bluuebunny/crossref_metadata_2025 huggingface dataset:
Compositional Variations in Porous Anodic Oxides Formed on Fe(100), Fe(110) and Fe(111) Single Crystals
Authors: Kowalski Damian , Fadillah Laras , Aoki Yoshitaka , Habazaki Hiroki
Published: May 2020

Anodizing is a high voltage electrochemical conversion process that forms barrier-type oxide layers or self-organized nanoporous/nanotubular structures. So far, alumina-like nanopores and titania-like nanotubes could be successfully synthesized on many valve metals and alloys. Recently, anodizing become possible for base metals such as polycrystalline iron and its alloys. The challenge in anodizing of iron lies in the proper control of corrosion/passivity, which can be successfully realized in organic electrolytes containing small amount of water.1-3 Anodic nanotubes and anodic nanopores may be formed on polycrystalline iron depending on electrochemical conditions adjusted in anodizing protocol. The polycrystalline iron is typically composed of the grains having the size of 2-10 µm. The kinetics of metal oxidation as well as oxygen evolution reaction, which is typically observed upon iron anodizing, may depend on the iron facet exposed to the electrolyte. In order to evaluate the dependence of the crystallographic orientation on the formed anodic film structure we investigated anodizing process on iron single crystals, namely Fe(100), Fe(110) and Fe(111). The compositional differences for porous films formed on single crystals were analyzed by means of by high resolution electron microscopy EDS elemental mapping.

References:

1. H. Habazaki, Y. Konno, Y. Aoki, P. Skeldon and G. E. Thompson, Journal of Physical Chemistry C, 2010, 114, 18853-18859.

2. Y. Konno, E. Tsuji, P. Skeldon, G. E. Thompson and H. Habazaki, J. Solid State Electrochem., 2012, 16, 3887-3896.

3. K. Shahzad, D. Kowalski, C. Y. Zhu, Y. Aoki and H. Habazaki, ChemElectroChem, 2018, 5, 610-618

Figure 1 Bright field TEM micrograph for FIB cross-section of anodic film formed at 100V on polycrystalline iron in ethylene glycol electrolyte containing 1.5M H2O and 0.1M NH4F. The corresponding EDS maps show the elemental distribution of oxygen (green) and superimposed fluorine (red) and oxygen (green).

Figure 1
(Invited) Advanced Inorganic and Polymer Nanocomposite Materials for Fuel Cell Applications
Authors: Cavaliere Sara , Zaton Marta , Jiménez-Morales Ignacio , Ercolano Giorgio , Farina Filippo , Jones Deborah J. , Rozière Jacques
Published: May 2020

The widespread adoption of clean energy converters such as proton exchange membrane fuel cells (PEMFC) is mainly hindered by the degradation of their component materials over time. To overcome this issue, our approach is based on the preparation of nanocomposite materials based on inorganic and polymer nanofibers with specific structures and improved properties. The size and morphology of the fibres and the macroporous architecture of the corresponding webs may bring improved mass transport and mechanical properties, with beneficial effects on the performance and lifetime of the resulting membrane-electrode assemblies (MEAs).

Among the methods for generating nanostructures, electrospinning is a top-down approach with the advantages of simplicity, high yield, low cost, high degree of reproducibility and ease to scale-up from an industrial perspective. The versatility of the technique allowed its application to all stages of the preparation of PEMWE materials, from electrolyte membranes to electrodes.

Polymer and inorganic fibre networks obtained by electrospinning are used to prepare reinforced membranes [1, 2]. This reinforcement, further intensified by ionic interactions between the fibres and the ionomer, extends the MEA lifetime and enables the fabrication of thinner membranes improving the PEMFC performance by lowering the electrical resistance.

Hierarchical structuring of electrodes was achieved using nanofibre catalyst supports and the deposition of catalyst nanoparticles, thin films or active sites on them. With this strategy we can prepare corrosion resistant supports including metal oxides doped with a range of aliovalent ions, with extended durability and high electrical conductivity [3]. A range of deposition techniques including Ni and Cu galvanostatic displacement, high overpotential pulsed Pt electrodeposition [4-6] and atomic layer deposition are investigated to prepare highly active ultra-low loaded electrodes.

This association of deposition techniques opens up a broad range of opportunities for tuning materials composition and architecture to develop and upscale a new generation of PEMFC cores.

References

[1] M. Zatoń, S. Cavaliere, D. J. Jones, J. Rozière, in Handbook of Nanofibers, Springer Nature Switzerland AG 2019
, 979-1015.

[2] S. Giancola, M. Zatoń, A. Reyes-Carmona, M. Dupont, A. Donnadio, S. Cavaliere, J. Rozière, D. J. Jones, J. Membr.
Sci.
2019, 570-571, 69-76.

[3] I. Jiménez-Morales, S. Cavaliere, M. Dupont, D. Jones, J. Rozière, Sust. Energy & Fuels, 2019, 3, 1526 -1535.

[4] G. Ercolano, F. Farina, S. Cavaliere, D. J. Jones and J. Rozière, J. Mater. Chem. A, 2017, 5, 3974-3980.

[5] M. A. Alpuche-Aviles, F. Farina, G. Ercolano, P. Subedi, S. Cavaliere, D. J. Jones, J. Rozière, Nanomaterials
2018, 8, 668.

