bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Keynote) In Situ and Operando Insight into CO2 electroreduction over Size- and Shape-Controlled Nanoparticles and Nanostructured Films
Authors: Roldan Beatriz 
Published: February 2020

Tailoring the chemical reactivity of nanomaterials at the atomic level is one of the most important challenges in electro-catalysis research. In order to achieve this elusive goal, we must first obtain a fundamental understanding of the structural and chemical properties of these complex systems. In addition, the dynamic nature of the nanostructured films and nanoparticle (NP) catalysts and their response to the electrochemical environment must be taken into consideration, since their working state might not be the state in which the catalyst was prepared, but rather a structural and/or chemical isomer that adapted to the particular reaction conditions. To address the complexity of real-world electrocatalysts, a synergistic approach taking advantage of a variety of cutting-edge experimental methods (EC-AFM, AP-XPS, XAFS) has been undertaken here.
This talk will focus on model electrocatalysts (Ag, Cu, Cu-M with M = Zn, Ga, Sn, Co, Ni, Au, Ag) for the electrocatalytic reduction of CO2. We will show how rationally design electrocatalytically active model NPs with narrow size, shape, interparticle distance distributions and tunable oxidation state. Furthermore, we will provide insight into structure/chemical state-reactivity correlations during the electrochemical reduction of CO2 through an in situ and operando approach under reaction conditions. The results are expected to open up new routes for the reutilization of CO2 through its direct selective conversion into valuable chemicals and fuels such as carbon monoxide, methane, ethylene, ethanol, and propanol.
(Invited) Molecular Electrochemical Catalysis of CO2 Reduction with Fe and Co Complexes. from Mechanistic Studies to Highly Selective CO Production and to More Reduced Products
Authors: Robert Marc 
Published: February 2020

Recent attention aroused by the reduction of carbon dioxide has as main objective the production of useful products - the “solar fuels” - in which solar energy would be stored. One route to this goal consists in first converting sunlight energy into electricity, then used to reduce CO2 electrochemically. Conversion of carbon dioxide into carbon monoxide is thus a key-step through the classical dihydrogen-reductive Fischer-Tropsch chemistry. We will describe our work in this field using variously substituted iron tetraphenylporphyrin derivatives, that prove to be the most efficient molecular catalysts of the reduction of CO2 to CO when generated electrochemical at the Fe(0) oxidation state, both in terms of selectivity, durability, overpotential and turnover frequency. These catalysts are remarkably active not only in organic solvent (e.g. DMF) but also in pure water at pH 7. Benchmarking of the catalytic performances, through catalytic Tafel plots, leads to a fair comparison between various reported catalysts and detailed mechanisms were obtained from electrochemical studies. Going further, a complete CO2 conversion electrochemical cell functioning in pure water was also designed. Finally, our recent work and strategy to reduce CO2 beyond CO (for generating hydrocarbons) will be briefly presented.
References
[1] A. Tatin, J. Bonin, M. Robert, ACS Energy Lett.
2016, 1, 1062
[2] S. Drouet, C. Costentin, M. Robert, J-M. Savéant, Science, 2012, 338, 90-94.
[3] C. Costentin, M. Robert, J-M. Savéant, Chem. Soc. Rev., 2013, 42, 2423-2436.
[4] C. Costentin, G. Passard, M. Robert, J-M. Savéant, J. Am. Chem. Soc., 2013, 135, 9023-9031.
[5] C. Costentin, G. Passard, M. Robert, J-M. Savéant, J. Am. Chem. Soc., 2014, 136, 11821-11829.
[6] C. Costentin, M. Robert, J-M. Savéant, A. Tatin, PNAS
2015, 112, 6882-6886.
[7] A. Tatin, C. Cominges, B. Kokoh, C. Costentin, M. Robert, J-M. Savéant, PNAS
2016, 113, 5526-5529.
[8] A. Maurin, M. Robert, J. Am. Chem. Soc.
2016, 138, 2492-2495.
[9] I. Azcarate, C. Costentin, M. Robert, J-M. Savéant, J. Am. Chem. Soc.
2016, 138, 16639-16644.
[10] H. Rao, L. Schmidt, J. Bonin, M. Robert, 2017, in press.
Linear and Non-Linear Impedance Spectroscopy of Composite Gadolinia-Doped Ceria and LSCM Perovskite: Deconvolution of CO2 and H2o Co-Electrolysis
Authors: Witt Jonathan Michael , Stuve Eric M. , Adler Stuart B. 
Published: February 2020

