bluuebunny/crossref_metadata_2025 huggingface dataset:
Activity and Stability of Iron-Based Spinel Oxides for Oxygen Evolution Reaction
Authors: Jiang Wulv , Liu Weiyan , Tang Fei , Gan Lin
Published: February 2020

In order to reduce the overpotential of oxygen evolution reaction (OER) and improve energy utilization efficiency of water splitting, spinel oxides have attracted considerable interests in OER electrocatalysis due to their potentially both high activity and high stability. Inspired from highly active Fe sites identified in Fe-contained (oxy)hydroxides, there are particular interests in developing Fe-based spinel oxides, yet correlations between their surface structures and OER activities still remain elusive. In addition, the electrochemical stability of spinel oxides has not received adequate concerns as usually deemed stable in alkaline solution. Recent studies have shown a substantial metal ion dissolution (e.g. Fe dissolution in Fe-containing metal oxides) during OER electrocatalysis, yet a fundamental insight into the metal dissolution process, its effect on the OER stability, and an efficient way to control the metal dissolution remain largely unaddressed.

Herein, we reveal the atomic and electronic structures (particularly the metal-oxygen hybridization) of a series of Fe-based spinel oxide nanoparticles (XFe2O4, X=Mn2+, Fe2+, Co2+, and Ni2+) by using aberration-corrected scanning transmission electron microscope, electron energy loss near edge spectroscopy, in-situ Raman spectroscopy combined with density functional theory (DFT) calculations. We show that substituting different divalent cations in the octahedral sites results in increasing metal-oxygen hybridization and thereby increasing activity in the order of Mn2+<Fe2+<Co2+<Ni2+, with the most active Ni-Fe spinel oxide even superior to a benchmark IrO2 catalyst. DFT calculations suggest that the divalent cation X2+ in the octahedral sites dominantly contributes to the metal-oxygen hybridization, suggesting that it is the divalent cation rather than the trivalent Fe3+ that constitutes the active site of the Fe-based spinel oxides.

We further compared the electrocatalytic stability of the Fe-based spinel oxide by using combined microscopic and spectroscopic methods by using in-situ electrochemical quartz crystal microbalance (EQCM) and identical-location transmission electron microscopy (IL-TEM). Distinctly different extents of metal dissolution were observed in the four spinel catalysts, showing significant metal dissolution (Mn/Fe) in MnFe2O4 and Fe3O4 whereas much less metal dissolution (Fe) in CoFe2O4 and NiFe2O4. Moreover, the Fe dissolution under potential-dynamic condition in the spinel oxides also shows quite different potential dependences, contributing to their different catalytic stabilities. Based on these results, we further developed a robust strategy to suppress Fe dissolution and thus improve the stability of the Fe-based spinels by intentionally adding Fe ions in the electrolyte.
Rational Design of Perovskite Oxide Nanofibers As Electrocatalysts for Oxygen Evolution Reaction
Authors: Zhao Bote , Liu Meilin
Published: February 2020

Oxygen evolution reaction (OER) is a necessary reaction for several promising energy storage and conversion technologies such as metal-air batteries, reversible fuel cells, water splitting for hydrogen production, and carbon dioxide reduction. Since the kinetics of the four-electron transfer process is notoriously sluggish, the development of highly efficient OER electrocatalysts is urgently needed. In this presentation, we will report our recent progress in design, synthesis, and characterization of perovskite oxides as highly efficient and robust electrocatalysts for OER, including double perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+
δ (PBSCF),[1] single perovskite La0.6Sr0.4Co1–xFexO3–δ
[2] nanofibers, and surface-modified perovskite nanofibers. The remarkable electrocatalytic activity of PBSCF with A/B site co-doping is attributed to the Fe site, as rationalized by theoretical computations and confirmed by experimental measurements. Further, the nanofibers of these materials (with a diameter of ~20 nm) demonstrate a significant enhancement in intrinsic activity while maintaining excellent durability, achieving performance superior to those of the commercial IrO2 catalyst. Moreover, a unique surface-modification strategy has been developed recently, resulting in more than two orders of magnitude enhancement in intrinsic activity of PBSCF nanofibers, which is more than three orders of magnitude higher than that of IrO2.

[1] Zhao, B. T., Zhang, L., Zhen, D. X., Yoo, S., Ding, Y., Chen, D. C., Chen, Y., Zhang, Q. B., Doyle, B., Xiong, X. H., Liu, M. L. A tailored double perovskite nanofiber catalyst enables ultrafast oxygen evolution. Nat. Commun.
8, 14586 (2017).

[2] Zhen, D. X., Zhao, B. T., Shin, H. C., Bu, Y. F., Ding, Y., He, G. H., Liu, M. L. Electrospun porous perovskite La0.6Sr0.4Co1–xFexO3–δ nanoﬁbers for efﬁcient oxygen evolution reaction, Adv. Mater. Interfaces
4, 1700146 (2017).
(Invited) Process Development and Quality Control for Manufacturing of Lithium-Ion-Batteries
Authors: Wohlfahrt-Mehrens Margret , Braunwarth Wolfgang , Kremer Lea Sophie , Scurtu Rares , Memm Michaela , Hoffmann Alice , Roessler Stefan
Published: February 2020

The development of efficient and sustainable low cost manufacturing techniques for the next generation lithium-ion cells with improved energy density is a key technology for industrial success. There is a strong need for further development of energy-efficient, resource and time saving electrode and cell manufacturing processes, which includes the identification of bottleneck factors along the whole production chain and the replacement of environmentally harmful intermediate steps (e.g. replacement of NMP for the cathode processing).

