Office Of Basic Energy Sciences Research Articles

Structure and Electrochemistry of Chromium Substituted Lithium Vanadyl Phosphate for Lithium-Ion Batteries

Lithium vanadyl phosphate (LiVOPO4) is an attractive cathode material for next-generation lithium ion batteries, having the ability to reversibly extract and insert two lithium ions to reach a theoretical capacity of 318 mAh/g. LiVOPO4 also has very high energy density over two voltage plateaus of about 2.5 and 4 V. However, the transition between the two voltage plateaus goes differently upon lithiation and delithiation, causing poor energy efficiency and cycling stability. Here we explore experimentally and by the first-principle calculations, if there is room to improve the efficiency and cyclability of this material with the use of chromium substitution. A series of lithium vanadyl phosphates with varying percentages of chromium from two different chromium sources, chromium oxide and chromium acetate, are synthesized by hydrothermal method. The structure and composition of the products are determined by x-ray diffraction and inductively coupled plasma atomic emission spectroscopy. The effect of chromium substitution on the reaction voltages is compared to the first-principle calculation results and the electrochemical performance as a function of chromium substitution is discussed. This research is supported as part of the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0012583

(Invited) Nanophotonic Structures for Solar Light Harvesting and the Generation of Hot Plasmonic Electrons

Future nanophotonic architectures for optical energy conversion and photocatalysis will require nanostructures with roles that work together cooperatively, such as structures with a large absorption cross section combined with features that enable guiding, propagating, and converting energy. Ultrafast optical responses in nanostructures are potentially important for modulating energy flow and also for characterizing and minimizing energy dissipation pathways in nanophotonic structures. Also, ultrafast extraction of hot plasmonic electrons from metal nanostructures is an important opportunity for increasing efficiency of solar energy conversion and photocatalysis. Efforts to greatly improve the efficiency of hot electron generation through plasmonic metamaterials, and characterization of hot electron dissipation pathways are described. I further describe efforts to induced long-range energy propagation in nanostructures. Nanostructured materials inspired by natural photosynthetic membranes represent an opportunity for efficient and directional energy transport. In natural photosystems, light harvesting complexes can transport excitons to the reaction center core with near unity conversion of absorbed photons to separated charge. A key to this process is the high rate of exciton hopping and the directionality of exciton flow due to an energy level waterfall effect of excitons in complexes as the reaction center core is approached. Efforts to induce similar behavior in biomimetically inspired nanostructures are described. Finally efforts to image exciton flow in light harvesting nanoscale materials are introduced. Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

Evolution of the Cathode-Electrolyte Interface of Li1 - xNi0.8Co0.15Al0.05O2 Electrodes Due to Electrochemical and Thermal Stress

The electrode-electrolyte interfaces (EEIs) play important roles in lithium ion batteries, often determining the capacity retention, safety, and lifetime. The EEI of the positive electrode is far less understood than its negative counterpart. In addition to possible electrolyte oxidation products, layered cathodes often exhibit pronounced surface phase transformations that can also limit the performance of the battery. For example, recent experiments have correlated charge-transfer impedance growth with surface phase transformations at Li1-xNi0.80Co0.15Al0.05O2(NCA) surfaces, which result from surface oxygen loss. [1] Electrolyte reactions with the active material play a role in surface oxygen loss as coating layers [2] and electrolyte additives [3] can mitigate impedance growth and capacity fade. Determining reaction pathways that promote surface oxygen loss is essential to optimizing the selection of coating layers or additives that further improve capacity retention. Here we report on our surface studies of NCA, to examine the evolution of the cathode-electrolyte interface (CEI) for stressed NCA electrodes held at high voltages (≥4.5V). Using a combination of surface sensitive x-ray absorption spectroscopy and x-ray photoelectron spectroscopy, we correlate transition metal reduction with electrolyte decomposition species at the cathode surface. From comparison of NCA electrodes held under various constant voltage conditions, we examine the influence of voltage and temperature on the formation of electrolyte decomposition species. Our work provides insight into possible reaction mechanisms that influence changes of the CEI layer for electrodes under thermal and electrochemical stress. This work was supported as part of NECCES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0012583 [1] S. Sallis et al., App. Phys. Lett. 108 (2016) 263902 [2] I. D. Scott et al., Nano Letts. 11 (2011) 414 [3] R. Wagner et al., Appl. Mater. Interfaces. (2016) 30871 Figure 1

Which LiVOPO4 Phase Works Best for Two Li Cycling?

