bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) A Surface Enhanced Infrared Absorption Spectroscopy Study on the Nitrogen Electrochemical Reduction Reaction on Gold Surfaces
Authors: Yao Yao , Zhu Shangqian , Wang Haijiang , Li Hui , Shao Minhua
Published: February 2020

Ammonia has received much attention as a potential energy storage medium and an alternative fuel for vehicles, in addition to its use as a kind of fertilizer. Recent studies showed that ammonia could be produced by N2 and H2O through an electrochemical method, with the advantages of zero CO2 emission and energy saving compared with the “Haber-Bosch” process.1-2 However, as the theoretical potentials of hydrogen evolution reaction (HER) and nitrogen reduction reaction (NRR) are very close, H2 is the dominant product due to the much fast reaction kinetics of the former. For this reason, the experimental studies on NRR mechanism are rather rare. In this study, the NRR mechanism on Au surfaces was first studied by surface enhanced infrared absorption spectroscopy (SEIRAS) technique. Au was selected as its excellent NRR activity but low HER activity.3-4

An Au nanofilm deposited on the Si prism by a chemical deposition method was used as the working electrode. Its cyclic voltammograms (CV) in a N2 saturated KOH solution is shown in Figure 1a. In the 1st segment (cathodic scan, solid red line), the reduction current resulting from the HER and NRR appeared at 0 V and arose sharply starting at -0.1 V. Figure 1b is the corresponding FTIR spectra of the 1st segment in Figure 1a. The bands at 3300 cm-1 and 1645 cm-1 attribute to the O-H stretching and H-O-H bending of water molecules. Those bands intensity increase significantly as a result of the change in the adsorption configuration of water molecules upon decreasing the potential. The bands at 1450 cm-1, 1298 cm-1 and 1109 cm-1 attribute to the H-N-H bending, -NH2 wagging and N-N stretching of adsorbed N2Hy species, respectively. Those bands started to appear at potentials below 0 V and increased with potential decreasing. This result indicates that the nitrogen reduction reaction on Au surfaces follows an associative mechanism, and the N≡N bonds in N2 tend to break simultaneously with the hydrogen addition. Similar spectroscopic studies on Pt surfaces will be also discussed.

Figure 1. a) Cyclic voltammograms of an Au film electrode deposited on the Si prism in a N2-saturated 0.1M KOH aqueous solution; potential scan rate: 2.5 mV s-1. b) FTIR spectra during the 1st segment from 0.4 V to -0.5 V on the Au film electrode in a N2-saturaed 0.1 M KOH solution. The reference spectrum was taken at 0.4 V.

References

Lan, R.; Irvine, J. T. S.; Tao, S. W. Sci Rep
2013,
3, 1145..

Renner, J. N., Greenlee, L. F., Ayres, K. E., Herring, A. M. The Electrochemical Society Interface
2015,
24, 7, 51-57.

Bao, D.; Zhang, Q.; Meng, F. L.; Zhong, H. X.; Shi, M. M.; Zhang, Y.; Yan, J. M.; Jiang, Q.; Zhang, X. B. Adv. Mater.
2017,
29, 1604799.

Shi, M. M.; Bao, D.; Wulan, B. R.; Li, Y. H.; Zhang, Y. F.; Yan, J. M.; Jiang, Q. Adv. Mater.
2017,
29, 1606550.

Figure 1
Advancing Ammonia Synthesis through Plasma-Assisted Catalysis
Authors: Barboun Patrick , Mehta Prateek , Herrera Franscisco , Go David B. , Schneider William , Hicks Jason C.
Published: February 2020

Plasmas can enhance the selectivity, activity, and product yields for many chemical reactions. In the presence of a catalyst, synergy between the catalyst and the plasma exists to assist in the activation of reactants to promote the chemical transformation. We have been particularly interested in the use of non-thermal plasmas for the catalytic production of ammonia from nitrogen/hydrogen gas mixtures. The industrial Haber-Bosch process for ammonia synthesis from nitrogen and hydrogen is carried out at high pressures (100-200 bar) and temperatures (400-500 °C). N2 dissociation is the fundamental barrier for this reaction, and plasma-catalysis has been suggested as viable way to activate N2 under ambient conditions. We have demonstrated that is possible to produce ammonia at atmospheric pressure and temperatures between 100 - 200 °C by coupling the catalyst with a non-thermal plasma. It is speculated that the plasma assists in activating the source gas by generating reactive species, such as vibrationally or electronically excited N2*, ions, and radicals, which interact on the catalyst surface to produce ammonia. In this presentation, we will discuss our experimental results from varying the gas composition, bulk gas temperature, plasma input power, and reactor space velocity and how these conditions influence the catalyst-plasma interactions using a variety of catalysts (Fe/Al2O3, Ru/Al2O3, Pt/Al2O3, Ni/Al2O3, and Co/Al2O3).
(Invited) Advanced Components Development for Electrochemical Ammonia Synthesis
Authors: Xu Hui , Zhao Shuai , Biddy Mary J. , Yan Yushan , Wu Gang
Published: February 2020

Ammonia is an essential industrial chemical for agricultural fertilizer, medical intermediates, and energy storage. For fuel cell electric vehicle applications, it can be used as a fuel directly or as a means of hydrogen storage due to its high energy density in the liquid state. Conventional ammonia production using Haber-Bosch processes require high pressure and temperature, which is energy intensive. In addition, approximately 1.9 tons of carbon dioxide is released per ton of ammonia produced, because fossil fuels are used as the energy source in the ammonia industry. Meanwhile, renewable energy sources like solar and wind have significantly penetrated into the energy market in the past decade. During off-peak times, a large portion of this renewable energy cannot be utilized and an economically viable technology has to be used to store this surplus, “stranded” energy. The strong need to store off-peak renewable energy provides an unprecedented opportunity to utilize electrochemically synthesized ammonia as a means of accumulating hydrogen equivalents and stranded energy.