One promising approach to increase both energy density of the cell and process efficiency is the reduction of passive materials in the cell by increasing the mass loading of active material on the electrodes. These thicker electrodes, however, suffer from some drawbacks like lower rate capability, lower mechanical flexibility and reduced adhesion to the current collector. In addition, the mixing and coating process parameters have to be adapted to avoid inhomogeneous binder distribution and mechanical disintegration of particles. The electrochemical and mechanical properties of the electrodes are strongly dependent on the 3D microstructure of the electrode (distribution of carbon black, porosity, distribution of the binder network). Both the mixing strategy during slurry preparation as well as the drying conditions during coating have a strong influence on the mechanical and electrochemical properties of the electrodes, which will be discussed in detail in the presentation. Another approach to optimize electrodes with high areal capacity is the preparation of 3D structured electrodes (e.g. gradient electrodes). We studied the addition of various pore forming additives and the preparation of multilayer electrodes via coating with a dual slot die system.

On the anode side silicon based materials are quite attractive due to high specific capacity and energy. However, practical use of silicon is still limited to low amounts of silicon < 5wt% in commercial cells. Anodes with higher silicon content suffer from low cycling life due to high volume change and electrode swelling. A promising approach to improve the cycling life of silicon based electrodes is the use of alternative 3D structured current collectors in combination with adapted binder systems.

In general, the cell manufacturing of Li-ion batteries requires precision and accuracy and includes a complex process chain with numerous process parameters. Optimized parameters for critical manufacturing steps during cell assembly as drying, slitting, electrolyte filling and formation will be presented and discussed in more detail.
Fabrication of PrBa0.5Sr0.5Co1.5Fe0.5O5+Δ Cathode By Inkjet Printing for High Performance Protonic Ceramic Fuel Cells
Authors: Kang Eun Heui , Han Gwon Deok , Park Jong Seon , Kim Keun Hee , Bae Kiho , Shim Joon Hyung
Published: February 2020

Proton ceramic fuel cells (PCFC) have recently received great attention due to their high output and long-term stability along with hydrogen as well as hydrocarbon fuel in the intermediate temperature region (400-600 ºC) where solid oxide fuel cells do not work properly. The development of a new perovskite cathode such as BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) and PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) was key to the success of high performance PCFCs. Of these materials, PBSCF is considered promising with relatively high two-phase (electron/hole-ion) conductivity and long-term stability. Therefore, the development of a manufacturing method for producing a high quality PBSCF layer is of great interest in the field of ceramic fuel cells. In this study, we have succeeded in fabricating porous PBSCF layers using the inkjet printing method. PBSCF slurry inks for printing have been successfully synthesized in ethanol solutions, satisfying the rheological properties required for inkjet printing. The thickness and pore size of the layers were controlled by the number of prints and color levels of the print image, respectively. To verify the feasibility of this technology, a commercial HP printer was used in manufacturing. As a result, we have confirmed a high output over 0.8 W/cm2 at 600 ºC from our PCFCs with about 10μm-thick BaZr0.2Ce0.6Y0.1Yb0.1O3 (BZCYYb2611) electrolyte. This performance is close to the highest PCFC performance ever reported. In addition, we have confirmed that it maintains its performance even in long-term stability tests of more than 100 hours. Our findings are expected to contribute to the easy and economical production of high performance PCFC components.
Degradation Mitigation of Infiltrated Solid Oxide Fuel Cell Cathodes Via Atomic Layer Deposited Zirconia Overcoats
Authors: Zhang Yubo , Wen Yeting , Huang Kevin , Nicholas Jason D.
Published: February 2020

To reduce Solid Oxide Fuel Cell (SOFC) cathode operating temperatures, solution infiltration has been used to fabricate Nano-Composite Cathodes (NCCs) comprised of nano-sized mixed ionic electronic conducting oxygen exchange catalysts on sintered, micro-porous, ion-conducting scaffolds.1,2 In these cathodes, degradation due to nano-particle coarsening and/or Sr segregation are a major concern.3 Recent studies have suggested that conformal zirconia overcoats several nm thick produced via Atomic Laser Deposition (ALD) can improve the long-term stability of SOFC cathodes. 4

Since, the low ~200oC ALD deposition temperatures do not coarsen the nanoparticle networks in infiltrated cathodes,5 here ZrO2 ALD overcoats of various thickness were deposited onto high=performance 12 vol% La0.6Sr0.4Co0.8Fe0.2O3-x (LSCF) - Gd0.2Ce0.8O2 (GDC) NCCs. Symmetrical cathodes were produced on both sides of dense, ~500 micron thick (Y2O3)0.08(ZrO2)0.92 electrolytes using previously described procedures.1 Then, porous La0.6Sr0.4MnO3 and gold grids were printed on both sides as current collecting layers, and 400oC-700oC Electrochemical Impedance Spectroscopy (EIS) measurements were performed with a push-contact setup to determine the NCC polarization resistance (Rp) from the EIS Nyquist plot x-intercepts. Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS) were also conducted on NCCs as function of overcoat thickness and degradation time at 650oC.

