bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Nanofab Lab . . . in a Box!™ for Teaching and Outreach
Authors: Zach Michael
Published: February 2020

Creating patterned nanowires or highly ordered nanostructures is normally a difficult and expensive project that requires use of a multimillion dollar clean room, expensive tools such as an electron beam lithography tool and highly trained technical team to use and maintain the instruments and laboratory. Once the first copy is made, traditional lithographic patterns need to be reproduced starting from bare wafers. Each and every copy of the nanowire circuits requires new wafers, many hours of patterning, photoresist developing, vacuum deposition and selective removal of materials. Once made, characterizing the product requires additional specialized equipment and skills. For all the work involved, there are no short cuts. The full complexity for making patterned nanowires delays hands on nanotechnology until graduate level classes for most students.

The undergraduate research group at University of Wisconsin – Stevens Point has introduced a practical alternative to these techniques for a wide variety of materials (metals, alloys, semiconductors and conductive polymers). Electroplate and Lift Lithography simplifies making patterned nanowires to two steps: electroplate the material on an ultrananocrystalline diamond template and lift the resulting structures away using Scotch tape. Making duplicate copies is accomplished in minutes by repeating the process on the non-sacrificial template. By growing wires for a longer duration, the patterned wires can be characterized with a simple USB powered microscope. The lack of expensive consumables or capital equipment makes this accessible to students even in rural, inner-city or tribal school districts.

As a STEM outreach activity, this provides some extraordinary opportunities for students and provides a pathway for high school students to make novel microwire/nanowire research contributions while they are still in high school. A volunteer from the audience will make nanowires and microwires in a live demonstration of the technique.

Warning for general high school and undergraduate audiences: After making wires, participants are not allowed to claim “I am no good at science” because you will have performed cutting-edge science. The amazing proof will be the wires that you may keep to show your friends!

Figure 1
Electrochemical Energy Conversion: How Can I Successfully Integrate It into My Teaching and Research?
Authors: Gross Michael D.
Published: February 2020

In graduate school I researched a variety of electrochemical concepts and applications including electrodeposition, solid state ion and electron transport, electrode design, and fabrication and characterization of solid oxide fuel cells. Joining the Bucknell University Chemical Engineering department with this background, I had a lot of questions on my mind: What kind of research projects can I realistically tackle with undergraduates?; Can the research be high-quality?; Can I afford the equipment?; How do I efficiently and effectively advise undergraduate researchers?; What kind of electrochemistry electives would be appropriate?; Can I integrate electrochemistry into the core curriculum? During my time at Bucknell I was able formulate very positive responses to all of these questions. To summarize, I have advised 31 undergraduate researchers in the synthesis, design, and characterization of solid oxide fuel cell materials, electrodes, and devices. Fourteen of those undergraduates have co-authored journal publications, many in ECS journals. I was able to do this with a PUI startup budget (along with some ingenuity and undergraduate engineers!). I created an “Electrochemical Energy Conversion” elective course that teaches principles of electrochemistry and applies those principles to fuel cells and batteries. As a member of the CAChE (Computer Aids for Chemical Engineering) Fuel Cell Task Force, I created 11 educational modules that incorporate fuel cell concepts into the core chemical engineering curriculum. In developing all of these educational experiences, my goal was to create an environment that allows students to develop a sense of relevance, competence, and autonomy – key elements in supporting student intrinsic motivation. Here I will share and discuss these experiences and approaches.
(Invited) Using Nanotechnology for Biosensor Applications
Authors: Williams Frances , Komirisetty Archana , Baker Doyle , Pradhan Aswini K
Published: February 2020

Sensor related research has greatly increased over the last two decades due to the need for technology and devices for health and environmental monitoring as well as for biological warfare detection.  New developments in biosensor design are crucial as these devices play important roles in daily life. This research work focuses on the development of sensors including microelectromechanical systems (MEMS) sensors and glucose biosensors that are integrated with advanced nano-materials and bio-coatings to create novel devices that are highly sensitive, inexpensive, accurate, and reliable.

More specifically, this paper presents a device based on electrochemical sensing using a working electrode with bio-functionalized zinc oxide (ZnO) nanorods.  Among all metal oxide nanostructures, ZnO nano-materials play a significant role as a sensing element in biosensors due to their properties such as high isoelectric point (IEP), fast electron transfer, non-toxicity, biocompatibility, and chemical stability. Further, the diameter of these nanostructures is usually comparable to the size of the biological and chemical species being sensed which is beneficial in generating signals that interface well with macroscopic instruments and have high device sensitivity.  The nanorods were immobilized with glucose oxidase (GOx) because of its stability and high selectivity to glucose.  The sensor was characterized for electrical response for the evaluation of the bio-functionalization, sensitivity and response time and yielded a linear range of 0.1mM-10.6mM, sensitivity of 18.15μA cm-1 mM-1and a limit of detection of 0.1mM

In addition, a MEMS sensor that incorporates a lead zirconate titanate (PZT) film will be presented.  For this device the piezoelectric properties of the PZT are exploited to produce sensors that perform optimally for mass sensing applications for sensing biochemical agents.  The sensor is designed to operate as a thin-film bulk acoustic resonator (TFBAR) whereas a piezoelectric is sandwiched between electrodes and senses a change in mass by measuring a change in resonance frequency. The effect of the PZT thickness on device resonance is also presented. The TFBAR sensor consists of 150 nm of PZT, 150nm of silicon dioxide, the silicon substrate, titanium/platinum bottom electrodes, and aluminum top electrodes.  The top electrodes are segmented to increase the sensitivity of the sensor.  The resonance frequency of the device is 3.2 GHz.  This research involves master’s and undergraduate level students.  Thus, the challenges as well as best practices in incorporating beginning-level researchers will also be presented.
A Theoretical Comparison of Optically Concentrating, Solar Water-Splitting Devices
Authors: Stevens John , Weber Adam Z
Published: February 2020