Vanadyl phosphates show promise as cathode materials in Li-ion batteries due to the ability to hold multiple Li-ions per redox center. Specifically, the V5+/V4+ and V4+/V3+ couples allow for the material to hold up to two Li-ions per vanadium. The great structural diversity of this family, producing seven VOPO4 and three LiVOPO4 polymorphs, raises a question on which of them would work the best as a Li-ion battery cathode. The electrochemical performance of some of the polymorphs was reported in the literature, but the comparison is complicated by differences is materials morphologies, electrode preparation methods, current densities, and voltage windows used. Here we use LiVOPO4-2H2O as the precursor to synthesize all three LiVOPO4 phases: α1 (layered, tetragonal), β (orthorhombic), and ε (triclinic), and compare their electrochemical performances under the same conditions. The transformation between phases and their relative stabilities are studied using x-ray diffraction and differential scanning calorimetry. The role of oxygen partial pressure in phase stability is discussed based on the experimental data and first-principle calculations results. The electrochemical performance of each phase is evaluated using galvanostatic discharge-charge between 1.5 to 4.5 V at various current rates. The lithium diffusion coefficients are calculated using cyclic voltammetry and galvanostatic intermittent titration technique. These tests reveal that all the three phases can work as multi-electron cathodes; the Li transport details specific to each phase are discussed in conjunction with the structures. This research is supported as part of the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0012583.

Insights Towards Mitigated Mn Dissolution through Structure-Sensitive Al2O3 Film Nucleation on LiMn2O4 By Atomic Layer Deposition

Dissolution of transition metal (TM) cations into organic electrolytes is a significant impediment to capacity retention in various lithium ion battery electrode materials. Interfaces engineered via substitutional doping and protective coatings, however, have been demonstrated to be effective techniques to reduce TM dissolution, preventing counterelectrode crossover1–3. In this work, we present an integrated theoretical and experimental approach to gain a molecular level understanding towards the functionality of protective thin films. As a model system, we consider Al2O3 film growth by atomic layer deposition (ALD) on spinel LiMn2O4 (LMO), a cathode material exhibiting the well-documented capacity fade mechanism of Mn dissolution. Using first principles DFT+U calculations in concert with in situ experimental characterization, the mechanisms for Al2O3 ALD film growth by trimethylaluminum (TMA) and H2O half-reactions are evaluated. Using thermodynamically stable low-index surface truncations, as well as stepped defect features4, we identify facile pathways for full demethylation of the TMA precursor on the LMO surface. Trends from microbalance experiments indicate sub-monolayer film coverage for ~10 ALD cycles, wherein film growth is initially slow, but gradually increases until the limit of a fully formed Al2O3 film is reached. DFT calculations suggest that sluggish film growth at the onset is predicated by site blocking from decomposed CH3 groups. An electronic structure descriptor is presented to demonstrate evidence that, in early ALD pulses, Al2O3 preferentially nucleates at sites on LMO that are most susceptible to Mn dissolution. The chemical nature of these relevant defect sites will be discussed further in the context of Mn dissolution through charge disproportionation, with enhanced stability by selective nucleation of the protective films. The unique mechanisms for ALD on LMO lead to modest enhancements in electrochemical performance for only ~1-2 ALD cycles, whereas cycling capabilities reduce with further TMA/H2O pulses in the limit of a fully formed coating on the substrate. This research was supported as part of the Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

(Invited) Tire-Derived Carbon Anodes for Lithium-Ion and Sodium-Ion Batteries

Carbon powders recovered from waste tires are considered as one of the most promising anodes for both lithium-ion and sodium-ion batteries. The tire-derived carbons obtained by pyrolyzing the acid-treated tire at 1100 °C. The carbon interlayer distances for crystalline carbon areas were determined to be 4.7 Å. These values are ideal for lithium and sodium intercalation. When the pyrolysis temperature is increased from 1100 to 1600°C, the capacity of the plateau below 0.2 V increases dramatically and this could help increase the full cell energy density. The 1600°C treated carbon shows a capacity of 203 mAh g-1after 100 cycles with sodium-ion batteries. We will report the current status of the tire-derived carbon powder scale up efforts and its use in energy storage applications. Acknowledgements This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division.

