bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of TiO2 Nanowires As Wide Gap Semiconductor Material in the Heterogeneous Catalysis of Benzophenone-4
Authors: Díaz Francisco , Márquez Francisco , Soto-Vázquez Loraine , Rivera Keila , Rolón Frankie
Published: February 2020

Water pollution has emerged as a primary concern in environmental issues due to the consumption of pharmaceuticals and personal care products which are chemical substances resilient to traditional remediation methods.  The heterogeneous catalysis of organic pollutants has been considered as a promising decontamination method because of its capability to mineralize recalcitrant pollutants at a lower cost than others.  TiO2 nanowires (TiO2NWs) were synthesized and characterized, and its catalytic activity was proved using benzophenone-4 (BP-4) as a target organic pollutant.  The TiO2NWs were synthesized following a hydrothermal method using TiCl4 as the precursor.  A pure rutile crystalline structure was determined by X-ray diffraction and Raman spectroscopy measurements.  Also with a high band gap energy was determined by UV-Vis spectroscopy.  Elongated and highly branched structures were obtained according to electron microscopy images.  During the photodegradation experiments a high catalytic activity was observed since 90% of photodegradation was achieved in 180 minutes of reaction.  Optimal experimental conditions were determined using a catalyst loading of 1.2 gL-1 at pH 5 when BP-4 initial concentration is 20 µM. When radiation and oxygen sources are not present, the reaction is negligible, and therefore no photodegradation occurs.  This suggests that BP-4 can not be degraded in short times by photolysis, catalysis or under anoxic conditions.  In conclusion, we successfully synthesized and characterized TiO2NWs and a high photocatalytic activity was showed with degradation rates of 90% of BP-4 in a relatively short period of time, suggesting that this process is a viable option to clean polluted water sources. The photoproducts of BP-4 should be characterized to confirm this process as an environmentally remediation solution.
Development of Functional Triboelectric Nanogenerators for Antibacterial Applications
Authors: Ke Yi-Yun , Chou Ting-Mao , Lin Zong-Hong
Published: February 2020

Pathogenic bacteria that give rise to diseases every year remain a major health concern. In recent years, tellurium-based nanomaterials have been approved as new and efficient antibacterial agents. In this paper, we developed the approach to directly grow tellurium nanowires onto commercial carbon fiber fabric and demonstrated that they can be used as triboelectric and antibacterial materials. During the operation of the as-prepared triboelectric nanogenerator, the release of tellurite (TeO3
2‒) ions would help to suppress the growth of Escherichia coli (E. coil) cells. We also studied the effect of electric output on the antibacterial activity. Higher electric output would contribute the better antibacterial activity. In addition, compared to Ag nanoparticles that are commonly used as antibacterial reagents, tellurium nanowires can provide higher antibacterial activity and lower toxicity.
(Invited) Properties and Applications of 2-Dimensional Layered Materials
Authors: Duesberg Georg S.
Published: February 2020

Two-dimensional transition metal dichalcogenides (TMDs) have moved to the foreground of the research community owing to their fascinating properties which make them of great interest for both fundamental studies and emerging applications. Thermally assisted conversion (TAC) of predeposited transition metal films and Chemical vapour deposition (CVD) show great promise for the scalable and industry-compatible synthesis of these materials[1]. Here we outline the production of an assortment of TMDs by TAC and CVD, and demonstrate their high-quality using an array of characterization techniques including Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy.

The potential of TMDs films for various applications in the realm of electronics and energy will be discussed. It is possible to structure and electrically address the films yielding simple devices such as transistors, diodes and sensors. The fabrication of high-performance gas sensors, with room temperature detection limits in the ppb range for NH3 will be described in detail[2]. The fabrication of large-scale heterojunction diodes, formed by transferring n-type MoS2 onto p-type Si, will be outlined. [3] Additionally, a novel catalyst platform for the hydrogen evolution reaction (HER), consisting of MoS2 (or other TMDs) grown directly on top of a carbon electrode, will be discussed[4].

[1] "Controlled Synthesis of Transition Metal Dichalcogenide Thin Films for Electronic Applications", Riley Gatensby, Niall McEvoy, Kangho Lee, Toby Hallam, Nina C. Berner, Ehsan Rezvani, Sinéad Winters, Maria O'Brien, Georg S. Duesberg, Applied Surface Science, 297, 139-146, (2014)

[2] "High Performance Sensors Based on Molybdenum Disulfide Thin Films", Kangho Lee, Riley Gatensby, Niall McEvoy, Toby Hallam, Georg S. Duesberg, Advanced Materials, 25(46), 6699-6702, (2013)

[3] "Heterojunction Hybrid Devices from Vapor Phase Grown MoS2", Chanyoung Yim, Maria O'Brien, Niall McEvoy, Sarah Riazimehr, Heiko Schäfer-Eberwein, Andreas Bablich, Ravinder Pawar, Giuseppe Iannaccone, Clive Downing, Gianluca Fiori, Max C. Lemme & Georg S. Duesberg, Scientific Reports, 4, 5458, (2014)

[4] "Molybdenum disulfide/pyrolytic carbon hybrid electrodes for scalable hydrogen evolution", Hugo Nolan, Niall McEvoy, Maria O'Brien, Nina C. Berner, Chanyoung Yim, Toby Hallam, Aidan R. McDonald and Georg S. Duesberg, Nanoscale, 6, 8185-8191, (2014)
Molybdenum Disulfide Motors Exhibiting Self-Exfoliation on the Surface of Water
Authors: Wang Hong , Sofer Zdenek , Moo James Guo Sheng , Pumera Martin
Published: February 2020