Recent advances in carbon capture create new opportunities for recycling CO2 into liquid fuels to store intermittent electrical energy1. One option is to co-electrolyze CO2 and H2O at high temperature using solid oxide electrolysis cells (SOECs). Although promising, the factors controlling rates of CO2 and H2O reduction in SOECs are not well understood, hampering development2,3. Traditional electrochemical techniques have difficulty resolving the various factors and mechanisms governing CO2 and H2O reduction. This limitation can potentially be overcome through the use of linear and non-linear electrochemical impedance spectroscopy (EIS and NLEIS) in conjunction with dynamic measurement of gas-phase species using mass spectrometry.
In regards to co-electrolysis, mixed ionic electronic conductors (MIEC) have gained interest as alternatives to nickel-yttria stabilized zirconia (Ni-YSZ) because the active region is not limited to the triple phase boundary and they are more stable in reducing environments3. Gadolinia-doped ceria coupled with perovskite La1-xSrxCr1-yMnyO3-δ (GDC-LSCM) has been a particularly well studied MIEC3.
We are currently conducting NLEIS and EIS measurements of CO2 reduction, water reduction, and co-electrolysis reduction experiments on button cells composed of GDC and LSCM as the working electrode with electrolyte YSZ under various temperatures and gas compositions. Gas atmospheres surrounding the cells contain various mixtures of water, CO2, CO, H2, and carrier gas such as Ar or N2. Currently hypothesized mechanisms/models on H2O and CO2 reduction are considered and scrutinized against NLEIS data in order to further reveal the nature of water and CO2 reduction.
References

Graves, C., Ebbesen, S. D., Mogensen, M., & Lackner, K. S. (2011). Sustainable hydrocarbon fuels by recycling CO2 and H2O with renewable or nuclear energy. Renewable and Sustainable Energy Reviews, 15(1), 1–23. https://doi.org/10.1016/j.rser.2010.07.014

Graves, C., Chatzichristodoulou, C., & Mogensen, M. B. (2015). Kinetics of CO/CO2 and H2/H2O reactions at Ni-based and ceria-based solid-oxide-cell electrodes. Faraday Discussions, 182(0), 75–95. https://doi.org/10.1039/C5FD00048C

Valdes-Espinosa, H., Stuve, E. M., & Adler, S. B. (2015). Modeling Water Reduction on 10 Mole% Gadolinia-Doped Ceria (GDC10) Porous Electrodes. ECS Transactions, 66(2), 229–251. https://doi.org/10.1149/06602.0229ecst
Selectivity and Efficiency of Heat Treated Sputter Deposited Thin Films of Copper towards the Carbon Dioxide Electro-reduction
Authors: Permyakova Anastasia A. , Patru Alexandra , Herranz Juan , Schmidt Thomas J. 
Published: February 2020

