bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the Role of Ni in Stabilizing the Lithium Rich Cathode Material, Li[Nixli(1-2x)/3Mn(2-x)/3]O2 (0 ≤x≤0.5)
Authors: Hy Sunny , Cheng Ju-Hsiang , Pan Chun-Jern , Chen Jing-Ming , Hwang Bing-Joe 
Published: February 2020

The class of lithium rich cathode material, Li[NixLi(1−2x)/3Mn(2−x)/3]O2 (0≤x≤0.5), shows great potential as a positive electrode for the next generation of high-energy materials for lithium ion batteries. These materials exhibit capacities exceeding 270 and over 300 mAh/g depending on the transition metal incorporated into the material structure[1]. However, over several cycles the material exhibits severe capacity deterioration and voltage decay. [2]. This is attributed to the instability of the material to change from layered to more spinel-like and the separation of the transition metals inducing migration of these transition metals to the bulk[3]. It has been suggested that Ni plays an important role in stabilizing this class of material [4]. In this study we try to elaborate further on the role of the secondary transition metal in stabilizing the structure and its relationship to oxygen by using soft and hard x-ray absorption spectroscopy to probe the electronic and local structural changes at different charged and discharged states for the Li[NixLi(1−2x)/3Mn(2−x)/3]O2 for x=0 ,0.2, and 0.5. The O K-edge, transition metal L II,III- edges were performed both in partial electron yield and fluorescent yield modes that probe the surface and bulk, respectively. The transition metal K-edges were performed to observe the oxidation states. Observation of the O-K edge pre-edge intensity increase can be attributed to the Ni redox couple. Closer examination of the lower and higher photon energy bands reveals a decrease of the 3d versus 4sp intensity bands at the charged state for the oxygen activated stoichiometry, x=0 and x=0.2 indicating hybridization from the reductive coupling mechanism. Mn L II,III-edges (figure) shows that with decreasing Ni content, the changes of the electronic structure from layered to more spinel-like occurs much earlier on and Mn redox couple participation. The results of the soft and hard x-ray absorption spectroscopy suggest the oxidation of oxygen will induce the reduction of Mn with an oxidation state between 3 – 4+ in order to stabilize the distorted structure and maintain the overall charge balance. When a secondary metal, nickel in this case, is incorporated, it will alleviate the changes by reducing in lieu of Mn thus maintaining the original non-distorted 4+ oxidation state.
[1] H. Yu, H. Zhou, The Journal of Physical Chemistry Letters, 4 (2013) 1268-1280.
[2] M. Gu, I. Belharouak, J. Zheng, H. Wu, J. Xiao, A. Genc, K. Amine, S. Thevuthasan, D.R. Baer, J.-G. Zhang, N.D. Browning, J. Liu, C. Wang, ACS Nano, 7 (2012) 760-767.
[3] S. Hy, W.-N. Su, J.-M. Chen, B.-J. Hwang, The Journal of Physical Chemistry C, 116 (2012) 25242-25247.
[4] D. Kim, J.R. Croy, M.M. Thackeray, Electrochemistry Communications, 36 (2013) 103-106.
Silicon-Immobilized Ferrocenyl Monolayers for All-Solid Molecular Charge Storage and Logic
Authors: Fabre Bruno , Zuilhof Han , Hapiot Philippe , Pujari Sidharam , Scheres Luc , Li Yan 
Published: February 2020