Figure 1 shows that ZrO2 ALD overcoats 1-10 nm in thickness did not significantly alter the 400-700oC LSCF-GDC NCC Rp. However, as shown in the 1000-hour, 650oC, open circuit Rp degradation tests of Figure 2, increased zirconia overcoat thickness resulted in increased performance stability (at least up to 5 nm of ZrO2). Specifically, the degradation dropped from ~31.6 %/khrs for uncoated LSCF-GDC NCCs, to ~28 %/khrs, ~18 %/khrs, and ~11.7 %/khrs with 1, 2, and 5 nm of ZrO2 overcoat, respectively. TEM analysis showed that the ZrO2 overcoat maintained a constant, conformal, target thickness after 1000 hours at 650oC. XPS analyses on 1000-hour, 650oC aged cells showed that zirconia overcoats decreased the Sr/(La+Sr+Co+Fe) ratio at the surface, providing a possible explanation for the reduced degradation rates of LSCF-GDC NCCs containing ZrO2 ALD overcoats.

Figure 1
Epitaxial Cobaltite Catalysts for Oxygen Evolution Reaction
Authors: Gunkel Felix , Weber Moritz L. , Bäumer Christoph , Dittmann Regina , Waser Rainer
Published: February 2020

Epitaxy of complex perovskite oxides has arrived at atomic scale precision. This opens new chances and opportunities to the field of electrolysis and water splitting, where perovskite oxides show

promising catalytic activity for the oxygen evolution reaction (OER). While representing ideal model systems for improving our scientific understanding of atomistic processes and scaling relations during OER, epitaxial heterostructures furthermore give access to atomic band engineering strategies and allow the generation of hybrid materials, which may combine beneficial properties of neighboring materials on the nanoscale. These strategies render novel opportunities to enhance chemical stability and to tune overpotentials of OER-active perovskite materials, not accessible in the bulk. Epitaxial catalysts can therefore play an important role in achieving new breakthroughs and guide lines in the field. Here, we discuss synthesis, electronic transport and electrochemical performance of atomically engineered cobaltite thin films. The epitaxial character of the OER catalysts allows to probe parameters such as electronic transport, evolution of crystal structure, over-potential and lifetime, in well-defined sample geometries and in absence of chemical admixture of binders or current collecting materials. As we reveal, single-crystalline epitaxial catalysts can show perfomance well-comparable to powder catalysts whilst revealing (100) crystallographic facets highly favored for oxygen evolution.

References

Weber & Gunkel, Epitaxial catalysts for oxygen evolution reaction: model systems and beyond, JPhys. Energy just accepted manuscript (2019)

Weber et al., Electrolysis of Water at Atmoically tailored Epitaxial Cobaltite Surfaces, Chemistry of Materials, 31(7), 2337 - 2346 (2019)

Gunkel et al., Ordering and phase control in epitaxial (Pr,Ba)CoO3-δ catalysts for oxygen evolution reaction, ACS Catalysis 8, 7029 (2017)
(Invited) Self-Forming High Energy Density Solid State Rechargeable Battery
Authors: Takeuchi Esther S , Marschilok Amy C. , Takeuchi Kenneth J
Published: February 2020

Solid state batteries are receiving attention due to the possibility of the incorporation of the high energy density of lithium metal coupled with increased safety due to the elimination of flammable organic electrolytes. The lithium/iodine (Li/I2) solid electrolyte battery system has been used successfully for decades as a primary battery to power implantable cardiac pacemakers and has demonstrated an exceptional record of predictability and reliability with high energy density (1536 Wh/L, 560 Wh/kg).

This presentation describes the demonstration of a lithium/iodine rechargeable battery based on the use of LiI rich lithium iodide-(3-hydroxyproprionitrile)2 solid state electrolyte. The battery is first assembled fully discharged using only the solid state electrolyte. The LiI is transformed into the active material where, on charge, lithium metal forms at the negative side of the battery and iodine forms at the positive side. To our knowledge, this is the first demonstration of a rechargeable self-forming solid state lithium battery with electrolyte including LiI(HPN)2. Results on cell formation, cycling, Coulombic efficiency as well as electrochemical impedance spectroscopy will be presented. The results show promise for this conceptual approach for achieving high energy density solid state rechargeable batteries.
Phase Transition of (Pr1-xNdx)2NiO4 Under Reducing Atmospheres
Authors: Wang Yudong , Zhou Xiao-Dong
Published: February 2020