[6] G. Ercolano, F. Farina, L. Stievano, D. J. Jones, J. Rozière, S. Cavaliere, Catal. Sci. Technol., 2019, 10.1039/C9CY01514K.
(Invited) Electroreduction of CO2 (CO2RR) on Pyrolysed Transition Metal Porphyrins
Authors: Kao Yi-Lin , Paul Stephen , Herrmann-Geppert Iris , Kramm Ulrike Ingrid , Bogdanoff Peter
Published: May 2020

Pyrolysed transition metal porphyrins (MeNxC) were originally developed as alternative catalysts for the electrochemical reduction of oxygen (ORR). The catalytic centers were identified as base transition metal ions, integrated into graphene layers of a carbon matrix via nitrogen atoms. The carbon serves as a conductive support and influences the entire catalytic process with its variable electronic and chemical properties. Thus, this class of materials can be classified as hybrid-material between inorganic and molecular catalysts.

Meanwhile it is known that this type of catalysts are also active towards the CO2RR. Our presentation will show results of electrochemical studies on pyrolysed transition metal porphyrins (MeNxC) as catalysts for the CO2RR under variation of the metal ions (Me: Fe, Co, Ni, Sn, Zn, Cu , Mn). Their activities are determined in gas diffusion electrode (GDE) configuration using CO2, CO or Ar gas feeds. The product composition of the gas phase at the outlet of the cell is analyzed simultaneously by mass spectroscopy. Soluble products are analysed via ion-chromatography. It is shown that the product composition of CO2RR, as well as the respective onset potentials, partial current densities, formation rates, and Faraday efficiencies vary strongly with the type of metal ions investigated in the catalytic center. Fe-, Co- and Ni-based catalysts form predominantly CO and suppress the competing hydrogen evolution reaction. CO-formation rates of 4 mmol/(hcm2)at -2V NHE and 200 mA/cm2 (Faraday efficiency close to 100%) were achieved on not yet optimized GDEs. The formation of significant amounts of hydrocarbons from CO2 was observed only on the Cu- based material. The analysis of the potential dependence during product formation under different gases fed to the GDE allows initial conclusions about the underlying mechanisms of the CO2RR.

Figure 1
Protein Assisted Fabrication of Metallic Nanorings and Spherical Nanoparticles for Electrocatalytic and Organocatalytic Applications
Authors: Pan Yani , Mauzeroll Janine
Published: May 2020

Inspiration from nature has driven the development and application of greener nanomaterials prepared using biotemplates in the field of nanoscience. Compared to traditional chemical routes, bioinspired nanomaterial synthesis has the advantage of mild synthetic conditions such as aqueous environment, ambient temperature, and no requirement for organic capping agent. In addition, the structures of some biomolecules make it possible to fabricate nanomaterials with complex and interesting morphology that are difficult to achieve through chemical methods. In this study, tobacco mosaic virus coat protein (TMV cp) was investigated as a versatile template to mediate the synthesis of nanorings and spherical nanoparticles under neutral and alkaline conditions, respectively. While the prepared silver nanorings displayed superior selectivity (95% Faradaic Efficiency) and stability of catalyzing CO2 electroreduction (CO2 RR) compared to free silver nanoparticles prepared by chemical methods, the platinum nanorings showed excellent electrocatalytic activity for hydrogen evolution reaction (HER). Spherical nanoparticles synthesized under alkaline conditions (Pt, Pd and Au NPs) were also investigated for their catalytic behavior towards organic transformations such as 4-nitrophenol reduction and alkyne hydrogenation.

References:

[1] Huang J. et al. Chem. Soc. Rev., 2015, 44, 6330.

[2] Pan Y. et al. Nanoscale, 2019, 11, 1895.

[3] Kim C. et al. J. Am. Chem. Soc., 2015, 137, 13844.

Figure 1
(Invited) Ligand Protected Au-Based Nanoclusters: A New Materials Domain for Efficient Electrochemical CO2 conversion with Broken Scaling Relationship
Authors: Alfonso Dominic R , Kauffman Douglas R.
Published: May 2020

The possibility of direct integration with renewable electric sources adds more potential to the electrochemical method as a promising route for CO2 conversion. In our previous joint experimental-computational efforts, Au25(SR)18
- nanoclusters having 25 gold atoms and 18 protecting thiolate ligands was the first Au nanocluster identified and utilized as catalysts for CO2 electro-reduction to CO. Here, we present first principles-based method coupled with Poisson Boltzmann implicit solvation model to screen other known synthesized atomically precise nanostructures within this class of materials. We proposed a list of promising CO2 reduction catalyst which has not yet been explored in the field to the best of our knowledge. The existence of strong scaling relationship between the carbon containing intermediates in transition metal catalysts poses mechanistic limitation for optimization of CO2 reduction efficiency. In the case of the nanoclusters, we demonstrate that the covalent nature of the active site specifically stabilize the COOH intermediate breaking the pre-existing scaling relationship between COOH and CO binding energies on metals. Our results point to the broader application of covalent aided active site in complex electrochemical processes. We anticipate that our study may hasten the expansion of the domain of materials for CO2 reduction electro-catalysts into a new realm of ligand protected gold-based nanoclusters.
(Invited) Self-Template Synthesis of Atomically Dispersed Fe/N-Codoped Nanocarbon As Efficient Bifunctional Oxygen Electrocatalyst
Authors: Yin Shu-Hu , Jiang Yan-Xia
Published: May 2020