The functionalization of technologically relevant conducting surfaces, such as oxide-free, hydrogen-terminated silicon (H-Si), with high-quality ferrocene (Fc) [1] and metal-complexed porphyrin [2] -terminated monolayers has been demonstrated to be a powerful bottom-up approach for the fabrication of electrically addressable charge-storage devices with low-power consumption.
Compared with metalloporphyrins, Fc is a much smaller molecule (average diameter of tetraphenylporphyrin and Fc are about 18 and 6.6 Å, respectively), and consequently is immobilized on silicon with a higher surface coverage, which gives rise to higher charge densities. Indeed, the surface coverages reached for high-quality ferrocenyl monolayers are in the range of (2.0–5.0) ×10-10 mol cm-2. This does not only allow for an extremely fast electron communication between the electroactive groups [3], but also yields charge densities in the range of 20–50 mC cm-2. These values are thus much higher than those measured for Si/SiO2 capacitors currently used in Dynamic Random Access Memories (5–10 mC cm-2).
Very recently, we also demonstrated that tailor-made micrometer-sized patterns of such redox-active monolayers could behave as light-activated molecular memory cells operating at low voltages with unprecedented capacitance performances [4]. The characteristics of this stimuli-responsive device are of great scientific interest for data-processing applications, such as redox-based Boolean logic gates [5]. In our system, the switching of the capacitance upon light irradiation that is observed only at a certain electrical potential constitutes the principle of all-solid two-input AND logic gate without the need of chemical inputs in solution. Such performances can be ascribed to the judicious combination between a photoswitchable conducting/insulating silicon substrate and high-quality microstamped redox-active assemblies.
[1] Fabre, B. Acc. Chem. Res.
2010, 43, 1509–1518.
[2] Lindsey, J. S.; Bocian, D. F. Acc. Chem. Res.
2011, 44, 638–650.
[3] a) Hauquier, F.; Ghilane, J.; Fabre, B.; Hapiot, P. J. Am. Chem. Soc.
2008, 130, 2748–2749. b) Zigah, D.; Herrier, C.; Scheres, L.; Giesbers, M.; Fabre, B.; Hapiot, P.; Zuilhof, H. Angew. Chem. Int. Ed.
2010, 49, 3157–3160.
[4] Fabre, B.; Li, Y.; Scheres, L.; Pujari, S. P.; Zuilhof, H. Angew. Chem. Int. Ed.
2013, 52, 12024-12027.
[5] de Ruiter, G.; van der Boom, M. E. Acc. Chem. Res.
2011, 44, 563–573.
Nonlinear Vibrational Study of Solvent Adsorption on the Cathode Surface of Li-Ion Batteries
Authors: Ye Shen , Yu Le , Liu Huijin , Qiao Yu , Osawa Masatoshi , Kuwata Naoaki , Kawamura Junichi 
Published: February 2020

To improve the performance of Li-ion batteries, it is important to understand the structures on the electrode/solution interface. In the present study, a surface sensitive nonlinear vibrational spectroscopic technique, sum frequency generation (SFG),1 was employed to evaluate the molecular structures of the solvent adsorption at the LiCoO2 cathode surface of the Li-ion battery, rather than those of the solvent in the bulk solution obtained by previous studies.
A LiCoO2 thin film was deposited on the CaF2 substrate surface. A broadband SFG system using a tunable infrared pulse (2.5~10mm) and a visible pulse (800nm) was used to characterize LiCoO2 surface in contact with electrolyte solutions consist of carbonate solvents, such as ethylene carbonate (EC), propylene carbonates (PC), diethyl carbonate (DEC) and dimethyl carbonate (DMC).2,3

Figure 1a shows the sps-polarized SFG spectrum at the LiCoO2 contacting with EC (middle panel, circles) and the fitting result (solid trace) in the infrared frequency region between 1700 and 1850 cm−1. As SFG does not occur in a homogenous bulk solution with inversion symmetry, the present result suggests that the EC molecules align on the LiCoO2 surface with a certain structure. The bottom panels are deconvoluted bands for the SFG spectrum. The upward and downward peaks represent the modes with reversed orientations as the schematic model shown in inset. These modes optically interfere with nonresonant signal cNR
(2) as well as themselves, generating constructive (upward) and destructive (downward) peaks depending on the adsorption geometry of the molecules. The top panel in Fig. 1a shows SFG spectrum after removing contribution from cNR
(2). Based on the spectral analyses, two adsorption geometries of EC molecules on LiCoO2 surface have been observed by the present SFG measurement, by pointing the C=O groups away from or towards the electrode surface, respectively.
Solvent adsorption has also been investigated in the other solvent solvents or their mixtures. Figure 1b shows the SFG spectra of different carbonate solutions after removal of cNR
(2). It is found that the SFG spectra of the mixed solvents containing EC molecule are quite similar to that of EC solvent. This implies that the preferential adsorption of EC molecules on the LiCoO2 surface compared to the linear carbonates of DEC and DMC, with a largely different molecular proportion from that in the mixed solution bulk.3 The present results is expected be useful to understand the initial stage for the solid electrolyte interphase (SEI) formation on the cathode surface.