Over the past few years, the use of nickelates as the cathode material in solid oxide fuel cells (SOFCs), has attracted a growing attention due largely to their superior properties to some commercialized perovskite materials. However, the nickelate does go through phase transition at operation temperatures. To improve the stability of Pr2NiO4, Nd was used to substitute Pr to form (Pr1-xNdx)2NiO4 (PNNO) which exhibits an improved phase stability. The phase degradation was found to accelerate when the PNO cathode is under an operation. It is known that the apparent oxygen partial pressure at the cathode/electrolyte interface is lower than that in cathode gas stream. In order to investigate the relationship between the accelerated phase transition and oxygen partial pressure, PNNO oxides are annealed under different PO2 conditions. Multiple post-analyses are carried out on these samples to obtain a quantitative relationship between the phase composition and PO2 during the annealing process.
(Invited) Additive Dual Nano Catalysts to Accelerate Oxygen Reduction Reaction in Cathode of Solid Oxide Fuel Cells
Authors: Chen Yun , Gerdes Kirk , Song Xueyan
Published: February 2020

The sluggish oxygen reduction reaction (ORR) in the cathode is hindering the power density of the solid oxide fuel cells (SOFCs). Infiltration of catalyst into the cathode of SOFCs is promising to accelerate the ORR. However, the degradation associated with the coarsening of infiltrated nano-catalyst is intense. To stabilize the catalyst, a ultra-thin ~5 nm Atomic Layer Deposition (ALD) is employed to coat a dual electrocatalyst into the porous lanthanum strontium manganite (LSM)/yttria-stabilized zirconia (YSZ) cathode. After 504 h operation at 750 °C, the ALD coating resulted in the SOFC peak power density enhancement by ~200 %. Remarkably, the nano-catalysts with ~ 10 nm in dimensions, are uniformly distributing on YSZ grain surface, triple phase boundaries and at LSM/LSM surface grain boundaries after 504 h operation at 750 °C. This study demonstrates an effective approach of stabilizing the nano-sized and minute amount of catalysts for enhancing ORR activity at elevated temperatures.
(Invited) Data Science in High Temperature Electrochemistry: New Tools for Quantitative Characterization
Authors: Mebane David S
Published: February 2020

Most of us are aware from the news -- and from our daily use of internet platforms such as Google and Facebook -- how rapidly data science technology is moving forward. Physical scientists are also interested in harnessing the power of these new tools, but most applications have been limited to 'big data' methods, in which large amounts of experimental and simulation data is mined for clues regarding new materials, processes and reactions. This presentation will show how data science methods and sophisticated models can be used as advanced characterization tools in high-temperature electrochemistry. In particular, the power of model-based Bayesian methods will be demonstrated: relatively small amounts of data yield surprisingly large amounts of information about electrochemical processes. The primary example discussed will be oxygen reduction on porous Sr-doped lanthanum manganate solid oxide fuel cell cathodes, in which impedance data yields accurate measurements of the active width and the distribution of current among bulk and triple-phase boundary pathways.
On the Reliability and Applicability of the Distribution of Relaxation Time Analysis for the Performance of SOFCs
Authors: Wang Yudong , Zhou Xiao-Dong
Published: February 2020

Since the early 1960s, extensive research programs on solid oxide fuel cells (SOFCs) have aimed at the development of high-efficiency techniques for electricity generation. The cell resistance, thus the cell performance, is often measured by using an electrochemical impedance spectroscopy (EIS) based on the response of the cell to alternating current of different frequencies. Distribution of relaxation time (DRT) can be used to analyze impedance data, which yields the dynamic property of an electrochemical system with higher resolution of frequency than EIS. The aim of this work is to address the following problems in the application of DRT: (1) how can we interpret the peaks in DRT functions to the physical or electrochemical processes in the electrodes, and (2) what are the limitations of the use of DRT to analyze SOFC performance.
Selective Silicon Oxide Overlayers for Solar Hydrogen Production By Seawater Electrolysis
Authors: Bhardwaj Amar A. , Esposito Daniel V. , Yip Ngai Yin
Published: February 2020

In PV-electrolysis, solar energy can be used to electrolyze water and produce energy-rich hydrogen (H2), a robust energy storage medium. This hydrogen can be fed into a fuel cell for dispatchable electricity to mitigate the daily intermittency of solar photovoltaic generation, or stored and transported over longer timescales. When used as a precursor for traditional fuels, H2 can bring solar energy to difficult-to-electrify sectors such as transportation.

However, solar hydrogen production consumes water, and many of the world’s most sun-drenched regions, such as arid coastal areas, have a scarcity of freshwater and an abundance of seawater. It would be preferable to perform PV-electrolysis with seawater instead of freshwater, but oxidation of the chloride ions from seawater causes the undesired chlorine evolution reaction (CER). This reaction competes directly with the desired oxygen evolution reaction (OER) at the water-splitting anode. CER possesses a strong kinetic advantage over OER, largely because CER involves the transfer of only 2 electrons, while OER is a 4-electron reaction. As such, CER can outcompete OER in saline electrolyte, greatly reducing the faradaic efficiency of the electrolyzer and producing toxic Cl2 gas that is difficult to dispose of.