Electrochemical Redox Behavior of β-Li3PS4 lithium-Ion Conducting Solid Electrolyte

Lithium-ion conducting solid electrolytes are a promising alternative to conventional liquid electrolytes for making fire resistant and thus safer Li-ion batteries. Recent improvements in the conductivity of sulfide-based glass/ceramic electrolytes (> 0.1 mS/cm) have prompted further investigation into their material properties and interfacial characteristics [1]. Particularly, β-lithium thiophosphate (β-Li3PS4), owing to its sufficiently high conductivity (~0.2 mS/cm), scalable synthesis route, and favorable bulk mechanical properties, is a potential electrolyte candidate for solid-state Li-ion batteries [2]. Existing issues, however, surround the interface between β-Li3PS4 and conventional 4 V cathodes due to the limited electrochemical stability window of the electrolyte (1.7-2.31 V, theoretical [3]). The resulting solid electrolyte interface poses high impedance resulting in poor rate capability. While oxide-based coatings of cathode active material particles have shown improvement, long term mechanical reliability of the coating is in question [4]. In order to address the interfacial impedance issue with the β-Li3PS4 solid electrolyte, it is important to characterize its redox behavior outside its stable voltage window. We have developed a novel technique based on cyclic voltammetry, which treats the solid electrolyte as an active material electrode and uses internal redox-capable standards (in this case, elemental phosphorus and sulfur) to systematically determine the species makeup of β-Li3PS4 at the β-Li3PS4/carbon interface as a function of the applied potential. Through this technique, we show that even in the absence of active material, β-Li3PS4 undergoes decomposition at the solid electrolyte/carbon interface producing redox active species of phosphorus and sulfur. Further, as the cell voltage is cyclically swept between 0-5 V vs. Li/Li+ and the oxidation states of these species change as a consequence, the result is a constantly changing interfacial composition during typical cell operation. This is unlike in case of liquid electrolytes which decompose into electrochemically irreversible species under normal operating conditions. In addition, via ex-situ XPS surface analysis of the β-Li3PS4/C interface, we have observed the formation of elemental sulfur and P2S5 upon oxidation of β-Li3PS4 solid electrolyte to 5 V vs. Li/Li+, confirming DFT-based theoretical predictions [3]. Formation of elemental sulfur is shown via the developed cyclic voltammetry based technique to be the cause for the apparent reversible cyclability of the sulfide-based solid electrolytes reported in literature [5]. Through our analysis we highlight the dynamic nature of the interface between β-Li3PS4 solid electrolyte and a high voltage material. Our technique may be used to characterize other superconducting sulfide-based solid electrolytes such as Li7P3S11 and Li10GeP2S12. Determining the properties of this redox capable solid-electrolyte/cathode interface and developing methods to mitigate the formation of high impedance species is an essential next step for sulfide-based solid electrolyte research. Acknowledgments We gratefully acknowledge support from the US Department of Energy’s Office of Basic Energy Science for the Chemo-mechanics of Far-From-Equilibrium Interfaces (COFFEI) small group, through award number DE-SC0002633.

Catalysts Facet Orientation and Surface Modifications for Improved Activity of Alcohol Oxidation

Many problems encountered in hydrogen-fuel-cell technology, particularly those of hydrogen storage and distribution, can be circumvented by replacing hydrogen with liquid fuels, such as methanol and ethanol. However, the electrocatalytic oxidation reactions of methanol and ethanol are slow and incomplete even on the best existing Pt-based catalysts, which greatly impeded the wide-spread application of direct alcohol fuel cell (DAFC). Our group demonstrated that one class of surfaces can be very active for the oxidation of methanol and ethanol [1]. These electrocatalysts consist of one Pt monolayer (PtML) under tensile strain when placed on extended or nanoparticle surfaces. Their activity and selectivity can be controlled with Pt-support interaction. Our experimental and DFT studies demonstrated a correlation between the strain induced by PtML-support interaction and the catalytic activity. Significant enhancement in the activity associated with the tensile strain and decreased activity associated with the compressive strain. Most recently, we deposited PtML on Au single crystals and shape-controlled nanocrystals enclosed with different crystallographic facets[1,2], and electrochemical behaviors (Figure 1a) suggested that the deposited PtML possessed facets matching to the underlying Au. Surface structure can determine catalytic properties and a large density of atomic steps on high-index facets is especially desirable for breaking chemical bonds such as C-C bond splitting in ethanol total oxidation. Such property of translating facet-specific features from substrates to the supported PtMLopens new opportunities to enhance catalytic performances. Another approach to improve activity involves modifying PtML surfaces with different co-catalysts. For example, Ru modified PtML/Au showed significantly enhanced activity for methanol oxidation and FTIR studies demonstrated that no adsorbed CO was formed during the reaction. The incorporation of co-catalysts such as Rh, Ir and Sn with PtML shifted onset potential of ethanol oxidation to more negative values (Figure 1b) and promoted a complete oxidation of ethanol to CO2. Details of electrochemical, structural and spectroscopic studies, discussion of reaction mechanisms and possibilities of these findings to resolve the major impediment hindering the development of practical DAFCs and to open new studies of C-C bond splitting in variety of important reactions will be presented in the meeting. Acknowledgements This work was financially supported by the US DOE, Office of Basic Energy Science, Material Science and Engineering Division, Division of Chemical Sciences, Geosciences and Biosciences Division (Contract No. DE-SC0012704).