The CO2 electro-reduction has the potential to store energy from intermittent renewable sources and to produce valuable carbon-neutral fuels or chemical feedstocks. However, current CO2 reduction technologies are challenged by high overpotentials, poor overall faradaic efficiencies (FE) and low selectivity, producing a mixture of carbon monoxide, methane, ethylene, formate, methanol, ethanol, and others. Catalyst performance is a significant contributor to these factors due to multiple proton-coupled electron transfer steps of CO2 electro-reduction reaction [1-3].
Recent experimental studies on Cu electrocatalysts have shown that higher CO2 and CO reduction efficiencies and selectivities towards certain valuable products could be achieved by modifying these metallic electrodes [4, 5]. For example, Cu thin films prepared by electrochemically reduced thermally grown Cu oxide (Cu2O) layers exhibit dramatically improved selectivity towards ethanol at significantly lower potentials (up to 50% FE at -0.35 V vs. RHE) in comparison to non-treated Cu catalysts (»3% FE at -0.35 V vs. RHE) [5].
Herein, inspired by these studies, we will present detailed examination of modified Cu thin film electrodes for CO2 reduction. Cu thin films are fabricated by reactive sputter deposition and subsequently modified by heat treatment varying the temperature and time of exposure. A combination of SEM/EDX, XRD and XPS were used for physico-chemical characterization. Whereas, CO2 electro-reduction products were monitored using in line GC for gas products and capillary GC, IC, NMR for liquid products. The results show that these modified Cu surfaces can improve the selectivity and efficiency of the catalyst.

Acknowledgements

Financial support of this work by the Swiss Competence Center for Energy Research Heat and Electricity Storage, the Competence Center Energy and Mobility, and Swiss Electric Researach and the Swiss Federal Office of Energy are greatly acknowledged.

References

[1] J. Herranz, J. Durst, E. Fabbri, A. Patru, X. Cheng, A.A. Permyakova, T.J. Schmidt, Nano Energy
2016, 29, 4.
[2] J. Durst, A. Rudnev, A. Dutta, Y. Fu, J. Herranz, V. Kaliginedi, A. Kuzume, A.A. Permyakova, Y. Paratcha, P. Broekmann, T.J. Schmidt, Chimia
2015, 12, 69.
[3] Y. Hori, «Electrochemical CO2 reduction on metal electrodes. Modern aspects of electrochemistry», eds C. Vayenas, R. White, M. Gamboa-Aldeco (Springer, New York), 2008, Vol 42, pp 89–189.

[4] Y. Chen, C. W. Li and M. W. Kanan, J. Am.
Chem. Soc. 2012, 134, 19969 – 19972.
[5] C. W. Li, J. Ciston and M. W. Kanan, Nature
2014, 508, 504 – 507.
Implicit Solvation for Electrochemical Interfaces
Authors: Schwarz Kathleen , Letchworth-Weaver Kendra , Sundararaman Ravishankar 
Published: February 2020

Solvation plays a key role in determining the capacitance behavior of the electrochemical interface, yet it presents significant challenges for computational modeling due to its complexity. We have recently demonstrated (doi: 10.1063/1.4976971) that the solvation models currently implemented in density functional theory (DFT) codes such as VASP perform poorly for the capacitance of aqueous metallic interfaces. In this talk, I identify solvation model characteristics that are necessary for capturing the nonlinear capacitance behavior of aqueous metallic interfaces.
Structure and Transport of “Water-in-Salt” Electrolytes from Molecular Dynamics Simulations
Authors: Borodin Oleg , Suo Liumin , Olguin Marco , Cresce Arthur v. , Vatamanu Jenel , Wang Fei , Ren Xiaoming , Dura Joseph A. , Faraone Antonio , Gobet Mallory , Munoz Stephen , Greenbaum Steven , Wang Chunsheng , Xu Kang 
Published: February 2020