This research aims to develop an OER-selective catalyst for seawater electrolysis by encapsulation with overlayers of silicon oxide (SiOx)—an amorphous film 2-20 nm thick that is fully stable in the acidic anodic environment. These overlayers were fabricated on planar thin-film platinum electrocatalysts by spin-coating an overlayer of PDMS precursor and converting the PDMS to SiOx in a UV-ozone treatment. The coated electrocatalysts were tested through electrochemical characterization in a three-electrode cell in an acidic aqueous electrolyte with the salinity of seawater. Through electrochemical tests including linear sweep voltammetry, we have shown SiOx-encapsulated Pt electrocatalysts to achieve greatly reduced CER activity compared to bare Pt, leading to faradaic efficiencies of up to 98%, compared to 2.7% for bare Pt. We see that SiOx selectively rejects transport of Cl- through to the buried catalyst while only slightly reducing maximum OER activity. In addition, SiOx has maintained its OER-selectivity throughout long-term operation in chronoamperometry tests. This research makes possible offshore ‘solar fuels rigs’ that use solar electricity to electrolyze seawater. With a SiOx-coated anode catalyst, the electrolyzer could suppress the competing chlorine evolution reaction and produce sustainable hydrogen at high faradaic efficiency.
(Invited) What Limits Photocatalytic Performance of Metal Oxide Semiconductors?
Authors: Wu Nianqiang
Published: February 2020

Metal oxides are stable and inexpensive as photocatalysts. However, some of metal oxides have relatively large band gap, which limits their ability to absorb sunlight. Other metal oxides have relatively small band gap, allowing for visible-light absorption. However, they still show limited photocatalytic activity. This talk will discuss the major factors that put constraints the separation, migration and lifetime of the photogenerated charge carriers in metal oxides.
(Invited) A “Cocktail” Approach to Effective Passivation of Metal Halide Perovskite Magic Sized Clusters and Quantum Dots Using Novel Planar Molecular Ligands Based on Trivalent Metal Nitrate Coordination Complex
Authors: Zhang Jin Z
Published: February 2020

Metal halide perovskites nanoparticles, including magic sized clusters (MSCs) and perovskite quantum dots (PQDs), exhibit interesting properties promising for emerging applications in energy and photonics. Their stabilization is critical for maintaining their properties and functionalities. One approach to stabilization is to use molecular ligands to passivate their surface. We have discovered a new class of molecular ligands based on trivalent metal nitrate coordination complex that is highly effective in passivating perovskite MSCs or PQDs. We can tune from PQDs to MSCs at will by adjusting the ligand concentration and/or using different ligands, with stronger binding ligands and higher ligand concentration favoring MSCs over PQDs. Both the MSCs and PQDs are highly stable and photoluminescent. Experimental evidence suggests that the planar geometry of the coordination ligands is critical for the outcomes observed. Such ligands should work for both nanoparticles and bulk films, and are likely more desired than linear or “cone-shaped” ligands. The results indicate that the size, shape, charge (including distribution), orientation, and inter-ligand interaction are critical characters affecting the effectiveness of passivation. Furthermore, due to the nature of multiple defects on the MSC or PQD surface, a combination of ligands is required for effective passivation, essentially a “cocktail” approach. We also found that the approach works well for both all inorganic perovskites such as CsPbBr3 as well as organo-metal halide perovskites such as CH3NH3PbBr3. We suggest that the passivation approach developed may be applicable to materials beyond perovskites.
(Invited) Structural Origins of Electronic Properties and Transport States in Halide Perovskites
Authors: Asbury John B.
Published: February 2020

The Asbury group has developed ultrafast infrared spectroscopy techniques to examine electronic processes in materials for photocatalysis and energy harvesting with particular focus on the influence that underlying molecular structures and structural fluctuations have on those processes. This talk will focus on the application of ultrafast infrared spectroscopy to examine the coupling of temperature-dependent lattice fluctuations on electronic transport states in perovskite photovoltaic and photocatalytic materials. The transition of photogenerated charges from free carrier states to large polarons to trapped states is directly observed through the corresponding mid-infrared transitions. Temperature dependent amplitudes of lattice fluctuations are examined through dephasing of vibrational modes and correlated with the nature of the transport states. Ligands attached to surface states provide unique insights into the nature of charge traps and help define pathways for their elimination. The ability to link underlying molecular structures with electronic properties provides unique insights that lead to new design rules in support of continued materials development efforts.
(Invited) Ultrafast Optical Spectroscopy of Plasmonic and Energy Conversion Materials
Authors: Wiederrecht Gary P
Published: February 2020

Ultrafast photoprocesses can play a leading role in determining the efficiency of optically induced catalysis and energy conversion. As a result, a rigorous understanding of the ultrafast radiative and nonradiative processes in relevant materials, such as plasmonic and semiconductor materials, and learning how to amplify the magnitude of the favorable photoprocesses, is important for ultimately improving their performance. For example, in nanostructured plasmonic materials the creation of energetic electrons before thermalization has been proposed for a wide number of applications in optical energy conversion and ultrafast nanophotonics. However, the use of "nonthermal" electrons is primarily limited by both a low generation efficiency and their ultrafast decay. We report experimental and theoretical results on the use of broadband plasmonic nanopatch metasurfaces comprising a gold substrate coupled to silver nanocubes that produce large concentrations of hot electrons, which we measure using transient absorption spectroscopy. The metasurfaces bear resemblance to perfect absorber type structures. We further find evidence for three subpopulations of nonthermal carriers, which we propose are due to localization of energetic carriers near the three band crossings of the Fermi surface. The bimetallic character of the metasurface strongly impacts the physics, with dissipation occurring primarily in the gold whereas the quantum process of hot electron generation takes place in both components. Our calculations show that the choice of geometry and materials is crucial for producing strong ultrafast nonthermal electron components and may help to guide future efforts in this area. Additional ultrafast studies of light harvesting and energy conversion materials are described, particularly in using assemblies of chromophore-functionalized biomolecules and also in perovskite materials. This work was performed, in part, at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, and supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
(Invited) Plasmon-Mediated Catalysis for Sustainable Energy
Authors: KIM Dong Ha
Published: February 2020