Water Management in Low Temperature Fuel Cells through in-Operando X-Ray Computed Tomography

For polymer-electrolyte fuel cells (PEFCs) and anion exchange membrane fuel cells (AEMFCs) optimal water management is essential. During start-up and at low operating temperatures, where water is present in a liquid form, it can block reactant delivery to electrocatalyst sites, resulting in significant mass-transport losses, flooding and low fuel cell power densities. Using synchrotron X-ray computed tomography (CT) we have previously shown how water transport properties depend on porous materials morphology and chemical composition, as well as cell compression.1-3 These ex- and in-situ studies isolate specific porous membrane / electrode assembly (MEA) component’s effect on water management (such as micro-porous (MPL) or gas-diffusion layer (GDL)). To understand water transport under operating conditions we use in-operandoX-ray CT studies, where water distribution is observed under various steady-state conditions. In-operando single serpentine channel (1x1 mm) fuel cell testing hardware for synchrotron X-ray CT is used with active area of 1 cm2. Steady-state water generation and removal is observed in PEFCs and AEMFCs for temperature of 30oC with chronoamperometric holds at current densities ranges of 20 – 100 mA/cm2. Furthermore, comparison of water distribution in PGM and PGM-free catalysts for both type of fuel-cells will be presented. In all of these systems water pooling is observed at the component interfaces, indicating the importance of interfaces design. Acknowledgment: The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Evaluation of the Durability of a Metal-Organic Framework Catalyst in High-Temperature Proton Exchange Membrane Fuel Cells (HT-PEMFCs)

A non-pgm Metal Organic Framework (MOF) catalyst was evaluated for durability in the high-temperature environment associated with HT-PEMFCs under various conditions. Due to the higher PGM loading typically required for these systems, it is an ideal candidate for research regarding non-PGM catalysts. However, a common issue regarding non-PGM materials is their lack of durability in the low temperature humidified environment of a PEMFC, and until these issues are resolved, it will continue to provide a hindrance towards mass commercialization. Prior work had demonstrated the high performance of this particular catalyst[1], initially in RDE and low temperature fuel cells, and now in HT-PEMFCs. Membrane Electrode Assemblies (MEAs) were tested at 200˚C using a commercial polybenzimidazole (PBI) membrane, and were evaluated under several durability criteria, including constant voltage testing at various potentials (for demonstration of prolonged use), temperature cycling (to mimic startup/shutdown) and corrosion testing to evaluate losses in these primarily carbon-based materials. Early indications demonstrate a highly stable catalyst, as after nearly 40 hours of non-continuous chronoamperometric testing, the fuel cell demonstrated negligible performance losses at 650mV in air at 2.5bar total pressure. Acknowledgment: The authors gratefully acknowledge the financial support from the Department of Energy-Energy Efficiency and Renewable Energy, Fuel Cell Technology Office under an Incubator grant (DE-EE0006965). Use of the Stanford Synchrotron Radiation Light source, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Use of Beamline 2-2 at SSRL was partially supported by the National Synchrotron Light Source II, Brookhaven National Laboratory, under U.S. Department of Energy Contract No. DE-SC0012704. Use of the beamline 9-BM in Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Analysis of Cathodic Reaction Process of SiCl4 in Ionic Liquids

