bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dispersing Effect of Poly (vinyl pyrrolidone) Addition on Platinum/Tin Phosphate/Carbon Black Bifunctional Catalysts for Direct Methanol Fuel Cell
Authors: Huang Chun Yuan , Cheng Yu Ching , Yen Shiow Kang 
Published: February 2020

Direct methanol fuel cells (DMFC) are electrochemical conversion device that can produce electricity at high fuel efficiencies, and Pt the excellent and major catalyst in them, is too expensive to be developed for applications widely. Before large-scale consumer use, three technological problems should be solved. 1. The activity of electrodes should be improved to increase efficiency, and then the amount (i.e. cost) of platinum catalyst in electrodes. 2. Poisoning effects of CO on Pt catalyst should be removed. 3. The conductivity of catalyst should be enhanced to reduce the energy waste in system.
Nano-sized platinum (Pt) particles were successfully reduced on tin phosphate (SnP) precipitated carbon black (C) to form Pt/SnP/C catalysts. In methanol oxidation reaction (MOR), these catalysts revealed the more electrochemical mass activity and less obvious CO poisoning effects than Pt/C to become potential for bi-functional catalysts. However, the serious agglomeration of Pt is observed. In this study, Poly (vinyl pyrrolidone) (PVP) was firstly added dispersed carbon black supports, assigned to C (PAD), to avoid the further agglomeration after SnP precipitation on them for increasing the specific surface area of SnP on which platinum was reduced, and hence enhancing the electrochemical performance as well as detoxifying function.
By using the characterization of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), and inductively coupled plasma-mass spectrometry (ICP-MS), the characterization of catalyst Pt/SnO2-SnP/C (PAD) was carried out.
The particle size of platinum is 4.431 nm by XRD analyses and 3.61~3.97 nm observed by TEM. In hydrogen oxidation reaction (HOR) tests, electrochemical surface area (ECSA) of Pt/SnP/C was 765 (cm2/mg), and that of Pt/SnP/C (PAD) increased to 1268 (cm2/mg). In methanol oxidation reaction (MOR), catalyst Pt/SnP/C (PAD) illustrates the higher mass activity 80.67 (A/gPt, at 0.4 V) and the lower on-set potential 0.2 V (vs. Ag/AgCl). No forward current peaks was observed, indicating the deletion of CO poison effect on Pt than Pt/SnP/C. In membrane electrode assembly (MEA) tests, Pt/SnP/C (PAD) also reveals the greater power density and open circuit voltage than Pt/C (Alfa). TEM observations show that SnP is the nucleation site of Pt which is more dispersed than Pt/SnP/C in catalyst, leading to the better electrochemical performance.
Evaluation of Varying Electrocatalysts for the Intermediate Temperature Electrochemical Synthesis of Ammonia
Authors: Ramaiyan Kannan Pasupathikovil , Maurya Sandip , Benavidez Angelica D , Nayak Shanti Kiran , Kim Yu Seung , Garzon Fernando H , Mukundan Rangachary , Kreller Cortney R. 
Published: February 2020

Ammonia synthesis by the Haber-Bosch (HB) process paved the way for rapid increase in crop production and sustained the needs of population growth. However, HB process is cost and energy intensive and releases about 260 million tons of CO2 every year. Considering the threat associated with CO2, finding an alternative, cheap and environmentally benign methodology for ammonia synthesis is highly desirable. Electrochemical synthesis through renewable electricity offers a viable alternative, although the synthesis rates reported are far from adequate. This is mainly due to the strong NºN bond (941 kJ mol-1) that poses a severe challenge for mild condition synthesis of ammonia. Several attempts toward electrosynthesizing ammonia at low and high temperatures included a variety of electrode materials ranging from glassy carbon electrode to precious metals and different proton and oxide ion conducting electrolytes [1]. Rates on the order of 10-9 mols-1cm-2 have been reported for both low and high temperature systems. This rate is still three orders of magnitude lower than the required rates for commercialization.
We have achieved ammonia synthesis rates of 1x10-8 mols-1cm-2 at 200 °C in a simple fuel cell configuration using a Sn2P2O7 – nafion composite membrane and Pt based catalyst [2]. Here we will present our results obtained with alternate electrocatalysts and discuss the role of applied potential and back pressure measurements on the synthesis rates of ammonia.
References

V. Kyriakou, I. Garagounis, e. Vasileiou, A. Vourros, and M. Stoukides, Catalysis Today, 2017, 286, 2-13.

K. P. Ramaiyan, S. Maurya, Y. S. Kim, F. H. Garzon, R. Mukundan, C. R. Kreller, Meeting Abstracts, ECS 231st meeting. Issue 31, 1464-1464.