High performance and durable bifunctional oxygen electrocatalysts are of great importance for the commercial application of environmentally friendly and sustainable energy through electrochemical devices such as rechargeable Zn–air batteries and fuel cells. Highly distributed catalysts with maximum atomic utilization are considered to be a promising alternative for current noble-metal-based catalysts. Herein, a high performance and durable bifunctional oxygen electrocatalyst for both ORR and OER is synthesized by a facile self-template and polypyrrole encapsulation method. The super performance atomically dispersed Fe/N-codoped double shelled hollow carbon nanospheres (AD-Fe/N-C-900) catalyst has a special open porous double shell hollow structure which is beneficial to exposure of more Fe-Nx active sites for ORR and OER, and improves mass transfer, resulting in a fabulous bifunctional ORR/OER electrocatalytic activity (△E =0.655 V), which is better than the commercial Pt/C (△E =1.035 V) and the commercial IrO2 (△E =0.93 V), along with remark durability and long-term stability for the ORR in alkaline medium. Based on our results and analysis, the remarkable electrocatalytic activity of AD-Fe/N-C-900 might be attributed to the high content of mesopore, high density of Fe-Nx active sites, and robust double shell hollow structure. The novel design of the atomically dispersed Fe/N-codoped porous double shell hollow nanocarbon enable boosted oxygen catalyst by a facile method has certain enlightening effect on the design and development of other bifunctional electrocatalysts in the next generation reversible energy conversion systems. Our work provides a design idea for the synthesis of high activity and stability bifunctional atom-level distributed catalysts.

Figure 1
Synthesis and Characterization of Nanostructured Reduced Graphene Oxide/PANI/Znoacetylcholinesterase Biosensor for Malathion Detection
Authors: Woldegebriel Belay Minase
Published: May 2020

PANI and PANI/ZnO were synthesized electrochemically on both glass carbon electrode and reduced graphene oxide modified glass carbon electrode. PANI, PANI/ZnO and PANI/ZnO/RGO nanocomposites were alsosynthesized by in-situ oxidation polymerization method and characterized by UV-visible and FTIR Spectroscopy. The absorption peaks in FTIR spectra of PANI/ZnO/RGO composite film were found to shift to higher wave number when compared with pure PANI and PANI/ZnO nanocomposite.Electrochemically and chemically produced PANI, PANI/ZnO and PANI/ZnO/RGO were characterized by cyclic voltammetry in 1MHCl aqueous solution. The cyclic voltammetry showed that the deposited PANI/ZnO on RGO/ was more electro active due to high surface area of RGO. The estimated electron transfer rate constant (ks) of PANI,PANI/RGO, PANI/ZnO,and PANI/ZnO/RGO 0.123s-1, 0.144s-1,0.1348 s-1and 0.1667s-1respectively. The synthesized PANI/ZnO/RGO with larger estimated electron transfer rate constant (ks) than others.Therefore PANI/ZNO/RGO/GCE was provided an excellent biocompatible environment for AChE and facilitate the electron transfer reaction in malathion detection.The resulting biosensor exhibited alinear response for acetylcholine in a concentration range of 100–1000µL. Under optimum conditions, the biosensor showed the inhibition rates of Malathion proportionalto their concentrations in the range of 10–40 nmol L-1,good reproducibility,no interference by heavy metal ions and high recovery values around 99.7.0%. The best electro analytical performances of this synthesized electrode was achieved with the detection limitof 11 nmol L-1 for malathion. The simplicity of preparation, high sensitivity and stability of this nanostructured AChE-PANI/ZnO/RGO/GC electrode should open novel opportunities and applications for fabricating robust sensors for detection of malathion.
Nonlinear Impedance Spectroscopy of Organic MIS Capacitors and Planar Heterojunction Diodes
Authors: White Matthew Schuette
Published: May 2020

We present a nonlinear impedance spectroscopy technique and demonstrate its ability to directly measure nonlinear processes including electron-hole recombination and space charge effects in organic-semiconductor-based diodes and MIS capacitors. The method is based on Fourier analysis of the measured higher harmonic current response to an AC voltage signal. Characterization of the higher harmonic response allows nonlinear impedance spectroscopy to measure material and device properties over a wide range of frequencies, which would otherwise be impossible using conventional impedance spectroscopy. As the higher harmonic signals are purely a product of nonlinear processes, they are independent of the linear device capacitance and resistance. This allows space charge and recombination effects to be investigated at several orders of magnitude higher frequency without fitting to an equivalent circuit model.
Double Approach Towards 3D Electrodeposited RuOx Porous Structure for High Energy/High Power Micro-Supercapacitors
Authors: Benali Karroubi Lotfi , Patnaik Sai Gourang , Tran Chau Cam Hoang , Guay Daniel , Pech David
Published: May 2020

Hydrous RuOx has been one of the well-studied materials for application in supercapacitors owing to its excellent properties (high conductivity similar to metals, redox activity capable of fast faradaic reactions and structural water enabling swift proton transfer and decreased diffusion distance). The main issue regarding supercapacitors is that, they suffer from low energy density compared to batteries. One way to overcome this problem is to increase surface area of the active material and hence the energy stored through 3D structuration of current collector. Multiple techniques have been used in this regard like 3D printing, pholitography methods...etc. However, these techniques are pretty complex, time consuming and have constraining conditions. Hence, it’s necessary to develop economic and simple routes for 3D structuration of electrodes for micro-supercapacitors. One simple, time efficient and easy to set up method that can be used under ambient conditions is the electrochemical structuration using dynamic hydrogen bubble template (DHBT). With this strategy, 3D scaffolds which can hold small quantities of intrinsic pseudocapacitve materials like RuOx can be fabricated. The challenge in this latter case is magnified, needing controlled decoration of active materials for efficient utilization and full benefit of the 3D framework. Hence, the pursuit of superior micro-supercapacitors not only needs controlled deposition, but also requires stable 3D scaffolds to maximize capacitance per footprint area1. We have previously shown electrodeposition of active RuOx on porous gold electrodes for micro-supercapacitors achieving a capacitance of 3 F/cm².2

One other approach would be to deposit the active material directly by the DHBT method. As RuOx is a good conductor this would not hinder its efficiency (this would not be the case for MnO2 for example). The difficulty here is that, not all metals can be deposited by the DHBT technique as other factors play a crucial role such as the exchanged current density towards H2 evolution and mechanical stability3.