Currently used lithium ion batteries for portable electronics utilize flammable and often toxic non-aqueous electrolytes in order to achieve high energy densities. They also require a low humidity manufacturing environment resulting in an increased cost. Aqueous electrolytes have recently emerged as potential intrinsically nonflammable alternatives after their electrochemical stability window was expanded beyond 3.0 V by employing a new class of “Water-in-Salt” electrolytes. In such super-concentrated electrolyte, the decomposition of salt anion occurs preferentially on the anode before hydrogen evolution takes place, creating a kinetic protection against electrochemical decomposition via a dense solid electrolyte interphase (SEI).
In this presentation, results from classical molecular dynamics (MD) simulations using a polarizable APPLE&P force field are analyzed in order to examine in detail the ion transport mechanism in bis(trifluoromethane sulfonyl)imide (LiTFSI-water) “Water-in-Salt” electrolytes (WiSE) for safe, green and low cost aqueous lithium ion batteries. They are complemented by Born Oppenheimer MD simulations of smaller systems that yield similar structural features. Simulations revealed an unusually low activation energy and fast ion transport for highly concentrated solutions even at low temperatures that is quite different from the dramatic increase of the activation energy for conductivity found in traditional battery electrolytes. A high conductivity and lithium transference number in WiSE is attributed to the formation of fast ion transporting pathways that are connected to the unexpected structure of WiSE electrolytes, which was confirmed by small angle neutron scattering experiments (SANS). The ability of MD simulations to describe dynamics of ion and solvent in WiSE electrolytes was further validated via pfg-NMR and conductivity measurements, while IR spectroscopy measurements provide a comprehensive picture of the salt electrolyte aggregation that is coupled with ion transport.
The connection between the double layer structure of WiSE electrolytes and its electrochemical stability will be briefly discussed.
Computational Study of the Effect of Surface-Bound Disulfide on the Oxygen Reduction Reaction
Authors: Allison Thomas C , Tong YuYe 
Published: February 2020

The ability of certain surface-bound species to significantly reduce or prevent activity on catalyst surfaces is well established. However, it was recently discovered that disulfide (S2–) bound to a Pt (111) surface could promote the oxygen reduction reaction (ORR). Despite this important observation, the mechanism by which it takes place remains unclear. As the ORR plays a critical role in areas such energy conversion, understanding some or all of the mechanistic steps in this process should be of great value in producing improved OOR catalysts and in understanding promotion effects of surface-bound species.
In this talk, periodic planewave calculations of the ORR on a Pt(111) catalyst surface with varying coverages of disulfide will be discussed. Comparison of computed and experimental IR spectra of intermediate species will be used to validate the computational methodology. The results of the calculations will be used in a mean-field microkinetic model to better understand the origin of the promotion effect due to the presence of the disulfide.
Density Functional Theory Studies of CO-Tolerant Stabilized Platinum Skin/Platinum Alloy Catalysts for the Hydrogen Oxidation Reaction
Authors: Tryk Donald A. , Yano Hiroshi , Shi Guoyu , Ogihara Yoshiyuki , Iiyama Akihiro , Uchida Hiroyuki 
Published: February 2020

Carbon monoxide is a common contaminant in hydrogen produced by the reformation of natural gas and acts as a poison for platinum-based catalysts in hydrogen anodes in polymer electrolyte fuel cells (PEFCs). CO poisoning can be alleviated through the use of Pt skin-covered Pt alloys including first row transition metals, e.g., Pt-Fe, Pt-Co and Pt-Ni, as well as second row transition metals, e.g., Pt-Ru, on which CO is known to adsorb more weakly than on pure Pt.1 Thus, hydrogen would be able to compete more successfully for adsorption sites. The weakened CO adsorption has usually been explained on the basis of the d-band center being lowered and antibonding orbitals becoming populated. However, our recent density functional theory (DFT) results, together with a range of experimental results, as reported by our group (H. Yano, et al.) separately at this Meeting, suggest that the situation is somewhat more complicated.2-5 In addition, little attention has been paid to the hydrogen oxidation reaction (HOR) itself, which we have found to be enhanced on these surfaces in parallel with experimental work.2,3 Our calculations indicate that the adsorption of H atoms is also weakened, so that the latter can become more mobile on the surface. The largest degree of weakening was found for the Pt-Fe alloy.3 Making use of realistic models for the surfaces, with (110) steps and (111) terraces, we found evidence for a new type of hydrogen spillover mechanism, in which H2 adsorbs at steps, dissociates, and the dissociated H atoms diffuse to (111) terraces.3,4 Finally, the calculations indicate that the Pt skin/Pt alloy structure is more rigid than that of pure Pt, which might be a factor in the enhanced durability of the catalyst under fuel cell operating conditions.5