Acknowledgements
This project is supported by ARPA-E under Award No. DE-AR0000687.
Electrochemical Behavior of 2-Halo-N-Phenylacetamides at a Carbon Cathode
Authors: Couto Petro Ana G. , Peters Dennis G 
Published: February 2020

Haloacetamides and haloacetanilides have been utilized for the synthesis of many compounds such as, but not limited to, β-lactams,1
N,N-bis-(phenylcarbamoylmethyl) dimethylammonium,2 and oxazolidine-2,4-diones.3 Therefore, it is important to understand fully how these haloacetamides behave as well as the reaction pathways they undergo. Electrochemical studies of 2-chloro-N-phenylacetamide have been reported at carbon cathodes, and were successful in demonstrating the reductive cleavage of the carbon–halogen bond. A mechanism for the aforementioned reduction has been proposed.4 This project’s primary objective is to compare the electrochemical behavior of a series of 2-halo-N-phenylacetamides and to elucidate a more complete mechanistic picture for the reduction of this class of compounds.
In the present investigation, we have conducted cyclic voltammetry and controlled-potential electrolysis studies of 2-iodo-N-phenylacetamide and 2-bromo-N-phenylacetamide at a carbon cathode to understand further the electrochemical behavior of 2-halo-N-phenylacetamides. Reduction of 2-bromo-N-phenylacetamide and 2-iodo-N-phenylacetamide in dimethylformamide (DMF) containing 0.05 M tetramethylammonium tetrafluoroborate (TMABF4) results in cyclic voltammetry peaks at –0.9 and –1.4 V (bromo) and –0.6 and –1.1 V (iodo) vs. a Cd(Hg) reference electrode. Analysis of the products resulting from controlled-potential electrolyses of both analytes by means of gas chromatography–mass spectrometry (GC–MS) indicates the presence of dehalogenated species as the primary products.

Casadei, M. A.; Di Rienzo, B.; Inesi, A.; Moracci, F. M., Electrochemical studies on haloamides. Part 3. Haloacetamides and halo-acetohydroxamates. J. Chem. Soc., Perkin Trans. 1
1992, 375–378.

Walker, M. J., Treating cough and tussive attacks. Google Patents: 2012.

Casadei, M. A.; Cesa, S.; Inesi, A., Electrochemical studies on haloamides. Part XII. Electrosynthesis of oxazolidine-2,4-diones. Tetrahedron
1995,
51, 5891–5900.

Pasciak, E. M.; Sengupta, A.; Mubarak, M. S.; Raghavachari, K.; Peters, D. G., Electrochemical reduction of 2-chloro-N-phenylacetamides at carbon and silver cathodes in dimethylformamide. Electrochim. Acta
2014,
127, 159–166.
Application of the Cation Pool Method for Fluorination and No-Carrier-Added Radio-Fluorination
Authors: Balandeh Mehrdad , Rios Alejandra , Allison Nathanael , Shirazi Daniela , Sadeghi Saman 
Published: February 2020

In 1999 Yoshida and co-workers developed the cation pool method which stabilized carbamate cationic intermediates generated during a two electron oxidation followed by deprotonation that takes place in the anodic compartment of a two compartment cell under low temperatures.1 The method allows for rapid reactions with nucleophiles that may be unstable during electrolysis and can be added to the reaction mixture at the end of electrolysis to form the final product.
Here, we report on the extension of the cation pool method for the application of electrochemical fluorination and radio-fluorination of methyl (phenylthio)acetate. Electrochemical fluorination and no-carrier-added radio-fluorination were successfully achieved using the cation pool method . Figure 1 shows the schematic of no-carrier-added electrochemical radio-fluorination of methyl (phenylthio)acetate using cation pool method. The cation pool method has tremendous potential for radiofluorination experiments. The excess concentration of cations may provide an efficient reaction mechanism for late-stage fluorination under low fluoride concentrations encountered in radiochemistry. Furthermore, radiochemical yield, which is reduced by decay of the radioisotope, can benefit from a rapid late-stage fluorination reaction. The cation pool can be prepared prior to cyclotron production of 18F isotope, thereby, providing a rapid late-stage fluorination reaction, maximizing radiochemical yield by minimizing decay through a rapid reaction of the previously prepared cations with 18F-fluoride.
Synthesis parameters such as temperature, supporting electrolyte concentration and type, and precursor concentration were studied and optimized. The fluorination and radiofluorination yields of 12% and 6.7% were obtained, respectively, using the optimum conditions. The products were characterized using gas chromatography–mass spectrometry (GC-MS), nuclear magnetic resonance (NMR), radio-thin-layer chromatography (radio-TLC) and high-performance liquid chromatography (HPLC). This method can also be applied for a late-stage no-carrier-added radiofluorination to develop new positron emission tomography (PET) tracers.

Figure 1. Schematic of no-carrier-added electrochemical 18F-fluorination of methyl (phenylthio)acetate using cation pool method.