The use of optically concentrating lenses provides a mechanism to reduce the cost and energy input required to manufacture solar fuels-producing devices. The direct production of hydrogen via water splitting could thereby be realized in a cost-competitive, low carbon fashion. In this work, a modeling approach is used to assess which concentrator architectures are appropriate for integration with wireless photoelectrochemical cells. The model captures optical, heat transfer, photoelectrochemical and climactic phenomena. The variation of design parameters such as lens type, optical concentration ratio, deployment location, cell dimensions and tracking schemes are explored.

It is found that the devices that perform most efficiently employ modest concentration ratios, continuous tracking of the sun, and maintain sufficiently small photovoltaic cell size in order to reduce potential losses in the electrolyte. However, designs that exhibit the lowest cost and energy input per unit of produced fuel have somewhat higher concentration ratios and simpler tracking mechanisms. Employing passive cooling to maintain sufficiently low cell temperature during extreme ambient conditions becomes difficult as the photovoltaic cell size and optical concentration ratio increase.

Figure 1
Toward High-Efficiency Scalable GaAs and GaAsxP1-X Photoelectrodes Grown Via Vapor Transport from a Solid Source
Authors: Boettcher Shannon Wachter
Published: February 2020

GaAs and related III-V semiconductors are attractive materials for high-efficiency water-splitting photoelectrodes, but their implementation is limited in part by the high cost of metal-organic chemical vapor deposition, which employs toxic and pyrophoric gas-phase precursors. We report the study of GaAs and GaAsxP1-x grown by close-space vapor transport (CSVT), which uses solid GaAs as a source and water vapor as a transport agent as an alternative low-cost technique for depositing GaAs films and microstructures. The free carrier type and density (1016 – 1019 cm-3) in the films was adjusted by addition of Te or Zn powder to the GaAs source powder. The electronic properties of films grown under a variety of conditions are evaluated and correlated with the film structure and impurity content. We show using photoelectrochemical and electron beam-induced current analyses that the minority carrier diffusion lengths of the n- and p-GaAs epitaxial films reached 2-3 µm and 5-7 µm, respectively. Hall mobilities approach those achieved for GaAs grown by metal organic chemical vapor deposition, 500 - 4,000 cm2 V-1 s-1 for n-GaAs and 50-240 cm2 V-1 s-1 for p-GaAs depending on carrier concentration. Related efforts to control carrier collection through surface texture as well as the growth of GaAs on Si as an inexpensive high-efficiency tandem photoelectrode will also be discussed.

Ritenour, A. J.; Boucher, J. W.; DeLancey, R.; Greenaway, A. L.; Aloni, S.; Boettcher, S. W. Doping and Electronic Properties of GaAs Grown by Close-Spaced Vapor Transport from Powder Sources for Scalable III-V Photovoltaics. Energy Environ. Sci. Accepted, 2014.

Ritenour, A. J.; Levinrad, S.; Bradley, C.; Cramer, R. C.; Boettcher, S. W. Electrochemical Nanostructuring of n-GaAs Photoanodes. ACS Nano, 2013, 7 (8), 6840–6849.

Ritenour, A. J.; Cramer, R. C.; Levinrad, S.; Boettcher, S. W. Efficient n-GaAs Photoelectrodes Grown by Close-Spaced Vapor Transport from a Solid Source. ACS Appl. Mater. Interfaces 
2012, 4, 69-73.
Development of Two-Step Water Splitting Systems Under Visible Light Using Sulfide Photocatalysts
Authors: Higashi Masanobu , Shirakawa Takashi , Abe Ryu
Published: February 2020

Photocatalytic water splitting using semiconductor materials has been attracting much attention due to the potential for the clean production of H2 from water using solar energy. Most of metal sulfide semiconductors, such as CdS, possess appropriate band levels for water reduction and oxidation as well as a narrow band gap allowing visible light absorption because the valence bands of them are mainly formed by S 3p orbital. However, the most of sulfides have no capability of O2 evolution from water due to the occurrence of self-oxidative deactivation by photogenerated holes. Even for the sacrificial H2 evolution, they require particular electron donor such as S2– and SO3
2– to generate H2 stably. In the present study, we attempted to combine some sulfides such as CdS with various reversible electron donors in order to develop two-step water splitting systems based on sulfide photocatalysts. We found that Pt/CdS can oxidize [Fe(CN)6]4– and generate H2 stably, and combining it with an O2 evolution system (TaON photoanode1)) enabled us to split water into H2 and O2 under visible light irradiation (Fig. 1).

1) Higashi, M.; Domen, K.; Abe, R. J. Am. Chem. Soc. 2012, 134, 6968–6971.

