bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metal Organic Frameworks: A Platform for Electrocatalytic Fuel Generation
Authors: Hod Idan , Farha Omar K. , Hupp Joseph T. 
Published: February 2020

Over the last two decades, metal-organic frameworks (MOFs) have attracted a great deal of scientific interest due to their extremely high porosity and surface areas. The vast number of combinations of node and ligand-based properties makes MOFs exciting candidates for a wide variety of applications, including gas storage, chemical separation and catalysis, where bulk crystalline powders or solution dispersions of MOFs have been utilized. However, only a few attempts have been made to explore the incorporation of MOFs into thin films to be used in electrocatalysis.
In this work we demonstrate that MOFs could be beneficial when utilized in an electrocatalytic system. An electrode-supported MOF scaffold was used as a platform for NiS electrodeposition to create a hybrid HER electrocatalyst. In aqueous pH 1 solution, the MOF-NiS hybrid exhibit significantly improved catalytic performance compared to a flat NiS-only based system, reducing the required overpotential at current density of 10 mA/cm2 by more than 200 mV down to 238 mV. It was found that the aquo- and hydroxo-rich nodes of the MOF appear to modify the immediate environment of the NiS electrocatalyst, rendering it more favorable for local proton delivery and/or transport.

Figure 1
Electrochemical and UV-Visible Spectroscopic Studies of Self-Organized Gold Nanoparticle~Cytochrome C Superstructures
Authors: Harper-Leatherman Amanda S. , Pacer Elizabeth R. , Abunar Bayan H. , Spiridigliozzi Julia K. , Graffam Molly E. , Garvey Elizabeth M. , Buzard Kaitlyn L. 
Published: February 2020

The addition of the protein, cytochrome c (cyt. c), to gold nanoparticles in solution results in self-organization of cyt. c into multilayered protein superstructures (abbreviated as Au~cyt. c superstructures) and stabilizes the thousands of organized cyt. c proteins to unfolding both when encapsulated in porous solids and when remaining in solution. Our research has shown that the electrochemical characteristics of superstructure-assembled cyt. c are enhanced compared to cyt. c alone and vary as the ratio of cyt. c to Au varies. In order to determine whether the enhanced electrochemical properties are directly related to the multiple protein layers of the superstructures staying intact at the electrode surface, the protein superstructures were stripped from the electrode surface and measured with UV-visible spectroscopy. The UV-visible absorbance of the cyt. c Soret peak, and subsequent calculated cyt. c electrode surface coverage, varied as the ratio of gold to protein varied. These results support the idea that at an optimal ratio of gold to protein when forming superstructures, the cyt. c electrochemical properties are enhanced and are related to multiple proteins remaining active within superstructures at the electrode surface. These results may prove useful to those developing bioanalytical devices when a good understanding of the interaction between protein and material surface is needed.
(Invited) High Performance Nano-Carbon/Silicon Solar Cells Via Strategic Doping Processes
Authors: Taylor André D. 
Published: February 2020