Plasmonics have been recognized as a promising platform that may premise the performance enhancement of diverse functions. In the Polymer Nanohybrid Materials at Ewha Womans University, a comprehensive approach for the design and synthesis of multifunctional hybrid nanomaterials has been systematically performed to seek their potential applications as key elements in green nano- and bio-technology. Of the numerous methodologies to achieve these goals, we pay special attention to surface plasmons as a versatile platform, based on which target-oriented properties can be obtained by integrating plasmonic nanostructures into the elements of catalysts. The incorporation of plasmonic properties recently emerged as the advanced strategy for achieving high performance catalysis. The hot carriers and near-field enhancement induced by localized surface plasmon resonance (LSPR) excitation are the key parameters that are responsible for the enhanced performances. Thus, the logical combination of the plasmonic nanostructures and electrocatalytic materials can be an effective strategy for further widening the application of the plasmonic effect. In this presentation we provides a concise overview of the fundamental principles of LSPR, the mechanism of plasmon-enhanced electrocatalysis, alternative design methods of plasmonic nanomaterials for various catalytic systems, and recent progress in plasmon-mediated electrocatalysis for the production of energy, including electrochemical conversion of different feedstock into fuels along with fuel cell catalysis.
(Europe Section Heinz Gerischer Award) The Physical Electrochemistry of Semiconductors
Authors: Lewis Nathan S.
Published: February 2020

Semiconductor photoelectrodes have remarkable differentiating properties from metal electrodes, including photo effects, simultaneous charge transfer from two different bands, different double layer structures, and effects of surface atoms and states. These differences play a profound role in the behavior of semiconductors as electrodes, as first recognized and developed by H. Gerischer in many instances. This presentation will discuss the use of contemporary methods of surface science including operando techniques to directly measure the band edge positions of semiconductor electrodes as proposed by Gerischer, will characterize mechanisms and rates of interfacial charge transfer within the model advanced by Gerischer, and will define the role of surface states as proposed by Gerischer in influencing the development of the double layer of the semiconductor/liquid interface, as well as the influence of monolayers of two-dimensional materials on interfacial energetics and kinetics of charge-transfer processes. The use of semiconductors to produce photo-driven fuel formation will also be described in detail for both oxidative and reductive processes in aqueous and non-aqueous solvents for both simple, one-electron outer sphere redox reactions as well as more complex multi-electron charge transfer processes associated with the direct production of fuels from sunlight.
(Invited) The Materials Genome and Electrochemistry
Authors: Warren James
Published: February 2020

In this presentation I will review the US Materials Genome Initiative and explore the progress made to create the infrastructure required to accelerate the discovery, design, development, and deployment of new materials at a fraction of the cost. The connections to Chemistry and Electrochemistry are in some sense both trivial and profound.
(Invited) Motivating the Collaboratory for High-Throughput Experimental Materials Science and Beyond...
Authors: Trautt Zachary Tim , Green Martin L.
Published: February 2020

A review of roadmapping reports and related documents published over the past decade in materials science and engineering has revealed a set of systemic needs centered around data management as well as emerging needs centered around application of artificial intelligence. In this talk, we will present a thorough of review of past roadmapping reports and related documents. We will then show that our proposed model for the Collaboratory would be an effective model for addressing both the systemic and emerging needs. We will show that the Collaboratory concept is comparable to other entities, which have been successful in other domains.

Figure 1
(Invited) Soft x-Ray Spectroscopy for in Situ and Operando Studies of Energy Conversion Materials
Authors: Heske Clemens
Published: February 2020

Synchrotron-based soft x-ray spectroscopies are powerful techniques to investigate the electronic structure of a variety of material systems. In particular, soft x-ray absorption (XAS) and emission (XES) spectroscopy, as well as their combination resonant inelastic soft x-ray scattering (RIXS), are uniquely suited for the investigation of applied energy conversion devices, including photoelectrochemical devices, thin-film solar cells, and batteries. To aid in the development of such devices, in situ and operando studies are often required to answer the pertinent materials questions, especially for information about surfaces and interfaces. Due to the photon-in-photon-out nature of XAS, XES, and RIXS with soft x-rays, it is, in fact, possible to investigate gaseous and liquid samples as well, making such in situ and operando investigations possible. However, since these spectroscopies and the corresponding synchrotron beamline environment usually involve ultra-high vacuum (UHV) conditions, this requires the development of sophisticated environmental cells, high-efficiency spectrometers, and optimized spectroscopy approaches. For example, the investigated materials are often very sensitive to x-ray radiation, which requires careful and custom-tailored experimental strategies. The presentation will discuss our recent progress in developing the experimental tool chest necessary for such in situ and operando soft x-ray studies, demonstrating how these techniques give insights into the electronic and chemical properties in the solid, liquid, and gas phase, as well as their interfaces.
(Invited) Connecting the Hydrogen Datahub to Scientists and the World
Authors: Gunter Dan , Cai Angela , Danilovic Nemanja , McDaniel Anthony H. , Karnesky Richard
Published: February 2020