Electrodeposition of semiconductor materials such as Si with very negative reduction potentials has been attempted in various non-aqueous solvents [1-3]. In particular, since ionic liquids exhibit relatively large electrochemical windows and are applicable under low temperature condition, they are expected to be one of the promising solvents for Si electrodeposition. Several studies have suggested the capability of ionic liquids to electrodeposit Si [4-6]. We also applied trimethylhexylammonium bis(trifluoromethylsulfonyl) imide (TMHATFSI) ionic liquid for the electrodeposition of Si [7-9]. To control this deposition process more precisely, its reaction mechanism should be elucidated further in detail. In the present study, we analyzed the reaction mechanism of SiCl4 during Si electrodeposition in ionic liquids using three approaches; 1) Electrochemical quartz crystal microbalance (EQCM), 2) X-ray reflectivity (XRR), and 3) Density functional theory (DFT) calculation. Electrodeposition of Si was conducted in TMHATFSI at 40 oC, controlled by thermo block. 3 electrodes cell (W.E. : Au, R.E. : Ag/Ag+, C.E. : Pt) was employed for the Si film electrodeposition. During XRR measurement, 2 electrodes cell (W.E. : Au, C.E. : Au) was used at 30 oC, controlled by thin thermo plate. EQCM measurement was carried out in Ar atmosphere, while the mixture of Ar and N2 was introduced into the electrolytic cell during the XRR measurement. The XRR measurement data were analyzed by GenX software. DFT calculation was performed by Gaussian09 package to support the XRR measurements. Results of the EQCM measurements during the cyclic voltammetry indicated a preliminary stage prior to the electrodeposition, in which no mass increase was detected in spite of substantial amount of charge transfer, suggesting the sequential reduction of SiCl4 through Si (III) and Si (II) species over the multiple stages. These were thought to be intermediate state in Si electrodeposition. Such a state was then investigated by using XRR measurement. The intensity of the reflectivity gradually decreased with the progress of the Si electrodeposition. Analyzed results of the XRR measurement indicated that a layer, which is thought to be polymer-like structure of Si containing dimer such as Si2Cl6, would be generated prior to the formation of metallic Si (0) films. This polymer-like structure was also supported by the results of DFT calculation; energy profiles showed that Si-Si bond formation between two SiCl4 molecules was more favorable than that between SiCl4 and Si surface, after SiCl4 received electrons from the surface. These results suggest that the cathodic reaction of SiCl4 proceeds through the formation of intermediate states containing polymer-like structure of Si. We would like to thank Dr. Apurva Mehta (SLAC National Accelerator Laboratory) and Mr. Trevor Petach (Department of Physics, Stanford University) for their kind advices and helps with the experiment. This study was financially supported in part by the Japan Science and Technology Agency (JST) CREST program. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Y. T. acknowledges the Leading Graduate Program in Science and Engineering, Waseda University, from MEXT, Japan.

(Invited) Descriptors, Defects, and DFT for Solid Oxide Fuel Cell Materials

Active oxygen materials that can rapidly transport and exchange oxygen with the environment play a critical role in many existing and developing technologies, e.g., solid oxide fuel cells (SOFCs), gas separation membranes, oxygen sensors, chemical looping devices, and memristors. In particular, reducing the working temperature of SOFCs, which is critical to their increased commercialization, is significantly inhibited by the slow oxygen reduction reaction at the cathode. The steps in the ORR and related oxygen transport are complex enough that it still remains an open challenge how to design improved cathode catalytic activities using either intuition or computational materials design tools. In this presentation we summarize our recent results on using the Oxygen 2p-band (or just “p-band”) as a descriptor for many important properties related to SOFC cathode performance for both perovskite and 214 Ruddlesden-Popper oxides. We demonstrate that the p-band, which is an easy to calculate bulk electronic structure descriptor, correlates with properties that include oxygen vacancy and interstitial defect energies [1, 2], oxygen diffusion coefficients [3, 4], surface exchange coefficients [1, 3], and cathode area specific resistance [1] (e.g., see Figure 1). This descriptor is therefore a powerful tool for active oxide materials design, and we describe its use to search for promising new SOFC cathode materials. The p-band descriptor highlights some of the intriguing differences in trends of defect chemistry and surface exchange behavior between the perovskite and 214 Ruddlesden-Popper phases. Specifically, the dominance of vacancy and interstitial defects, respectfully, in the oxygen exchange and transport in these two classes of materials leads to opposite trends in their behavior with p-band and generally in the behavior with oxygen bond strength and state of oxidation. We show the results of detailed calculations of the defect behavior in 214 Ruddlesden-Popper La2-xSrxMO4+d (M = Co, Ni, Cu) compounds and demonstrate how the crossover in dominant defects with doping can be understood in terms of simple trends in oxidation chemistry. We further demonstrate that the previously identified but somewhat elusive peroxide defects are stable in Ruddlesden-Popper phases over some doping domains and can play a role in the oxygen transport in these materials. Acknowledgement We gratefully acknowledge financial support from the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under award number DE-SC0001284, Department of Energy (DOE), National Energy Technology Laboratory (NETL), Solid State Energy Conversion Alliance (SECA) Core Technology Program (Funding Opportunity Number DEFE0009435), and the National Science Foundation Software Infrastructure for Sustained Innovation (SI2) (award no. 1148011). Computing in this work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by U.S. National Science Foundation with grant number ACI-1053575, and the National Energy Research Scientific Computing Center (NERSC) allocation of the CNMS at ORNL (CNMS2013-292).