References

[1] Shen, Y. R. The Principles of Nonlinear Optics; Wiley: N. Y., 1984; [2] Liu, H.; Tong, Y.; Kuwata, N.; Osawa, M.; Kawamura, J.; Ye, S. J. Phys. Chem. C
2009, 113, 20531. [3] Yu, L.; Liu, H. J.; Wang, Y.; Kuwata, N.; Osawa, M.; Kawamura, J.; Ye, S. Angew. Chem. Int. Ed.
2013, 52, 5753.
Oxygen Reduction for Fuel Cells: Mechanistic Studies and the Design of New Catalysts
Authors: Gewirth Andrew , Barile Christopher , Tse Edmund , Hoang Thao 
Published: February 2020

In this talk, we discuss aspects of our work related to the structure and reactivity of electrode surfaces. We report on our efforts directed at establishing the mechanism of oxygen and peroxide reduction on many different metal surfaces.
First, we evaluate Pt-Pt bond strains developing during the oxygen reduction reaction (ORR) as determined by in situ EXAFS measurements obtained with and without the presence of O2 The change in Pt-Pt bond distance in carbon-supported nanoclusters under O2 is found to be a maximum of 0.23 (±0.15) % to 0.40 (±0.20) % larger than under a N2 atmosphere. The Pt-Pt surface bond strains are discernible at macroscopic scales in cantilever-based bending measurements of Pt thin films under O2 and Ar over the same potential range. EXAFS - measured Pt-Pt bond strains correspond to a stress thickness and are well matched to the experimentally determined values obtained using the cantilever bending method. The electrochemical stress method is useful in evaluating reactivity in other contexts, such as the oxygen evolution reaction (OER).
The understanding derived from the mechanistic work provides directions for synthesis of advanced catalysts for oxygen reduction. In particular, we have synthesized a series of bio-insipired metal coordination polymers exhibiting oxygen reduction activity. Complexes exhibit modest activity in acid, but have good activity in base where the per metal activity at maximum power is greater than that afforded by Pt. Extension of our initial synthetic work shows that a µ-η1-η1 motif for oxygen coordination gives a lower overpotential relative to the more structurally defined µ-η2-η2 geometry, probably because dioxygen coordinated in the former way is more susceptible to nucleophilic attack. Recent efforts directed at mimicking the trinuclear site in the multicopper oxidases will be described.
Finally, we use the catalyst motif developed for ORR studies in a novel proton transfer switch, the operation of which will be described.
Theoretical and Experimental Studies on Electrocatalytic Activities of Boron Nitride
Authors: Uosaki Kohei , Elumalai Ganesan , Noguchi Hidenori , Masuda Takuya , Lyalin Andrey , Nakayama Akira , Taketsugu Tetsuya 
Published: February 2020

Oxygen reduction reaction (ORR) is one of the most important processes in fuel cells as well as in biological system. Pt based electrocatalyst is the most prominent ORR catalyst showing low over potential. Major challenges to commercialize the Pt based electrocatalyst are its high cost, less abundance, and still sluggish kinetics. These problems can be addressed by using metal-free carbon materials doped with various elements such as N and B. N- and B-doped carbon materials have been demonstrated to be effective metal free ORR catalyst. Therefore, one may expect that the consecutive substitution of carbon atoms in graphene by B- and N-atoms will result in an increase of ORR activity. In extreme case, if all the carbon atoms in graphene are substituted by B- and N-atoms, hexagonal boron nitride (h-BN) monolayer, which is an insulator with a wide band gap (˜5.8eV), can be obtained. Theoretical investigations show that atomically thin h-BN becomes semiconducting if some defects are introduced or it is placed on metal substrates and may acts as electrocatalyst for ORR.1, 2 Here, we studied the electrocatalytic behavior of BN of several shapes such as nanotube and nanosheets (BNNS) supported on Au toward ORR by using typical three electrode rotating disk electrode (RDE) in O2 saturated 0.5M H2SO4solution. The overpotential for ORR at Au electrode was reduced in all cases, confirming the electrocatalytic activity of BN, but the most significant effect was observed when BNNS was used as an electrocatalyst where ca. 280 mV reduction of overpotential was achieved.
References
1. A. Lyalin, A. Nakayama, K. Uosaki, and T. Taketsugu, Phys. Chem. Chem. Phys., 15, 2809-2820 (2013) .
2. A. Lyalin, A. Nakayama, K. Uosaki, and T. Taketsugu, J. Phys. Chem. C., 117, 21359-21370 (2013).
Bio-Inspired Electrocatalysis of Oxygen Reduction
Authors: Chlistunoff Jerzy , Sansiñena José-María 
Published: February 2020

