bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and Evaluation of Gel Fuel and Liquid Fuel Hybrid Structure of Fructose Fuel Cell
Authors: Yamakawa Atsuya , Todaka Keisuke , Imai Satomitu 
Published: May 2020

An enzyme-type biofuel cell (EBFC) is a device that converts chemical energy into electrical energy by a redox reaction, using an enzyme as a catalyst to generate electricity. EBFCs have the features that it can operate at normal temperature, normal pressure, and neutrality. In addition, fuel can be selected depending on the type of enzyme, and the structure is simple and the easy to miniaturize. Therefore, EBFCs are expected to be a power source for medical and mobile devices. EBFCs have problems of low output and low lifetime. Hoshi et al. proposed using GCFC (large specific surface area) for the electrode, to improve the output [1]. EBFCs generally use oxygen in the cathode reaction. Therefore, oxygen supply is important in EBFCs. Kuroishi et al. reported on the improvement of output in air exposure type EBFCs using gel fuel [2]. However, the gel did not function well after a few minutes owing to drying i.e., they have a short lifetime. In this study, a new structure to solve these problems was proposed.
In this study, fructose was used as the fuel. Figure 1 shows the operating principle of EBFCs using enzymes of fructose dehydrogenase (FDH) and bilirubin oxidase (BOD). Figure 2 shows the hybrid structure of liquid fuel and gel fuel, which was proposed in this work. The electrode uses GCFC. The distance between the two electrodes and the thickness of the gel fuel is 3 mm. The specifications of the used enzyme, liquid fuel, and gel fuel are shown in Table 1. Figure 3 shows the cyclic voltammetry (CV) of the anode to determine the optimum concentration of the fuel (200 mM). Next, we compared the power density of a conventional gel fuel cell (original gel fuel cell) and a fuel cell with liquid fuel dropped on the cathode side of gel fuel cell (cathode wetting gel fuel cell). Figure 4 shows the power density of the original gel fuel cell and the cathode wetting gel fuel cell. The power density of the cathode wetting gel fuel cell is extremely reduced. This indicates that the gel fuel cell requires the cathode to be dry to provide sufficient oxygen. Therefore, the hybrid structure was adopted to make the gel dry on the side of cathode and to prevent the drying of the gel by contacting with the liquid fuel on the side of the anode. Figure 5 shows the power density of the three types of EBFC. The power density of the hybrid was 74.0 μW / cm2, which is almost equivalent to that of just using gel. Figure 6 shows the time history of the maximum power density. The gel fuel type halved power density after 45 minutes. However, the hybrid type achieved a power density of 61 μW/cm2, even after 120 minutes. This was the most important feature of this study. Figure 7 confirms that the high level of the maximum power density, even after 24 hours, was maintained to at least 62.3% (46.1 μW/cm2) of the initial value.
[1] K. Hoshi et al. Jpn. J. Appl. Phys, 55 02BE05,2016
[2] K. Kuroishi et al. IEICE Transactions on Electronics, pp151-154,2019

Figure 1
Understanding the Overcoated Catalyst Using in Situ Synchrotron X-Ray Techniques
Authors: Li Tao 
Published: May 2020

Carbonaceous feeds, such as oil, gas, and coal, can be catalytically converted to useful products. Many of these reactions are conducted under harsh conditions, where the metal catalysts will rapidly sinter and lose activity. Overcoating is a methodology which preserves catalyst integrity under reaction conditions by depositing protective layers around the catalysts. Recently, we show that overcoating the metal nanoparticles with alumina using atomic layer deposition (ALD) will reduce the sintering and coking while the lifetime and reactivity of catalyst increase dramatically compared to the catalyst without ALD overcoating. It is believed that nano-sized pore (less than 2 nm) was formed during the calcination of ALD overlayer at high temperature. However, the mechanism of pore formation is still poorly understood due to the limited characterization technique.
Understanding the mechanism of the pore formation and further controlling the pore size are crucial for the development of the ALD overcoated catalyst. Recently, we demonstrated that small angle X-ray scattering (SAXS) can be used to characterize these ALD overcoated catalysts. From SAXS analysis, the thermal treatment resulted in the formation of ~ 3.5 nm pores. Moreover, the evolution of pore size was monitored by in situ SAXS technique. The pore size increases with increasing annealing temperature. In this proposal, we aim to investigate the mechanism of pore formation during the calcination using in situ SAXS as well as wide angle X-ray scattering, to understand how the ramping rate, gas used, nature of supports and overcoated materials affect the formation of the pore.
Template-Dewetted Au Nanoparticles on TiO2 Nanocavities for Photocatalytic Reduction and Scavenging of Hg(II)
Authors: Altomare Marco , Spanu Davide , Schmuki Patrik , Recchia Sandro 
Published: May 2020