In the current work, we report two different strategies for the 3D deposition of RuOx. The first is the successful fabrication of highly porous 3D platinum current collector using DHBT followed by a conformal coating of hydrous RuOx to achieve a specific capacitance as high as 7 F/cm². The second is the direct electrodeposition of the active material, RuOx, in a 3D porous structure. These two approaches are characterized and discussed within the framework of fabricating superior micro-supercapacitors with excellent capacitance and low internal resistance.

References

1. N. A. Kyeremateng, T. Brousse, and D. Pech, Nat. Nanotechnol., 12, 7–15 (2017)

2. A. Ferris, S. Garbarino, D. Guay, and D. Pech, Adv. Mater., 27, 6625–6629 (2015)

3. Plowman, B. J., Jones, L. A., & Bhargava, S. K. Chem. Commun., 51, 4331–4346 (2015)

Figure 1
Solar Desalination Using Dye-Sensitized Photoanode in a Redox Flow Desalination Cell
Authors: Mohandass Gowri , Trivedi Dhara , Kim Taeyoung , Krishnan Sitaraman
Published: May 2020

Water desalination is a promising technological solution for assuring water security in many parts of the world. Although conventional desalination techniques, such as thermal desalination, reverse osmosis (RO), and electrodialysis (ED), are currently in use for supplying freshwater, it may not be a sustainable solution in the long term due to the heavy reliance on fossil fuels to power the process. The desalination driven by sunlight could be a potential, energy-conserving alternative to the existing techniques. Here, we demonstrated the use of redox-active photoanode to power the water desalination. We have used a dye-sensitized photoanode (of the Grätzel cell) as one of the electrodes of a water desalination cell, in which a redox couple (I−/I3
−) mediates light-to-energy conversion and sustains ion transport and ion separation in the cell. The cell consisted of electrode channels recirculating the redox couple and feed channels fed with 50 mM NaCl, which were divided by an alternative array of anion and cation exchange membranes. The short-circuit current (J
sc) achieved in the integrated solar desalination cell was 2.75 mA/cm2 using a Xenon lamp (100 mW/m2), which was significantly higher than previously reported DSSC-based solar desalination (J
sc = ~ 0.1 mA/cm2 [1]). This improved current density allowed for a reduction in NaCl concentration from 50 mM in the feed to 38 mM in the effluent, indicating that integrating photon-to-electron conversion and water desalination processes within a single device is a viable approach for solar-powered water desalination.

[1] Chen et al., Exploration of a photo-redox desalination generator, J. Mater. Chem. A, 2019, 7, 20169
Unraveling the Temperature Mediated Dual Band Edge in TiO2 Nanotubes with Improved Photocatalytic Property
Authors: Bhowmick Sangita , Saini Chetan , Gupta Mukul , Singhal Rahul , Sen Raja , Kanjilal Aloke
Published: May 2020

The resurgence of photocatalytic activity of TiO2 is driven in past few decades owing to its potential to meet several contemporary global challenges, such as pollutant degradation, nonfossil fuel production from CO2, or H2 generation from aqueous solutions [1]. Among three TiO2 polymorphs anatase TiO2 (A-TiO2), rutile TiO2 (R-TiO2) and brookite TiO2, first two are the mostly investigated phases for photocatalytic application. However, the use of TiO2 photoelectrodes is limited owing to the recombination of photo-generated (e-h) pairs in the bulk, and also at the electrode/electrolyte interface. The overall efficiency associated with A-TiO2 is still considered to be higher with respect to R-TiO2 due to higher charge carrier mobility and slower charge recombination kinetics [2].Nevertheless, proper ratio of anatase-rutile phases (Degussa P25) is superior in photocatalytic activity than that of pure rutile or anatase phase. On the other hand, anodic TiO2 nanotubes TNTs have attracted wide interest due to their high surface-to-volume ratio with preferential electron transport towards the Ti back-contact, and a scalable synthesis by electrochemical anodization [3]. However, thermal annealing is needed to obtain anatase and rutile phases, besides achieving suitable ratio of mixed-phases for relatively high photocatalytic performance through efficient inter-granular charge transfer and minimizing the recombination processes. Temperature induced changes in surface morphology, grain size, crystal structure and composition also have significant influence on the photo-electrochemical properties of TNTs. Here, we report the synthesis of TNTs, and the correlation of optical band gap with structural transformation from anatase to rutile through intermediate mixed phases as a function of temperature and their corresponding effect on photocatalysis application. This is confirmed by means of UV-Vis spectroscopy, X-ray diffraction (XRD) and Raman Spectroscopy. X-ray Photoelectron Spectroscopy (XPS) analyses has also been carried out to understand the change in chemical behavior with annealing temperature, gives a clear evidence of sub-stoichiometric to stoichiometric TiO2 (Ti4+) phase transformation with increasing temperature via removal of the fluorine (F) species from the NT surface which eventually changes the crystallinity of the samples as observed in XRD patterns. Further, to comprehend the change in the local coordination environment of the constituent atoms in TiO2 nanotubes with annealing temperature, the samples have been characterized by X-ray Absorption Spectroscopy (XAS). Density functional theory (DFT) has also been employed to understand the underlying mechanism.