Polymer electrolyte fuel cells (PEFCs) are clean power sources, where a fuel is “burned” by means of two electrocatalytic reactions occurring simultaneously on the anode (fuel oxidation) and the cathode (oxygen reduction reaction, ORR) of the cell. Platinum is the most frequently used cathode catalyst, but its world resources are limited and the platinum market is volatile. These factors virtually prevent commercialization of PEFCs for transportation purposes.
In biological environments, oxygen reduction is catalyzed by enzymes and some enzymatic oxygen reduction catalysts, e.g., copper laccase exhibit the catalytic activity superior to that of platinum.1While practical application of copper laccase is not possible due to temperature, pH, and other limitations, its excellent catalytic activity demonstrates that it is possible to develop non-precious metal based ORR electrocatalysts with higher activities than Pt.
It is well known that the biological function and activity of heme proteins, which contain Fe coordinated by a porphyrin ring, can be modified through axial coordination of the metal center. These phenomena have become a foundation of our approach to create an effective bio-inspired oxygen reduction catalyst. As opposed to copper laccase, porphyrin based ORR catalysts exhibit quite reasonable stability in strongly acidic environments, such as those in PEFCs. In our talk we will present new results in our recent study on the effects of axial coordination of the iron center on oxygen reduction catalysis by selected iron porphyrins.2Special emphasis will be placed on the correlations between redox and electronic properties of the porphyrins determined using spectroelectrochemical techniques (Fig. 1) and their catalytic activity in ORR.

Acknowledgements

The financial support from the University of California is gratefully acknowledged.

References

1) H. Schweiger, E. Vayner, and A. B. Anderson, Electrochemical and Solid-State Letters, 8(11) A585-A587, 2005
2) J. Chlistunoff, J.-M. Sansiñena, Effects of Axial Ligation and Electron Donors on Oxygen Reduction Catalysis by Metalloporphyrins, 224th ECS Meeting, San Francisco, CA, 10/27/2013-11/01/2013
Characterization and Functional Improvements of Roll-to-Roll Manufactured Biofuel Cells
Authors: Tuurala Saara Anniina 
Published: February 2020

A power source integrated with printed electronics could have a remarkable market potential in several mass-marketed consumer products, e.g. as package integrated functionalities or as part of diagnostic devices. One important requirement is that the power source should be biodegradable or possible to incinerate with normal household waste. This demand is not easily met by traditional battery technology. In addition, the material costs of the power source should be reasonable, should not significantly increase the price of the product, and the cells should be made from roll-to-roll (R2R) in a cost effective way.
Enzymatic biobatteries are a potential alternative to traditional batteries for low power applications. Due to the use of enzymes as catalysts and harmless organic fuels, biobatteries are non-toxic, disposable and renewable. Hence, they have potential to be developed to meet the demands that were addressed before.
In the past years we have studied printing of enzymatic layers, their electrochemical performance, functionality, and stability [1-5]. Mass manufacturing of printed enzymatic electrodes was presented in 2012 by Smolander et al. [6]. We demonstrated R2R processability of biologically active materials and the manufacturing of anodic and cathodic layers by rotary screen printing using VTT’s ROKO pilot scale printing line. The R2R manufacturing was successful and functional enzymatic power sources were constructed using these electrodes.
The characterization of the bio power sources indicated two main challenges: stability of the electrodes and moisture control of the power source. In this presentation the stability of the electrodes will be presented as well as improvements of the cell performance by adjusting the ink and activation electrolyte, as well as running conditions. The running life time was increased by adding moisture absorbing material into the power source. After these various optimization procedures app. 1.5 fold increase in the maximum power density and app. 4 fold increase in the energy output was achieved.

Acknowledgments

The support by Tekes, the Finnish Funding Agency for Technology and Innovation (co-funded by industrial companies) is acknowledged.
References
[1] M. Smolander et al., Enzyme and Microbial Technology 43 (2008) 93–102
[2] S. Tuurala et al., ECS Transactions, 25 (33) 1-10 (2010)
[3] P. Jenksins et al., Bioelectrochemistry 87 (2012) 172-177
[4] P. Jenkins et al., Enzyme and Microbial Technology 50 (2012) 181– 187
[5] S. Tuurala et al., Electroanalysis 2012, 24, No. 2, 229 – 238
[6] M. Smolander et al., Abstract #1453, 221st ECS Meeting, 2012
Functional Interfaces for Biomimetic Energy Harvesting: CNT-DNA Matrix for Enzyme Assembly
Authors: Hjelm Rachel M , Garcia Kristen , Babanova Sofia , Artyushkova Kateryna , Banta Scott , Atanassov Plamen 
Published: February 2020