Anodically-grown arrays of TiO2 nanocavities[1] are used as substrate for solid state dewetting of Au thin films (≤ 20 nm-thick).[2,3] The resulting Au nanoparticle-decorated structures are explored as a photocatalytic platform for the reduction and scavenging of Hg(II) ions in aqueous solutions under solar illumination.[4]

The presence of the dewetted Au nanoparticles leads to a strong improvement of the photocatalytic Hg(II) reduction performance. Different reaction pathways are recognized for the Hg(II) abatement, which depend on parameters such as the Hg ion concentration, the Au nanoparticle size/loading, and the presence/absence of chloride ions and their concentration.
ICP-MS analysis of photocatalytically treated water streams confirms that under any experimental condition explored the removed Hg(II) is always accumulated on the photocatalyst surface.
Interestingly, in the presence of chlorides (to simulate contaminated sea water), and with relatively high Hg concentrations (10 ppm) and Au nanoparticle loadings (Au film initial thickness ~ 20 nm), a massive growth of calomel (Hg2Cl2) nanowires is observed. The nature of the photo-produced nanowires was confirmed by EDS and XPS analysis. The Hg2Cl2 nanowires nucleate at the surface of the Au nanoparticles, and their morphology (width, length, aspect-ratio) can be tuned by adjusting the Au nanoparticle size and illumination time.
On the other hand, in the absence of chlorides and/or at lower Hg(II) concentrations, Hg removal occurs via accumulation on the photocatalyst surface through the formation of AuHg alloy (amalgam) nanostructures.
Both mechanisms lead to an effective abatement of Hg: under solar light illumination, the scavenging process can lead to a Hg removal efficiency as high as 90% after 24 h. Regeneration of the Hg-loaded exhaust photocatalyst can be performed by photo-electrochemical anodic stripping, which converts the deposited Hg(0)/Hg(I) into soluble Hg(II), allowing for the accumulation of the scavenged Hg into small volumes of concentrated wastes. After four photocatalyst use/regeneration cycles, only a 10% decrease of activity was observed.
Besides the relevance of the photocatalytic results for water remediation technologies, our findings can also provide reliable nanostructuring tools for the templated synthesis of amalgam nanoparticles of tunable composition and size, or for the controlled growth of calomel nanowires for electro-analytical or sensing applications.
[1] J. E. Yoo, K. Lee, M. Altomare, E. Selli, P. Schmuki, Angew. Chemie Int. Ed.
2013, 52, 7514–7517.
[2] C. V. Thompson, Annu. Rev. Mater.
Res.
2012, 42, 399–434.
[3] M. Altomare, N. T. Nguyen, P. Schmuki, Chem. Sci.
2016, 7, 6865–6886.
[4] D. Spanu, A. Bestetti, H. Hildebrand, P. Schmuki, M. Altomare, S. Recchia, Photochem. Photobiol. Sci.
2019, 18, 1046–1055.
Improving the Stability of Lithium Metal By Porous Metal Oxide Coating
Authors: Kim Hohyeong , Lee Min Su , Yim Tai Hong , Jae-Young Park 
Published: May 2020

Medium and large battery technology for energy storage devices or electric vehicles requires long life times and low cost as well as excellent safety. As a next generation high energy density type secondary battery, a lithium ion battery has been developed. However, when lithium metal cathodes is used, a redox reaction occurs at the interface between the electrode surface and the electrolyte, and lithium ions are eluted and lithium electrodeposits are concentrated. This phenomenon causes a problem that dendrite grows and causes an internal short circuit of the battery.
In this study, metal oxide nanoparticles were coated to form a porous layer on the surface of lithium metal for suppressing dendrite growth and interfacial transport of lithium ions during charging/discharging. The porous metal oxide coated Li metal unit cell showed an improvement of life times with maintaining the initial potential difference during charging/discharging.
Towards Structural Batteries Enabled By Fiber Reinforced Composites
Authors: Muralidharan Nitin , Westover Andrew S , Meng Chuanzhe , Pint Cary L. 
Published: May 2020