Hybrid approaches that combine silicon (Si) and nano-carbon (nano-C) materials-based thin films (i.e., single walled carbon nanotube (SWNT) films or graphene) have recently led to novel and promising photovoltaic devices. The main advantage is that the intrinsically high photovoltaic efficiency of Si can be realized in a cost-effective manner owing to the low-temperature solution processibility inherent to the fabrication of nano-C/Si junctions. Indeed, efficiencies up to 15% have recently been reported, which surpasses the best efficiency of any polymer/Si hybrid solar cells developed with a similar motivation towards reduced fabrication cost. This superiority is mainly due to the excellent electrical properties of the nano-C materials in comparison to conventional conjugated polymers. In this talk, we demonstrate that easy to handle metallocenes and related complexes can be used to both p-type and n-type dope SWNT thin films, using a simple spin coating process [1]. We report n-SWNT/p-Si photovoltaic devices that are >450 times more efficient than the best solar cells of this type currently reported and show that the performance of both our n-SWNT/p-Si and p-SWNT/n-Si devices is related to the doping level of the SWNT. Furthermore, we establish that the electronic structure of the metallocene or related molecule can be correlated to the doping level of the SWNT, which may provide the foundation for controlled doping of SWNT thin films in the future [1]. In a separate approach we will show how HF treatment of SWNTs followed by current stimulation is a very effective method for oxygen removal with broad applications for carbon electronics [2]. Finally, we will describe how direct solution casting of silver nanowires (AgNWs) onto the SWNT/Si junctions leads to a significant improvement of photovoltaic properties owing to enhanced carrier transport in the bilayer AgNW/SWNT composites [3]. This improvement becomes particularly more pronounced with increasing junction area, which results in a significantly high efficiency of ~11 % in SWNT/Si solar cells with the largest junction area (49 mm2) developed so far [3].
[1] X. Li, L.M. Guard, J. Jiang, K. Sakimoto, J.-S. Huang, J. Wu, J. Li, L. Yu, R. Pokhrel, G.W. Brudvig, S. Ismail-Beigi, N. Hazari and A.D. Taylor (2014) Controlled doping of carbon nanotubes with metallocenes for application in hybrid carbon nanotube/Si solar cells, Nano Letters, 14 (6), 3388–3394. DOI: 10.1021/nl500894h
[2] X. Li, J-S. Huang, S. Nejeti, L. McMillon, S. Huang, C.O. Osuji, N. Hazari, A.D. Taylor (2014), The Role of HF in Oxygen Removal from Carbon Nanotubes: Implications for High Performance Carbon Electronics, Nano Letters, 14 (11), 6179-6184. DOI: 10.1021/nl502401c
[3] X. Li, Y. Jung, J-S. Huang, T. Goh , and A.D. Taylor (2014), Device Area Scale-Up and Improvement of SWNT/Si Solar Cells Using Silver Nanowires, Advanced Energy Materials, 4 (12), 1400186. DOI: 10.1002/aenm.201400186
Li@SWCNT and Cup-Stacked Carbon Nanotubes for Dye-Sensitezed Solar Cells
Authors: Matsubara Elaine Yoshiko , Rosolen Jose Mauricio , Bregadiolli Bruna Andressa , Congiu Mirko , Graeff Carlos Frederico de Oliveira 
Published: February 2020

Carbon Nanotubes (CNTs) are extensively studied for energy applications, mainly as additives in composite electrodes to promote electric and thermal conductivity, reinforce the mechanical strength, and enhance the flexibility and performance. Also, introduction of this nanomaterial into the semiconductors electrodes can reduce the resistance of the active materials and produce a composite nanomaterial, due to the electronic interactions between carbon nanostructures and other nanomaterials or substrates.
The studies developed by our group are concentrating on the synthesis of doped carbon nanotubes having different pristine properties produced by CVD or arc-reactor methods for energy devices applications.
The synthesis of Li@SWCNT by arc-reactor method produced selectively metallic tubes, with wettability in water and polar solvents [1]. For Cup-stacked carbon nanotubes (CSCNT) synthetized by CVD method, the tubes present semiconductor properties, high defective structure and wettability too. Herein, we realized studies in photoanode and counter electrode for dye-sensitized solar cells (DSSC) about the use of these two CNTs due to their special properties.
The photovoltaic properties were characterized by photocurrent-voltage (J-V) curves under illumination and impedance spectroscopy in order to study the incorporation of CNTs effects in the photoanode (CSCNT) and counter electrode (Li@SWCNT).
The CSCNT presented better performance for photoanode in DSSC due to the semiconductor and defective structure that promotes better interaction between CSCNT and TiO2 paste used to prepare the electrode. The addition of CSCNT in the concentration range 0.3 to 0.1 wt% (TiO2 electrode doping with CSCNT) has positive effects on the efficiency of DSSC, like the increase of the photocurrent and the efficiency, further on the photoanode remains transparent. The best result was obtained for 0.26% wt% of CSCNT.
On the other hand, Li@SWCNT showed best results when used as counter electrode. This material showed the same behavior as platinum in impedance spectroscopy and was incorporated by spray method in the FTO glass substrate.
[1] Matsubara, E.Y.; Luengo, C.A. and J.M. Rosolen. Lithium-doped endohedral single-walled carbon nanotubes can arise during tube growth. Chemical Physics Letters 590, 175–179 (2013).
Effect of Gate Electrode in Electrochemical Cells
Authors: Chowdhury Tazima , Grebel Haim 
Published: February 2020