Our work aims to design and implement advanced components (e.g. catalyst and membrane) to transform electrochemical synthesis of ammonia (EAS) 1-2 and to integrate this process with off-peak renewable energy. The reactants are nitrogen and water that are immediately available and abundant. Novel metal oxide and metal nitride catalysts for the nitrogen reduction reaction (NRR) have been designed and synthesized, which may boost the ammonia production rate by at least an order of magnitude; the developed catalyst can also effectively suppress competing hydrogen evolution reaction. Second, high temperature anion exchange polymer membrane and composite ceramics electrolyte have been explored to further enhance process stability and ammonia production rate; they also enable the EAS at a wide temperature range, from 80 ℃ to 350 ℃. Techno-economic analysis (TEA) of the EAS system integrated with renewable energy will be analyzed to evaluate the cost feasibility. Faradic efficiency and overall electrical efficiency in the context of capital cost and operations cost will also evaluated.

Acknowledgement: ARPA-E REFUL Program under award # DE_AR000814

Reference:

Marnellos, G., and M. Stoukides, “Ammonia synthesis at atmospheric pressure,” Science, 282(2), 98-100 (1998).

Licht, S, Cui, B., Wang, B., Li, F-F, Lau, J., and Liu, S., “Ammonia syhthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3”, Science, 345, 637-640 (2014)
Differential Pulse Voltammetry of Nitrobenzene
Authors: Haque Inam ul
Published: February 2020

Removal of nitrobenzene from water is of current interest due to its toxicity (1) as a mutagen and carcinogen. Water sample with initial known concentration of nitrobenzene (4mM) was taken and treated with adsorbent: spent tea leaves (2). After treatment with adsorbent nitrobenzene was analyzed using such electrochemical techniques (3) as differential pulse, Figure 1, and square wave voltammetry (curve not shown) to obtain a calibration curve for quantitative estimation of nitrobenzene.

Cyclic voltammetry was employed for preliminary work (4). A calculated amount of cetyltrimethylammonium bromide (CTAB) was added to a specific volume of all nitrobenzene solutions as the supporting electrolyte. All analyses were carried out in 0.1 M aqueous CTAB at a platinum cathode using EG&G VersaStat II.

This study shows that spent tea leaves can be effectively used for the removal of nitrobenzene from aqueous solutions. A substantial decrease in the concentration of nitrobenzene was observed after treating 100 mL of 4mM nitrobenzene solution with different weighed amounts of adsorbent (spent tea leaves) when a contact time of one hour was allowed, Figure 1.

References

(1) A. Hartwig, The MAK-Collection for Occupational Health and Safety, pp.1473-1544 (2017)

DOI: 10.1002/3527600418.mb33341e5917

(2) E. Heraldy, R. R. Osa and V. Suryanti, AIP Conference Proceedings, 1710, 030025 (2016)

(3) S. Manivannan, J. Jeong, D.-K. Kang, and K. Kim, Electroanalysis (2017) DOI:10.1002/elan.201700451

(4) I. U. Haque, AASCIT Journal of Materials (2017)

Figure 1
Metal- and Reagent-Free Anodic Dehydrogenative Coupling Reactions
Authors: Waldvogel Siegfried R.
Published: February 2020

The dehydrogenative cross-coupling is a hot topic of contemporary organic synthesis. The anodic cross-coupling reaction of aromatic substrates is established without necessity of leaving functionalities or mediating catalyst. Employment of electric current as terminal oxidant is reagent-free and consequently, avoids the generation of reagent waste since only electrons are flowing. The method can be conducted in an undivided cell, is suitable for scale-up and inherently safe. Therefore, it is highly attractive for a sustainable synthesis. The key for this electroorganic synthesis is the use of 1,1,1,3,3,3-hexafluoroisopropanol as electrolyte component.[1] The high hydrogen-bonding donor capability allows a decoupling of oxidation potential from the nucleophilicity.[2] This solvent effect can be controlled by the addition of methanol or water.[3] By this method we were able to make in almost exclusive selectivity ortho-meta coupled 2,3’-biphenols,[4] non-symmetric 2,2-biphenols,[5] and phenol-arene cross-coupling products.[6]

References:

[1] A. Kirste, M. Nieger, I. M. Malkowsky, F. Stecker, A. Fischer, S. R. Waldvogel, Ortho-selective Phenol coupling reaction by Anodic Treatment on Boron-doped Diamond electrode using Fluorinated Alcohols, Chem. Eur. J. 15 (2009) 2273.

[2] B. Elsler, A. Wiebe, D. Schollmeyer, K. M. Dyballa, R. Franke, S. R. Waldvogel, Source of Selectivity in Oxidative Cross-Coupling of Aryls by Solvent Effect of 1,1,1,3,3,3-Hexafluoropropan-2-ol, Chem. – Eur. J. 21 (2015) 12321

[3] A. Kirste, B. Elsler, G. Schnakenburg, S. R. Waldvogel, Efficient anodic and direct phenol-arene C,C cross-coupling – the benign role of water or methanol, J. Am. Chem. Soc. 134 (2012) 3571.

[4] A. Kirste, G. Schnakenburg, S. R. Waldvogel, Anodic Coupling of Guaiacol Derivatives on Boron-doped Diamond Electrodes, Org. Lett. 13 (2011) 3126.