References

1. P.Roy et al., Angew. Chem., 50,13,(2011)

2. Yalavarthi, R., et al., Catalysts, 9,2,(2019)

3. J.M.Macak et al., Small, 3,2,(2007)
Electrochemical Reactivity of Flavonoids and Flavonoid-Metal Ion Complexes with the Superoxide Anion Radical
Authors: Lewis Tyra , Martic Sanela
Published: May 2020

Reactive oxygen species (ROS), such as the superoxide anion radical, O2ׄ-, are by-products of aerobic cellular metabolism.1,2 ROS may serve as signaling molecules in some cellular processes, depending on the balance of ROS produced and ROS scavenging mechanisms at work.1 However, they may also lead to undesirable reactions in biological systems.1 Specifically, an excess production of ROS can cause oxidative stress, contributing to cellular death and the development of some pathological diseases, like cancer and Parkinson’s disease.1-3

Dietary flavonoids serve as antioxidant supplements to fight against ROS-induced damages in the system.4 Flavonoids are also known to play a role as metal ion chelators, in a biological environment, which subsequently modulates the antioxidant capacity of the flavonoid compound.1,4 Hence, greater understanding of flavonoid chemistry with ROS in the context of metal ions is needed.

In this work, a previously established three-electrode electrochemical assay was used to evaluate the reactivities of flavonoids and flavonoid-metal ion complexes with electrochemically-generated superoxide anion radical, O2ׄ-.5 Cyclic voltammetry (CV) was used with a glassy carbon working electrode, a Pt wire counter electrode and Ag/AgNO3 reference electrode immersed in DMF, in this assay. CV was used to measure the electrochemical signal associated with O2ׄ- and its modulation in the presence of a specific flavonoid and metal ion (Cu(II), Zn(II), Fe(III), Mn(II), Cd(II)). Data indicated that flavonoids depleted a signal associated with O2ׄ- and that this reactivity was regulated in the presence of metal ions.

References

1 P. Sharma, A. B. Jha, R. S. Dubey, and M. Pessarakli, J. Bot., 2012, 1–26 (2012).

2 M. P. Murphy, Biochem. J., 417, 1–13 (2008).

3 C. L. Bourvellec, D. Hauchard, A. Darchen, J.-L. Burgot, and M.-L. Abasq, Talanta, 75, 1098–1103 (2008).

4 K. E. Heim, A. R. Tagliaferro, and D. J. Bobilya, J. Nutr. Biochem., 13, 572–584 (2002).

5 N. L. Zabik, S. Anwar, I. Ziu, and S. Martic-Milne, Electrochim. Acta, 296, 174–180 (2019).
Investigating the Mechanical Properties of Na Metal for Solid-State Batteries
Authors: Chang Jiun-Yeu , Wang Michael , Sakamoto Jeff
Published: May 2020

In recent years, increasing power density and reducing cost has fueled interest in developing all solid-state batteries. Na metal anodes have garnered attention because of its abundance and high theoretical capacity (1165 mA h g–1) [1]. However, similar to solid-state Li-ion conductors, it has been reported that dendrite growth through Na-ion conductors also occurs. It has been hypothesized that dendrite propagation through the electrolyte is dependent upon the elastic and plastic properties of the alkali metal anode [2]. Therefore, a better understanding of the mechanical properties of bulk Na can promote the further development of Na-based solid-state batteries.

In this study, several analyses were performed to gain insight into the mechanical properties of Na metal. Tensile and compressive tests were performed by using a load frame contained in an inert atmosphere. From the resulting stress-strain graphs, the yield strength was determined to be 0.283 MPa. An acoustic technique was employed to determine that the elastic modulus of Na was 4.6 GPa. Because Na has a relatively low melting point (98°C), the deformation mechanism of Na during battery operation is likely dominated by creep. To investigate the creep behavior of Na, tension creep measurements were performed. The creep exponent of Na was determined to be n = 7.4. Lastly, to better understand the mechanical behavior of Na at the various interfaces in a solid-state battery, compression tests were performed on varying substrates. Three interfaces were examined: Oil/Na (simulating a frictionless interface), current collector/Na, and Na/Na-β’’-alumina.

We believe the mechanical measurements in this work will provide new insights into in the design requirements for solid-state batteries utilizing Na metal anodes.

REFERENCE

1. Sun, B., Li, P., Zhang, J., Wang, D., Munroe, P., Wang, C., ... & Wang, G. (2018). Dendrite‐Free Sodium‐Metal Anodes for High‐Energy Sodium‐Metal Batteries. Advanced Materials, 30(29), 1801334.

2. LePage, W. S., Chen, Y., Kazyak, E., Chen, K. H., Sanchez, A. J., Poli, A., ... & Dasgupta, N. P. (2019). Lithium Mechanics: Roles of Strain Rate and Temperature and Implications for Lithium Metal Batteries. Journal of The Electrochemical Society, 166(2), A89-A97.
Evaluation of Porous Ni(Zn) Materials As 3D Matrices for Li Metal Electrodes
Authors: Fatahine Mohamed , Guay Daniel , Roué Lionel
Published: May 2020

Due to its very high theoretical capacity (3861 mAh g-1 or 2062 mAh cm-3) and low redox potential (-3.04 V vs standard hydrogen electrode), lithium metal is one of the most attractive anode materials for batteries. However, its use in rechargeable batteries such as Li-S and Li-air batteries is problematic due to the uncontrolled formation of lithium dendrites during charge/discharge cycling, which can induce cell short circuit, aggravated adverse reactions, dead Li formation, polarization increase and large volume changes, resulting in safety concerns and low coulombic efficiencies. Various strategies have been evaluated to prevent the growth of Li dendrites such as: (i) electrolyte engineering for modifying the physicochemical properties of the solid electrolyte interphase and better regulating the current distribution during Li deposition; (ii) interface engineering by covering the Li surface with a protective coating before cycling; (iii) use of solid electrolyte or reinforced separator to mechanically block Li dendrite propagation and (iv) development of 3D substrates inducing a more uniform Li-ion flux in addition to act as stable hosts that guide Li plating and minimize the electrode volume variation upon cycling [1-3].