Electrochemical cells consist of two half-cells containing each an anode and a cathode. There is an ionic contact between the two half-cells to maintain the flow of ionic charge. In order to maintain the charge flow in a voltaic cell, a salt bridge is placed between the two half-cells. We replaced the salt-bridge by a third electrode - a conductive and permeable gate electrode. A bias potential was then applied to this gate electrode. In that way, we were able to control the external current of the cell. This would be the first step towards the realization of ion transistors.
In preliminary studies, several gate electrodes were considered: layers of functionalized carbon nanotubes (CNT) and metal plate capacitors. Cyclic voltammetry and electrochemical impedance spectroscopy revealed the effect of the gate bias on the effective capacitance and impedance of the cell.
Current-Voltage measurements (I-V curves) were made on layered structures, which were made of p-type and n-type CNT. These data clearly exhibited the formation of barrier(s) between the two layers. Cyclic voltammetry (CV) measurements were carried out using an electrochemical workstation (CHI760C, Electrochemical Instrument) at room temperature and using 0.01 M solution of NaCl as electrolyte. Various scan rates of 0.01, 0.05, 0.1 and 0.5 Vs-1 were assessed. Two graphite rods, one serving as a working and the other as a counter electrode, were used. Ag/AgCl (3M KCl filled) electrode served as the reference. The gate electrode was placed in the middle of the cell, between the working and counter electrodes. The corresponding specific capacitances were calculated from the CV data.
Electrochemical impedance spectroscopy (EIS) was performed for each of the gate electrodes, as well. The data were taken at a dc bias of 0.24 V with sinusoidal signal of small magnitude over sub to kilo Hertz frequency range. The capacitive behavior was more pronounced at low frequencies. Membranes composed of p-i-n structures, a p-type layer of CNT, followed by an insulating layer of MMA and finished by an n-type CNT all deposited on a 10-micron Teflon filter substrate exhibited the larger capacitive behavior compared to p-n layered membranes or metallic capacitor.
Chrono-potentiometry method was performed for gate electrodes. The curve within a potential window indicated from the time constant better capacitive behavior in p-i-n than other two gate electrodes. The value indicated in milli farad magnitude which is similar to the range of values found in cyclic voltammetry and electrochemical impedance spectroscopy techniques.
References:
[1] Y. Zhang, H. Grebel, “Controlling Ionic Currents with Transistor-like Structure”, ECS Transactions 2 (18). 2007
[2] S. Sreevatsa, H. Grebel, “Carbon Nanotube Structures as Ionic Barriers: A New Corrosion Prevention Concept”, ECS Transactions 19 (29) 91-100. 2009
(Invited) Roll-to-Roll Synthesis of Vertically Aligned Carbon Nanotubes with Embedded Redox Polymers
Authors: Roberts Mark E. , Arcila-Velez Margarita Rosa , Zhu Jingyi , Podila Ramakrishna , Karakaya Mehmet , Rao Apparao M. 
Published: February 2020

