bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Structure and Reactivity of Hybrid Functional Materials in Electrocatalysis
Authors: Kulesza Pawel J 
Published: February 2020

Our research interests aim at establishing structure/property relations leading to rational designs of functionalized materials for efficient electrocatalysis and electrochemical energy conversion and storage. There has been growing interest in the electrochemical reduction of carbon dioxide, a potent greenhouse gas and a contributor to global climate change. Given the fact that the CO2 molecule is very stable, its electroreduction processes are characterized by large overpotentials. To optimize the hydrogenation-type electrocatalytic approach, we have proposed to utilize nanostructured metallic centers (e.g. Pd, Pt or Ru) in a form of highly dispersed and reactive nanoparticles generated within supramolecular network of distinct nitrogen, sulfur or oxygen-coordination complexes. Among important issues are the mutual completion between hydrogen evolution and carbon dioxide reduction and specific interactions between coordinating centers and metallic sites. We have also explored the ability of biofilms to form hydro-gel-type aggregates of microorganisms attached to various surfaces including those of carbon electrode materials. Upon incorporation of various noble metal nanostructures and/or conducting polymer ultra-thin films, highly reactive and selective systems toward CO2-reduction have been obtained. Another possibility to enhance electroreduction of carbon dioxide is to explore direct transformation of solar energy to chemical energy using transition metal oxide semiconductor materials. We show here that, by intentional and controlled combination of metal oxide semiconductors (titanium (IV) oxide and copper (I) oxide), we have been able to drive effectively photoelectrochemical reduction of carbon dioxide mostly to methanol.
Application of mixed-metal oxides as active matrices is also of particular importance to electrocatalytic oxidations of small organic molecules in low-temperature fuel cell technologies. The hydrous behavior, which favors proton mobility and affects overall reactivity, reflects not only the oxide’s chemical properties but its texture and morphology as well. For example, during oxidation of ethanol (e.g. at PtRu), when rhodium nanoparticles have been dispersed in between WO3 and ZrO2 layers, significant current enhancements are observed. The result can be rationalized in terms of the formation of nanoreactors in which Rh induces splitting of C-C bonds in C2H5OH molecules before the actual electrooxidtion steps.
We also consider nanoelectrocatalytic systems permitting effective operation of the iodine-based charge relays in dye sensitized solar cells. The ability of palladium or platinum nanostructures to induce splitting of I-I bonds in the iodine (triiodide) molecules is explored here to enhance electron transfers in the triiodide/iodide-containing 1,3-dialkylimidazolium room-temperature ionic liquids.
(Invited) Nickel-Based Anode Electrocatalysts for Alkaline Exchange Membrane Fuel Cells
Authors: Atanassov Plamen , Serov Alexey 
Published: February 2020

Over the last decade UNM has been involved in the design of Platinum Group Metal-free (PGM-free) anode catalysts for the emerging field of Alkaline Membrane Fuel Cells (AMFC). Initial effort was directed towards catalysts for selective hydrazine oxidation.1-3 These series materials were based on allowing Ni with oxophillic metal (Zn, La, etc.) to enhance hydrazine dehydrogenation step in contrast to N-N bond splitting as a base for much desired catalyst selectivity.4, 5 These Ni-based electrocatalysts were further designed to include Ni alloys with refractive metals6 (Mo, W, Cr) and demonstrated exceptional dehydrogenation selectivity, thus creating the base for the development hydrogen oxidation catalysts in alkaline media. The nickel-based electrocatalysts were synthesized as nanoparticles supported on various carbon blacks and modified carbon blacks with loadings of up to 50 % wt. (see Figure A & B). Synthesized martials were comprehensively characterized by physical-chemical methods: XRD, BET, SEM, TEM and XPS. Electrochemical activity of the catalysts was studied with Rotating Disk Electrode (RDE) technique and in a single membrane electrode assembly (MEA) AMFC. MEA design was optimized with respect to critical fabrication parameters such as: catalyst layer thickness (loading), catalyst-to-ionomer ratio, and catalyst deposition as Catalyst Coated Membrane (CCM) vs. gas-diffusion electrode (GDE). It was found that NiMo/C electrocatalyst has a mass activity similar to palladium supported on carbon.7 The MEA performance obtained in H2/O2 single MEA fuel cell tests using Tokuyama membrane and ionomer reached a peak power density higher than 120 mW.cm-2 at relative humidity (RH) of 70 %. When Ni0.9Cu0.1 supported on Ketjen Black catalysts was used (see Figure C), a record high peak power density was demonstrated: up to 350 mW.cm-2. These new nickel-transition metal alloy catalysts are being studied in detail by spectroscopy and modeled by DFT to establish relevant structure-to-property correlation and demonstrate their utility in H2/O2 AEMFC.
Acknowledgement: DOE-EERE FCTO, Incubator Program DE-EE0006962 “Development of PGM-free Catalysts for Hydrogen Oxidation Reaction in Alkaline Media” (Alexey Serov, PI).