Beyond the most highly studied graphene, transitional metal dichalcogenides (TMDs) are now another focus in two-dimensional (2D) materials research, due to their unique physical and electronic properties. A novel molybdenum disulfide (MoS2) based motor was developed. The motor can display autonomous motion on the surface of water and undergo self-exfoliation at the same time. Large scale of 2D MoS2 nanosheets in solution phase can be obtained through the exfoliation of sodium intercalated bulk MoS2. Surface tension resulting from the naphthalene distributed in the MoS2 particles is able to propel the motion of the particles at the water surface. The Marangoni effect offers a strategy to fabricate TMD motors that can exhibit motion in an unmodified aqueous environment. The coupling of self-exfoliation and autonomous motion of the MoS2 motor provides a new platform for applications of MoS2 in small scale motors. As MoS2 nanosheets have shown great potential in biomedical and environmental areas, the MoS2 motor is envisioned to be used in sensing, cargo delivery and removal of heavy metals.
Layered Transition Metal Dichalcogenides As Electrocatalysts for Hydrogen Evolution and Their Trends Emerging from Electrochemical Treatment
Authors: Chia Xinyi , Ambrosi Adriano , Sofer Zdenek , Luxa Jan , Pumera Martin
Published: February 2020

Layered transition metal dichalcogenides (TMDs) are thrust into the limelight within the scientific community thanks to their properties that can be exploited for a myriad of applications in electrochemistry and electrocatalysis of hydrogen evolution reaction (HER). Of interest, we investigate the correlation between electrochemical treatment of exfoliated MoS2, WS2, MoSe2 and WSe2 nanosheets in the hopes of electrochemically activating their electrochemical and electrocatalytic properties. In the electrochemical aspect, we show that electrochemical activation is achieved, for all TMDs except WS2, via electro-reduction at selected reductive potentials based on their innate electrochemistry while all TMDs become electrochemically deactivated upon electro-oxidation. Across all TMDs, MoSe2 exhibits most prominent charge transfer activation. Scrutinizing further, we conclude that molybdenum metal and selenium chalcogen type are more prone to electrochemical activation than tungsten metal and sulfur chalcogen type. Contemporary research into TMDs as prospective electrocatalysts for hydrogen evolution has been overwhelming; driven by the ardent pursuit of cheaper alternatives to the rare precious metal platinum, which is the best electrocatalyst to date. TMDs are abundant in nature and also exhibit promising electrocatalytic performance for HER. It provides an interesting perspective to explore the influence of electrochemical potential on the efficiency of the TMDs as a HER electrocatalyst. We found that MoS2 demonstrated better HER performance upon electro-reduction whereas the electro-oxidation of WS2 deteriorated the HER performance significantly. Conversely, the HER efficiency of MoSe2 and WSe2 remained largely unperturbed by electrochemical pretreatment. Therefore, in terms of HER electrocatalysis, we conclude that sulfur-containing TMDs are more receptive to electrochemical redox treatment compared to selenium-containing TMDs. These findings are advantageous towards the electrochemistry of TMDs and provide insights into the effectiveness and feasibility of electrochemical activation for charge transfer and HER electrocatalysis applications. The administration of such knowledge to electrochemical and energy applications in future will be indefinitely beneficial.
(Invited) Controlling the Band Structure of Black Phosphorus
Authors: Kim Keun Su
Published: February 2020

Two-dimensional (2D) atomic crystals have emerged as a class of materials that may impact our future electronics technology [1]. A key issue is controlling their electronic state to overcome the limit of natural properties. In this regard, there are rapidly growing interests in black phosphorus, a layered material consisting of 2D phosphorene layers. The low-energy band structure of black phosphorus has been widely predicted to be tunable by external perturbations, such as applied strain and electric field [2]. In this talk, I will introduce our recent angle-resolved photoemission spectroscopy studies on the tunable band gap of black phosphorus. By the in-situdeposition of alkali-metal atoms on the surface of black phosphorus, we found that the vertical electric field from dopants modulates the band gap, and changes the material from a narrow-gap semiconductor to a band-overlapped semimetal [3]. At the critical density of this semiconductor-semimetal transition, the material becomes a 2D Dirac semimetal, whose band dispersion is highly anisotropic, linear in armchair and quadratic in zigzag directions [3].

[1] E. S. Reich, Nature 506, 19 (2014).

[2] H. O. H. Churchill and P. Jarillo-Herrero, Nature Nanotech. 9, 330 (2014).

[3] J. Kim, S. S. Baek, S. H. Ryu, Y. Sohn, S. Park, B. G. Park, J. D. Denlinger, Y. Yi, H. J. Choi, and K. S. Kim, Science 349, 723 (2015).
(Invited) Interplay of Charge and Lattice Distortion in Few Layers of Transition Metal Dichalcogenides
Authors: Chou Mei-Yin
Published: February 2020

Transition metal dichacogenides have layered structures in the bulk and exhibit various characteristics ranging from normal semiconductors to charge density waves (CDW) to magnetism.  Current fabrication techniques have made it possible to extract a single composite monolayer in the laboratory and to measure the physical properties of this truly two-dimensional system. It is also possible to vary the charge carrier density by external gating methods, adding another control parameter to the monolayer configurations.  Given these new possibilities, we have performed first-principles calculations to explore the connections among charging, lattice distortion, electronic properties, and charge density waves. In particular, we will report the results for various charge density wave systems in two dimensions and explain the mechanism of forming these phases. In addition, we have also found that substantial hole doping can give rise to a CDW-to-superconductor (SC) phase transition in VSe2.