According to this latter strategy, the present study is focused on porous Ni and Ni-Zn electrodes elaborated by the dynamic hydrogen bubble template (DHBT) method [4]. The Li wettability of these electrodes as a function of their porosity and composition will be presented. Their ability to better control lithium dendritic growth will be discussed on the basis of cycling experiments in Li/S batteries, electrochemical dilatometry experiments and operando optical microscopy analyses.

References

[
1
] X.B. Cheng, R. Zhang, C.Z. Zhao, Q. Zhang, Toward safe lithium metal anode in rechargeable batteries: a review, Chem. Rev 117 (2017) 10403-10473.

[
2
]X.B. Cheng, J.Q. Huang, Q. Zhang, Review-Li metal anode in working lithium-sulfur batteries, J. Electrochem. Soc. 165 (2018) A6058-A6071.

[
3
] D. Lin, Y. Liu, Y. Cui, Reviving the lithium metal anode for high-energy batteries, Nat. Nanotechnol. 12 (2017) 194-206.

[
4
] M. Hao, V. Charbonneau, N. N. Fomena, J. Gaudet, D. R. Bruce, S. Garbarino, D. A. Harrington, D. Guay, . Hydrogen Bubble Templating of Fractal Ni Catalysts for Water Oxidation in Alkaline Media. ACS Appl. Energy Mater. 2 (2019) 5734-5743.
Electroactive Molecularly Imprinted Polymer for Selective Detection of 4-Nitrophenol
Authors: Ren Tianyu , Si Bo , Chen Yuan , Halpern Jeffrey M , Seitz William Rudolf
Published: May 2020

We propose to develop a reusable electro-chemical sensor for selective detection of 4-nitrophenol (4-NP), based on molecularly imprinted polymer (MIP) technology. MIP technology is the design of an artificial receptor with high selectivity for a specific analyte. Our approach combines N-isopropylacrylamide (NIPAM) backbone polymer with different functional monomers to improve the selectivity and sensitivity of 4-nitrophenol (4-NP) detection.

The key points of our sensor polymer are:1) reduced amount of covalent crosslinker methylene bis-acrylamide (MBA) to increase rebinding kinetics and affinity and 2) modified polymer backbone with an electroactive block deposited on a gold surface. To get rapid high affinity template rebinding, we used a reduced amount of covalent crosslinker and used noncovalent crosslinking based on acid-base and hydrophobic interactions. To form acid-base crosslinking, we used 4-vinylpyridine (4-VP) as the basic monomer and methacrylic acid (MAA) as acidic monomer.

In MIPs synthesis part, our strategy takes the advantage of reversible addition fragmentation-chain transfer (RAFT) polymerization to control the polymer chain length and modify the terminus as poly-ferrocene methyl methacrylate (FMMA), an electroactive block. The RAFT agent contains R group and Z group which are at different ends of polymer. The Z side is reduced to a thiol and deposited on gold. The PolyFMMA block is on the R side. RAFT agent, FMMA monomers and initiator were added to a batch system to synthesis the first electroactive block. Then, all chemicals including backbone monomers, functional monomers, crosslinkers and templates (4-NP) were added to form the major polymer block. After synthesis, templated-MIPs were dialyzed to remove the template for further target selective detection.

One of the major challenges of our sensor is polymer tangling which affect measurement stability. To reduce polymer tangling effects, we dissolved the template-removed MIPs into tetrahydrofuran (THF) and controlled the gold electrode surface coverage. We deposited MIPs on an additional flat gold chip and used atomic force microscope (AFM) to characterize the surface coverage distribution.

The modified gold electrode can be used in electrical impedance spectroscopy (EIS) or cyclic voltammetry (CV) to measure charge transfer distance before and after template rebinding to detect unknown concentration target analytes.
Titanium-Based Anode Materials with Al-Doped ZnO ALD Coating for High-Performance Lithium-Ion Batteries
Authors: Jin Ye , Yu Han , Liang Xinhua
Published: May 2020

In commercial lithium ion batteries, graphite is used as the most common anode material, which are easy to generate lithium dendrites, when operating at a high current rate, causing an internal short circuit and thus suffering from critical safety issues. Titanium-based anode materials are a class of alternative materials to graphite, which has a potential to offer a significant safety advantage over the graphite anode. Lithium titanate oxide (Li4Ti5O12, LTO) and titanium dioxide (TiO2) are two of the most studied titanium-based anodes because of their properties of intrinsic safety and small volume expansion. Recently our group deposited high electronic conductive Al-doped ZnO (AZO) films on the LTO and anatase TiO2 samples by atomic layer deposition (ALD). The optimum AZO-coated LTO exhibited a superior rate capability and cycling stability at 55 ℃ within a potential rage of 0.1 V to 3.0 V; the optimum AZO-coated TiO2 delivered a much higher capacity than that of the uncoated TiO2 even after 500 cycles of discharge/charge at 1 C rate (1 C = 168 mAh g-1). The coating of AZO thin films is believed to improve the conductivity of the active materials, protect the active materials from the electrolyte, and suppress the undesirable interfacial reactions between them.
Synthesis and Modification of TiO2 nanostructured Materials for Energy Storage
Authors: van der Zalm Joshua , Salverda Allison , Chen Aicheng
Published: May 2020

Increasing energy demand is inexorably linked to the need for efficient energy storage techniques. For practical applications, it is highly desirable to decrease the size of electrical components and to increase the storage capacities while maintaining power, stability, and charging-discharging speeds. Much focus has been directed towards the development of supercapacitors. These are often fabricated from carbonaceous or metal oxide materials with high surface areas to maximize electrode/electrolyte interactions. The use of nanostructured TiO2 electrodes has been explored for this application due to their low cost, high stability, and highly tunable morphology.