The Energy Materials Network (EMN) is a U.S. Department of Energy (DOE) initiative bringing together consortia of national laboratories, industry, and academia towards a common goal of accelerating energy materials development. HydroGEN is an EMN consortium of six DOE national laboratories that is focused on advanced water-splitting materials challenges. In coordination with the other consortia in the EMN, HydroGEN has created a data portal, or DataHUB, based on the free/open source Comprehensive Knowledge Archive Network (CKAN). Core capabilities include storage, discovery, and access of data generated by experimental and simulation studies. From our experience developing user-facing data portals such as the Materials Project and the Hydrogen Effects Database, we know that the usage and utility of data portals can be increased with dedicated development of end-user software tools focused on making data upload, processing, and visualization more powerful and easier to use in scientists’ existing working environments. In addition, we are working to introduce robust dataset revision control, data and metadata value entry validation, and linking of datasets and resources across a project. We hope that these capabilities will enhance the scientific value of the datasets in the HydroGEN DataHUB, and provide a basis for the broader vision of data sharing processes with other EMN and repositories (Citrine, Granta, Materials Project, etc.). This talk will provide an overview of our progress and vision in building these capabilities for the HydroGEN DataHUB.
(Invited) The FC-PAD Consortium: Advancing Fuel Cell Performance and Durability
Authors: Kleen Gregory , Papageorgopoulos Dimitrios C , Weber Adam Z. , Borup Rod L.
Published: February 2020

The Fuel Cell Performance and Durability (FC-PAD) consortium was formed to advance performance and durability of polymer-electrolyte fuel cells (PEFCs) at a pre-competitive level in order to further enable their commercialization. This consortium coordinates national laboratory activities related to fuel-cell performance and durability, provides technical expertise, and harmonizes activities with industrial developers. The consortium serves as a resource that amplifies DOE EERE’s impact by leveraging the core capabilities of several labs in conducting low technology-readiness-level research. Consortium members include Argonne National Laboratory, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, the National Renewable Energy Laboratory, and Oak Ridge National Laboratory.

This consortium incorporates national laboratory investigators with proven experience (developed in prior projects) related to durability, transport, and performance, and combines them into one highly coordinated effort. The consortium is divided into six thrusts: three thrust areas related to components ((1) Electrocatalysts and Supports, (2) Electrode Layers, (3) Ionomers, Gas Diffusion Layers, Bipolar Plates, Interfaces), and three cross-cutting thrust areas ((4) Modeling and Validation, (5) Operando Evaluation: Benchmarking, ASTs, and Contaminants and (6) Component Characterization and Diagnostics.) In addition, four external-lab FC-PAD projects are led by 3M Company, General Motors, United Technologies Research Center, and Vanderbilt University. The core national lab team supports those four projects utilizing national lab capabilities.

The major challenge addressed by this consortium is to develop the knowledge base, design rules, and understanding of underlying phenomena in order to mitigate durability concerns and optimize performance through understanding the science of integration, while simultaneously reducing cost. Current research focuses on achieving high performance and durability in low Pt-loaded PEFCs. FC-PAD has conducted significant analysis of MEA electrode structures, analyzed the structures to understand the performance and durability losses, comprehensively defined the current commercial material baseline materials, and used this information to developed new electrode architectures that are designed to minimize existing electrode layer losses. In this talk, in addition to discussion of the consortium itself, recent results will be highlighted including analysis of electrode layers from inks to structure to conditioning to performance.

Acknowledgments

We want to acknowledge all of the FC-PAD researchers, particularly the Research Thrust Coordinators: Deborah Myers (ANL), K.C. Neyerlin (NREL), Ahmet Kusoglu (LBNL), Rajesh Ahluwalia (ANL), Rangachary Mukundan (LANL), Karren More (ORNL). This work is funded through the DOE FC-PAD Consortium with thanks to DOE EERE FCTO.
(Invited) Duramat: Durable Materials Research to Improve Module Reliability
Authors: Schelhas Laura Theresa , Barnes Teresa M. , Gordon Margaret
Published: February 2020

The Durable Module Materials (DuraMAT) Consortium brings together the national lab and university research infrastructure with the photovoltaic (PV) and supply-chain industries. Our goal is to discover, develop, and de-risk new materials, designs, and accelerated tests for PV modules. DuraMAT is working to establish a central data resource for PV system performance and materials data, a generalized multi-scale and multi-physics/stress model for modules, disruptive accelerated testing protocols, and materials forensics to understand degradation modes in fielded modules. We will provide an overview of the DuraMAT DataHUB, including information on the PV Fleets time series data hub. The DataHUB enables us to access different types of data on PV modules, materials, accelerated testing, and system performance in a single location, along with data analytics tools. The DuraMAT multi-physics model has the ability to model detailed physics, environmental stresses, and material property changes on full-scale modules. Our accelerated testing work focuses on combined accelerated stress testing (C-AST). C-AST enables accelerated testing at the extremes of natural climactic conditions to accelerate field failure modes. We have demonstrated the C-AST approach on mini-modules with different backsheet materials and will present results on two field relevant failures at the conference. C-AST is able to mimic failure modes seen in the field that are not detected in traditional accelerated testing protocols. Finally, the DuraMAT materials forensics effort is our application of traditional national laboratory characterization tools applied to PV modules. These have identified causes for delamination, backsheet degradation, anti-soiling coating functionality and other materials challenges. This kind of foundational knowledge provides guidance for improved module materials.
Measuring Important Properties of EuD4tea: A Material Solution looking for a Problem
Authors: Miller John , Hollerman William A
Published: February 2020