*In collaboration with Yang-hao Chan and Chih-Piao Chuu.
Passivating Defects and Tunning the Schottky Barrier for Two-Dimensional Semiconductors
Authors: Liu Yuanyue , Stradins Pauls , Wei Suhuai
Published: February 2020

Two-dimensional semiconductors show great promise for next-generation (opto)electronics, yet a number of issues have to solved  before realizing their full potential. Here by using atomistic theory, we show that: (i) The harmful electronic states induced by chalcogen vacancies can be removed by chemisorption of oxygen molecules. This reaction occurs with a barrier that correlates with the cohesive energy of the semiconductor. The repair of the electronic structure originates from the isovalence between O2 and X when bonded with metal. Based on these findings, we propose an approach to improve the performance of 2D semiconductors by using O2 to passivate the defects. [1] (ii) The problem of large and untunnable Schottky barrier at the metal–semiconductor interface can be solved with new electrode materials. [2]

[1] Y. Liu, P. Stradins, S. Wei, Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201508828; [2] Y. Liu, P. Stradins, S. Wei, submitted
(Invited) Atomically Thin Two-Dimensional Organic-Inorganic Hybrid Perovskites
Authors: Dou Letian , Wong Andrew , Yu Yi , Yang Peidong
Published: February 2020

Intense research efforts have focused on two-dimensional (2D) materials in the last decade. Layered organic-inorganic hybrid perovskites, which were discovered more than 20 years ago and have proved to be promising semiconductor materials, have not been made into atomically thin sheets and investigated so far. In this talk, we report the solution-phase growth of single and few unit-cell-thick single crystalline 2D hybrid perovskites of (C4H9NH3)2PbBr4 with well-defined square shape and large size. In contrast to other 2D materials, the hybrid perovskite sheets exhibit an unusual structural relaxation, and this structural change leads to a band gap shift compared to the bulk crystal. The high quality 2D crystals exhibit efficient photoluminescence, and color tuning could be achieved by changing sheet thickness as well as composition via the synthesis of related materials. This study opens up the possibility of fundamental research into the synthesis and properties of atomically thin 2D hybrid perovskites, and introduces a new family of 2D semiconductors for nanoscale optoelectronic devices.
Microstructural Modelling and Simulation of Mixed Conducting SOFC Cathodes
Authors: Joos Jochen , Carraro Thomas , Weber André , Ivers-Tiffée Ellen
Published: February 2020

Chemical composition and microstructure determine the electrochemical performance characteristics of mixed ionic-electronic conducting (MIEC) cathodes. This work focuses on the performance simulation and evaluation of porous LSCF cathodes with the same nominal chemical composition, but with microstructures differing in grain size, porosity and tortuosity. A numerical tool is presented, which mimics the sintering process, thus generating realistic (synthetic) 3D microstructures.  This tool was validated by comparing microstructure parameters of the generated structures with those derived from “real” cathodes, reconstructed via FIB-tomography.

Together with adequate performance models [1, 2], this approach allows to decouple the influence of material composition and microstructure on performance. It enables us to analyze microstructure development at different sintering parameters (temperature or time). Thus, this tool provides guidelines for designing high-performance cathodes (e.g., ideal material fractions, cathode thickness, etc.).

References

[1] T. Carraro, J. Joos, B. Rüger, A. Weber, E. Ivers-Tiffée, Electrochim. Acta 77, p. 315 (2012)

[2] S. Adler, J. Lane, B. Steele, J. Electrochem. Soc. 143, p. 3554 (1996)

Figure 1
Electrochemical Frequency Modulation for Estimating Exchange Current Density in Solid Oxide Fuel Cells
Authors: Das Debanjan , Hall Derek M. , Lvov Serguei N.
Published: February 2020

Electrochemical frequency modulation (EFM), a non-linear electrochemical technique was applied for the first time to solid oxide fuel cells (SOFC) to obtain effective exchange current density and transfer coefficient values. EFM has been used extensively in corrosion studies and this study investigates the feasibility of the technique in determining kinetic parameters in a SOFC. The study was carried out on a sub-commercial SOFC stack at 750 °C running on 3 % humidified H2. Values obtained from EFM data were compared to values obtained from electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) at similar operating conditions. A kinetic model based on generalized Butler-Volmer equation was used as the basis for the analysis. The results indicated that the values obtained via EFM were in agreement with EIS and Tafel analyses. The obtained values for a cell within a SOFC stack closely ranged from 11 - 16 mA cm-2 for effective exchange current density and 0.88 – 1.3 for transfer coefficient with good consistency. The values obtained from EFM were also further validated using theoretically developed equations for the specific operating condition. Causality factors, an internal check in EFM which relates the input potential to the output current, was also used to verify the validity of the data obtained by EFM.
Carbon and Redox Tolerant Infiltrated Oxide Fuel-Electrodes for Solid Oxide Cells
Authors: Skafte Theis Løye , Sudireddy Bhaskar Reddy , Blennow Peter , Graves Christopher
Published: February 2020