Figure 1
Optimization of Photoelectrochemical Performance of Long TiO2 Nanotubes By Li-Doping Induced Defect Passivation
Authors: Tsui Lok-kun , Zangari Giovanni
Published: February 2020

Photoelectrochemical conversion of sunlight into storable fuels has great potential to overcome the challenge posed by sunlight’s transient nature. TiO2 nanotubes are an attractive system for this application due to their high surface area, 1D charge transport, and stability in solution and under irradiation. The photoelectrochemical performance of TiO2 nanotubes need to be optimized by balancing increased light absorption in longer nanotubes against the limitations imposed by the presence of trap states which would increase recombination of photogenerated charges. Although nanotubes from anodizing in low water content electrolytes can access the widest range of nanotube lengths, their high density of trap states facilitates recombination processes.[1] It has been demonstrated that 7 mm long nanotubes maximize efficiency in Nb doped TiO2 nanotubes.[2] Recently, we have shown that trap state passivation can be readily achieved by electrochemically induced Li doping accompanied by the formation of Ti3+ states in TiO2 nanotubes. This treatment suppresses recombination by pre-filling the traps with electrons and yields up to a 2x enhancement in the photoelectrochemical performance for 1 mm long nanotubes (Figure 1 (a)), providing a potential route to extend the length-vs-photocurrent maximum to longer tubes.[3] With this Li doping process we are able to demonstrate a 15 micron long nanotube array yields the highest photocurrent between 1 and 21 mm, generating 1.5 mA/cm2 of photocurrent under simulated sunlight (Figure 1 (b)). Studies by electrochemical impedance have confirmed the trap state passivation mechanism by direct inspection of the density of trap-state levels and electron paramagnetic resonance spectroscopy measurements have identified Ti3+ states that accompany this doping process.

Figure Caption

Figure 1. (a) Lithium modified TiO2 nanotubes show up to 2x enhancement in photoelectrochemical performance at 1.0 VSCE. (b) Photoelectrochemical performance of TiO2 nanotubes up to 21 microns in length shows an optimum at 15 microns after Li doping.

References

References

[1]         L. Tsui, G. Zangari, Electrochim. Acta 121 (2014) 203.

[2]         C. Das, P. Roy, M. Yang, H. Jha, P. Schmuki, Nanoscale 3 (2011) 3094.

[3]         L. Tsui, M. Saito, T. Homma, G. Zangari, J. Mater. Chem. A (2014). In-Press.  10.1039/C4TA05620E

Figure 1
Detection of Mercury with a Surface-Enhanced Raman Scattering Biosensor
Authors: Zheng Peng , Wu Nick
Published: February 2020

There is a risk that toxic heavy metals are released from dental amalgams. This study has demonstrated a sensitive and selective biosensor based on surface-enhanced Raman scattering (SERS), which is capable of measuring mercury(II) ions in human saliva from ppt up to ppb level.  In the biosensor system, the SERS probe and the solid-state chip were functionalized with complementary single-stranded DNA, respectively, except for three artificially designed T-T mismatches. Only in the presence of mercury ions can the SERS probe be captured by the chip due to hybridization of ssDNA, rendering the specific detection of mercury ions. Finite Difference Time Domain (FDTD) simulations have showed that the excellent performance of the SERS biosensor is attributed to the strong coupling between SERS probe and the chip with a high enhancement factor.
(Invited) Improving Charge Transport in TiO2 nanoparticle Based Hybrid Photoanodes through Spatial Control of Graphene Nanoribbon Assembly
Authors: Tung Vincent , Sodhi Jaskiranjeet , Chen Yen-Chang , Ishihara Hidetaka
Published: February 2020

Two-dimensional (2-D) graphene nanomaterials have spurred immense research interests ranging from water splitting solar cells to other energy storage devices because of their tantalizing morphological, nano-mechanical, and electrical properties. However, they tend to be delegated to secondary roles for establishing conductive pathways, as unwanted aggregation detrimentally decreases the fill factor (FF). In this study, we demonstrate the co-assembly of geometrically engineered graphene nanoribbons (GNRs) with TiO2 nanoparticles (T-GNR) at an optimized weight ratio effectively alleviates the aforementioned constraints while synergistically improving junctions (VOC
), electrical contact (JSC
) and FF in photoelectrochemical (PEC) cells. Uniform and controllable-sized GNRs help define the domain of TiO2 nanoparticles well below the upper limit of charge carrier transport length (300 nm), thus effectively eliminating unwanted grain boundaries that are known to act as electron traps. Tip sonication is used to systematically decrease the size of individual GNRs in order to determine a geometric conformation that favors charge transport around TiO2 nanoparticles. Finally, we present the increasing temperature dependence on photocurrent density based on the elimination of defect and surface oxidation from annealing. Through this study, we identified a large gain in photocurrent density of a 3-layered (3L) tip-sonicated T-GNR assembly at 200°C, 72.6% higher than pure TiO2 nanoparticles while simultaneously improving the junction properties and open circuit potential. It also introduced a FF of 66.6% as compared with a pure layer of TiO2 FF of 52.4%.
Synthesis of Zinc Oxide Quantum Dots for Flexible Solar Cell Applications
Authors: Widel Zachary X.W. , Brain Samantha J. , Truffa Julianne , Keleher Jason J
Published: February 2020

Economic distress resulting from dependence on diminishing fossil fuels has emphasized the urgent need for new, clean, and efficient fuel sources.  Developments in understanding solar energy, a versatile, renewable resource, have resulted in the production of bio-inspired materials, including solar cells, which harness the power of light to produce energy.  Commercially available solar cells face severe cost, efficiency, and structural limitations, which must be overcome as the energy crisis progresses. Therefore, interest in the use of dye-sensitized solar cell (DSSC) and quantum dot solar cell (QDSC) technologies as lower cost and higher efficiency alternatives have been on the rise. Unfortunately, many existing QDSCs contain cadmium metal, which is banned in many countries due to its toxicity and leachability into aquatic environments. Furthermore, as a means to combat the structural limitations of traditional solar cells, research on conducting polymeric matrices has been a field of expanding interest. This work sought to employ a “green synthetic” route in the preparation of QDSCs with a conductive polymeric (cellulose) matrix as the active substrate. ZnO quantum dots (QD’s) were synthesized in an alkaline aqueous solution under ambient conditions.  The ZnO QD’s were blended with titanium dioxide (TiO2) nanoparticles in an azeotropic ethanol/water mixture and the resulting dispersion was functionalized with various light absorbing dye molecules. This nanocomposite was combined with the conductive polymer matrix, creating a thin film photoanode for photon capture. The resulting photovoltaic (PV) cell was tested to determine the voltage across the circuit. Current results show that the addition of QDs to the solar cell system results in increased stability as well as a sustainable voltage greater than 50% higher than that of their DSSC counterpart.
Low-Cost MEMS Packaging Using Polymer-Based Air-Gaps
Authors: Phillips Oluwadamilola , Kohl Paul A
Published: February 2020