[5] B. Elsler, D. Schollmeyer, K. M. Dyballa, R. Franke, S. R. Waldvogel, Metal- and Reagent-Free Highly Selective Anodic Cross-Coupling Reaction of Phenols, Angew. Chem. Int. Ed. 53, (2014) 5210.

[6] A. Kirste, G. Schnakenburg, F. Stecker, A. Fischer, S. R. Waldvogel, Anodic phenol arene cross-coupling reaction on boron-doped diamond electrodes, Angew. Chem. Int. Ed. 49 (2010) 971.

Figure 1
Microelectrode Glucose Detection at the Human Mucosa
Authors: Burgess James D. , Li Li , Kelley Thomas , Shin Minchul
Published: February 2020

Earlier work by this research group developed the ability to detect cholesterol at the human oral mucosa using a microelectrode double potential pulse method. Hydrogen peroxide produced by the oxidase enzyme accumulates at the electrode-tissue interface and is oxidized serially by sequential potential step perturbations. A second step measures the background prior to significant generation of hydrogen peroxide providing semi-real-time signal correction. The corrected signal contains unremoved background that arises from reversible surface chemistry coupled to the potential perturbation where the short time between the first potential step for hydrogen peroxide oxidation and the second potential step for background measurement does not allow compete re-establishment of the surface condition that is reached during accumulation of hydrogen peroxide over longer time. The magnitude of the reversible charge correlates with the amount of exposed platinum surface atoms that serve as the catalyst for hydrogen peroxide oxidation. Normalization of data from different electrodes is possible using the negative charge that passes upon returning the potential to the initial potential after the first step. Data for detection of glucose at the human mucosa is presented.
Metal-Initiated/Catalyzed Diels-Alder Reaction between Electron Rich Dienes and Dienophiles
Authors: Hussaini Syed Raziullah , Chiba Kazuhiro , Okada Yohei , Imada Yasushi , Wang Zhiguo , Ozaki Atsushi , Pal Arpan , Yamaguchi Yusuke , Paramel Mathew
Published: February 2020

The Diels-Alder (DA) reaction is one the most used reaction for the construction of organic compounds. However, the DA reactions between electronically mismatched partners are difficult to achieve thermally. A few methods can perform this transformation using a radical cation strategy. These approaches either give low yields of DA products or require the use of expensive materials or specialized setups. We have found that a paperclip can catalyze/initiate a Diels-Alder (DA) reaction at room temperature between electron-rich dienes and electron-rich dienophiles. The reaction gives excellent yields of DA products in a highly regio- and diastereoselective manner. The reaction mechanism is speculated to involve an electron transfer from one of the metals present in the paperclip to the dienophile. The talk will discuss our efforts in testing the hypothesis that certain metal(s) in a paperclip are responsible for the DA reaction and showcase our systematic search for this metal catalyst/initiator in light of suspected reaction mechanisms. Preliminary screening of substrate scope of the reaction will also be presented. The reaction has the potential to become the most economical, sustainable and practical method for the formation of DA products between electron-rich partners, thus expanding the scope of the DA reaction.
Pd-Catalyzed C–H Functionalization Via Electrochemical Oxidation
Authors: Mei Tian-Sheng
Published: February 2020

The development of site-selective catalytic methods for the conversion of carbon−hydrogen (C−H) bonds to carbon−carbon(C−C) and carbon−oxygen (C−O) bonds remains a significant challenge in synthetic chemistry. During the past decade, transition-metal-catalyzed site-selective C−H functionalization has emerged as a promising tool to construct carbon−carbon (C−C) and carbon−heteroatom (C−Y) bonds. Pd(II)-catalyzed C−H oxygenation reactions, in particular, have received significant attention. Previous studies have revealed that C−O reductive elimination, which is typically sluggish from Pd(II) centers, takes place under comparatively mild conditions from Pd(III) or Pd(IV) centers. While these transformations hold great promise in offering new disconnections in retrosynthetic analysis, the need for an external chemical oxidant constitutes a practical disadvantage in these systems. The most typical oxidants in Pd-catalyzed C−H oxygenation include PhI(OAc)2, t-BuOOAc, and K2S2O8. These oxidants have drawbacks in that they produce undesired byproducts, have poor atom economy, or are expensive. Electrochemical oxidation has a rich history in synthetic chemistry and has become a promising alternative to traditional chemical oxidants because it obviates the use of dangerous and toxic reagents. We have demonstrated the first example of Pd(II)-catalyzed C(sp3)−H oxygenation via anodic oxidation. This process offers an alternative to conventional methods that require harsh chemical oxidants and represents an environmentally benign tool for coupling various oxygen anions, including acetate, toslyate, and alkoxides, with C(sp3)−H bonds.
Photoredox-Mediated Ring-Opening Metathesis Polymerization: Methods, Scope, and Scalability
Authors: Pascual Laura M M , Lu Pengtao , Kensy Victoria K , Lee Daniel C , Goldstone John , Boydston Andrew J
Published: February 2020

Photoredox-mediated ring-opening metathesis polymerization (PhotoROMP) is a novel method for the preparation of ROMP polymers. As opposed to metal-mediated ROMP, which requires metal initiators, PhotoROMP utilizes organic photo-oxidants and vinyl ether initiators. In a recent study, a variety of pyrylium and thiopyrylium photo-oxidants were evaluated, demonstrating that milder photo-oxidants achieved higher conversions, and that thiopyrylium salts generally out-performed pyrylium salts. Further studies showed that polyolefins with polar functionality, such as protected alcohols and halides, can be prepared via PhotoROMP. This functionality could be leveraged for post-polymerization processing and functionalization. An evaluation of the stereochemistry of these polymers demonstrated that they are atactic, with roughly 75% trans olefin content. Ongoing work will probe the scalability of this reaction via flow chemistry. The polymer produced will be injection molded and the mechanical properties of PhotoROMP polymers and copolymers will be determined.