To solve the current issues of coking and redox instability related to the presence of nickel in conventional fuel electrodes in solid oxide cells (SOCs), porous Ce0.9Gd0.1O1.95 (CGO) electrodes were studied using symmetric cells. These electrodes showed low polarization resistance (Rp) due to high electrocatalytic activity, but high ohmic resistance (Rs) due to low electronic conductivity. When infiltrated with Sr0.99Fe0.75Mo0.25O3-δ (SFM) aqueous precursor solution and subsequently calcined at low temperatures (<1100 °C), the electronic conductivity was enhanced, due to a mixture of phases, primarily consisting of SFM, SrFeO3 and the highly electronically conducting SrMoO3 impurity phase. However, Rp of the cells increased, which is likely because the infiltrated material is less electrocatalytically active and was partly blocking the reaction sites. The electrocatalytic activity could be regained by infiltrating nano-sized CGO or NiCGO (10 wt.% Ni relative to CGO) on top of the SFM, while still sustaining the high electronic conductivity. Compared with the porous CGO electrodes, the electrode performance was greatly improved; at 800 °C in H2/H2O 83 %/17 %, RS of the electrodes decreased from ~0.26 Ω·cm2 to close to 0 Ω·cm2 and RP was restored to 0.03 +/- 0.01 Ω·cm2. Similar performance improvement was observed at 650 °C. Thus, performance comparable to, or better than, state-of-the-art fuel electrodes has been achieved. Upon exposure to a fuel gas of 50 %/50 % CO/CO2 at 750 °C, Rs of the cells was largely unaffected while Rp increased by a factor of 2-4 compared with Rs and Rp measured in 50 %/50 % H2/H2O. The Ni containing cells coked when the CO/CO2-ratio was raised above the carbon deposition equilibrium, while none of the non-nickel cells coked or showed signs of intolerance to a CO/CO2-atmosphere (see figure). Stability towards redox cycles and variations in oxygen partial pressure of the infiltrated cells was also proven.

Figure: (a) RS and (b) single electrode RP of three different cell types for 15 h in CO:CO2 90:10 at 750 °C (above the carbon deposition threshold). The NiCGO and SFM is infiltrated into the plain CGO electrode. The inserts on the right are top-down images of the cells after testing.

Figure 1
(Invited) An Atomically Precise Oxygen Evolution Catalyst
Authors: Kauffman Douglas R.
Published: February 2020

The O2 evolution reaction (OER) is an important anodic process for many aqueous electrochemical applications, including H2 evolution from water and CO2 reduction. Precious metals like Iridium, Ruthenium and/or Platinum are traditionally-used electrochemical anodes because they can efficiently oxidize H2O into O2 with high catalytic activity and good long term stability. However, recent efforts have tried to replace expensive precious-metal anodes with inexpensive and earth-abundant materials. Ni-based materials are promising replacements for precious metal-based OER catalysts because they show high activity and good long-stability. Unfortunately, the literature contains some debate as to the nature of the catalytic reaction center in Ni-based materials. This uncertainty stems from typical catalyst samples containing heterogeneous particle sizes and surface structures, and the literature contains a wide range of reported reaction rates and rate determining steps. My talk describes a combination of experimental and computational techniques to characterize the OER chemistry at an atomically-precise organometallic nickel complex. Single-crystal X-ray diffraction identified the catalyst’s crystal structure as a hexagonal “tiara-like” Ni6(PET) structure (PET = phenylethyl thiol).  Laboratory and synchrotron-based X-ray spectroscopies were used to characterize the electronic structure of the Ni6(PET)12 complex (PET = phenylethylthiol). Electrocatalytic testing showed that Ni6(PET)12 outperformed bulk NiO and Pt, and that it had comparable OER performance to that of Ir. Density functional theory (DFT) was used to model the OER at a realistic Ni6(SCH3)12 models to determined Gibbs free energy changes (ΔG) associated OER steps. Computationally predicted potential determining steps and OER onset potentials were in excellent agreement with experimentally-determined values. Interestingly, DFT results suggest subtle changes in adsorbate binding configuration can drastically alter the OER onset potentials. Our results highlight how atomically-precise nanocatalysts can facilitate the development of difficult-to-obtain structure-property relationships because they allow joint experimental and computational studies on nearly identical systems.
Perovskite-Based Oxide Catalysts to Improve the Oxygen Evolution and Reduction Activity
Authors: Kim Nam-In , So Inseop , Park Jun-Young
Published: February 2020

Unitized regenerative fuel cells (URFCs), which include water electrolysis and fuel cells, have received many attentions due to the production of hydrogen gas and electricity in one electrochemical device. Water electrolysis is one of the most pollution-free and renewable ways to produce hydrogen. However, the slow kinetics of oxygen evolution reactions (OERs) in the URFC anode are limited by high polarization resistance for oxidation of water. Likewise, oxygen reduction reactions (ORRs) for the fuel cell cathode also show slow rates due to the multi-step electrochemical reactions demands of 4-electrons in reactions, limiting the overall reaction rate of the fuel cells.

Up to date, the noble metal-based catalysts, such as carbon-supported iridium, ruthenium, platinum and alloys, have still used as OER and ORR catalysts. The use of precious metal-based materials is not suitable for the commercialization of the electrochemical cells. In order to replace these noble metal catalysts, studies of perovskite-based oxide catalysts for URFCs have carried out intensively these days. In particular, various dopants in the perovskite materials may help to improve the electrochemical properties significantly.

Herein, the perovskite-based catalysts are synthesized by the glycine-nitrate combustion method with various A site material (Nd, Sm and Gd) in ABO3 structure. Then, the ashes are calcined at 900 oC for 4h in electric furnace at a heating rate of 5 oC min-1. The physicochemical properties of the final products are characterized by several analytic tools such as X-ray diffraction, scanning electron microscope, transmission electron microscope and BET.

For electrochemical analysis, a rotating disk electrode system is used with an Hg/HgO and a Pt wire and a 0.1 M KOH solution for reference, counter and electrolyte, respectively. The pre-conditioning of catalysts is carried out by cyclic voltammetry (CV) at a scan rate of 100 mV s-1 for 50 cycles with nitrogen-purged electrolyte. The OER (1.2 V ~ 1.7 V) and ORR (0.05 V ~ 1.2 V) activities are measured by linear sweep voltammetry (LSV) at a scan rate of 5 mV s-1 and for the performance and long-term stability.