Electrochemical double layer capacitors (EDLCs), often referred to as supercapacitors, have been the focus of considerable research to develop ultra-high surface area materials with high power and energy density. Activated carbon represents the state-of-the-art EDLC electrode material due to its high porosity, high surface area, and chemical stability. More recently, vertically aligned carbon nanotubes (VACNTs) have emerged as an alternative material due to their high conductivity, stability, facile synthesis and the ability to control the ion-accessible area by varying nanotube density.
VACNT electrodes have been used to achieve high power EDLCs; however, scalable manufacturing methods remain elusive, and the ability to grow VACNTs directly on current collectors will help overcome many hurdles facing commercial application. While the chemical vapor deposition (CVD) method is relatively versatile in terms of controlling CNT characteristics (e.g., tube diameter, number of walls, and dopant ratio), three primary factors limit continuous manufacturing of nanomaterials: i) substrate size determined by reactor geometry, ii) requirements of complex catalytic substrate preparation, and iii) high operating temperatures that are incompatible with traditional current collectors (e.g., Al foil).
In this work, we present a continuous, roll-to-roll process for synthesizing VACNT forests directly on inexpensive Al foil using the ferrocene-xylene liquid injection floating catalyst technique. The Al foil is continuously drawn through a chemical vapor deposition reactor operating at ambient pressure and a relatively low temperature (600 °C). EDLC electrodes comprising VACNT forests synthesized in continuous and stationary CVD processes were directly assembled into supercapacitor cells, which yielded high power densities (1270 W/kg) and energy densities (11.5 Wh/kg). These devices exhibited very low internal series resistance due to their intimate contact with the current collector and excellent cycle stability with no loss in performance over multiple thousands of cycles.
The energy density of VACNT electrodes is increased by integrating high charge capacity redox polymers within the VACNT eelctrodes. In the continuous process, electroactive conducting polymers and redox polymers are embedded into VACNTs using electrochemical methods and physical adsorption processes. Current progress on the performance and limitations of incorporating redox polymers with carbon nanomaterials will be discussed along with the advantages and challenges in future material development.
Graphene for Energy: Which Promising Applications and How?
Authors: Quesnel Etienne 
Published: February 2020

With thousands of publications per year, graphene has raised a particularly great attention these last years. It is true that with an extraordinary combination of physical and technical properties including high flexibility, lightness, electronic mobility and ability to easily change its chemical properties by surface chemistry, graphene appears as an outstanding material which characteristics can interest many fields of application. Among them, energy conversion, production or storage are of such interest that the European's biggest research initiative, the “Graphene Flagship[1]” dedicated a specific work package only to that topic.
The present talk aims at reviewing some of these energy applications where graphene and graphene related materials are thought to provide disruptive performances. Actually, fulfil of these promises will depend on the control of the full value chain going from graphene production to integration into the energy devices. Moreover, to fully benefit from graphene properties, the integration strategies have to address the interfacing issue of graphene with hosting material. Further graphene functionalization steps are thus often necessary to adapt the surface graphene properties. It leads to the development of various graphene functionalization technologies without which a successful transfer of graphene into energy applications would be impossible. Various examples dealing with graphene doping, nano-structuring or nano-decorating will be discussed to illustrate the key role of these enabling technologies.

[1] http://graphene-flagship.eu/
Enhancement of Platinum Mass Activity at Polymer-Wrapped Carbon Nanotube-Based Fuel Cell Electrocatalysts
Authors: Nakashima Naotoshi , Hafez Inas , Berber Mohamed Reda , Fujigaya Tsuyohiko 
Published: February 2020

Polymer electrolyte fuel cells (PEFCs) are one of the most promising power sources for cars and houses due to their high-energy conversion efficiency [1-7].
Cost reduction and improved durability are the two major targets for accelerating the commercialization of PEFCs. To achieve these goals, the development of a novel method to fabricate platinum (Pt)-based electrocatalysts with a high mass activity, deposited on durable conductive support materials, is necessary.
In this study, we report a facile approach to grow homogeneously dispersed Pt nanoparticles (Pt) with a narrow diameter distribution in a highly controllable fashion on polymer-wrapped carbon nanotubes (CNTs)[8]. A PEFC cell employing a composite with the smallest Pt nanoparticle size (2.3 nm diameter) exhibited a ~8 times higher mass activity compared to a cell containing Pt with a 3.7 nm diameter. This is the first example of the diameter control of Pt on polymer-wrapped carbon supporting materials. using a minimal amount of Pt.
References
[1] M. R. Berber, T. Fujigaya, N. Nakashima, M. R. Berber, T. Fujigaya, N. Nakashima, J. Mater. Chem. A, 2014, 2, 19053.
[2] M. R. Berber, T. Fujigaya, N. Nakashima, ChemCatChem, 2014, 6, 567.
[3] M. R. Berber, T. Fujigaya, K. Sasaki, N. Nakashima, Scientific Reports, 2013, 3, art. no. 1764.
[4] T. Fujigaya, M. Okamoto, N. Nakashima, ChemCatChem, 2013, 5, 1701.
[5] T. Fujigaya, N. Nakashima, Adv. Mater., 2013, 25, 1666-1681.
[6] T. Fujigaya, C.R. Kim, K. Matsumoto, N. Nakashima, Poly. J. 2013, 45, 326-330.
[7] T. Fujigaya, T. Uchinoumi, and K. Kaneko, N. Nakashima, Chem. Commun. 2011, 47, 6843.
[8] I. H. Hafez, M. R. Berber, T. Fujigaya, N. Nakashima, Scientific Reports, 2014, 4, art no.6295.
Detection of Salmonella on Bird Feces Contaminated Leafy Green Vegetables Using Phage-Based Magnetoelastic Biosensors
Authors: Dai Jing , Chai Yating , Hu JiaJia , Horikawa Shin , Chin Bryan A 
Published: February 2020