Figure 1
Miniature Biological Fuel Cells for Sensing Applications
Authors: Di Lorenzo Mirella
Published: February 2020

Biological fuel cells (BFCs) are a type of fuel cell in which enzymes, pure or inside whole cells, are used as catalysts. BFCs presents several advantages over abiotic fuel cells, such as low operational temperature and pressure and cost-effectiveness. On the other hand, key challenges of BFCs are mainly associated to low power densities and, in the case of pure enzymes, limited half-life.

Widely explored as a technology for wastewater treatment and simultaneous electricity generation, BFCs have enormous potential as self-powered sensors, which is currently gathering increasing attention.

This talk will provide an overview of our current research into miniature BFCs for sensing applications for either environmental monitoring or healthcare. To improve the sensing potential of BFCs we focus on: device design, electrode morphology and low-cost materials. Miniaturisation can lead to highly sensitive devices. The large electrode surface area to volume ratio in small-scale BFCs, in fact, increases the active surface area for reaction, thus leading to high fuel consumption efficiency, while the short electron spacing minimises the internal Ohmic losses. Micro-structured electrodes have demonstrated to lead to high current densities, and therefore greater baseline signal and detection limits of the sensor. Finally, with the aim of generating cost-effective devices, we explore the use of low cost materials, such as paper and biomass-derived oxygen reduction catalysts as a green and cheap alternative to platinum at the cathode.
Electron Transfer Driven Measurement and Quantification of Biological Analytes in Practical Matrices
Authors: Krishnan Sadagopan
Published: February 2020

Electroanalysis offers several unique advantages such as simplicity, sensitivity, low-cost, selectivity, automation, and miniaturization. In order to successfully extract some or all of these advantages for analysis of desired compounds, the surface design of electrodes and detection mechanisms need to be worked out. In this regard, carbon nanostructure modified electrodes have been known for a while now for development of sensitive electrochemical biosensors and biocatalytic systems. We have been able to make some unique contributions in the measurements of serum insulin levels relevant to type 1 and type 2 diabetes conditions, serum autoantibodies as prospective early diabetes markers, urine formaldehyde levels, enzyme-specific drug activity assay, and single drop electroanalysis of oxidative pharmaceuticals. Specifically, we designed covalent and non-covalently functionalized carbon nanotubes and magnetic nanomaterials in our immunoassays and enzyme bioelectrode designs to selectively oxidize drugs or for the detection of various biological analytes. Quantitative insights on the functionalization and surface immobilized amounts of biomolecules were obtained. Research findings from these projects will be discussed in this presentation.

Representative References.

Singh, and S. Krishnan, Electrochemical Mass Sensor for Diagnosing Diabetes in Human Serum, Analyst
2014, 139, 724 – 728.

Walgama, N. Means, N. F. Materer, and S. Krishnan, Edge-to-edge Interaction between Carbon Nanotube-Pyrene Complexes and Electrodes for Biosensing and Electrocatalytic Applications, Phys. Chem. Chem. Phys.
2015,17, 4025-4028.

Singh, and S. Krishnan, Voltammetric Immunosensor Assembled on Carbon-Pyrenyl Nanostructures for Clinical Diagnosis of Type of Diabetes, Anal. Chem.
2015,87,2648-2654.

Singh, C. Rodenbaugh, and S. Krishnan, Magnetic Optical Microarray Imager for Diagnosing Type of Diabetes in Clinical Blood Serum Samples, ACS Sensors
2016, 1, 437-443.

Niroula, G. Premaratne, S. A. Shojaee, D. A. Lucca, and S.Krishnan, Combined Covalent and Noncovalent Carboxylation of Carbon Nanotubes for Sensitivity Enhancement of Clinical Immunosensors,Chem. Commun.
2016, 52, 13039-13042.

Walgama, M. Gallman, and S. Krishnan, Single Drop Electroanalysis and Interfacial Interactions: Sensitivity versus Limit of Detection, Electroanalysis
2016, 28, 2791-2796.

Premaratne, S. Farias, and S. Krishnan, Pyrenyl Carbon Nanostructures for Ultrasensitive Measurements of Formaldehyde in Urine, Analytica Chimica
Acta,

2017

, 970, 23–29.
Oxidative Activation Mechanism for Glycerol Carbonate Electrosynthesis
Authors: Hoe Hui Huang , Kirk Donald W.
Published: February 2020

The electrochemical synthesis of glycerol carbonate from glycerol and potassium carbonate enables utilizing electrical power under mild reaction conditions to upgrade the glycerol waste into valuable glycerol carbonate while consuming carbon dioxide. To further scale up the bench-scale process for industrial application, understanding the reaction mechanism is essential. Conventional electrochemical reaction with carbon dioxide species in acidic and neutral conditions involves carbon dioxide species activation by forcing electron into neutral-charged carbon dioxide species. Under alkaline system of study however, the reductive activation is no longer feasible considering the double negatively-charged carbonate ions impose electrostatic repulsion to electron. The separated cell study reveals that while products formed on both cathode and anode, significantly more product is formed on the anode. This suggests that the glycerol carbonate reaction is oxidative in alkaline system, in contrast to the reductive reaction proposed in acidic and neutral system. This also implies that anodic activation of reactant species is much easier than cathodic activation under alkaline condition, which is reasonable considering both glycerol and carbonate can be easily activated by anodic reaction than cathodic reaction. From the results, the novel alkaline electrochemical production of glycerol carbonate from waste glycerol and carbon dioxide, involves a unique oxidative mechanism different from the conventional acid and neutral system. This confirms the opportunity to bypass the kinetic limit of the conventional system, making the industrial production of glycerol carbonate more economically viable. However, more questions need to be addressed to complete the puzzle of the reaction mechanism, such as the type of intermediate involved and the type of bond broken during reaction.
Electroncatalysis by Soluble Pyrococcus
furiosus [NiFe]-Hydrogenase and its Hydrogenase Subcomplex: Tuning the Catalytic Bias
Authors: Jones Anne Katherine , Nazemi Zahra Katherine
Published: February 2020