A. Grimaud, K.J. May, C.E. Carlton, Y.-L. Lee, M. Risch, W.T. Hong, J. Zhou and Y. Shao-Horn, Nat. Comm., 4, 2439 (2013).

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

J. Kim, X. Yin, K.-C. Tsao, S. Fang and H. Yang, J. Am. Chem. Soc., 136, 14646 (2014).

J.-I. Jung, H.Y. Jeong, M.G. Kim, G. Nam, J. Park and J. Cho, Adv. Mater., 27, 266 (2015).

J. Suntivich, K.J. May, H.A. Gasteiger, J.B. Goodenough, Y. Shao-Horn, Science, 334, 1383 (2011).

J. Suntivich, H. A. Gasteiger, N. Yabuuchi, Y. Shao-Horn, Nature Chemistry , 3, 546 (2011).

T. Reier, M. Oezaslan, P.Strasser, ACS Catal., 2, 1765 (2012).

I. C. Man, H. Y. Su, F. C. Vallejo, H. A. Hansen, J. I. Martínez, N. G. Inoglu, J. Kitchin, T. F. Jaramillo, J. K. Nørskov, J. Rossmeisl, ChemCatChem, 3, 1159 (2011)
Self-Supported Three-Dimensional Macroporous Nickel Phosphide Electrodes for Overall Electrochemical Water Splitting
Authors: Liu Lifeng , Wang Xiaoguang , Li Wei , Xiong Dehua
Published: February 2020

Water electrolysis is considered as the “cleanest” way to produce hydrogen, when the required electricity is derived from renewable energy sources such as solar or wind. To overcome the prohibitive cost barrier to market penetration and to enable widespread deployment of water electrolyzers, it is of paramount importance to develop efficient, cheap, and durable electrocatalysts to expedite hydrogen and oxygen evolution reactions (HER and OER). Notwithstanding remarkable progress in bi-functional electrocatalysts, there are few materials that can simultaneously catalyze HER and OER in the same medium. In this presentation, we report a self-supported three-dimensional macroporous electrode composed of micro/nano-hybrid structures of nickel phosphide – an emerging non-precious electrocatalysts. The electrode is fabricated by a simple, cost-effective, and readily-scalable method, and can be directly used as either cathode or anode in an alkaline electrolyzer. Overall electrochemical water splitting has been realized using an electrolyzer constructed by two identical the as-fabricated electrodes, and a high energy efficiency of 91% is achieved at 10 mA cm-2. Our finding would significantly simplify the fabrication procedure of water electrolyzers and substantially lower the production costs, given the unique bi-functionality, easy and cost-effective synthetic process of our self-supported nickel phosphide macroporous electrodes.

Figure: SEM image showing the morphology of the self-supported three-dimensional nickel phosphide electrodes.

Figure 1
Prostate Cancer Biomarker Detection Using a 16-Sensor Electrochemical Microfluidic Immunoarray
Authors: Jones Abby L , Otieno Brunah A , Sharafeldin Mohamed , Joshi Amit A , Krause Colleen E , Rusling James F
Published: February 2020

A semi-automated multiple biomarker-based diagnostic microfluidic device for on-line capture and detection of prostate cancer biomarkers is described herein.  In the United States, the lifetime risk of men developing prostate cancer is 1 in 7.  Strategies in detection and staging of prostate cancer include prostate specific antigen (PSA) test, digital rectal exam (DRE) and biopsy. These practices often fall short in terms of sensitivity, specificity and inability to distinguish between aggressive and indolent forms of prostate cancer.  Inaccurate sensitivity and specificity can lead to unnecessary treatments that adversely affect the patients’ quality of life.  Measurement of small panels of molecular biomarkers in serum holds tremendous potential for cancer diagnostics and personalized therapy. The protein panel includes PSA, CD-14, ERG, GOLM-1, PEDF-1, IGF-1, VEGF-D and IGFBP-3, many of which are thought to be specific for aggressive prostate cancer. The protein analytes are captured from serum samples in a two channel on-line microfluidic chamber by magnetic beads labeled with antibodies and signal transducing elements.  Captured analytes are then magnetically separated, washed, and introduced into a two channel detection chamber housing an array of 8 or 16 nanostructured, antibody-labeled electrodes.  Ultra-low detection limits in the sub fg ml-1 range was achieved for the protein panel. Using this strategy, 8-16 proteins can be detected simultaneously in 30 minutes.  Measurements of the selected biomarker panel will be tested with prostate cancer patient samples in future to assess its diagnostic capability.
Electrochemical Behavior of Selenocystine at Gold Substrates
Authors: Karnaukh Elizabeth A. , Wang Haopei , Walker Lindsey M. , Buzzeo Marisa C.
Published: February 2020

Selenium is an essential trace element for humans, found primarily as the amino acid selenocysteine. Proteins containing selenocysteine in their active site, such as thioredoxin reductases, play an integral role in physiological processes. Mutation studies in which selenocysteine is replaced by its abundant sulfur analogue cysteine demonstrate the requirement of selenium for proper functioning. Several questions exist regarding the unique chemistry achieved by selenocysteine in the cellular context. Using a combination of electrochemical and spectroscopic techniques, we have examined the selenocysteine / selenocystine redox couple under physiological conditions. Reactivity of the diselenide affords stable modification of gold substrates, which in turn allows for voltammetric study of solution-based chalcogen species that would otherwise be impeded by surface chemistry. The potential use of selenium-modified substrates in biosensing applications will be discussed.
Preparation and Characterization of Bucky Paper Electrodes for Enzyme Electrocatalysis
Authors: Akinwale Mayowa Akiwande , Montealegre Roberto , Walgama Charuksha , Krishnan Sadagopan
Published: February 2020