Packaging of microelectromechanical systems (MEMS) is vital to maintaining device performance and minimizing the impact of environmental threats. Packaging accounts for a substantial portion of the total cost of the MEMS device. In the approach taken here, the movable  MEMS component is encapsulated by a sacrificial polymer in order to protect the device during processing. The component is then packaged in a traditional way, such as by overmolding on a substrate or lead-frame packaging. Thermal decomposition of the sacrificial polymer releases the MEMS device either during or after component packaging. A thermally decomposable sacrificial material, polypropylene carbonate (PPC) and overcoat material BCB (benzocyclobutene) was used for protection of the MEMS device during packaging. PPC decomposition products permeate through the overcoat to leave an air cavity. Control of the thermal decomposition of polypropylene carbonate is an integral part of the process because the MEMS device needs to be released at a critical point in the process.

In this study, the thermal decomposition temperature of the PPC was modified by kinetically inhibiting the thermal decomposition via end-capping. Reacting the hydroxyl-end group of polypropylene carbonate with chemical moieties such as organohalides and mono/difunctional acids alters the thermal stability of these materials. Furthermore, additives such as metal halides and multifunctional alcohols can also alter the thermal decomposition PPC.  In this presentation, the status of these modified polymers in this cavity-forming MEMS packaging process will be discussed.
Effects of B-Site Doping on Double Perovskite Structure Materials for Oxygen Evolution Reactions
Authors: Park Jun-Young , Cho Sung-Hwa , Kim Nam-In
Published: February 2020

In water-splitting electrochemical devices, oxygen evolution reaction (OER) is the most important reaction process because the overall cell efficiency depends strongly on the reaction rate of the OER [1-3]. Over the past decades, noble metal catalysts such as iridium oxide (IrO2), ruthenium oxide (RuO2) and carbon-supported platinum (Pt/C) have shown excellent performances for the OER. However, these noble metal based catalysts have drawbacks for using catalysts of the water-splitting devices due to high cost and limited durability [4-5].

Recently, in order to overcome these technical issues, several perovskite structure-based oxides, which are used as the cathode materials of solid oxide fuel cells, are considered for replacing expensive noble metals [6-7]. To achieve high efficient electrocatalyst for OERs, in this work, transition metals such as Fe, Ni and Cu are doped in the B-site of ABO3 perovskite structure to enhance electrochemical performances. These OER catalysts are synthesized by the combustion method using nitrate precursors [8-10].

Synthesized OER catalysts are characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). To compare effect of different doping materials, electrochemical measurements such as cyclic voltammetry (CV), OER and long-term durability test are measured by rotating disk electrode (RDE) system. For the electrochemical analysis of the OER catalysts, Pt wire and Ag/AgCl electrodes are used as a counter electrode and a reference electrode in alkaline media (0.1 M KOH). The OER activity is measured by the linear sweep voltammetry (LSV) from 1.2 to 1.7 V at a scan rate of 5 mV s-1
with rotating rate of 1600 rpm.

 

Y. J. Sa, K. Kwon, J. Y. Cheon, F. Kleitz, S. H. Joo, J. Mater. Chem. A, 1, 9992 (2013).

J. I. Jung, H. Y. Jeong, J. S. Lee, M. G. Kim, J. Cho, Angew. Chem. Int. Ed., 53, 4582 (2014).

F. Cheng, T. Zhang, Y. Zhang, J. Du, X. Han, J. Chen, Angew. Chem. Int. Ed., 125, 2534 (2013).

Y. Gorlin, T. F. Jaramillo, J. Am. Chem. Soc, 132, 13612 (2010).

Y. Liang, Y. Li, H. Wang, J. Zhou, J. Wang, T. Regier, H. Dai, Nat. Mater., 10, 780 (2011).

S. Yoo, A. Jun, Y. W. Ju, D. Odkhuu, J. Hyodo, H. Y. Jeong, N. Park, J. Shin, T. Ishihara, G. Kim, Angew. Chem. Int. Ed., 53, 1 (2014).

