metallic anodes has limited the development of MVIBs, especially those involving Ca. This is primarily due to the fact that the solid-electrolyte interphase (SEI), a passivating layer which forms between the electrolyte and anode, often does not allow for the migration of ions in MVIBs. [1,2] In this work, we develop an understanding of the SEI in MVIB systems using a computational approach combining density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations.  We first identify the principle components of the SEI by studying the decomposition of the solvents and salts comprising various electrolytes on Li, Ca, and Al surfaces using AIMD. Following this, we identify electrolytes which can be used with a Ca metal anode by investigating the diffusion of Ca ions through the likely inorganic compounds produced using DFT. Finally, we investigate the decomposition of these electrolytes in the presence of external electric fields to more fully understand these reactions in electrochemical systems. We anticipate the promising new electrolytes proposed in this work will help guide experimentalists in the development of rechargeable MVIBs.
J.Y. and M.S. were supported by funds from Binghamton University. DFT calculations were performed on the Spiedie cluster at Binghamton University, as well as the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by NSF Grant No. ACI-1053575, under allocations TG-DMR170127 and TG-DMR180009.
 Ponrouch et al., Nat. Mater. 15 169 (2016)
 Wang et al., Nat. Mater. 17 16 (2017)
 J. Young and M. Smeu, J. Phys. Chem. Lett. 9 3295 (2018)
4:45 PM - ET03.02.10
Structure of Room Temperature Ionic Liquids from X-Ray Scattering and Ab Initio Molecular Dynamics Simulations
Tuan Anh Pham1,Riley Coulthard2,Mirijam Zobel3,Steven Buchsbaum1,Desiree Plata2,Brandon C. Wood1,Francesco Fornasiero1,Eric Meshot1
Lawrence Livermore National Laboratory1,Yale University2,University of Bayreuth3Show Abstract
Room temperature ionic liquids (ILs) have recently emerged as highly promising electrolytes for a wide range of emerging energy technologies, including next-generation supercapacitors and ion-batteries, due to their high thermal stability, ionic conductivity and wide electrochemical windows. The chemical and structural diversity of ILs creates a vast design space that could be exploited to optimize the device performance and stability. However, many mechanistic details remain enigmatic, including the fundamental nature of the cation-anion interactions and their relevance in determining structural and electronic properties of the liquids. Having this detailed information for the bulk liquid is a prerequisite for eventually deciphering the complexity the arises at nanostructured electrode interfaces, which are ubiquitous among energy storage devices. In this presentation, we combine high-level first-principles simulations and synchrotron X-ray characterization experiments to unravel the key structural, chemical and electronic properties of several archetypal ILs comprised of imidazolium-based ILs. In particular, we utilize extensive ab initio molecular dynamics simulations to probe the local density distribution and medium-range order of the ILs, which can be directly compared and validated by X-ray scattering measurements. Soft and tender X-ray absorption spectroscopy at the K-edge of fluorine, phosphorus, and sulfur contained on the anion also complements the chemical and electronic picture from the simulations. Our integrated theoretical and experimental approach relates these structural and chemical signatures with the intrinsic cation-anion interactions, by considering ILs with anions having significant differences in the molecular geometry, chemical composition, and charge distribution.
This work was supported by the U.S. Department of Energy at the Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
ET03.03: Poster Session I: Electrocatalysis
Tuesday AM, November 27, 2018
Hynes, Level 1, Hall B
8:00 PM - ET03.03.01
Enhancing Electrocatalytic CO2 Reduction Using a System-Integrated Approach to Catalyst Discovery
Thomas Burdyny1,Wilson Smith1
Delft University of Technology1Show Abstract
Electrocatalytic CO2 reduction has the dual-promise of neutralizing carbon emissions in the near future, while providing a long-term pathway to create energy-dense chemicals and fuels from atmospheric CO2. The field has advanced immensely in recent years, taking significant strides towards commercial realization. While catalyst innovations have played a pivotal role in increasing the product selectivity and activity of both C1 and C2 products, innovations at the systems level have resulted in the scaling up of CO2 reduction processes to industrially relevant current densities. This has been achieved by using membrane-electrode assemblies, gas-diffusion electrodes and pressurized systems to provide ample CO2 to the catalyst. The immediate gains in performance metrics offered by these system-integrated catalytic configurations, however, go beyond reduced system losses and high current densities, suggesting that different reaction pathways and improved kinetics are possible when catalysts are tested under these conditions.