U. Martinez, et al., Physical Chemistry and Chemical Physics, 14 (2012) 5512-5517

T. Sakamoto, et al., Journal of Power Sources, 234 (2013) 252-259

A. Serov et al., Angewandte Chemie, Int. Ed., 126 (2014) 10419-10715

T. Sakamoto, et al., Journal of Power Sources, 247 (2014) 605-611

T. Sakamoto, et al., Electrochimica Acta, 163 (2015) 116-122

T. Asset et al., Electrochimica Acta, 215 (2016) 420-426

S. Kabir et al., Journal of Materials Chemistry A, (2017) DOI:10.1039/C7TA08718G

Figure 1
Tunable and Efficient Tin Modified Nitrogen-Doped Carbon Nanofibers for CO2 Electroreduction
Authors: Zhao Yong , Liang Jiaojiao , Ma Jianmin , Wang Caiyun , Wallace Gordon 
Published: February 2020

Electrochemical reduction of CO2 (CO2ER) into value-added chemical feedstocks and liquid fuels using renewable energy is a promising route for CO2 recycling.[1] The major challenges are the large overpotential for CO2 activation and the competitive H2 evolution in aqueous mediums.[2] Although some nanostructured noble metal catalysts have demonstrated impressive electrocatalytic activity and selectivity for CO or formate production over CO2ER, the low abundance and high cost limit their large-scale applications.[3] Efficient and cost-effective electrocatalysts with high energy efficiency and product selectivity are highly desirable to drive the development of CO2ER.
In our study, we developed a low-cost Sn particle modified N-doped carbon nanofiber hybrid catalyst via a straightforward electrospinning technique coupled with a pyrolysis process.[4] Its electrocatalytic performance was tuned by the coverage of Sn nanoparticles and the structure of N species on the nanofiber surface. The pyridinic-N supported Sn nanodots drove efficient formate formation with a high current density of 11 mA cm-2 and a faradaic efficiency of 62% at a moderate overpotential of 690 mV. After a simple acidic leaching treatment, only atomically dispersed Sn species remained on the surface of pyridinic-N-doped carbon nanofibers. This catalyst dominantly promoted the CO2-to-CO conversion with a high faradaic efficiency of 91% at a low overpotential of 490 mV.
The change of product selectivity was attributed to the difference in local chemical and electronic environment (Sn-Sn or Sn-N) surrounding the Sn active sites, which facilitated different intermediate stabilization and reaction pathway. The abundance of Sn nanodots and the strong electronic interaction between Sn and pyridinic-N-doped carbon may promote the formate formation, while the efficient CO production over the Sn atoms modified nanofibers may arise from the intrinsically high activity and selectivity of the formed Sn-N moieties.
References
[1] J. Qiao, Y. Liu, F. Hong and J. Zhang, Chem. Soc. Rev., 631-675 (43) 2014.
[2] E. E. Benson, C. P. Kubiak, A. J. Sathrum, J. M. Smieja , Chem. Soc. Rev. 89-99(38) 2009.
[3] Q. Lu, Jonathan Rosen, F. Jiao, ChemCatChem, 38-47 (7) 2015.
[4] Y. Zhao, J.J. Liang, C.Y. Wang, J.M. Ma, G.G. Wallace, Tunable and efficient tin modified nitrogen-doped carbon nanofibers for electrochemical reduction of aqueous carbon dioxide, Adv. Energy Mater., accepted on 16/10/2017.
Multiplexed 3D Paper Platform for Electrochemical and Enzymatic Catalytic Conversions in a Complex Cascade System
Authors: Andersen Nalin I , Artyushkova Kateryna , Gonzales Ivana , Atanassov Plamen 
Published: February 2020