W. Zhou, J. Sunarso, M. Zhao, F. Liang, T. Klande, A. Feldhoff, Angew. Chem. Int. Ed., 52, 14036 (2013).

T. Grewe, X. Deng, H. Tüysüz, Chem. Master., 26, 3162 (2014).

J. Kim, A. Jun, J. Shin, G. Kim, J. Am. Chem. Soc, 97, 651 (2014).

J. H. Kim, M. Cassidy, J. T. S. Irvine, J. Bae, Chem. Master., 22, 883 (2010).

* Corresponding authors: jyoung@sejong.ac.kr (J.-Y. Park).
Electrochemical Synthesis of Ammonia Using Molybdenum-Based Catalyst
Authors: Bateni Hamed , Botte Gerardine G
Published: February 2020

Introduction

Today, ammonia is one of the most important chemical products, which is applicable in the production of fertilizer, explosive materials, and refrigerant (1). The traditional ammonia synthesis method is the Haber-Bosch process, in which nitrogen and hydrogen gases react on enriched iron catalyst at high pressure and temperature. Moreover, the final hydrogen conversion is low due to thermodynamic restrictions (2). Electrochemical synthesis of ammonia is a promising process to overcome the limitation of the conventional catalytic rectors such as the low conversion, severe environmental pollution, and high energy consumption (3). Several metals such as platinum (Pt), iridium (Ir), and iron (Fe) based catalysts have been tested for ammonia production through the electrochemical process (4). Apart from catalyst, different kinds of electrolyte including liquid electrolyte, molten salts, composite membrane, and solid state electrolyte have been tested for ammonia synthesis. Liquid electrolytes are effectively active at lower temperature with respect to other electrolytes (5).

Although several studies have been performed on electrochemical synthesis of ammonia, most of them represent very low ammonia production rate even in high pressure or high temperature conditions.

In this study, liquid electrolyte containing molybdenum (Mo) based catalyst will be investigated to facilitate electrochemical synthesis of ammonia at atmospheric pressure and ambient temperature. The effect of catalyst concentration on the process yield will be studied to develop an appropriate catalytic media for the cathodic reaction of electrochemical reduction of nitrogen to ammonia.

Pure hydrogen and nitrogen will be used in the process and product analysis will be performed using ammonia ion-selective electrode (ISE) to determine the concentration of ammonia.

 

References

1. M. Karolewska, E. Truszkiewicz, B. Mierzwa, L. Kępiński and W. Raróg-Pilecka, Applied Catalysis A: General, 445, 280 (2012).

2. W. Wang, X. Cao, W. Gao, F. Zhang, H. Wang and G. Ma, Journal of Membrane Science, 360, 397 (2010).

3. I. A. Amar, R. Lan, C. T. Petit and S. Tao, Journal of solid state electrochemistry, 15, 1845 (2011).

4. M. Hasnat, M. Karim and M. Machida, Catalysis Communications, 10, 1975 (2009).

5. S. Giddey, S. Badwal and A. Kulkarni, International Journal of Hydrogen Energy, 38, 14576 (2013).
The Roles of the Particle Size of Ge-Based Electrodes on the Electrochemical Performance of Lithium-Ion Batteries
Authors: Mishra Kuber , Isenhower John , Zhou Xiao-Dong
Published: February 2020

High capacity negative electrode materials such as silicon and germanium have been known to undergo massive volume change during lithiation/delithiation process. The large volume expansion in Si (~400%) and Ge (~280%) has been attributed to the fracture of the electrode materials, delamination from the current collector and losing contacts with the binder, resulting in rapid loss of capacity.1

Here we report our studies on the effects of particle size on the electrochemical performance of Ge electrode. Ge particles of different sizes (0.1-0.3, 0.3 -0.5, 0.8-1, >1 µm, ) are obtained by varying the time of ball milling and their capacity performances were measured by assembling a coin cell with the lithium metal as the counter electrode.

The obtained results displayed the rapid capacity loss of the electrode with Ge particle size >1 µm, while the ones up to ~0.5 µm displayed significant stability. For the first 40 cycles tested, the Ge particles up to 0.5 µm retained ~90% of the initial charge capacity, and the ones with particle size 0.1-0.3 µm retained more than 95% of the initial charge capacity at the current density of 500 mA/g . For the Ge particle size > 1µm, the capacity retention even at the low current density of 100 mA/g at the end of 40 cycles was measured to be ~37%.

This result demonstrates that above an optimum size, the Ge electrode exhibits rapid degradation of the performance. Further work is being carried out to determine the optimum size of the Ge electrode which yields a stable electrochemical performance. Fracture behavior of the Ge particles based on fracture mechanics will be reported. Theoretical analysis based on a rigorous continuum mechanics model will be used to extract critical size for Ge-based electrodes.

References:

1.             Wang, C.; Wu, H.; Chen, Z.; McDowell, M. T.; Cui, Y.; Bao, Z., Self-healing chemistry enables the stable operation of silicon microparticle anodes for high-energy lithium-ion batteries. Nat Chem
2013,
5 (12), 1042-1048.

Figure 1
Electric Current Rectifying Device That Is Completely in Liquid State: A Theoretical Proposal
Authors: Guerrero-Garcia Guillermo Ivan , Raidongia Kalyan , Huang Jiaxing , Olvera de la Cruz Monica
Published: February 2020

In recent years there has been an increasing interest in the development of electronic devices using non-conventional soft matter materials, as a novel alternative to traditional solid state electronic devices. These traditional solid state devices are fragile and usually are made of non-biocompatible materials. The possibility of producing resilient nano-electronic devices opens a new avenue in the development of technological applications. In this work, we propose the theoretical construction of an electric current rectifying device using a mixture of electrolytes in a configuration that is completely in liquid state.
Tin Oxides with Nano and Micron-Sized Pores for Functional Electrochemical Devices
Authors: Kim Eun-Ji , Shin Heon-Cheol
Published: February 2020

Metal oxides with one-dimensional (1-D) nano-channels have drawn much attention as potential electrode materials for high performance functional electrochemical devices. This is mainly because the large surface area of nanostructures and the 1-D pathway of reactants/products in channels result in low activation and concentration polarizations, respectively. In spite of such advantages, the expected high rate and high efficient operation of the devices adopting the electrodes with nano-channeled structure might not be quite sustainable particularly when the rate of surface reaction far exceeds that of mass transport through the channels. That is, the reactants/products would be seriously depleted/accumulated in the channel at the very high rate of surface reaction, possibly leading to the significant decrease in total reaction rate. One way to solve this problem is to prepare the hybrid porous structure composed of both nano-sized and micron-sized pores, where the latter efficiently provides the reactants to or receives the products from the nano-channels.