Triboluminescence (TL) is the light emitted from a material when it undergoes fracture. While this unique phenomenon has been known for over 400 years, no theory has yet to predict whether a material will emit TL. However, this has not stopped scientists from coming up with many unique applications. One such application is the use as the active element for impact and damage sensors. Around the turn of the 21stcentury, researchers used TL to patent a sensor capable of discerning the locations of an impact. Their simple design involved coating a structure with a triboluminescent material or creating a composite triboluminescent object. A sensor would then be embedded within the structure or mounted on its surface. Impacts to the structure would produce light, which would be recorded and analyzed to determine the location. In addition, researchers proposed that several different triboluminescent materials could be used and arranged at various locations. The advantage is that when an impact takes place, its location could be determined by the wavelength emitted. For example, by placing two different triboluminescent materials at known distances from the detector, it is possible to determine the approximate location of the impact by measuring the emitted wavelength.

Material property measurements such as triboluminescent yield and the prompt fluorescence decay time are important considerations for any luminescent material. TL emission has to be sufficiently bright, so that the light signal reaching from the point of fracture to the detector, through a fiber optics cable, is strong enough to be detected. The majority of the known triboluminescent materials do not emit light with sufficient intensity to allow detection with compact and inexpensive detectors. A few materials, such as Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA), is bright enough to be seen in daylight and has more than twice the triboluminescent emission yield of zinc sulfide doped with manganese (ZnS:Mn) when subjected to low energy impacts. Research has also shown that adding specific dopants to EuD4TEAcan increase the triboluminescent emission yield by more than a factor of five over ZnS:Mn, which is often used as a basis for comparison.In fact, EuD4TEA has been found to be one of the brightest known TL materials and is a potential candidate for application as an impact sensor.

The purpose of this presentation is to present results from recently completed light yield and prompt fluorescence decay time measurements for EuD4TEA. Emphasis will be placed on current efforts to utilize this data for a variety of potential applications to measure impacts in extreme environments. Basically, EuD4TEA is a material solution looking for a problem.
Narrow Band Emission of Pr3+-Activated Oxide-Oxynitride Pervskites Under Near-UV Lights Controlled By Bandgap Engineering
Authors: Sato Yasushi , Yoshimura Natsumi , Tomita Koji , Kakihana Masato
Published: February 2020

In this study, the photoluminescence of Pr3+-acitvated oxide-oxynitride perovskites, CaMxTa1-xO2+xN1-x (M : Zr and Hf) with the range from 0.0 to 1.0 were investigated. This solid-solution system should be expected that the wavelength at maximum exciation intensity is widely adjusted along with bandgap energy between valence and conduction bands by the control of the O/N and Zr (or Hf) /Ta ratios [1]. Thus, the sharp emission peak from Pr3+ in the solid-solution system can be excited by near-UV or blue lights if the width of bandgap energy is adujusted from 2.8 to 3.2 eV. The solid-solution sample were prepred by polymerizable complex method. The obtained precursors were heat-treated under NH3 gas flow at 900-1100oC. XRD patterns indicated that all the samples were of single phase with orthorombic perovskite structure. In the case of CaZrxTa1-xO2+xN1-x, XRD patterns also show the shift of diffraction peaks to low angle region by increasing with Zr4+ concentaration. The absorption was shifted to high-energy sides with increasing Zr4+ concentration. Especially, the bandgap energy were sucessfully adjusted from 2.7 to 3.2 eV while the x was changed from 0.25 to 0.90 by the control of the Zr4+/Ta5+ and O/N ratios. Furthremore, the solid-solution system showed the intersting photoluminous behavior. The single emission peaks were observed at 612 nm when the bandgap enegries were adjusted at around 3.0 eV for the samples with x from 0.55 to 0.70, Such red emission peak can be assigned to the electron transition between 1D2 and 3H4 levels of Pr3+ ions (Fig. 1). In contrast, when the bandgap energy became larger than 3.0 eV, the PL spectra was gradually changed. Several emission peaks were observed in the range from 490 to 750 nm, which can be assinged as the electron transition between 3P0 to 3H4, 3H5 and 3F2 levels [2]. This behavior should be atributed to the width of the bandgap energy of the host compounds. This work was partially supported by JSPS “KAKENHI” (15K06445) and (18K04714). [Reference] [1] Wu et al., Int. J. Hydrogen Energy, 37 (2012) 13704, [2] Nakamura et al., J. Sol-Gel Sci Technol, 61 (2012) 362.