[NiFe]-hydrogenases are highly efficient biological redox catalysts with the ability to interconvert H2, protons, and electrons (H2 ⇆ 2H+ + 2e−) at remarkable rates. Definition of the catalytic mechanism and particularly the parameters which make catalysis better in one reaction direction than in the other is important in both understanding microbial metabolism and in discovering and creating sustainable catalysts to underpin a H2-energy economy. The Pyrococcus
furiosus soluble [NiFe]-hydrogenases (PfSHI) is an oxygen-tolerant, group 3, soluble [NiFe]-hydrogenase, which grows optimally near 100 °C. This heterotetrameric enzyme consists of a heterdimeric [NiFe]-hydrogenase subcomplex and a dimeric NAD(P)-reducing diaphorase. Herein, the ability of PfSHI and its hydrogenase subdimer (PfSHIH2ase) to catalyze H2 production and oxidation electrocatalytically is studied using protein film electrochemistry. Electrochemical data show that both enzymes are active in hydrogen production and oxidation at low overpotentials. However, the activity of the two enzymes is not the same. The hydrogen subdimer is less active in H2 oxidation under 100% H2 atmosphere than the holoenzyme, but H2 production activity under 100% N2 atmosphere is unaffected by removal of the diaphorase subunits. Since absolute determination of turnover rates requires knowledge of electroactive coverage of enzyme on the electrode surface a parameter which is difficult to determine, the catalytic bias, i.e. the ratio of the maximal rates for hydrogen oxidation and proton reduction, was used to evaluate quantitatively the impact of mutation on activity. For PfSHI, the uneven response toward H2 production and H2 oxidation resulted in a dramatic shift in the catalytic biases which is calculated to be 7.1 in comparison with PfSHIH2ase that is 1.4 under similar conditions. The influence of pH and temperature on the catalytic biases of PfSHI and PfSHIH2ase was also evaluated. Both enzymes oxidize H2 more efficiently under basic conditions, at pH 8.0, and reduce protons faster in acidic conditions, pH 5.5. The catalytic biases are also temperature dependent. For PfSHI, the rates of both oxidative and reductive catalysis increase with temperature. However, the rate of H2 production increases much faster, resulting in a considerable decrease of the biases. The PfSHIH2ase enzyme is marginally faster in the oxidative direction at low temperatures. However, the increase in temperature causes an uneven increase in catalytic H2 production and H2 oxidation rates which results in a shift in the catalytic bias to favor the proton reduction direction at elevated temperatures. However, the bias of PfSHI shifts more with temperature than the catalytic bias of PfSHIH2ase. The shift in catalytic bias with temperature may indicate that there are different rate-determining steps for the forward and reverse reactions each with a distinct temperature dependence.

Figure 1
Electroorganic Oxidation of Pyridones
Authors: Rodene Dylan Daniel , Gade Narendar R , Jee Joann , Roper Thomas D , Gupta Ram B.
Published: February 2020

Electroorganic synthesis can be utilized as a green alternative in complex organic synthesis reactions for pharmaceutical compounds, mitigating or eliminating complex stoichiometric oxidants during organic synthesis. An electrochemical oxidation reaction can make a synthetic transformation more cost effective and more efficient when compared to traditional oxidation processes. Recently, literature has indicated that in waste water treatment applications, benzene and phenols are completely oxidized, resulting in CO2 formation, but interestingly also resulting in some partial oxidation products of quinones and catechols. Following a similar scheme to intentionally produce partial electrochemical oxidation products and oxidation intermediates can yield interesting new chemistries.

In this work, we will focus on heterocyclic electrochemistry and their partial oxidations specifically for pyridones. Pyridones and pyridines are considered for their possible use in biological reactions or in mimicking bioorganic processes. Various electrochemical oxidations with pyridones as an organic substrate are being explored, specifically N-alkyl pyridones.

Herein, focus will be on examining various cyclic voltammograms for different supporting electrolyte systems while comparing one and two electrochemical cell systems. Reaction rates and possible electrochemical mechanisms will be developed similarly to literature on electrochemical sensors. Furthermore, the electrochemical analysis will be derived and compared to the reaction products characterized by LC-MS.
Mechanism of Ligand-Assisted Electrodeposition of La2O3 on Gold Electrochemical Quartz Crystal Microbalance Electrodes
Authors: Medina Adan , Ivory Cornelius F. , Wall Nathalie A , Clark Sue , Beyenal Haluk
Published: February 2020