This work was supported by funds for the “Superlative, Stable, and Scalable Performance Fuel Cells (SPer-FC)” project from the New Energy and Industrial Technology Development Organization (NEDO) of Japan.
References

H. Igarashi, T. Fujino, Y. Zhu, H. Uchida, and M. Watanabe, P
hys. Chem. Chem. Phys. 3, 306 (2001).

G. Y. Shi, H. Yano, D. A. Tryk, M. Watanabe, A. Iiyama, and H. Uchida, Nanoscale
8, 13893 (2016).

G. Y. Shi, H. Yano, D. A. Tryk, A. Iiyama, and H. Uchida, ACS Catal.
7, 267 (2017).

Y. Ogihara, H. Yano, T. Matsumoto, D. A. Tryk, A. Iiyama, and H. Uchida, Catalysts
7, 8 (2017).

G. Y. Shi, et al., to be submitted.

Fig. 1. Adsorption energies for (A) H2 or 2H, (B) CO, and (C) H2O at step edges (triangles) and terraces (squares). In (A), the solid symbols denote dissociated 2H, while the open symbols denote undissociated H2. In all cases except for PtRu, undissociated H2 does not adsorb on the surface, either at step edges or terraces. On pure Pt(221), H2 dissociates spontaneously when close to the surface, while on Pt1AL–PtFe, Pt1AL–PtCo and Pt1AL–PtNi, it “floats” away from the surface.3

Figure 1
Doping Amorphous Ti Oxides to Decrease Oxygen Reduction Rates
Authors: Groenenboom Mitchell C. , Keith John A. 
Published: February 2020

Galvanic corrosion is powerful enough to degrade materials that are individually corrosion resistant. Metal oxidation at an anodic reaction site on the less noble metal is coupled to reduction reactions at a cathodic reaction site on the more noble metal. The oxygen reduction reaction (ORR) is a major controlling reaction for galvanic corrosion in atmospheric conditions.1-2 Thus, inhibiting ORR rates is a chance to inhibit galvanic corrosion. We use Kohn-Sham density functional theory to predict dopants that best inhibit ORR rates on natively formed Ti oxides.
We created an amorphous TiO2 surface model that both agrees with experimental XRD data and predicts an ORR overpotential in good agreement with experimental measurements (exp = 0.45 V, PBE = 0.5 V and HSE06+VASPsol = 0.43 V). By modeling the ORR intermediates adsorbed to metal dopants embedded into our model surface at their most favorable oxidation states, we successfully predicted dopants that have been experimentally verified to reduce ORR currents by up to 77%. PBE predicted overpotentials agree with those predicted by hybrid DFT (HSE06) with VASPsol continuum solvation. Further work studying the potential impact of oxygen vacancies will be discussed.
References
1. Mansfeld, F.; Parry, E. P., Galvanic Corrosion of Bare and Coated Al Alloys Coupled to Stainless Steel 304 or Ti-6Al-4V. Corros. Sci.
1973,
13, 605-621.
2. Zhou, X.; Luo, C.; Hashimoto, T.; Hughes, A. E.; Thompson, G. E., Study of Localized Corrosion in AA2024 Aluminium Alloy Using Electron Tomography. Corros. Sci.
2012,
58, 299-306.
Understanding and Tailoring the Performance of Transition Metal Oxides for the Oxygen Evolution Reaction
Authors: Tripkovic Vladimir , Hansen Heine A. , Garcia Lastra Juan Maria , Vegge Tejs 
Published: February 2020