Here we present the fabrication of nanostructured TiO2 films via a facile anodic process. Characterization of the films was carried out by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Electrochemical reduction of the formed TiO2 film was further performed to increase its capacitance, which was confirmed by cyclic voltammetry and electrochemical impedance spectroscopy. The performance of the symmetric capacitor constructed with the modified TiO2 films will be presented.
Characterizing the Source of Inconsistent Modification of ELP By Cyclic Voltammetry
Authors: Feeney Stanley , Morales Marissa A , Balog Eva Rose M , Halpern Jeffrey M
Published: May 2020

Elastin-like polymers (ELPs) have gained attention recently for their potential as biorecognition element platforms for biosensors. For surface-bound ELP to be used as a biorecognition platform, consistent surface modification is required to ensure a consistent electrochemical response model. Consistent electrochemical response of gold surfaces with ELP has been a challenge in practice, but can be achieved with careful modification procedure, keeping variables such as temperature, ELP concentration, time of modification, and dissolution procedure consistent. We hypothesize that further ELP surface modification inconsistencies are due to ELP that physiosorbs to the gold surface and other surface-bound ELP. This presentation will share data demonstrating that inconsistencies in electrochemical measurements of surface-bound ELP are due to inconsistent physisorption of non-chemisorbed ELP molecules. Cyclic voltammetry in KOH was applied to surface-bound ELP at different ELP concentrations in order to reduce the ELP - gold thiol surface. This reduction corresponds to a peak in the cyclic voltammogram. The area under this peak is equal to the charge exchanged for the reduction of the thiol bond, which correlates to the amount of ELP removed from the gold surface. Additionally, electrochemical impedance spectroscopy (EIS) was used with a Randles circuit model to determine the charge transfer resistance of the surfaces. By comparing the trend of charge transfer resistance to modification concentration and chemisorbed ELP, we show that the inconsistencies in charge transfer measurements are related to physiosorbed ELP and not chemisorbed ELP.

Acknowledgements: The authors would like to acknowledge the financial support from NSF (CBET 1638896) and the Collaborative Research Excellence Initiative Pilot Research Program at the University of New Hampshire. The authors also would like to acknowledge the assistance of Dr. Balog’s laboratory and Dr. Halpern’s laboratory.
Gas Diffusion Barrier of Vapor Phase Infiltrated Pen with Room Temperature ALD
Authors: Yoshida Kazuki , Saito Kentaro , Miura Masanori , Kanomata Kensaku , Hirose Fumihiko
Published: May 2020

Metal oxides like aluminum oxide (Al2O3) and silicon oxide (SiO2) are well known as gas barrier materials to moisture. The gas barrier films are used in various applications like food packaging, pharmaceuticals, chemicals, and organic electronics. Especially in the field of organic electronics, the high gas barrier performance is essential to avoid organic semiconducting material degradation from moisture. Because of the most attractive point in these devices is their possibility that of flexible device fabrication, we must use a flexible polymer film substrate. The polymer film substrate is thermally fragile, and it includes voids in polymer chains. From this, we have to deposit the gas barrier film at low temperature and uniformly coat the voids. To overcome these problems, we developed the room-temperature atomic layer deposition (RT-ALD) technologies. In this study, we examine gas barrier coatings with a combination of vapor phase infiltration (VPI) for higher barrier performances. The VPI produces a polymer-inorganic hybrid layer by infiltrating inorganic materials into polymer substrates in the subsurface region. It is possible to fill in the voids in polymer substrates.

For VPI, we used tris(dimethylamino)silane (TDMAS) as the infiltration gas and plasma excited humidified Ar as oxidation gas. The infiltration process was operated at room temperature of 25 °C. The PEN film was infiltrated by being kept in a vacuum chamber with a TDMAS pressure of 200 Pa for 6 hours. After infiltration, the PEN films were exposed to plasma excited humidified Ar to oxidize surface absorbant. In the RT ALD, we used trimethylaluminum (TMA) and dimethylzinc (DMZ) as the precursor and oxidation gas was the same as VPI. We fabricated the gas barrier films with a ZnO single layer and a laminated Al2O3/ ZnO.

In figure 1, we show Si 2p narrow scan spectra of TDMAS infiltrated PEN by X-ray photoelectron spectroscopy. The Si 2p peak existed after 90 min Ar bombardment etching. It indicates the TDMAS molecules penetrated in the PEN film. We also confirmed that its surface became smooth and its morphology was changed by using AFM. The surface modification by VPI was evaluated with a water contact angle meter. In this paper, we will release the WVTR data and discuss its performance compared with the pristine PEN.