The outbreak of foodborne diseases caused by bacteria, such as O157:H7 E. coli and Salmonella has become a great concern in food safety[1]. The consumption of foodborne bacteria contaminated vegetables is one of the causes of foodborne disease. Vegetables can be contaminated by animal manure, for example, bird feces. Bird feces contain Salmonella which is a pathogen that lives in the intestines of the infected birds and is shed through feces. Bird could fly over or land on leafy green vegetables, such as spinach, iceberg lettuce and cabbage, leading to the potential bird feces contamination. Recently, USFDA found that the outbreak of Salmonella in peanut butter may be linked to the exposure of bird feces to the raw, unshelled peanuts that were stored outdoors where birds were observed flying over and landing on the in-shell peanuts[2]. Even though water washing can remove feces and reduce bacterial contamination, it is still difficult to eliminate bacteria at all. Therefore, rapid detection Salmonella in bird feces contaminated leafy green vegetables is required. The phage-based magnetoelastic biosensor has been developed to detect Salmonella on food surface [3, 4]. In the present work, we optimized the current detection procedures to detect Salmonella on bird feces contaminated vegetables using phage-based magenoelastic biosensors. Several parameters influencing the effectiveness of detection were optimized, such as, blocking agent concentration and incubation time. A protocol was developed to visualize Salmonella on biosensor surface to correlate the resonance frequency measurement of biosensors. Our detection protocol could contribute to screening the leafy green vegetables after harvesting to reduce effort and cost.
Reference:
1. WHO: Food safety and foodborne illness. In Fact sheet no 237; 2007.
2. FDA: Inspectional Observations. Denver, CO; 2012.
3. Chai, Y, Horikawa, S, Wikle, HC, Wang, Z, Chin, BA, Surface-scanning coil detectors for magnetoelastic biosensors: A comparison of planar-spiral and solenoid coils. Applied Physics Letters. 2013. 103:p.173510.
4. Lakshmanan, RS, Guntupalli, R, Hu, J, Kim, D-J, Petrenko, VA, Barbaree, JM, Chin, BA, Phage immobilized magnetoelastic sensor for the detection of Salmonella typhimurium. Journal of Microbiological Methods. 2007. 71:p.55-60.
Carbon Nanofibers As Transducer Layers in Potentiometric Sensors
Authors: Jaworska Ewa , Madejak Joanna , Kisiel Anna , Maksymiuk Krzysztof , Michalska Agata 
Published: February 2020

Many reports on application of nanostructured materials for potentiometric sensing purposes point out advantages of carbon nanostructures [1,2]. In this case, for the first time, carbon nanofibers (CNFs) were used as ion-electron transducers. Stable suspensions of CNFs in water or organic solvent (inks) were prepared. Potassium selective electrodes with CNFs solid contact and plasticized poly(vinyl chloride) or polyacrylate based membranes were prepared based on different carbon nanofibers ink. The effect of CNFs dispersion stabilizing agent used on the performance of resulting all-solid state potassium selective electrodes was evaluated. Analytical parameters of sensors, prepared using carbon nanofibers (as an effective transducer layer in ion-selective electrodes) are similar to those of all-solid-state sensors based on conducting polymers.
REFERENCES
1. G. A. Crespo, S. Macho, F. X Rius, Anal. Chem. 2008, 80. 1316-1322.
2. F. X. Rius - Ruiz, G. A. Crespo, D. Bejarano - Nosas, P. Blondeau, J. Riu, F. X. Rius, Anal. Chem. 2011, 83, 8810-8815.