Nanomaterials are emerging as attractive platforms for enzyme immobilization for various electrocatalytic applications1-3. The superior electronic properties and large surface area of such nanomaterials gained significant attention in developing enzyme electrocatalytic systems4-5. In this study, we have prepared and characterized multiwalled carbon nanotube based “flexible” bucky papers for enzyme electrocatalysis. We have prepared bucky papers with different thicknesses ranging from 80 to 400 μM using the vacuum filtration method6. They are characterized by microscopy and electrochemistry for surface morphology and for electrochemical properties including conductivity and capacitance. These bucky papers are further immobilized with bilirubin oxidase enzyme to perform direct oxygen reduction without any redox mediators. Additionally, applicability of these bucky papers for membrane bound heme-enzyme catalysis is under examination. Our findings on this project will be presented.

1. S. Krishnan and J. F. Rusling, Thin Iron Heme Enzyme Films on Electrodes and

Nanoparticles for Biocatalysis, Chapter 5, p.125, in New and Future Developments

in Catalysis, S. Suib (Ed.), Elsevier Publishers (2013)

2. M. F. De Volder, S. H. Tawfick, R. H. Baughman, A. J. Hart, Science 339, 535-539 (2013).

3. R. D. Milton, F. Giroud, A. E. Thumser, S. D. Minteer, R. C. T. Slade, Chem. Commun. 50, 94-96 (2014).

4. S. Cosnier, R. Haddad, D. Moatsou, R. K. O’Reilly, Carbon 93, 713-718 (2015).

5. R. J. Lopez, S. Babanova, Y. Ulyanova, S. Singhal, P. Atanassov, ChemElectroChem 1, 241-248 (2014).

6. L. Hussein, G. Urban, M. Kruger, PCCP 13, 5831-5839 (2011).
Ultra-Low Amount of Pt Decorated Pd-Based Nanoparticles for the Oxygen Reduction Reaction
Authors: Xiao Weiping , Liu Sufen , Xin Huolin L. , Wang Deli
Published: February 2020

Ultra-low amount of
Pt decorated
Pd-based nanoparticles
for the oxygen reduction reaction

Weiping Xiaoa,Sufen Liua, Huolin L. Xinb, and Deili Wanga,*

a, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P.R. China

b, Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA

* Email: wangdl81125@hust.edu.cn

Carbon-supported Pt-based catalysts have been considered as an ideal catalyst for the oxygen reduction reaction (ORR)1. In this regard, it is of great essential to enhance the utilization efficiency of Pt to reduce the overall fuel cell system cost. Recently, Pd-based nanomaterials as catalysts for ORR have attracted much attention because of their unique properties, such as the similar properties to Pt, and the relatively low cost compared with Pt2
,
3. Based on this, it is of great significance to design a highly active and stable PdM@Pt core-shell structure nanoparticle with PdM core and ultrathin Pt shell.

Here, carbon supported Pd3V@Pt/C core-shell structure nanoparticle has been systematically synthesized via a simple impregnation-reduction method, followed by a spontaneous displacement of Pt. Electrochemical tests reveal that the half-wave potential of Pd3V@Pt/C shifts positively of 80 mV compared with that of Pd/C and the Pt mass activity of Pd3V@Pt/C improves by factors of 10.9 at 0.80 V relative to that of Pt/C. This can be attributed to the strain arising from the mismatch in lattice constant between the Pd3V core and ultrathin Pt shell. Furthermore, the morphology and elemental composition of the Pd3V@Pt/C nanoparticles before and after potential cycling tests are determined using an aberration-corrected Nion scanning transmission electron microscopy (STEM) equipped with an Enfina electron energy loss spectrometer (EELS). After 10 K potential cycling tests, there is no obvious morphology change, because the Pt-rich shell plays an important role in preventing degradation.

Acknowledgements

This work was supported by the National Natural Science Foundation (21306060, 21573083), the Program for New Century Excellent Talents in Universities of China (NCET-13-0237), the Doctoral Fund of Ministry of Education of China (20130142120039), the Fundamental Research Funds for the Central University (2013TS136, 2014YQ009).

References

         (1)    Wang, Y. J.; Zhao, N.; Fang, B.; Li, H.; Bi, X. T.; Wang, H., Chem
. rev
., 2015, 115, 3433-3467.

         (2)    Zhao, X.; Chen, S.; Fang, Z.; Ding, J.; Sang, W.; Wang, Y.; Zhao, J.; Peng, Z.; Zeng, J. , J
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., 2015, 137, 2804-2807.

         (3)    Park, J.; Zhang, L.; Choi, S.-I.; Roling, L. T.; Lu, N.; Herron, J. A.; Xie, S.; Wang, J.; Kim, M. J.; Mavrikakis, M., ACS nano, 2015, 9, 2635-2647.
Synthesis and Conductivity of Directly Cross-Linked Chitosan / Bis(2-chloroethyl) Ether-1,3-Bis[3-(dimethylamino)Propyl]Urea Copolymer As Alkaline Anion-Exchange Membranes
Authors: Qiao Jinli
Published: February 2020

Anion-exchange membrane fuel cells (AEMFCs) researches have recently made a noticeable comeback from proton-exchange membrane fuel cells (PEMFCs) dominant era. The alkaline membrane fuel cells can get faster electrokinetics, lower fuel crossover, reduced CO poisoning, and use of non-precious metal catalysts. 1-3However, the conductivity and stability of AAEMs are still far less than commercial membrane Nafion.4

 Chitosan (CS) is a low-cost biopolymer, which has very good mechanical and chemical stability along with good film formation property. 5However, since CS is just a weak alkaline conductivity, it cannot be directly used to fuel cell membrane. In this work, we report a novel series of alkaline anion-exchange membranes: Chitosan /Bis(2-chloroethyl)ether-1,3-bis[3-(dimethylamino)propyl]urea copolymer (PUB) membranes. By incorporation of PUB, the OH- conductivity of the CS/PUB membrane was found to be greatly improved and reached high up to 4.25×10-3S cm-1.