A strategy is presented for studying multiple modalities of catalysts in a paper-based platform using stencil-printed electrodes and surface enhanced Raman spectroscopy (SERS). Microfluidic devices improve precision of experiments, shorten experiment times, and allow multiplexed analyses of catalytic reactions. By strategically configuring multiple modalities of catalysts, one can generate desired chemical conversions. As a proof of concept, the full oxidation of glycerol will be studied where three modalities of catalysts (biological, molecular, and inorganic) will be used in series. We report on a 3D paper-based platform for multiplexed characterization of catalysts and chemically converted analytes. The enzyme oxalate decarboxylase coupled with electrocatalysts will be demonstrated 1,2. The components within the device are modular and can be made by researchers using common laboratory tools. By strategically manipulating porous media, stencil-printing electrodes, and placing SERS detection zones, one can devise a customizable tool useful for understanding the interactions of different catalysts for complex chemical conversion reactions.
References:

Hickey, D. P., McCammant, M. S., Giroud, F., Sigman, M. S. & Minteer, S. D. Hybrid enzymatic and organic electrocatalytic cascade for the complete oxidation of glycerol. J. Am. Chem. Soc.
136, 15917–15920 (2014).

Abdellaoui, S., Hickey, D. P., Stephens, A. R. & Minteer, S. D. Recombinant oxalate decarboxylase: enhancement of a hybrid catalytic cascade for the complete electro-oxidation of glycerol. Chem. Commun.
51, 14330–14333 (2015).

Figure 1
Charge Transfer Characteristics of Diaza-Anthraquinones in Different Solvents and Their Application As Organic Active Material in Redox Flow Batteries
Authors: Hofmann Jonas D. , Janek Jürgen , Schröder Daniel 
Published: February 2020

Redox flow batteries (RFBs), with their independent scalability of power and capacity and their versatility concerning applicable active materials and solvents, pose a promising technology to meet the challenges of cost efficient large scale stationary energy storage. This holds particularly for RFBs based on the redox active material class of quinones that can be derived from naturally abundant resources at low cost.
In this work, we electrochemically investigate the modified quinone 2,3-diaza-anthracenedione, and two of its derivatives, as promising active material for aqueous redox flow batteries. Interestingly, these anthraquinone derivatives exhibit varying charge transfer properties depending on their functionalization and the applied solvent and pH value. In general, a positive redox potential shift of about 300 mV is achieved by the incorporation of a diaza moiety into the anthraquinone base structure. Moreover, our experiments at low pH prove that the addition of a methoxy group to the base structure of the 2,3-diaza-anthracenedione strongly increases the electrochemical stability in aqueous acidic media. A functionalization with two hydroxyl groups in close vicinity to the carbonyl group evokes a negative redox potential shift of 54 mV in acidic and 264 mV in alkaline solution.
For this study the influence of protonation and hydrogen bonding on the charge transfer characteristics of diaza-anthraquinones was investigated specifically by comparison of measurements taken in non-aqueous solvents and in aqueous solutions at high and low pH. Whereas at low pH values solely one voltammetric anodic and cathodic wave can be observed for the occurring two-electron transfer, peak splitting takes place at high pH values for two of the derivatives, which is highly unusual for quinonoid compounds. Further, measurements in non-aqueous solvents reveal a greater potential difference between the two subsequent electron transfers compared to the pristine anthraquinone. This indicates a discrepancy in charge transfer kinetics evoked by the incorporation of a diaza-moiety into the anthraquinone base structure.
Our findings allow for a deeper understanding of the redox characteristics of diaza-functionalized quinonoid compounds that could lead up to efficient active materials for future redox flow batteries with organic active material.

Figure 1
(Invited) Ordered, Nanoporous Carbon Scaffolds (NCS) for Use in Energy Conversion and Related Applications
Authors: Birss Viola , Li Xiaoan , Atwa Marwa , Mayall Robert Matthew , Ai Chengying , El Sawy Ehab N 
Published: February 2020