A study of the exchangeable protons in the QA site of photosystem II

Plants have developed the only biological system capable of oxidizing water. Through the oxidation of water plants are able to convert light energy into chemical energy. This water oxidation is catalyzed by photosystem II (PSII) at a site called the oxygen‐evolving complex (OEC). The OEC consists of a tetranuclear manganese cluster and is the only known biological system capable of oxidizing water (Blakenship 2001).Removal of the manganese cluster allows for study of the mechanism called photoactivation, a light‐and dark‐dependent process by which the OEC assembles. Further study of this process can provide great detail as to repair of PSII following inhibition (G. Dismukes 2008). Removal of the manganese cluster and associated extrinsic proteins also allows unhindered exploration of electron transfer during photochemical events. Plastoquinone A (QA) and plastoquinone B (QB) are electron carriers found in PSII. Despite sharing the same molecular structure, QA and QB exhibit unique redox properties determined by their protein environment. QA participates only in one‐electron transfers, transiently forming paramagnetic semiquinone QA−•(SQA), whereas QB function as a two‐electron gate. Hydrogen bonding from nearby amino acids residues is believed to be partly responsible for such differences in redox properties due to redistribution of electron density. High‐resolution electron paramagnetic resonance (EPR) spectroscopy has the ability to measure magnetic interactions between unpaired electrons and nearby nuclei and provide information about the strength of these interactions (Rutherford, A. W. 1999).Previous pulsed EPR studies established the formation of the H‐bonds between carbonyl oxygens of the QA−• and an amide nitrogen from the protein backbone, and the amino nitrogen, Nd, of an imidazole (Rutherford; Lakshmi). Two‐dimensional pulsed EPR of the SQA in Mn depleted, CN‐treated PSII at pH 9.8, resolved five pairs of cross‐peaks from different types of protons (Lakshmi). They were assigned to the methyl, β‐methylene, and ring protons of the SQA and two protons of the H‐bonds. Unfortunately, these assignments were not verified by the influence of 1H2O/2H2O exchange on the spectra. As a consequence, the assignment of the couplings is not consistent with the values obtained in the DFT calculations (T.‐J. Lin and P. J. O'Malley 2011). In this work we performed 2D pulsed EPR with the SQA in the PS II samples in 1H2O and 2H2O buffered solution in order to unambiguously identify contribution of the exchangeable protons and to determine corresponding hyperfine couplings. These results form a more supported basis for comparison with the results of theoretical computations.Support or Funding InformationPulsed EPR studies were supported by DE‐FG02‐08ER15960 Grant from Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Sciences, US DOE (S.A.D.), and NCRR/NIH Grants S10‐RR15878 and S10‐RR025438 for pulsed EPR instrumentation. Continuous wave EPR studies were supported by NSF‐MRI CHE‐1229498.

DFT investigation of the effect of spin-orbit coupling on the NMR shifts in paramagnetic solids

RP acknowledges financial support from the People Programme (Marie Curie Ac- tions) of the European Union’s Seventh Framework Pro- gramme (FP7/2007-2013) under REA grant agreement n◦ 317127. Via our membership of the U.K.’s HPC Materials Chemistry Consortium, which is funded by EPSRC (n ◦ EP/L000202), this work made use of the facilities of ARCHER, the U.K.’s national high-performance computing service, which is funded by the Office of Science and Technology through EPSRC’s High End Computing Programme. Research was also carried out at the Center for Functional Nanomaterials, Brookhaven National Lab- oratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract n◦ DE-AC02-98CH10886.