The development of 3D structures exploring the properties of nano-materials and biological molecules allows us to mimic natural metabolic processes such as Krebs or Calvin cycle by creating “artificial” metabolic pathways called metabolons. The utilization of metabolons in biomimetic energy-harvesting systems leads to increased fuel oxidation and as a result increased Columbic efficiency. The specific order and minimized distance between the enzymes from those metabolons are the main reasons for subsequent and more effective fuel consumption.
In this study a complex carbon nanotubes (CNTs) – DNA matrix for specific enzyme immobilization was created. It composed of “brush” type aligned CNTs covalently attached on electrochemically modified gold surface. This forest like CNTs structure was used as a substrate for the development of a DNA scaffold. This DNA scaffold had a designed sequence that allows strong attachment of DNA to the CNTs surface by wrapping the nanotubes through pi-pi stacking and at the same time has a unique nine base pair motif that was further hybridized. The hybridized part of the DNA was used to specifically attach zinc finger (Znf268) that was genetically fused to small laccase (SLAC).
Zinc fingers are small protein structural motifs that can recognize dsDNA and specifically bind to it. We used this property to control the SLAC immobilization by fusing the Znf268 to the enzyme and attaching it to the CNTs-DNA scaffold (Fig. 1). Due to the specific interactions of zinc fingers with DNA we will be able to immobilize enzymes in particular order and distance creating metabolons.
Figure 2 shows Atomic Force Microscopy (AFM) images of the gold surface at the different stages of its modification to the creation of the CNTs forest. The modification procedures were also confirmed with x-ray photoelectron spectroscopy (XPS).
To prove the concept we used SLAC, which is an enzyme from the family of well-known multi-copper oxidases that are able to reduce oxygen and form water [1]. The enzyme was immobilized by the described approach and characterized by XPS (Fig. 3). The presence of copper in the XPS spectrum unambiguously proofs the success of the immobilization procedure. The developed herein approach for specific enzyme immobilization can be applied for all types of enzymes for the development of bio-cathodes as well as bio-anodes in the design of energy-harvesting systems.
The developed herein approach for specific enzyme immobilization can be applied for all types of enzymes for the development of bio-cathodes as well as bio-anodes in the design of energy-harvesting systems.
[1] Szilvay, G., S. Brocato, D. Ivnitski, C. Li, P. De La Iglesia, C. Lau, E. Chi, M. Werner-Washburne, S. Banta P. Atanassov Chem. Commun., 2011, 47, 7464–7466.
Heterogeneous Proton Transfer As an Explanation for the Unusually Thick Cyclic Voltammograms and Unusually Small Second Redox Wave of Para-Quinones in Aprotic Solvents
Authors: Staley Patrick Andrew , Smith Diane K. 
Published: February 2020

Quinones are well-known to undergo two reversible reductions at glassy carbon electrodes in aprotic solvents, first to a radical anion and then to a dianion, eq 1. Despite 50+ years of voltammetric investigation of this chemistry, two unusual features of quinone voltammetry—that the second redox wave is smaller than the first, and that the area between the two waves is thicker than CV simulations say it should be—was typically ignored until Gupta and Linschitz made note of the difference in height of the redox waves in 1997.1 The current explanation for the unequal wave heights, advanced by Macías-Ruvalcaba and Evans in 2010,2 is that some of the radical anion is trapped in the form of a pi dimer in solution. Macias-Ruvalcaba and Evans hypothesize that this dimer can be reduced at the same potential as the monomer radical anion, but only by 1 e- per dimer, resulting in smaller current than expected. There currently is no explanation in the literature for the thickness between the two waves.
In this study, concentration dependence of the CVs of differently substituted quinones showed that radical dimerization cannot be a general explanation for the small second redox wave. In some cases the thickness between the waves appears as its own quasi-reversible wave. Addition of phenols to a quinone solution produces a quasi-reversible wave at the same potential due to hydrogen bonding to the radical anion. The McCreery lab showed that oxide content of the surface of glassy carbon can change its chemistry through the presence of functional groups such as phenols.3 In low concentration duroquinone studies, different surface treatments show that with higher oxide content a new wave grows in that is at the same potential as the wave seen in a 1:1 addition of naphthol to the quinone redox system. This indicates that the odd thickness in quinone CV’s may be due to hydrogen bonding of the quinones to phenolic groups on the glassy carbon surface followed by proton transfer.
REFERENCES
1. Gupta, J. ;Linschitz, H. Hydrogen Bonding and Protonation Effects in Electrochemistry of
Quinones in Aprotic Solvents. J. Am. Chem. Soc., 1997, 119(27), 6384-6391.
2. Macías-Ruvalcaba, N.; Evans, D. Association Reactions of the Anion Radicals of Some
Hydroxyquinones: Evidence for the Formation of π and σ–Dimers As Well As a Neutral-Anion
Radical Complex. J. Phys. Chem. C, 2010, 114(2), 1285-1292.
3. Kuo, T.; McCreery, R.L. Surface Chemistry and Electron-Transfer Kinetics of Hydrogen-Modified Glassy Carbon Electrodes. Anal. Chem. 1999, 71, 1553-1560.