In this work we discuss the underlying reasons for the observed changes in catalytic activity between low and high current density studies. In particular, nanoscale transport phenomena is combined with experimental observations to show that the local reaction environment around a CO2 reduction catalyst is substantially different at low current densities (<20 mA/cm2) from those at practical applied current densities (>200 mA/cm2). Specifically, the combined requirements for both CO2 and protons (H+) at a catalyst’s surface in CO2 reduction leads to substantial cation, anion and pH gradients at the surface. At substantial current densities this results in alkaline reaction conditions at the catalyst’s surface regardless of the chosen material, configuration or electrolyte. These conditions alter the binding energy of reactants and intermediates as compared to low current operating conditions, resulting in different product distributions and reaction efficiencies than are observed in the classical H-cell testing configuration.
Further, we extend these findings to design a practical electrochemical cell configuration (e.g. large electrode areas of >100 cm2 operating at current densities of 200 mA/cm2). We find that while the majority of catalytic materials are tested under ideal ‘inlet’ conditions (e.g. saturated CO2, ideal electrolyte conditions, no reaction products), a catalytic material also needs to be designed to operate with high performance under the ‘outlet’ conditions of an electrochemical device (e.g. the segment of active catalyst area near the outlet of the cell). We discuss how the deviation between inlet and outlet conditions has large implications for the required functionality of the catalyst, and the maximum size of a CO2 reduction unit cell.
8:00 PM - ET03.03.02
Ni3P and NiFeOOH Core-Shell Nanoparticles Decorated in Nitrogen-Doped Carbon for Efficient Water Oxidation
Baicheng Weng1,Corey R. Grice1,Fenghua Xu1,Yanfa Yan1
The University of Toledo1Show Abstract
Transition metal Ni-based catalysts are potential candidates to replace expensive and scarce noble metal-based oxygen evolution reaction (OER) catalysts such as RuO2 and IrO2. Herein, we report a facile and environment-friendly method to synthesize core-shell nanoparticles consisting of Ni3P core and NiFeOOH thin shell homogeneously studded in N-doped carbon matrix (Ni3P@NiFeOOH/C). The obtained Ni3P@NiFeOOH/C catalyst exhibits excellent OER activity and stability in both alkaline and neutral electrolytes, and is among the most active OER electrocatalysts yet reported in literature. Ni3P@NiFeOOH/C reaches a 10 mA cm-2 current density at a potential of 1.49 V (vs. RHE) in alkaline electrolyte and achieves 1 mA cm-2 at 1.56 V (vs. RHE) in neutral electrolyte, respectively, outperforming the noble metal oxide catalysts, RuO2 and IrO2. The superior performance can be ascribed to the synergetic effect of Ni3P supporting catalyst, NiFeOOH shell, and N-doped carbon matrix. A two-electrode electrochemical water-splitting device combining Ni3P@NiFeOOH/C OER catalyst with Ni3P hydrogen evolution reaction (HER) catalyst delivers a stable current density of 10 mA cm-2 at 1.59 V and 1.75 V for over 17 h in alkaline and neutral electrolyte, respectively. Our design and synthesis strategy offer insights for developing new highly active electrocatalysts for water splitting and CO2 reduction.
8:00 PM - ET03.03.04
Ionic Transports in Liquid Under Confinement
Yuepeng Guan1,Jin Suntivich1
Cornell University1Show Abstract
This presentation presents an ionic-transport measurement in aqueous electrolytes that are confined within the cavities of nanoporous solids. Ionic transport plays an important role in electrochemical energy storage devices. Many studies have reported high ionic transport in nanoporous materials, for example, in porous carbon and in metal-organic framework materials. However, very little is understood how the confinements affect ionic transport. In this presentation, we present our measurement of the ionic transport through different nanoporous materials with controllable pore sizes and surface charges. We use these experimental measurements to establish the ionic transport ability and the role of electrical-double layer on ionic diffusions. These results provide insights into the elusive role of the electrical-double layer on confined ionic diffusions and a design strategy of future nanoporous materials for energy storage devices.