The rapid preconcentration of lanthanides in aqueous solution is of interest to enable follow-on analysis of nuclear fallout samples. The large negative overpotential of La reduction along with its instability in aqueous solutions has limited electrode-assisted preconcentration efforts to Hg amalgam and carbon paste electrodes. Previous work has shown that lanthanum films can be deposited on the electrochemical quartz crystal microbalance (eQCM). The frequency response of the eQCM tracked the formation of a La film during the cathodic sweep of cyclic voltammograms that resulted in the hydrogen reduction reaction. Recent findings determined that the lanthanum film associated with potentials beyond the cathodic stability limit of water are directly related to the increase in surface pH due to water hydrolysis. Additionally, x-ray photoelectron spectrometry and auger nanoprobe spectrometry results confirm that the films produced in this manner are La(OH)3. The formation of lanthanum film is likely to follow an electroprecipitation mechanism due to the basic environment on the electrode surface during the hydrogen reduction reaction. Surprisingly, the addition of the ligand α-hydroxyisobutyric acid resulted in films of the form La2O3 rather than La(OH)3. The mechanism of ligand-assisted La2O3 formation is being investigated. These findings will aid in miniaturizing the electrochemical preconcentration of lanthanides on microelectrodes.
Mesoporous Mn2O3 Nanoparticles Via Hydrothermal Process for Supercapacitor Applications
Authors: Li Zhen-Yu , Song Jinho , Akhtar M. Shaheer , Yang O-Bong
Published: February 2020

In recent year, Mn2O3 nanomaterials exhibit a high surface area, narrow pore size distribution, large pore volume, and high thermal stability. MnOx materials have shown promising candidates for active electrode materials for various electrochemical systems like fuel cells, supercapacitors etc., due to their high specific capacitance, low cost, abundance and environmentally benign nature. In this work, the mesoporous Mn2O3 nanoparticles (NPs) were synthesized by manganese acetate, citric acid and sodium hydroxide through hydrothermal process at 150 oC for 3h. The synthesized mesoporous Mn2O3 NPs were characterized in terms of their morphology, surface, crystalline, electrochemical and electrochemical properties. For supercapacitor applications, the synthesized mesoporous Mn2O3 NPs based electrode showed the excellent specific capacitance (Csp) of 460 Fg−1 through good electrocatalytic activity by observing good electrochemical properties in 6M KOH. Excellent Csp might be explained by the facts in improving the surface area, porous surface and uniformity, which might favor in generating large active sites and fast ionic transport over the good electrocatalytic surface of the Mn2O3 electrode. The fabricated supercapacitors exhibited good cycling stability after 1000 cycles by maintaining ~ 86% of initial Csp.
Photoelectrochemical Analysis of Tin Selenide (SnSex) Thin Films Formed Using Electrochemical Atomic Layer Deposition (E-ALD)
Authors: Howell Pauline , Stickney John Lewellen
Published: February 2020

Tin selenide is an attractive material for photovoltaic devices as an absorber layer.1 There are two derivatives: SnSe and SnSe2. SnSe is a p-type material that exhibits a band gap of 1.0 eV. SnSe2 is a n-type material with a band gap of 1.6 eV.1 In this study, tin selenide thin films have been electrochemically deposited using a process known as electrochemical atomic layer deposition (E-ALD). E-ALD uses the phenomenon known as underpotential deposition to deposit an atomic monolayer of each element separately. This process is known as a cycle and is repeated until the desired thickness is achieved.2 These films need further optimization for the selection of one species over the other. Initial photolectrochemical studies have shown the current thin film is p-type and is an option for a photocathode for hydrogen production in a photoelectrochemical cell. Further studies will include improving the deposition cycle used to increase the photoresponse of the material and to gain control over the appearance of SnSe or SnSe2.

Subramanian, B; Snajeeviraja, C.; Jayaychandran, M. Review on materials properties Sn(S,Se) compound semiconductors useful for photoelectrochemical solar cells. Electrochem.
2002, 18 (8), 349-366.

Stickney, J. L.; Villegas, I.; Suggs, D. W.; Gregory, B. W., Electrochemical Atomic Layer Epitaxy (ECALE). Abstr Pap Am Chem S
1991,
201, 289-Coll.
Dynamic Nanostructuring as a Tool to Fabricate High Performance Copper Based Hydrogen Evolution Electrocatalyst
Authors: Manna Liberato , Shinde Dipak , De Trizio Luca
Published: February 2020

Electrochemical production of hydrogen using electricity obtained from renewable sources such as Solar and wind represents an attractive avenue for clean and sustainable energy production and storage. Herein we report a low cost, highly active and stable copper based catalyst for hydrogen evolution reaction (HER) fabricated by chemical solution deposition. The catalyst exhibits self-optimizing behavior under hydrogen evolution conditions. Structural and morphological studies performed on pristine and self-optimized catalyst indicates that it undergoes nanostructuring from porous nanoplates to foam-like interconnected nanowires composed of ultra-small Cuo nanoparticles (2~3 nm in size) as shown in figure 1. Electrochemical impedance spectroscopy performed after various CV cycles suggests that there is substantial reduction in charge transfer resistance which is associated with large increase in effective double layer capacitance of the catalyst. This agrees well with the morphological analysis, wherein, nanostructuring was observed after CV cycling. A dissolution-reprecipitation based mechanism is suggested to explain the observed morphological changes. The proposed catalyst exhibits hydrogen evolution current of 10 mA/cm2 at an overpotential of 105 mV. The detailed results will be presented in the meeting.