It has been known that an anodic oxidation process is a quite effective way to create the metal oxide films with well-defined 1-D nano-channeled structure. Among the anodic metal oxides with 1-D structure, tin oxide is worthy of attention due to its widespread use in various applications, such as catalysis, gas sensing and energy storage. In this work, meso- and macro- hybrid porous structure is created without a template by an anodic oxidation process. From the experimental results, it is suggested that the substrate, the anodizing time, the thickness of the pre-anodized tin have an important effect on the size and density of macro-pores in hybrid porous structure. For example, the well-defined meso/macro hybrid porous tin oxides can be created when silicon was used as a substrate to anodize tin thin film. On the basis of the mechanical analysis of the different substrates and different thicknesses of tin film on them, it is suggested that the substrate with high elastic modulus might result in high compressive stress to the anodic tin oxide and generate local cracks in the initial stage of anodizing process, which grow to macro-pores with semispherical shape in the later stage.

From two step anodizing process including the intervening selective etching of tin oxide, highly-open meso/macro hybrid porous tin oxide is successfully prepared. Anodic tin oxide formed under the macro-pores has meso-porous structure with radial shape, ideally suited for high rate and high efficient functional electrochemical devices.
Direct Electrochemical Synthesis of Epitaxial Germanium Nano- and Micro-Wire Arrays at Room Temperature in Water
Authors: Fahrenkrug Eli , Gu Junsi , Maldonado Stephen
Published: February 2020

The ability to synthesize structurally and electrically integrated group IV semiconductor nanostructures directly into devices is desirable for continued miniaturization of transistors. However, the most common nanofabrication architectures are largely incompatible with the high temperature semiconductor growth processes currently available. We developed a new aqueous electrochemical synthesis strategy termed electrochemical liquid-liquid-solid (ec-LLS) growth that uses a liquid metal as a traditional cathode and as a recrystallization solvent to synthesize crystalline semiconductors at room temperature. This presentation will highlight data that extends the ec-LLS strategy to using nanoscale arrays of liquid gallium (Ga(l)) and GaxIn1-x alloy electrodes supported on Si wafers for the electrodeposition of epitaxial Ge nanostructures. Detailed electron microscopy will be presented which verifies the epitaxial and single crystalline nature of the structures integrated with the wafer substrates. The influence of electrode composition on resultant morphology, crystal quality, and solid-state electrical properties will be discussed. The coupling of this ec-LLS synthesis technique with liquid metal photolithography techniques developed in our lab will also be mentioned within the context of growing complex 1D, 2D and 3D Ge crystals with high degrees of spatial control.
On the Electrochemical Dealloying of Binary Al-Cu and Ternary Al-Cu-Sn Alloys
Authors: Song Tingting , Yan Ming , Shi Zhiming , Atrens Andrej , Qian Ma
Published: February 2020

Chemical de-alloying of binary Al75Cu25 (at.%) alloy (consisting of α-Al and Al2Cu) can be used to prepare bulk nanoporous Cu which shows promise for a number of applications. Chemical de-alloying of ternary Al67Cu18Sn15 alloy (consisting of α-Al(Cu), Al2Cu and β-Sn(Al,Cu)) can result in nanoporous Cu3Sn-Cu-Cu6Sn5composites where re-alloying between Cu atoms released from de-alloying and Sn atoms in the precursor is involved.  Compared to chemical de-alloying in toxic and expensive solutions, electrochemical de-alloying in neutral salt solution has the advanategs of being pollution-free, inexpensive and readily available.

This paper reports the results obtained from electrochemical dealloying of binary Al75Cu25 alloy and ternary Al67Cu18Sn15 alloy by using potentiodynamic polarization, cyclic voltammetry (CV) and potentiostatic polarization measurements. For electrochemical de-alloying of the binary Al75Cu25, the asynchronous dealloying behaviour and the final size of the porous structure are both potential dependent. For de-alloying of the ternary Al67Cu18Sn15, the concurrence of de-alloying and re-alloying is potential dependent. In addition, when the applied potential (-0.5 V) is below the critical potential of the Al2Cu phase (-0.41 V), electrochemical de-alloying of Al75Cu25 can be complete leading to nanoporous Cu (52 ± 10 nm). However, complete de-alloying does not occur to the ternary Al67Cu18Sn15 alloy under the same condition due most likely to the existence of β-Sn(Al,Cu) phase.
FDTD Analysis for Devices with Glass Substrates and Its Application to Antireflection Coating on Organic Solar Cells
Authors: Kubota Shigeru , Kanomata Kensaku , Ahmmad Bashir , Mizuno Jun , Hirose Fumihiko
Published: February 2020