Figure 1
Elucidating Aluminum-Ion Intercalation and Its Effects on the Local Crystalline Framework Using Solid-State NMR Spectroscopy
Authors: Jadhav Ankur L. , Hawkins Brendan E. , Xu Jeffrey H. , Messinger Robert J.
Published: May 2020

Rechargeable multivalent-ion batteries are safe and low-cost alternatives to traditional lithium-ion batteries. However, higher Coulombic charge density of the multivalent ions results into sluggish diffusion of their respective cations within crystalline transition metal compounds. The Chevrel phases Mo6X8, where X is a chalcogen atom (e.g., S or Se) are among the few materials known to reversibly and electrochemically intercalate both divalent (e.g. Mg2+, Zn 2+, etc.) and trivalent (Al3+) ions. Thus, understanding the ion intercalation and charge transfer mechanisms within these unique compounds may provide insights into the molecular-level design of new intercalation electrodes for rechargeable multivalent ion batteries. Here, we use multi-nuclear solid-state magic-angle-spinning (MAS) NMR spectroscopy to reveal the ion intercalation and charge transfer mechanisms of zinc and aluminum intercalation in Chevrel electrodes Mo6S8 and Mo6Se8.

Ex situ single pulse solid-state 27Al MAS NMR measurements were performed on the thio-chevrel electrodes at different states-of-charge to observe changes in the environments and to quantify the local populations of aluminum ions within the host crystal structure, revealing both intercalated ions and additional aluminum species associated with surface layers and/or decomposition products. Al-Mo6Se8 batteries were made for the first time and their electrochemical properties were compared to the thio-chevrel Mo6S8. Ex situ
77Se and 95Mo measurements on the seleno-chevrel Mo6Se8 at charged and discharged states revealed that the electrons are transferred to the anionic chalcogen framework the electron charge transfer mechanism and its effects on the local crystalline framework environments upon aluminum ion intercalation. These results were then generalized for zinc intercalation into chevrel phase electrodes.

Overall, the solid-state NMR measurements combined with the electrochemical measurements yield molecular-level insights into the coupled aluminum ion intercalation and electron charge transfer processes that occur in a model crystalline transition metal electrode. Unique reversible anionic redox reactions were observed for multivalent ion intercalation into chevrel, which is very different that typically observed for lithium-ion intercalation into transition metal oxides, where the electrons are stored into the d-orbitals of the transition metal. The results suggest materials design principles aimed at designing multivalent-ion intercalation electrodes with improved electrochemical properties.

Figure 1
Protocols to Observe Changes in the Lower Critical Solution Temperature Induced By an Applied Potential
Authors: LaFreniere Joelle , Ren Tianyu , Roberge Emma , Balog Eva Rose M , Seitz William Rudolf , Halpern Jeffrey M
Published: May 2020

Dynamic light scattering, or DLS, is commonly used to determine the lower critical transition temperature (LCST) of a temperature induced stimuli-responsive polymer. By applying a temperature sweep, the coacervation or agglomeration of stimuli-responsive polymers can be observed. For materials, such as Poly(N-isopropylacrylamide), or pNIPAM, which have a reverse LCST, the polymers are soluble at lower temperatures and condense or precipitate out of solution at higher temperatures. The transition temperature is the transition between this soluble and condensed state.

Our lab has developed a protocol to look at changes in the LCST behavior in the presence of an applied potential. By lining the DLS cuvette with a conductive tape, we can apply the potential across the 1 cm light path. After a certain voltage threshold, changes in the observed LCST behavior is found with pNIPAM. To the best of our knowledge, this result has never been recorded. Typically, the LCST of pNIPAM is not adjustable, but using this technique, we can observe the effect with an applied potential. We share this protocol for other groups to use to investigate the effect of applied potential on the coacervation of stimuli-responsive polymers. We intend to report details of our protocol and initially observed results of the observed behavior in the presence of an applied potential.

Acknowledgements: The authors would like to acknowledge the financial support from NIH (P20 GM113131), NSF (CBET 1638896), the Collaborative Research Excellence Initiative Pilot Research Program at the University of New Hampshire, and the Hamel Center of Undergraduate Research at the University of New Hampshire. The authors also would like to acknowledge the assistance of Dr. Balog’s laboratory and Dr. Halpern’s laboratory.
Electrochemically Tagging Elastin-like Polymers-Modified Au Surfaces
Authors: Nadar Priyanka , Gasperoni Charles , Morales Marissa A , Balog Eva Rose M , Halpern Jeffrey M
Published: May 2020

We are exploring Elastin-like-Polymer (ELP) as a transducing enhancement element for biosensors. While previous work in our lab has investigated surface-bound ELP conformational state with electrochemical impedance spectroscopy to understand its stimuli-response, we would like to use ELP as an electrically active transducer in sensor applications. To achieve this, we must understand how much of the ELP is covalently attached to the electrode and functionalize the electrochemically-inert ELP with a faradaic tag. We present a proof-of-concept model for modifying the C-terminus of the ELP with Toluidine Blue O, an electrically active phenothiazine compound. Our system uses simple and accessible conjugation chemistry for this purpose and is conducted in aqueous solution. Further, reducing the thiol bonds will remove the covalently-bound ELP from the electrode surface to obtain an estimate of the ELP surface coverage

Thus far, we have successful decoupled the thiol-gold bond using the cyclic voltammetry reduction technique.. Electrochemical impedance spectroscopy confirmed that the modified electrode after thiol desorption returned to a similar state compared to a bare electrode. Additionally, we successfully measured an electrochemical signal attributed to the Toluidine Blue O tag conjugated to ELP based on its redox properties (Figure 1). We intend to further expand this work by refining the conjugation protocol, comparing various tags and conjugation chemistries, and relating surface coverage to desorption amounts of covalently bound ELP.

Acknowledgements: The authors would like to acknowledge the financial support from the College of Medicine at Drexel University, NSF (CBET 1638896), the Collaborative Research Excellence Initiative Pilot Research Program at the University of New Hampshire, and the Hamel Center of Undergraduate Research at the University of New Hampshire. The authors also would like to acknowledge the assistance of Dr. Balog’s laboratory and Dr. Halpern’s laboratory.