Figure 1. a) TEM image of Cu based catalyst after cycling, b) Linear sweep voltammograms of various electrodes obtained at a sweep rate of 10 mV/S

Figure 1
Investigation of the Nano-Heterojuntion Electrochemistry Effect By Using in-Situ Spectrum and Electrical Measurement System
Authors: Hong Zhong-Jie , Wang Yong-Jia , Huang Li Wei , Lai Po-Hao , Wang Chia-Ching , Chen Ching-Hsiang , Yeh Ping-Hung
Published: February 2020

In this research, the broadband light (from 365-940 nm) and room temperature gas (NO, CO) sensing can be achieved by using nano-heterojunction (Ge and SnO2 nanowire) device; the detail analysis can be measured by in-situ spectrum and electrical measurement system. The in-situ spectrum and electrical measurement can provide the response immediately to investigate the interface defect, band bending and Joule-heating effect through the response of the devices. For broadband light detection experiment, the visible light (532 nm) beam was illuminated at different parts of the nano-heterjunction device (p-type semiconductor, n-type semiconductor, and interface). The broadband light responses only happen at interface part, not at both nanowires. For gas detection experiment, the Raman spectrum and electrical signal can be used for studying gas molecule and nano-heterjunction dynamics. Base on the abovementioned experiment, we can find the parameters to create and design new nano-device in smart way.
Pyridine Functionalized Pt/C: Ligand-Mediated Bifunctional Catalyst for the Enhanced Oxygen Reduction and Methanol Oxidation Tolerance in Fuel Cells
Authors: Lu Linfang
Published: February 2020

Ligand is usually deemed to be unfavorable towards catalytic reactions. Herein, we found that a certain amount of pyridine modified Pt/C catalyst showed enhanced oxygen reduction reaction (ORR) activity compared to surface cleaned Pt/C. The surface coverage of pyridine is a key factor to regulate the ORR activity. Pt/C catalyst with a pyridine surface coverage of 60% shows 50% enhancement towards ORR mass activity. The specific activity is increased with the surface coverage of pyridine (6 times enhanced specific activity was achieved at a surface coverage of 80%). The enhancement of the activity is due to the competition between the steric effect and electronic effect induced by pyridine, which was elucidated by in-situ FTIR, CO stripping and DFT calculation. On the other hand, the MOR activity was decreased linearly with the coverage of pyridine, indicating the MOR activity was dominated by the steric effect of ligand. Consequently, the pyridine-saturated Pt/C catalyst showed 10 times enhanced methanol-tolerant ability accompanied by maintaining the ORR activity when used as a cathode catalyst in fuel cells. More ligands (such as oleylamine, butylamine, triphenylphosphine) were further compared and discussed in this presentation.

Figure 1
Photoelectrochemical Methanol Oxidation on TiN Nanoparticles Supported on TiO2
Authors: Baturina Olga A , Epshteyn Albert , Simpkins Blake
Published: February 2020

Titanium nitride (TiN) is a metallic nitride that has optical properties similar to gold, thus enabling it to support plasmonic resonances in visible region [1, 2]. It has been considered as an attractive alternative to noble plasmonic metals due to low cost, high mechanical and thermal stability and flexibility in terms of material design [2]. While the plasmon-driven photocatalytic reactions of gold nanoparticles have been demonstrated, very little work has been reported on photocatalytic properties of supported TiN nanoparticles. It has been shown recently [3] that cubic 50 nm TiN nanoparticles supported on TiO2 nanowires provide greater photocurrent enhancement for photoelectrochemical water splitting compared to spherical Au nanoparticles. Increased hot carrier generation by the TiN nanoparticles followed by more efficient carrier collection by TiO2 was cited as the cause.

Here, plasmonic and catalytic properties of a TiN/TiO2 nanoparticle composite are probed in methanol oxidation reaction. The effects of variables such as plasmonic nanoparticle loading and particle size on the efficiency of visible to chemical energy conversion are investigated and discussed.

TiO2-supported TiN photocatalysts were made from commercial 20 and 50 nm TiN (PlasmaChem), and TiO2 nanoparticles (Degussa) by wet chemistry methods. X-Ray Photoelectron Spectroscopy and high resolution transmission electron microscopy were used for the analysis of the catalysts’ surface composition and morphology, respectively. Electrochemical experiments were conducted in a three-electrode photoelectrochemical cell. The TiN/TiO2 films on FTO-coated glass served as the working electrodes (WEs), while platinum foil and Ag/AgCl in 3 M NaCl (BioLogic, Inc) were used as counter and reference electrodes, respectively. LED lights (ThorLabs) were used as a light source.

References

[1] G.V. Naik, J.L. Schroeder, X. Ni, A.V. Kildishev, T.D. Sands, A. Boltasseva, Optical Materials Express, 2 (2012) 478.

[2] U. Guler, A. Boltasseva, V.M. Shalaev, Science, 344 (2014) 263.

[3] A. Naldoni, U. Guler, Z.X. Wang, M. Marelli, F. Malara, X.G. Meng, L.V. Besteiro, A.O. Govorov, A.V. Kildishev, A. Boltasseva, V.M. Shalaev, Advanced Optical Materials, 5 (2017).
The Nature of Hydrated Protons on Platinum Surface
Authors: Kim Youngsoon , Noh Chanwoo , Jung YounJoon , Kang Heon
Published: February 2020

The nature of hydrated protons formed at water/metal interfaces is one of the most intriguing research questions in the field of interfacial chemistry. We coadsorbed hydrogen and water on a Pt(111) surface in ultrahigh vacuum and studied the ionization of adsorbed hydrogen atoms to H+ ions by employing a combined experimental and theoretical approach. Spectroscopic evidence obtained by mass spectrometry and reflection absorption infrared spectroscopy as well as corresponding density functional theory calculations consistently show that adsorbed hydrogen atoms ionize into multiply hydrated proton species (H5O2
+, H7O3
+, and H9O4
+) on the surface, rather than H3O+. Then, upon addition of a water overlayer, the metal-bound hydrated protons spontaneously evolve into three-dimensional fully hydrated proton structures via proton transfer along the water overlayer. The stability of hydrated protons on Pt surface and their bulk dissolution behavior suggest the possibility that surface hydrated protons are a key intermediate in electrochemical interconversion between adsorbed H atoms and H+(aq) in water electrolysis and hydrogen evolution reactions.
Palladium-Based Alloy Nanoparticles for Direct Liquid Fuel Cells
Authors: Kim Jun-Yong , Ko Young-Jin , Lee Wook-Seong , Seong Tae-Yeon
Published: February 2020