The advent of electric automobiles has garnered great interest in multifunctional electrochemical energy storage architectures which have the potential to store and release energy on demand while simultaneously being subjected to static or dynamic load conditions. At the forefront of these technologies are energy storage integrated fiber reinforced composites which promise substantial benefits to both mechanical as well as electrochemical performance. In this context, the design of interfaces that dually store energy and maintain composite mechanical integrity under load is of critical importance. Here, I will illustrate our systematic efforts on the development of multifunctional structural energy storage composites starting with CNTs grown on lightweight stainless steel meshes and incorporation of these materials into energy storing composite laminates where we simultaneously test mechanical and electrochemical performance. To further augment the energy storing capability of the carbon nanotubes, we electro-deposit ultrafast redox active pseudocapacitive nickel oxide and iron oxide onto the CNTs to fabricate fiber reinforced nickel-iron asymmetric redox pseudocapacitiors or nickel-iron ‘ultra-battery’ composites. Overall, composites showcase high power densities of 10 kWh/kgActive and comparable energy densities of 20 Wh/kgActive. Furthermore, these multifunctional composites demonstrate good mechanical (tensile, flexural and load impact) behavior while simultaneously exhibiting stable charge/discharge performance during in-situ mechano-electrochemical measurements. These results thus forge a path toward practical multifunctional composites by combining (1) in-situ mechano-electrochemical testing to assess structural energy storage performance, (2) effective reinforcements and prevent failure at structural interfaces, and (3) redox-active materials processed to augment energy density. Overall, these results provide new insights and creates a framework for developing such multifunctional energy storage architectures for a multitude of load-bearing applications.
References:
[1] N. Muralidharan, A. Westover, et al., Carbon Nanotube Reinforced Structural Composite Supercapacitor, Sci. Rep. 8, 2018, 17662
[2] N. Muralidharan, et al., Multifunctional Structural Ultrabattery Composite, Nano Lett. 2018, 18, 7761-7768
(Invited) Probing Electronic Transport Properties in Two-Dimensional Materials Using First Principles Calculations
Authors: Kuroda Marcelo A. 
Published: May 2020

Heterostructures formed with two-dimensional (2D) materials preserve atomically sharp crystalline interfaces, offering novel platforms for a wide range of applications. Due to their one- to few-atom thickness, quantum mechanical effects and atomistic details play key roles in their properties. Here I will present the use of first principles calculations (density functional theory) to characterize and control electronic and spin transport in systems formed with these layered materials. First, I will describe the underlying mechanisms governing the contact resistance in lateral heterojunctions based on transition metal dichalcogenides (MX
2 with M = Mo or W and X = Se or Te). By joining semiconducting (2H) and metallic (1T') phases, these lateral structures have been proposed to improve charge carrier injection in these materials with respect to that obtained via direct deposition of metals [1,2]. We find that contact resistance values of < 10 W·cm may be achieved by enhancing the coupling between electrodes in lead and channel via phase engineering. Next, I will describe the features of the mechanical modulation of tunneling current (piezoresistivity) in vertical transition metal dichalcogenide heterostructures [3]. The piezoresistive effect measured in these systems is rationalized in terms of the electronic properties of the electrode (e.g. work function, d-bands, etc.), as well as the junction's thickness and composition. Finally, I will characterize the tunneling magnetoresistances in graphene/chromium trihalides heterostructures that were recently demonstrated experimentally [4]. Our description based on the ballistic transport evince the importance of quantum confinement and interlayer magnetic coupling emerging at these length scales [5]. In addition, our results show remarkable agreement with experimental measurements. The virtues and limitations of these approaches will also be discussed.
Acknowledgements: The author gratefully acknowledges the financial support from NSF DMR-1848344 grant.
References:
[1] R. Kappera et al., Nat. Mater. 13, 1128 (2014).
[2] S. Cho et al., Science 349, 625 (2015).
[3] D. Fu et al., Appl. Phys. Lett. 103, (2013).
[4] T. Song et al., Science 360, 1214 (2018).
[5] J. J. Heath et al., arXiv:1910.01102 (2019).
(Invited) First Principles Electron Transport Calculations: From Molecular Contacts to Large 2D Devices
Authors: Brandbyge Mads 
Published: May 2020