Nanoporous carbon materials are of significant interest for use in various electrochemical applications, including as catalyst supports in fuel cells, sensors, and as electrodes in supercapacitors, redox flow batteries, and lithium batteries. The nanoporous carbons under study in our group include both soft- and hard-templated ordered mesoporous carbons as well as colloid-imprinted carbons (CICs). While all of these carbons have well-controlled and narrow pore size distributions and high surface areas, they are all produced in the form of powders, which can cause problems when used in electrochemical devices. This is due to challenges in relation to reproducible powder packing and binders must normally be used to hold particles together. The binder may then block ions and electrons from passing through the pores and between particles, thus preventing full utilization of their surfaces. Furthermore, fine particulates may also cause health concerns (e.g., PM2.5).
In order to overcome these challenges, our research group has focussed on the development of a series of novel nanoporous carbon scaffolds (NCS membranes), possessing a fully ordered and monodisperse porous structure. The NCS materials have pore diameters in the range of 5 to 100’s of nm and contain a fully inter-connected nano/macro-porous network (porosity ~80%). These NCS membranes, which can be made to be 0.5 - 100’s of microns in thickness, also have a very good conductivity of 2-10 S/cm and are fully electrochemically accessible in aqueous solutions, exhibiting a capacitance of 40-100 F/g. The fabrication method used to form these novel NCS membranes is also environmentally friendly and has been demonstrated to be applicable for manufacturing at large scale.
Due to these exceptional properties, the NCS materials are of great interest for use in a wide range of clean energy and water remediation products. In this presentation, the preparation and properties of these materials will be discussed, including the successful loading of the NCS membranes with catalytic metal nanoparticles and internal surface functionalization. An overview of the application of the NCS material in PEM fuel cells, redox flow batteries, capacitors, and in nanofiltration applications will also be presented.
(Vittorio de Nora Award Address) New Tools for Brain Research
Authors: Deligianni Hariklia (Lili) 
Published: February 2020

At the system level neuroscience is trying to understand how neural circuits work in learning, memory, multisensory integration, motor coordination and how the electrochemical function of these circuits is compromised in the case of disease. Diseases that involve the nervous system are highly complex and mostly not well understood. The Global Burden of Disease Study 2010 (GBD 2010), estimated that a substantial proportion of the world’s disease burden came from mental, neurological and substance use disorders. We need new tools and methods at the system level to effectively tackle these conditions and to better elucidate brain function and disease.
One such tool is a novel cognitive computing platform, IBM's TrueNorth chip, that enables the use of deep learning techniques in an ultra-low power environment. We have used deep learning with a convolutional neural network (CNN) and TrueNorth technologies for real-time analysis of brain-activity data at the point of sensing. This approach has the potential to create true closed-loop insights (analytics) and therapies for next generation of wearable and implantable devices at the intersection of neurobiology and artificial intelligence.
Neurotransmitters are small proteins secreted between neurons to facilitate neural communication. These compounds are key to information processing during behavior. However, until recently, this chemical communication had not been characterized because biosensors suitable to monitor sub-second chemical events in micron dimensions were unavailable. Cyclic voltammetry at carbon-fiber microelectrodes provides measurements with sub-second time resolution and has been used to examine the dynamics of neurotransmitter concentrations. To enhance the sensitivity and the selectivity of these measurements, we have developed polymeric coatings for bare carbon electrodes. Dopamine, serotonin and adenosine are neurotransmitters that were measured with this methodology.
Another tool that we have developed is a novel nanoscale electrode array with superior sensitivity and improved spatial resolution which can be used in the future to gain improved understanding of dopamine dysregulation. We report on the scalable fabrication of dopamine neurochemical probes of a nanostructured glassy carbon that is smaller than any existing dopamine sensor and arrays of more than 6000 nanorod probes. Compared with a flat glassy carbon surface, the nanostructured glassy carbon nanorods provide about 7X higher signal per unit area (current density) for dopamine sensing. The glassy carbon nanorods were fabricated by pyrolysis of a lithographically defined polymeric nanostructure with an industry standard semiconductor fabrication infrastructure. The scalable fabrication strategy offers the potential to integrate these nanoscale dopamine rods with an integrated circuit control system, with other sensors and with different modalities of neural activation.
Ionic Transport in Aptamer Functionalized Nanochannel Array
Authors: Devarakonda Sivaranjani , Du Pengfei , Ganapathysubramaniam Baskar , Shrotriya Pranav 
Published: February 2020