In this study, we report a synthesis of small size, well-dispersed, and durable metal alloy nanoparticles based on palladium for direct liquid fuel cells: It achieved by supramolecular self-assembly of surfactant on the carbon supporter and polymer protective coating with ion impregnation. From the physical analysis, we confirm that the particle size and dispersion uniformity of synthesized Pd-based alloy nanoparticles was comparable to those synthesized by micro-emulsion methods. The resulting palladium based alloy nanoparticles exhibits superior electrocatalytic activities, especially long-term stability, toward electro-oxidation of formic acid and alcohols than those of palladium nanocatalysts. This work not only offers a powerful route to the synthesis of Pd-based alloy catalyst but also provides important possibility to solving the bottleneck of direct liquid fuel cell anode catalyst.
Semi-Integral Electroanalysis of the Electrochemistry of Tris(2,2`-bipyridine) Complexes
Authors: Cabral Diogo Moulin , MacFarlane Douglas R
Published: February 2020

The 2,2`-bipyridine (bpy) ligand is one of the most widely used in coordination chemistry. It was first synthesized at the end of the 19th century, with the iron(II) tris(bpy) being the first complex of this ligand ever observed1. Over the years a diversity of metals complexed with bpy have been synthesized and extensively studied, and recently some applications of these complexes have been proposed, e.g. the use of iron (II) and nickel (II) tris(bpy) complexes for non-aqueous electrolytes of batteries2 and the use of cobalt (II) tris(bpy) for thermo electrochemical cells3. Also, currently there is a growing interest in using ionic liquids (ILs) for electrochemical applications, because these compounds, broadly defined as salts that are liquid at or close to room temperature, usually present some interesting properties, such as low volatility, non-flammability and intrinsic ionic conductivity. The semi-integral electroanalysis is a powerful method for investigating the kinetics of redox reactions and determining the diffusion coefficients4 and was used to aid the interpretation of the electrochemical behaviour of tris(bpy) complexes.

The purpose of this work was to study the electrochemistry of the tris(bpy) complexes of cobalt (II)5, nickel (II) and iron (II)6 in ILs and organic solvents, thus contributing to the understanding of how these compounds behave in these media. Four ILs (two having the imidazolium cation and two the pyrrolidinium cation) and three organic solvents were used and the basic electrochemical properties of these complexes were investigated, including the redox potentials and the chemical and electrochemical reversibility of the redox reactions, as well as the kinetics of the oxidation reactions. The semi-integral electroanalysis was used for determining diffusion coefficients and for a qualitative analysis of the reversibility of the redox reactions.

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(Invited) Low-Pt Catalyst Concepts for the Electrochemical Oxygen Reduction Reaction
Authors: Strasser Peter
Published: February 2020

Reducing the Pt content of ORR catalyst used in low temperature fuel cell cathodes continues to be a goal of much fundamental scientific interest and tremendous technical importance. Reducing Pt content using composition, size and shape-controlled bi-metallic nanostructures is a widely popular strategy and has shown much promise. Here, I will share recent work from our group on the development, analysis, and understanding of low-Pt bimetallic ORR electrocatalysts for use in PEM fuel cell cathodes.
(Invited) Facets of Nanocrystal: A Knob to Tune Electrocatalytic Activity
Authors: Park Jinho , Feng Zhenxing , Shao-Horn Yang , Lee Seung Woo
Published: February 2020

The electrocatalytic reactions strongly depend on the surface atomic structures of the electrocatalysts. Thus, tuning the surface facets of the nanoparticles can be a powerful tool to control the activity for a specific electrocatalytic reaction. In previous studies, we employed high-resolution transmission electron microscopy to reveal the surface atomic structure of Pt nanoparticles, where the amount of high-index surface facets on Pt nanoparticles was quantified.1,2 Correlating the surface steps on Pt nanoparticles with the electrochemical activity and stability clearly showed the significant role of surface steps in enhancing intrinsic activity for CO and methanol electro-oxidation.1 On the other hand, the oxygen reduction reaction (ORR) activity of Pt nanoparticles is not influenced by surface steps in contrast to methanol oxidation reaction (MOR) activity.2 More recently, we demonstrate the synthesis of Pd@Ir core−shell concave nanocubes as an advanced electrocatalyst for acidic oxygen evolution reaction (OER). The Pd@Ir core−shell concave nanocubes were successfully prepared by atomic layer-by-layer deposition of Ir atoms on the surface of free-standing Pd nanocubes in a liquid phase. Using X-ray photoelectron spectroscopy (XPS), the right composition and oxidation states of these nanocubes are confirmed. In the 0.1 M HClO4 electrolyte, the synthesized Pd@Ir concave nanocubes showed significantly increased activity compared to the IrO2 nanoparticles. The improved activity is mainly due to well-controlled surface structures based on high-index facets. We also observed that the specific activity of Pd@Ir concave nanocubes increased after the chronoamperometry test for 10 hours.

S. W. Lee, S. Chen, W. Sheng, N. Yabuuchi, Y.-T. Kim, T. Mitani, E. Vescovo, and Y. Shao-Horn, Roles of surface steps on Pt nanoparticles in electro-oxidation of carbon monoxide and methanol, Journal of the American Chemical Society, 2009; 131(43): p. 15669-15677.

S. W. Lee, S. Chen, J. Suntivich, K. Sasaki, R. R. Adzic, and Y. Shao-Horn, Role of surface steps of Pt nanoparticles on the electrochemical activity for oxygen reduction, The Journal of Physical Chemistry Letters, 2010; 1(9): p. 1316-1320.