The combination of Density Functional Theory (DFT) with non-equilibrium Greens functions (NEGF) allows for first principles calculations of electronic devices under working conditions, i.e. under the non-equilibrium conditions in the presence of finite electronic current[1]. I will show examples of how the DFT-NEGF method is used to gain insights into the non-equilibrium conduction and current-induced atomic forces in molecular contacts[2]. I will describe how we apply DFT-NEGF including electrostatic gating to study devices based on 2D materials[3,4]. Finally, I will present a recently developed multi-scale approach, combining spatial regions described by DFT with larger regions described by DFT-derived tight-binding. We have employed the multi-scale approach to study transport in molecular-based 2D graphene nanomesh structures going towards the (100 nm)-by-(100 nm) scale[5].

References:

[1] N. R. Papior, N. Lorente, T. Frederiksen, A. Garcia, M. Brandbyge, Comp. Phys. Comm., 212, 8, (2017). M. Brandbyge, J-L. Mozos, P. Ordejon, J. Taylor, K. Stokbro, Phys. Rev. B 65, 165401 (2002).
[2] J. Brand, S. Leitherer, N. R. Papior, N. Néel, Y. Lei, M. Brandbyge, J. Kröger, Nano Lett. 19, 7845 (2019); S. Leitherer, N. Papior, M. Brandbyge, Phys. Rev. B 100, 035414 (2019).
[3] N. R. Papior, T. Gunst, D. Stradi, M. Brandbyge, Phys. Chem. Chem. Phys., 18, 1025 (2016); Stradi, N. R. Papior, O. Hansen, M. Brandbyge, Nano Lett. 17, 2660 (2017); M. Palsgaard, T. Gunst, T. Markussen, K. S. Thygesen, M. Brandbyge, Nano Lett.,
18, 7275 (2018)
[4] N. Papior, G. Calogero, S. Leitherer, M. Brandbyge, Phys. Rev. B 100, 195417 (2019).
[5] G. Calogero, I. Alcón, N. Papior, A.-P. Jauho, M. Brandbyge, J. Am. Chem. Soc. 141, 33, 13081 (2019); G. Calogero, N. Papior, M. Koleini, M. H. L. Larsen, M. Brandbyge, Nanoscale 11, 6153 (2019); G. Calogero, N. R. Papior, B. Kretz, T. Frederiksen, A. Garcia-Lekue, M. Brandbyge, Nano Lett. 19, 576 (2019).
(Invited) Anodic TiO2 Nanotube Layers: Efficient Photocatalyst
Authors: Macak Jan M. 
Published: May 2020

The self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 13 years motivated by their possible range of applications including photocatalysis, solar cells, hydrogen generation and biomedical uses [1,2]. The synthesis of these 1D TiO2 nanotube layers is carried out by a conventional electrochemical anodization of valve Ti metal sheet.
Among other TiO2 nanomaterials, these nanotube layers stand out due to their directionality, tunability of dimensions, ability to absorb significant amount of incident light and the possibility to utilize nanotube interiors and exteriors for decoration-coating of secondary materials.
One of the most significant applications of TiO2 nanomaterials is photocatalysis, which is very effective to decompose various pollutants (e.g. dyes) and kill bacteria [3,4].
The presentation will focus on the utilization of the nanotube layer for photocatalytic removal of various species in the liquid phase [5, 6] as well as gas phase [7]. We will also show that various secondary materials have a positive influence on photo-electrochemical properties of nanotube layers [8, 9]. Experimental details and some recent photocatalytic results will be presented and discussed.
References:
[1] J. M. Macak et al., Curr.
Opin. Solid State Mater.
Sci.,
2007, 1-2, 3.
[2] K. Lee et al., Chem. Rev., 2014, 114, 9385.
[3] K. Rajeshwar et al., J. Photochem. Photobiol. C: Photochem. Rev.
2008, 9, 171.
[4] Ch. Wei et al., Environ.Sci. Technol.
1994, 28, 934.
[5] J.M. Macak et al., Small, 2007, 3, 300.
[6] H. Sopha et al., Appl. Mater. Today,
2017, 9, 104.
[7] H. Sopha et al., Electrochem. Commun.,
2018, 97, 91.
[8] S. Ng et al., Adv. Mater. Interfaces
2017, 1701146.
[9] F. Dvorak et al., Appl. Mater. Today,
2019, 14, 1.
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.