The membranes were prepared by a solution-casting method, where 2g chitosan (degree of deacetylation=80.0-95.0，supplied by Sinopharm Chemical Reagent Co.Ltd.China) was dissolved in deionized water with 2 wt.% acetic acid to form 2 wt.% chitosan solution. Then, PUB was mixed with the above chitosan solution at room temperature. At last, 0.5mg GA was mixed with Chitosan/ PUB composite solution to get a homogeneous appearance. Membranes were obtained with a thickness about 50-100µm. The membrane characteristics were measured using OH-conductivity and water uptake.

Fig. 1 shows the picture of as-prepared Chitosan/ PUB. It is obvious that the membrane is standing and flexible.

Fig. 2 displays the OH- conductivity and WU of Chitosan:PUB=1:0.25;1:0.5,1:0.75 membranes. The OH- value is different with increasing PUB contents and reached 4.25×10-3 S cm-1 when polymer composition is 1:0.25:0.1 by mass. The more details, including the effect of cross-linking method on its conductivity, will be reported in the meeting.  

References

1. J. Zhou, M. Ünlü, I. Anestis-Richard, P.A. Kohl,J. Membr. , 350,286(2010)

2. Merle, Géraldine, Matthias Wessling, Kitty Nijmeijer, J. Membr.  377, 1 (2011)

3. J. Ma, Nurul A. Choudhury, Yogeshwar Sahai*, Rudolph G. Buchheit, J. Power Sources, 196, 8257 (2011)

4. Y. Liu, X.H. Cao, R. Hua, Y.Q. Wang , Y.T. Liu , C. Pang , Y. Wang, Hydrometallurgy, 104
,150 (2010)

5. G. Wang, Y. Weng, D. Chu, D. Xie, R. Chen, J. Membr. 326(2009) 4e8

Fig. 1 Membrane pictures of Chitosan/PUB membrane. Polymer composition:Chitosan/ PUB/GA = 1: 0.5:0.1 by mass.

Fig.2 OH- conductivity and water uptake of PVA/PUB/GA membranes in different PUB contents in polymer.

Figure 1
Conductance and Capacitance of Electrode-Respiring Geobacter Sulfurreducens Biofilms Using a Quartz Crystal Microbalance and Electrochemical Impedance Spectroscopy
Authors: Babauta Jerome T. , Beyenal Haluk
Published: February 2020

Model electrochemically active bacteria such as Geobacter sulfurreducens are well-established and are often used to study microbial interactions within biofilms that transfer electrons to electrodes. In the presented work, we utilized a quartz crystal microbalance (QCM) coupled to electrochemical impedance spectroscopy (EIS) to simultaneously monitor biofilm growth and the microbial interaction with the electrode. The QCM monitored the frequency shift from the background resonant frequency in real time while the current increased because of biofilm growth. At select times during biofilm growth, we halted the current and obtained biofilm impedance spectra. The short-term and long-term electrode interactions of G. sulfurreducens biofilms were demonstrated. In the short-term, the frequency shift was linear with respect to current for the biofilm. In long-term biofilm growth up to the exponential phase, a second linear region was observed. Biofilm impedance spectra taken across these times revealed a reproducible electrochemical signal. Conductance of the biofilm was linear with current whereas capacitance reached a limiting value towards the end of exponential growth. We show that a simple iV relationship can explain the linear behavior of conductance and current. Capacitance could be used to identify the transition between different growth phases. We compare the biofilm response on the QCM to capacitive, electrochemically-deposited polyaniline films. Our results suggest that the QCM can be used in applications where it is beneficial to identify electrochemically active bacteria that form efficient current-producing biofilms.
(Invited) Overcoming Biocathode Limitations in Bfcs: Enhancing O2 Concentration with Micelles
Authors: Hickey David P , Albertson Kelan , Milton Ross D , Minteer Shelley D.
Published: February 2020

Enzymatic fuel cells (EFCs) are capable of utilizing a wide range of sugars and short-chain alcohols as fuel sources. Using an enzymatic catalyst at either the anode or cathode, EFCs are able to operate under physiological pH and temperature. Recent advancements in bioanodic materials have allowed for generation of current densities in excess of 2 mA cm-2; however, the majority of EFCs are limited by current density generated at the biocathode. Typical enzymatic biocathodes utilize a copper oxidase, such as laccase or bilirubin oxidase, to bioelectrocatalytically reduce molecular oxygen to H2O. However, biocathodes are often limited by slow diffusion of O2 to the electrode interface, which is ultimately the result of relatively low solubility of O2 in aqueous solutions (mole fraction solubility, xO2
= 2.3×10-5). By contrast, the solubility of O2 in organic solvents such as nonane or perfluorooctane (xO2
= 2.1×10-3 and 5.3×10-3, respectively) are much higher than in aqueous conditions.