Organic photovoltaics (OPVs) have been receiving growing interest, because they can provide large area and low cost solar cells for next generation. A power conversion efficiency (PCE) of more than 10 % under AM 1.5 illumination has been reported for the OPVs, although higher level of PCE is required for large-scale commercialization. Since the maximum thickness of light absorbing layer (around 100 nm) is determined by the low carrier mobility of organic semiconductors, it is important to develop antireflection technologies that can enhance light trapping in the thin absorbing layer. A popular method for analyzing light propagation within solar cells is the finite-difference time-domain (FDTD) simulation. In the FDTD method, the electric and magnetic field are spatially discretized on the grid and the temporal evolution of the field intensities is obtained through numerical integration. An advantage of the FDTD method is that it can obtain optical response for a wide wavelength range in a single simulation by Fourier transforming the results obtained by a brief input pulse. However, the FDTD simulation suffers from a considerable increase in calculation time when there is a glass substrate in the light path, which is much thicker than the other material layers within solar cells. To overcome this problem, in this study, we explore a new technique for FDTD simulation, to significantly reduce computational cost in the presence of a thick substrate, and apply this technique to the optical design of moth eye antireflection coatings on OPVs. In the proposed method, the absorption spectrum is averaged to eliminate the interference effect of light passing through a thick glass substrate and reproduce incoherent light addition within the substrate. We compare the proposed averaging method with the other two types of averaging methods, and show that the proposed algorithm gives the most accurate solution. In addition, our method is quite robust and independent of detailed values of control parameters. The validity of the results is checked by the comparison with the results obtained by the characteristic matrix method. In addition, we apply the proposed method to optimize the geometric pattern of moth eye array and maximize light trapping in OPVs. The results show that the combination of the FDTD simulation with our averaging method is quite useful to design broadband antireflection coatings for solar cells having thick glass substrates.
Effects of 3-Aminopropyl Triethoxysilane (APTES) on Stability, Optical Properties and Morphology of Gold Nanoparticles
Authors: Farrell Monique , Rutherford Gugu , Pradhan Aswini K
Published: February 2020

The purpose of this study was to determine the extent to which 3-aminopropyl triethoxysilane (APTES) could impact the stability, optical properties and morphology in gold (Au) colloidal solutions. Several concentrations ranging from 48mM to 475mM were utilized throughout the duration of the study. Ultraviolet–visible absorption results confirm extensive red shifts in the absorbance spectrum from 500nm to 650nm respectively. SEM characterization confirms that red shifts are largely due to aggregation of nanoparticles as opposed to particle growth. With the addition of APTES, the photoluminescent properties of the gold increased as a function of the concentration as well as time. Our findings suggest that the degree of aggregation and ultimately the change in optical properties is a strong function of the concentration of APTES, pH and time; independent of being in solution or adhered to a substrate. This work is important for future use of synthesized or purchased nanoparticles that will be manipulated or modified using this chemical.

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Quinone Electrochemistry: From the Electron Transport Chain to Electron Mediators and Orientational Moieites
Authors: Minteer Shelley D. , Giroud Fabien , Milton Ross D , Tan Boxuan
Published: February 2020

Quinones play a vital role in electron transport chains (ETC) in mitochondrial (eukaryotic) and bacterial (prokaryotic) cells. Within the mitochondrial ETC, ubiquinone (coenzyme Q) is responsible for transporting electrons and protons from complexes I and II to complex III, where the ETC ultimately produces adenosine triphosphate (ATP) from ATP synthase. Within bacterial cells, ubiquinone and menaquinone also act as electron and proton carriers between large membrane-bound complexes. Quinone functionality is also required for many oxidoreductase enzymes, which utilize a pyrroloquinoline quinone (PQQ) cofactor.

Naphthoquinone derivatives have been investigated for their suitability within enzymatic fuel cells (EFCs). At the bioanode, the electrochemical properties of naphthoquinone derivatives can be exploited to yield a bioanodic architecture that can mediate electron transfer between anodic enzymes and the electrode. In contrast, the chemical properties (not electrochemical redox properties) of the same naphthoquinone electrode architecture can be utilized at the biocathode of an EFC to efficiently orientate oxygen-reducing enzymes to undergo the direct bioelectrocatalytic reduction of oxygen.

The use of the same electrode architecture at the bioanode and biocathode of EFCs results in a simplified EFC design, which ultimately results in lower manufacturing costs of devices.
(Invited) Glycofullerenes for Biological Applications
Authors: Martin Nazario
Published: February 2020

The carbohydrate-protein interaction is a key issue in a variety of biological processes. Actually, this molecular recognition is usually one of the selective steps triggering different biological processes affording biological functions. This interaction is characterized by a high selectivity, strong dependence on some specific metal cations and a remarkable low affinity.

The way in which mother Nature solves this low affinity is by means of the so-called multivalent interactions, which involves using many copies of receptor (lectines) and a multivalent presentation of the ligand (sugar). Thus, the development of the required tools for a better understanding of the biological processes involving carbohydrates are based in the design and preparation of multivalent carbohydrates systems.

We have recently shown that fullerenes are appealing suitable spherical molecular scaffolds for the construction of globular structures decorated at will on the periphery in the search for new biologically active supermolecules.1 In this communication, the most recent advances in the synthesis of giant globular structures on different carbon nanostructures as well as their efficiency in inhibiting the Ebola virus infection will be discussed.

References:

a) J.-F. Nierengarten, J. Iehl, V. Oerthel, M. Holler, B. M. Illescas, A. Muñoz, N. Martín, J. Rojo, M. Sánchez-Navarro, S. Cecioni, S. Vidal, K. Buffet, M. Durka, S. P. Vincent, Chem. Commun.
2010, 46, 3860 – 3862; b) M. Sánchez-Navarro, A. Muñoz, B. M. Illescas, J. Rojo, N. Martín, Chem. Eur. J. 2011, 17, 766; c) J. Luczkowiak, A. Muñoz,  M. Sánchez-Navarro, R. Ribeiro-Viana, A. Ginieis, B. M. Illescas, N. Martín, R. Delgado, J. Rojo, Biomacromolecules
2013, 14, 431−437.