References

Yoshida, J. et al. Direct Oxidative Carbon−Carbon Bond Formation Using the “Cation Pool” Method. 1. Generation of Iminium Cation Pools and Their Reaction with Carbon Nucleophiles. J. Am. Chem. Soc.
121, 9546–9549 (1999).

Figure 1
Mechanistic Insights into Furfural Reduction on Transition Metals Electrodes from First-Principles Methods
Authors: Shan Nannan , Hanchett Marry K. , Liu Bin 
Published: February 2020

Furfural is a significant platform compound derived from biomass. Electrocatalytic reduction of furfural on transition metals emerges as a sustainable approach compared to heterogeneous catalysis to obtain valuable chemicals and fuels, such as furfuryl alcohol (FA) and 2-methylfuran (MF). Although the product selectivity was shown to be strongly depended on the intrinsic properties of the transition metal electrodes, similar as CO2 reduction, the complex chemical nature of furfural presents challenges to investigate the reaction mechanisms, which are still under debate.
Density functional theory (DFT) calculations have been performed for electrocatalytic reduction of furfural to FA and MF on the close-packed (111) and stepped (211) surfaces of Cu, Ag, Pb, and Ni electrodes. The elementary reaction steps have been evaluated based on computational hydrogen electrode (CHE) model. A novel Brønsted–Evans–Polanyi (BEP) relationship has been established for C-O bond cleavage which is necessary for MF production. On Cu, Ag, Pb, and Ni, at both terrace and stepped sites, the first hydrogenation step of C=O, leading to mh6 or mh7 formation, influences the overall reaction activity and product selectivity. It has been found that the pathway via mh6 is more competitive than that via mh7 for FA formation on Cu, Ag, and Pb, whereas on Ni, both mh6 and mh7 routes are competitive due to strong interactions between the furan ring and the substrate. The C-O bond cleavages of furfural, the partially hydrogenated intermediates (mh6 and mh7) and FA were considered as the parallel pathways to produce MF besides FA formation pathways. It is well-known that solvation can facilitate the hydrogenation reactions involving proton-electron pairs. In this work, solvation was confirmed to decrease the C-O bond cleavage energy barriers, which could boost MF production and potentially tune the product selectivity on transition metal electrodes.
Identification and Characterization of Metal-Oxide Powders with Energy-Resolved Density of Electron Traps Measured By Reversed Double-Beam Photoacoustic Spectroscopy
Authors: Ohtani Bunsho , Nitta Akio , Takase Mai , Takashima Mai 
Published: February 2020

Although organic compounds are practically identified by their elemental compositions and nuclear magnetic resonance (NMR) patterns, metal-oxide powders cannot be identified by bulk composition and crystalline structure. Such a difference between molecules and powders is attributable to existence of both surface and bulk for metal-oxide powders. What has been conventionally evaluated as structural properties of metal-oxide powders is crystal phase, primary particle diameter, secondary particle diameter and specific surface area, but those properties reflect only bulk composition or size. In other words, a lack of sufficient analytical method that enables measurement of a property reflecting surface structure has prevented characterization and thereby identification of metal-oxide powders. In this study, we focus on energy-resolved density of electron traps (ERDT) located mainly on the surface of metal-oxide powders, and evaluate ERDT in various particulate samples as a function of energy from valence-band top (VBT) by reversed double-beam photoacoustic spectroscopy (RDB-PAS), in which photoabsorption of trapped electrons directly excited from valence band to electron traps by scanned continuous light is measured by PAS [1].
Representative ERDT patterns of titania powders are shown in Fig. 1. Conduction-band bottom (CBB) depending on the crystalline phase and total density of electron traps increasing with increase in the specific surface area indicate that CBB and total density of electron traps can reflect bulk composition and bulk size, respectively. On the other hand, ERDT patterns of TIO-1 and TIO-13 seem to be clearly different. This result indicates that ERDT can reflect surface structural property. By calculating degree of coincidence z, multiplied by each degree of coincidence for ERDT pattern matching, total density of electron traps and CBB position, some given pairs of two samples which are made by the same manufacturing method show higher z values than those of other pairs. Therefore, it is suggested that an ERDT/CBB pattern can be a fingerprint for metal-oxide powders. Evaluation of VBT by observing ERDT of mixture sample is also discussed.

Fig. 1 Representative ERDT/CBB patterns as energy function from VBT for titania powders.
[1] A. Nitta, M. Takase, M. Takashima, N. Murakami, B. Ohtani, Chem. Commun., 52, 12096-12099 (2016).