Electrohydrodynamically Assisted Deposition of Efficient Perovskite Photovoltaics

Adv. Mater. Interfaces. 2015, 3, 1500762 Some information was missing in the acknowledgements section. The updated acknowledgements section is: V.C.T. and S.G. would like to acknowledge the funding support from NASA MIRO Grant: NNX15AQ01A. V.T. gratefully acknowledges the support of user proposal (#3192 and #3715) at the Molecular Foundry, Lawrence Berkeley NationalLab, supported by the Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. S.G. would like to acknowledge the National Science Foundation DMR- 1056860. The authors are indebted to Daniel Sun and Wendy L. Queen for XRD characterizations, Dr. Yi Liu and Teresa L. Chen for the fruitful discussion in charge carrier dynamics, and Marisol Prado and Jose Hernandez for the assistance in instrumentation. The authors apologize for any inconvenience caused.

Berichtigung: Programming A Molecular Relay for Ultrasensitive Biodetection through 129Xe NMR

Die Danksagung in dieser Zuschrift muss wie folgt lauten: “This work was supported by NIH R01-GM097478 and CDMRP-LCRP Concept Award no. LC130824. The ITC was purchased via NIH S10-DO016260. We thank Drs. George Furst and Jun Gu for assistance with NMR spectroscopy. We thank Dr. David Christianson for the CAII plasmid and assistance with crystallography. This work is based upon research conducted at the Northeastern Collaborative Access Team beamlines, which are funded by the National Institute of General Medical Sciences from the National Institutes of Health (P41 GM103403). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research, and by the National Institutes of Health, National Institute of General Medical Sciences (including P41GM103393).”

Corrigendum: Programming A Molecular Relay for Ultrasensitive Biodetection through 129Xe NMR

The acknowledgement section in this Communication should read as follows. “This work was supported by NIH R01-GM097478 and CDMRP-LCRP Concept Award no. LC130824. The ITC was purchased via NIH S10-DO016260. We thank Drs. George Furst and Jun Gu for assistance with NMR spectroscopy. We thank Dr. David Christianson for the CAII plasmid and assistance with crystallography. This work is based upon research conducted at the Northeastern Collaborative Access Team beamlines, which are funded by the National Institute of General Medical Sciences from the National Institutes of Health (P41 GM103403). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research, and by the National Institutes of Health, National Institute of General Medical Sciences (including P41GM103393).”

(Invited) In-Situ Study of Electric Double Layer and Ionic Transport at the Solid/Liquid Interface Using Scanning Probe Microscopy

The structure and dynamics of the solid/liquid interface are of fundamental interest for electrochemical capacitors technology. Theories describing the electrical double layer (EDL) have been proposed; yet a full molecular level experimental description is lacking to fully understand its interfacial structures, dynamics and reactivity for both capacitive and pseudocapacitive processes. Due to the characteristic sizes of EDLs, this requires characterization techniques capable of resolving nm length scales. Atomic Force Microscopy (AFM) has recently shown great interest for characterizing the electrochemical storage processes at the nanoscale, where local phenomena at the tip-sample junction can be measured and analyzed. Here, we demonstrate the use of AFM based techniques to understand electrochemical processes at the solid/liquid interfaces. Using force spectroscopy reinforced with molecular dynamics (MD) simulations, we were able to image the EDL in a room temperature ionic liquid (RTIL) on electrified surfaces (1). In the dense layered structure of about 4 nanometers thick at graphite surfaces, single step edges were found to result only in short range changes in the ionic liquid ordering. At the same time, formations of dislocation type topological defects were observed on planar surfaces in a 3D manner. The influence of applied potential on the ions structure showed a complex cation/anion transition together with ionic reorientation, in excellent agreement with MD simulations. State-of-the-art AFM techniques in liquid environment also enabled to spatially resolve pseudocapacitive intercalation pathways. For the first time, we demonstrated how the ionic transport at the solid/liquid interface can be tracked using changes in mechanical properties when cations are inserted from an aqueous solution into 2D layered transition metal carbides (MXenes) (2). For Ti3C2, the insertion of ions results in a strong elastic coupling between MXene layers which results in a significant and measurable change of electrode stiffness. The tracking of spatially resolved elastic properties at the nanoscale allowed identifying fast ionic channels into MXene particles, strongly depending on the intercalated cation radius and charge. As the development of AFM techniques in liquid environment improves, achieving time-resolved tracking of ion storage in energy materials becomes more accessible, and can lead to tuning surface interactions for improved supercapacitor performance. This work was supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, and Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Measurements were performed at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences. References 1) J. M. Black, B. Okatan, G. Feng, P. T. Cummings, S. V. Kalinin, N. Balke. Nano Energy 2015, 15, 737-745. 2) J. Come, Y. Xie, M. Naguib, S. V. Kalinin, Y. Gogotsi, P. R. C. Kent, N. Balke. Advanced Energy Materials 2016, 1502290.