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Inkjet Printed Single Walled Carbon Nanotubes As Active Semiconductors in Thin-Film Transistors and Circuits
Authors: Dodabalapur Ananth , Kim Bongjun , Jang Seonpil , Geier Micheal , Hersam Mark C.
Published: February 2020

Inkjet printed single walled carbon nanotubes (SWCNTs) can be incorporated as active layers in thin-film transistors with promising performance.  When the channel length is much larger than the average nanotube length (~ 1 mm), charge transport takes place through a network of nanotubes and the SWCNT film behaves like an effective medium with a mobility in excess of 25 cm2/V-s, which makes them suitable for a number of applications.  In such devices, the on/off current ratio can be very high (> 105). In devices with channel length less than individual nanotube dimensions, we can get high transconductance devices which can be either p- channel or ambipolar depending on the details of the device structure. We will describe in detail characteristics of both types of SWCNT Transistors.

The materials combination of inkjet-printed single-walled carbon nanotubes (SWCNTs) and zinc tin oxide (ZTO) is very promising for large-area thin-film electronics. We compare the characteristics of conventional complementary inverters and ring oscillators measured in air (with SWCNT p-channel Thin-film transistors (TFTs) and ZTO n-channel TFTs) with those of ambipolar inverters and ring oscillators comprised of bilayer SWCNT/ZTO TFTs. This is the first such comparison between the performance characteristics of ambipolar and conventional inverters and ring oscillators. The measured signal delay per stage of 140 ns for complementary ring oscillators is the fastest for any ring oscillator circuit with printed semiconductors to date. We also demonstrate novel voltage controlled ring oscillators which are promising for analog to digital conversion circuits.
(Invited) New Methods to Probe the Surfactant Structure Surrounding Swcnts
Authors: Ziegler Kirk J , Xu Jia , Clar Justin , Bonzongo Jean-Claude J
Published: February 2020

The surfactant structure surrounding single walled carbon nanotubes (SWCNTs) plays an important role in their separation by nearly any method. However, characterizing the structure of these molecular layers remains difficult. The structure of the surfactant or other molecules around the SWCNTs could also have important implications in toxicology and drug delivery. While changes to the local environmental surrounding SWCNT can be observed by photoluminescence (PL), it does not directly probe the surfactant or its structure. Here we describe how proton NMR and Pulsed Field Gradient NMR can monitor the interaction of surfactant with the SWCNTs. By combining PL and Proton NMR analysis, we aim to understand the formation and morphology of surfactant structures that form around SWCNTs, especially differences that exist for metallic and semiconducting species. We find that the observed critical micelle concentration (CMC) is dependent on the SWCNT loading. In some cases, the observed CMC is actually below the surfactant-only solution. The ultimate goal is to learn how to control these structures around SWCNTs to influence their interaction with biological materials and other surfaces.
Modifying Carbon Nanotubes with Electroactive Systems
Authors: Martin Nazario
Published: February 2020

The readily available and highly versatile electron donor exTTF molecule has proved its efficiency for the design of unprecedented receptors for fullerenes and other carbon nanoforms. In this regard, custom-made tweezers and macrocyclic receptors are proving a valuable alternative to achieve the affinity and selectivity required to meet goals such as the selective extraction of higher fullerenes, their chiral resolution or the self-assembly of functional molecular materials.[1] In this presentation some important breakthroughs based on electroactive systems derived from exTTF as molecular and macrocyclic receptors for single wall carbon nanotubes will be highlighted. Bowl and belt-shaped CNTs receptors based on this concave-convex complementarity principle will also be presented.[2] The recognition motives have been applied with the aim of  modifying their electronic properties,[3] as well as for the hierarchical organization of mesoscopic 3D helical fibers.
[4]

References:

[1] a) E. M. Pérez, L. Sánchez, G. Fernández, N. Martín, J. Am.
Chem. Soc., 2006, 128, 7172-7173; b) E. M. Pérez, N. Martín, Chem. Soc. Rev., 2008, 37, 1512-1519; c) D. Canevet, E. M. Pérez, N. Martín, Angew. Chem. Int. Ed. 2011, 50, 9248 – 9259.

[2] a) M. Gallego, J. Calbo, J. Aragó, R. M. Krick Calderon, F. H. Liquido, T. Iwamoto, A. K. Greene, E. A. Jackson, E. M. Pérez, E. Ortí, D. M. Guldi, L. T. Scott, N. Martín Angew.
Chem. Int. Ed., 2014, 53, 2170-2175; b)  A. de Juan, Y. Pouillon, L. Ruiz-González, A. Torres-Pardo, S. Casado, N. Martín, Á. Rubio, E. M. Pérez Angew.
Chem. Int. Ed.,
2014, 53, 5394-5400; c) H. Isla, E. M. Pérez, N. Martín, Angew. Chem. Int. Ed., 2014, 53, 5629-5633.

[3] a) C. Romero.Nieto, R. García, M. A. Herranz, Ch. Ehli, M. Ruppert, A. Hirsch, D. M. Guldi, N. Martín, J. Am.
Chem. Soc., 2012, 134, 9183−9192; b) C. Romero-Nieto, R. García, M. A. Herranz, L. Rodríguez-Pérez, M. Sánchez-Navarro, J. Rojo, N. Martín, D. M. Guldi. Angew. Chem. Int. Ed, 2013, 52, 10216-10220. 

[4] J. López-Andarias, J. L. López, C. Atienza, F. G. Brunetti, C. Romero-Nieto, D. M. Guldi, N. Martín, Nat.
Commun., 2014, DOI: 10.1038/ncomms4763.

Figure 1