We have developed a strategy to combine the high O2 solubility of organic solvents with the biocompatibility afforded by aqueous solutions, in which phospholipid micelles are used to trap O2 and transport it to the cathode surface. By modifying the phospholipid composition, various properties of the corresponding micelle can be tuned to cause dispersion upon contact with the electrode surface thereby increasing the localized O2 concentration. The net result is a dramatic increase in current density generated at the biocathode.
The Role of Micropore and Mesoporous in Activated Carbon As Air-Cathode Catalyst in Microbial Fuel Cell for Oxygen Reduction Reaction
Authors: Liu Yi , Li Kexun
Published: February 2020

Porous structure of activated carbon (AC) is important for mass transfer and catalyst when AC is used as air-cathode catalyst in microbial fuel cell (MFC). In this work, several carbon samples including two kinds of micropore carbon and mesoporous carbon with different pore sizes are prepared as air-cathode catalyst layer to explore the role of micropore and mesoporous during the process of oxygen reduction reaction (ORR). The catalytic activities of all samples are tested by linear sweep voltammetry (LSV), Tafel and rotating disk electrode (RDE). Besides, these carbon materials are also analyzed by Nitrogen adsorption-desorption isotherms, air permeability test, In situ FTIR and H2 temperature programmed reduction. Among these carbon samples, AC shows the best ORR performance, because its mesoporous structure is benefit for oxygen pass and micropore structure can promote catalytic activity. Thus, the electrochemical performance of activated carbon contribute to the own functions of micropore and mesoporous.
Characterization and Optimization of Gas Diffusion Cathode for Single-Chamber Microbial Fuel Cells Application
Authors: Chan Shirley , Phan Tony , Babanova Sofia , Santoro Carlo , Atanassov Plamen , Bretschger Orianna
Published: February 2020

Microbial fuel cells (MFCs) are bioelectrochemical systems that utilize different species of microorganisms to break down organic substrates and generate electricity. Those microorganisms are able to transfer the electrons from the oxidation process to electron acceptors, such as carbon anode electrodes. The electrons are transferred through an electrical circuit from the anode to the cathode, where the oxygen reduction reaction (ORR) occurs. The rate of organic substrate removal and magnitude of electricity generation from MFCs depend on the operational efficiency of both electrodes - biotic anode and abiotic cathode.

Our study focuses on the development, characterization, and optimization of gas diffusion ORR cathodes for single-chamber MFC applications. Gas diffusion cathodes rely on the passive diffusion of oxygen from air to complete the ORR. The gas diffusion cathode developed for this study (GDC) had a novel PTFE and polyethylene (PE) diffusion layer. The gas diffusion layer was heat pressed onto a carbon cloth substrate. The carbon cloth substrate was used as a current collector and support for the catalytic layer. Different combinations and concentrations of catalyst and binder were evaluated in this study. Activated carbon, nickel, plain carbon and non-platinum based catalysts were tested. After the best catalyst had been selected, different binder materials were evaluated. These include PTFE, PE, and a PTFE/Polyethylene glycol mixture.

The initial electrochemical characterization of the cathodes was performed in a three-electrode setup with a titanium mesh counter electrode and Ag/AgCl reference electrode. 0.1M phosphate buffer solution was used as the electrolyte. Durability studies of the cathode were conducted in a single chamber MFC, with swine waste as the organic substrate and carbon brush as the anode.

Potentiostatic polarization curves were carried out to evaluate the influence of the catalyst and the binder on the cathode performance (Fig. 1). As can be seen, the non-platinum based catalyst demonstrated the highest performance, with a current density of 0.34 mA/cm2 at -0.2 V vs. Ag/AgCl, followed by the activated carbon/carbon black catalytic layer with current output of 0.14 mA/cm2 at the same potential. The cathode with PE as the binder (Fig. 1b) showed the highest performance and reproducibility, but had low durability. It has also been established that MFC operation under continuous flow results in a loss of cathode performance, attributed to the presence of pollutants in the wastewater.

Figure 1
Paper-Based Biofuel Array for Self-Powered Wearable Biosensors
Authors: Shitanda Isao , Momiyama Misaki , Nohara Saki , Iwashita Risa , Tsujimura Seiya , Hoshi Yoshinao , Itagaki Masayuki
Published: February 2020

We name the Printable Electrochemistry for the development field of printable electrochemical devices [1,2]. Recently, we focus on several paper-based fully-printable electrochemical devices such as biofuel cell [3], biosensor [4] and reference electrode [5].

 Paper-based biofuel cell have been attracted as a potential application as energy harvesting power sources in Internet of things (IoT) field [6,7]. In the present study, we newly developed paper-based wearable biofuel cell array fabricated by screen-printing.

 Figure 1 shows a schematic illustration of one of our wearable biofuel cell array. The paper-based biofuel cell array exhibited a maximum power density of 1 mW. The present flexible paper-based biofuel cell is highly applicable to the development of low cost, flexible, ubiquitous energy devices. In the present study, we discuss the characteristics of the wearable biofuel cells in detail.

[1] I. Shitanda et al., Electrochim. Acta 54 (2009) 4933.

[2] I. Shitanda et al., Sens. Actu. B: Chem. 160 (2011) 1606.

[3] I. Shitanda et al., Chem. Commun. 49 (2013) 11110.

[4] I. Shitanda et al., Chem. Lett. 42 (2013) 1369.

[5] I.Shitanda et al., Analyst, 140 (2015) 6481.

[6] Claudia W. Narváez Villarrubia et al., Electrochem. Commun, 45 (2014) 44.

[7] Carolin Lau et al., Int. J. Hydrogen. Energy, 42 (2015) 14661.

Figure 1