The oxygen evolution reaction (OER) is a bottleneck in direct solar and electrocatalytic water splitting cells, and rechargeable aqueous metal-air batteries. Improving the cost-efficiency of these devices requires development of efficient and cheap oxygen evolving catalysts. A good catalyst material should fulfil several important criteria: the composition and structure should be stable at conditions of interest, it should be able to conduct electrons from the active site, and it should be sufficiently active to catalyze water oxidation to oxygen. Furthermore, the catalyst should be cheap and non-toxic.
We explore two different oxide classes: pristine and doped perovskite oxides (ABO3, where A is the alkaline earth or lanthanide metal and B the 1st row transition metal) and several MnO2polymorphs. Stability and the electronic conductivity of doped materials are assessed and compared to pristine catalysts by computing formation energies and analyzing the electronic structure of bulk crystals, respectively. After selecting stable dopants, we calculate the relevant surface termination and deduce the reaction overpotential from the energetically most favorable reaction mechanism.
For the perovskite oxides, we identify Fe4+, Co3+(IS), Ni3+ and Mn3+/Mn4+ pairs as electronically conductive species and distinguish among three different electron conduction types: intrinsic conductance (Fe4+ and Ni3+), electron polaron hoping along the Metal-Oxygen-Metal chains (Mn3+/Mn4+) and conduction via oxygen holes in the valence band. Although, the intrinsic stabilities of La perovskites are rather low, they are likely to be the most stable catalysts in open systems because they do not form carbonates. From a combinatorial analysis on La perovskites, we identify the most promising oxygen evolving catalysts.
We find that the OER activity of MnO2 polymorphs reduces in the αMnO2 > βMnO2 > γMnO2 sequence. We pinpoint αMnO2 as the most active catalyst and subsequently investigate whether its performance can be furthered by doping. The electronic conductance is greatly improved by creating Mn3+ sites, i.e. Mn3+/Mn4+ pairs, which is accomplished by intercalating electrolyte ions (e.g. Na+ or K+) inside αMnO2 voids. From catalytic analysis, we identify Pd and Co doped αMnO2 as the most active catalyst for oxygen evolution.
This work was supported by the Horizon 2020 framework, grant number 646186

Figure 1
(Invited) Electrochemical Energy Storage of Magnesium in Hydrated and Anhydrous Tungsten Oxides
Authors: Wang Ruocun , Augustyn Veronica 
Published: February 2020

Transition metal oxides are of interest as cathodes for rechargeable, non-aqueous Mg2+ batteries due to the possibility for high voltage and capacity when paired with a magnesium metal anode. In general, it has been found that Mg2+ storage in oxides is much more sluggish than monovalent cation storage such as Li+ or H+. Several strategies have been proposed to overcome the kinetic activation barrier of Mg2+ storage in oxides, including the use of interlayer structural water and nanostructuring. While hydrated metal oxides such as MnO2 and V2O5 have been investigated, relatively little is known about the exact role of the structural water in such materials during Mg2+ storage. In this study, we utilize a model system of crystalline tungsten oxides with different degrees of hydration (WO3·nH2O, where n = 0, 1, or 2). This materials system allows for an investigation of two different types of structural water: one that is covalently bound to tungsten, and one that is present only in the interlayer. The effect of covalently bound water has not yet been investigated for Mg2+ storage. Using cyclic voltammetry and ex situ Raman spectroscopy and scanning electron microscopy, we find that in these materials, the Mg2+ energy storage mechanism is due to intercalation. Moreover, we find that the interlayer water in WO3·2H2O is not stable in a non-aqueous electrolyte and that the material quickly transforms to WO3·H2O. However, the covalently bound water in WO3·H2O is stable and as a result, this material exhibits faster kinetics than WO3. The improved kinetics come at the expense of the capacity, which decreases by approximately half as compared to the anhydrous material. These results provide additional insights into the benefits and drawbacks to use of hydrated metal oxides for Mg2+ storage.