Theoretical Investigation of Atomic-Scale Structure and Energetics of the Metal-Electrolyte Interface

Understanding the complex and inherently multi-scale interface between a charged electrode surface and a fluid electrolyte would inform design of more efficient and less costly electrochemical energy storage and conversion devices. Joint density-functional theory (JDFT) [1] bridges the relevant length-scales by joining a fully ab initio description of the electrode with a highly efficient, yet atomically detailed classical DFT description [2] of the liquid electrolyte structure, avoiding the costly statistical sampling of the liquid required by molecular dynamics calculations. Leveraging JDFT within our framework to treat charged systems in periodic boundary conditions [3], we then predict the voltage-dependent structure and energetics at the interface between a liquid electrolyte and single-crystalline metallic electrodes. We compare the JDFT-predicted interfacial water structure next to a metallic electrode with results obtained from classical and ab initio molecular dynamics simulations. We go on to elucidate the physical origin of the experimentally measured voltage-dependent differential capacitance of an Ag(111) electrode in aqueous electrolytes, examining the crucial role of ion desolvation and plating onto the electrolyte. Finally, we conclude with an exploration of how the choice of cation and anion in the electrolyte affects the atomically-detailed structure of the metal-liquid interface, yielding fundamental insight into processes in electrodeposition and corrosion. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. [1] S.A. Petrosyan et al, Phys. Rev. B 75, 205105 (2007) [2] R. Sundararaman, K. Letchworth-Weaver, T. A. Arias, J. Chem. Phys. 140, 144504 (2014) [3] K. Letchworth-Weaver and T. A. Arias, Phys. Rev. B. 86, 075140 (2012)

Divalent Tin Oxide (SnO) Carbon Composite As Superior Anode in Sodium-Ion Batteries

In the sodium system, perhaps the greatest technical hurdle to overcome is the lack of a high-performance anode material, which has good capacity, is easy to synthesize, safe, non-toxic and is low cost. The opportunity in this area is to develop a new anode material that meets all of these criteria. To date there are a handful of examples in the literature that show the chemistry and battery performance of ambient temperature sodium ion battery anodes. Most of these are various carbon materials, Sn, Sb or SnSb, intermetallics, and sodium titanium oxides, but for one reason or another many of these fall short of all the attributes needed. Our approach is to develop novel oxygen-containing intermetallic nanocomposite anodes with a high surface area/volume ratio that includes a specially tailored cocktail of individual elements and intermetallic phases to enable sequential electrochemical reactions that are designed to reduce the volume expansion while increasing the volumetric capacity. In this case we have been developing a carbon composite consisting of semi-conducting divalent tin oxide (SnO). In the case of a conversion reaction and then sodiation of expelled Sn, then the irreversible capacity will be lower than for SnO2 due to the smaller amount of oxygen in the system. In fact we have synthesized an attractive anode system for sodium-ion batteries (SIBs) that consists of SnO_C made by high-energy ball milling simply carbon with commercially available SnO. Figures 1a and 1b show the voltage profiles of the first two cycles, and the capacity with cycle numbers. The results demonstrate the viability of this material as an anode for SIBs. This material and its detailed in operando X-ray characterization will be discussed at the talk. Figure 1. (a) First two voltage profiles of Na/SnO_C composite SIB anode. Note the low first cycle irreversibility capacity loss; (b) capacity and coulombic efficiency over 35 cycles. Acknowledgements This work is supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Figure 1