8:00 PM - ET03.03.05
Graphene Oxide Enhanced Performance and Durability of Proton Exchange Membrane Fuel Cells (PEMFCs)
Likun Wang1,Yuchen Zhou1,Stoyan Bliznakov1,Miriam Rafailovich1,Danielle Kelly2,Audrey Shine3,Guan Hao Chen4
Stony Brook University1,Friends Academy2,Plainview Old-Bethpage JFK High School3,St. Georges High School4Show Abstract
Proton exchange membrane fuel cells (PEMFCs) has attracted tremendous attentions as energy conversion device due to its high energy density, low operating temperature and environmentally friendly emission. Numerous efforts have been made to explore efficient catalysts for the reaction when valuable progress brings the large-scale commercialization of PEMFCs to the table. However, durability of the PEMFCs hindered the commercialization process. Here, we reported a simple, low-cost and readily scalable method to mitigate this effect by the incorporation of graphene oxide (GO). In our study, GO is deposited on the Nafion membrane or into the catalysts layer. The maximum power output of the cell under H2/air atmosphere showed an enhancement over 20%. More importantly, the durability of PEMFCs was significantly improved by the GO introduction. 26.1% of maximum power degradation was observed for the cell without GO while only half amount decrease obtained for the cell with GO after 30K cycles of accelerated stress test based on DOE2020 protocol. Nearly 100% enhancement for the durability of PEMFCs can be attributed to the prohibition of H2O2 production. The promising durability promotion effect induced from low-cost GO involvement will help to accelerate the large-scale commercialization of PEMFCs.
8:00 PM - ET03.03.06
Effect of the Oxygen Vacancies and Concentration of Ce3+ Valence State on Enhanced Electrochemical Performance of One Step Solvothermally Synthesized CeO2 Nanoparticles
Ju-Hyung Yun2,Hyeong-Ho Park1,Manjeet Kumar2,Joondong Kim2
Korea Advanced Nano Fab Center (KANC)1,Incheon National University2Show Abstract
Environment friendly, low-cost and high performance energy storage systems have been progressively required because of the global warming which has become an imperative and unavoidable factor. The increasing environmental setbacks along with the depletion of fossil fuels necessitate the tradition of solar photovoltaic and wind power as a source of electrical energy in practice[1, 2]. But, the unavailability of power from photovoltaic systems during night time and fluctuation in wind speed of the deliverable power have directed the researchers towards the usage of energy storage devices. Moreover, to maximize the productive use of electric vehicles, it is very essential to meet up with the intermittent energy needs and variable power demands. Correspondingly, high power delivery and long cycling stability is some of the most important criterion to be fulfilled by an energy storage device.. To accomplish these demands, devices which could entail huge initial power to start up and show capability of charging with quicker rate are prerequisite. Therefore, supercapacitors have been explored as an upgraded energy storage devices to replace batteries and conventional capacitors with superior features.
In this work, different sized CeO2 nanoparticles were synthesized using one step low-cost solvothermal method with various reaction time. Defect states were induced due to the reduction of Ce4+ into Ce3+ valence state. X-ray photoelectron spectroscopy results recommend that Ce3+ valence states and defects in the form of oxygen vacancies be present on the surface of CeO2 nanoparticles. Such availability of oxygen vacancies provided high specific capacitance 142.5Fg-1 at a current density of 0.25Ag-1 in three electrode system using 1 M Na2SO4 electrolyte. There is an increase in faradaic reactions taken place on the surface which is attributed to the high surface area, more oxygen vacancies, and increased diffusion rate. The highest energy density is obtained to be ~12.68 Wh/kg, and the stability result confirmed that the capacitance retention is ~75 % after 1000 cycles of operation indicating that well optimized CeO2 is a potential candidate as electrode materials for supercapacitor applications due to their fast mutation between Ce4+ to Ce3+ oxidation state.