We report theoretical and experimental results of the influence of surface immobilized aptamers on ionic transport through nanochannels. The ionic transport in a polyelectrolyte functionalized nanochannel may be modified either by electrostatic mechanisms that involve changes in double layer formed near the pore walls or through steric hindrance of the surface chains on the transport of solution ions. Arrays of well-defined nanochannels are fabricated using two-step anodization process of aluminum on ITO coated glass substrate. The anodization voltage and electrolyte are chosen to achieve the desired nanochannel radius and distribution. The alumina nanochannels are functionalized with thrombin binding DNA aptamers (TBA) to enable the formation of monomolecular films of polyelectrolytes on the nanochannel surface. The functionalized nanochannel arrays are then exposed to different concentrations of α-thrombin and change in impedance across the nanochannel array are characterized in order to identify the influence of protein/aptamer binding on the ionic conduction in the nanochannels. Both DNA aptamers (specific to thrombin) and α-thrombin are charged species and their interactions produce modulation of surface charges and modify the net ionic conductance across the nanochannel. We also characterized changes in ionic conductance in presence of γ-thrombin, an uncharged protein that has similar physiological structure as α-thrombin but no affinity towards TBA. Ionic and solution transport in the nanochannel is modeled using coupled Poisson-Nernst-Planck equation and Navier-Stokes equations. The conformation and charge density of aptamer monomolecular films on the nanochannel surface was modeled based on molecular dynamics simulation results of aptamer and thrombin/aptamer complexes (Gosai et al., 2016). The predicted changes in ionic conductance are compared to experimental results to identify the influence of electrostatic and steric interactions on the ion transport in polyelectrolyte functionalized nanochannel. The results show that aptamer functionalized alumina nanochannel have potential to be used for the development of disposable and point of care devices by employing relatively facile and inexpensive fabrication methodologies.
Reference:

Gosai, A., Ma, X., Balasubramanian, G., Shrotriya, P., 2016. Electrical Stimulus Controlled Binding/Unbinding of Human Thrombin-Aptamer Complex. Sci. Rep. 6, 37449. doi:10.1038/srep37449
Metal-Organic Framework Supported on Food Waste-Derived Carbon As an Efficient Bifunctional Catalyst for Oxygen Electrocatalysis
Authors: Wang Hao 
Published: February 2020

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are a core pair in many energy storage and conversion systems, such as regenerative fuel cells and rechargeable metal-air batteries. Unfortunately, both reactions possess sluggish kinetics, involving multiple charge-/proton-transfers and oxygen bond breaking (in ORR)/recombining (in OER) processes at the “solid-liquid-gas” triple phase interfaces. Therefore efficient bifunctional catalysts are urgently needed. The most efficient oxygen-relative electrocatalysts are made from precious metal, but there is no a single catalyst based on precious metals that can serve the need for both ORR and OER.
Metal-organic frameworks (MOFs) are porous crystalline materials self-assembled with metal nodes and organic linkers with various compositions, high specific surface areas, tunable pore structures, and easily functionalized. Therefore, MOFs have provided opportunities for advancements in oxygen electrocatalysis. MOFs-based ORR/OER electrocatalysts are generally used in two ways: (1) by self-sacrificing through pyrolysis, and (2) in pristine phases. The former is at the expense of MOFs’ properties, while the latter falls short of meeting the practical target due to the poor conductivity of pristine MOFs, requiring carbon support. Conventional carbon supports are synthesized from fossil fuel precursors with harsh synthetic conditions and high energy consumption. Sustainable carbon materials should be derived from renewable resources (especially agriculture/food waste), and the preparation process should be green, facile and easy to scale up.
Herein, a Co(mIm)2 (mIm=methyl-imidazole) MOF was incorporated with N-doped pomelo-peel-derived carbon (NPC) as a synergistic ORR/OER bifunctional catalyst in an alkaline electrolyte (Fig. 1A). Through rotating disk electrode voltammetry, an optimized composite exhibits an ORR/OER overpotential gap, ΔE (E
OER@10 mAcm-2-E
ORR@-1 mAcm-2), as small as 0.79V (Fig. 1B), putting the catalyst among the best of the reported bifunctional electrocatalysts so far. The catalyst also demonstrated a 4-electron transfer pathway and superior catalytic stability. The Co-N4 ligation in MOF, electrochemical active surface area, and the strong interactions between MOF and support are attributed as the main contributors to the bifunctional catalytic activity. These factors act synergistically, resulting in substantially enhanced bifunctional catalytic activity and stability.

Figure 1