Figure 1
(Invited) Tracking Ionic Transport and Electrochemical Reactions in Low-Dimensional Nanomaterialsfor Energy Storage
Authors: Zhu Yimei 
Published: February 2020

Lithium-ion batteries are one of the most popular rechargeable energy storage devices for portable electronics and electrical vehicles. To design safe, high-energy electrodes with long-cycle life, we need a better understanding of how electrode materials function in real-time at nanoscale. In this presentation, I will show a method we developed for performing in-situ electron microscopy and spectroscopy to track lithium transport and electrochemical reactions. Three examples will be given. One is on lithium conversion reaction in individual iron fluoride nanoparticles and the other is on lithium intercalation reaction in spinel titanate nanoplatelets. The third one is on lithium diffusion in doped hollandite nanorods which exhibit intriguing 1D tunnel structure that can be manipulated for charge transfer. The microscopy investigations were integrated with bulk x-ray and electrochemical measurements as well as theoretical calculations at atomic scale based on DFT and meso scale based on phase-field theory. The kinetics of ionic transport and the role of defects in the lithiation process will be discussed.
The author would like to thank F. Wang, L. Wu, W. Zhang, F. Xu, Q. Meng, M. Hybertsen, AC. Marschilok and ES. Takeuchi for their collaborations. The work was supported by the U.S. DOE/BES under contract DE-SC0012704.
Bioelectrode Engineering - Control of Catalytic Film Thickness for Enzymatic Fuel Cells
Authors: Li Huaiguang , Buesen Darren , Williams Rhodri , Henig Joerg , Stapf Stefanie , Winkler Martin , Happe Thomas , Plumeré Nicolas 
Published: February 2020

Redox hydrogel films are commonly applied for bioelectrode fabrication and we recently demonstrated that such matrices can be engineered to efficiently protect the hydrogenases from O2 damage to enable their integration into H2/O2 biofuel cells [1,2]. The formation of these films is highly reproducible for thicknesses between 30 to 300 µm. However, the most relevant thickness range for technological applications is in the low micrometer thicknesses which are more challenging to produce due to film thickness heterogeneities. Here, we propose the in-situ gelation of monodispersed viologen-modified macromolecules to achieve homogeneous films with thicknesses down to 100 nm. The relative standard deviations of the mean film thickness, was found to be only 4.8%. Electroanalytical investigations reveal defect-free, efficient electron transfer pathways over the complete film. We illustrate the advantage of this method and the importance of the film homogeneity for bioelectrocatalytic applications by investigating the behavior of bioanodes built from ferredoxin-NADP+-oxidoreductase or NiFe-hydrogenase for NADPH and H2 oxidation, respectively. The ability of forming thin films reveal that peak catalytic performances are reached at 10-fold lower catalyst loading compared to conventional approaches owing to the extreme homogeneity in film morphologies. This method will be generally transposable to other related applications, involving catalyst deposition by drop-casting with strict demands for film homogeneity.
[1] N. Plumeré, O. Rüdiger, A. Alsheikh Oughli, R. Williams, J. Vivekananthan, S. Pöller, W. Schuhmann, W. Lubitz, Nature Chemistry, 2014, 6, 822–827.
[2] V. Fourmond, S. Stapf, H. Li, D. Buesen, J. Birrell, O. Rüdiger, W. Lubitz, W. Schuhmann, N. Plumeré, C. Léger, J. Am.
Chem. Soc., 2015, 137, 5494-5505.
Financial support by the Cluster of Excellence RESOLV (EXC 1069) and by the ERC Starting grant REDOX SHIELDS is gratefully acknowledged.
Field Demonstration of Potentiostatically Enriched Microbial Fuel Cell Wastewater Treatment System
Authors: Mohamed Abdelrhman , Zmuda Hannah M. , Coats Erik R. , Beyenal Haluk 
Published: February 2020

The ability of microbial communities to exchange electrons with inert electrodes has fueled decades of scientific curiosity and laboratory investigations. Numerous studies have focused on developing applications of bioelectrochemical systems for energy generation, chemical synthesis, and sensor design. In particular, microbial fuel cells (MFCs) have been proposed as a promising technology for energy recovery from organic sources, including domestic and industrial wastewater. Many studies demonstrated the utility of microbial fuel cells in the treatment of wastewater in various reactor sizes from milliliter to cubic meter scale. In order to develop MFCs to be a viable technology for commercial applications, researchers aimed to optimize MFC operation, including optimizing MFC design, electrode materials and geometry, microbial community enrichment, startup and power harvesting strategies.
Most studies have reported startup strategies that includes connecting MFCs to a load, including resistors, capacitors, and power management systems. In this study, we demonstrate an active MFC startup strategy by controlling the potential of both the anode and cathode during the initial microbial community enrichment. The anode and cathode potentials are controlled using a custom dual potentiostat relative to a common Ag/AgCl reference electrode, with a common auxiliary electrode as a current sink/source.
Active MFC startup strategy is demonstrated in a large scale reactor (1200 liter) treating domestic wastewater. Sixteen MFCs (16 anodes and 16 cathodes) are enriched, each using an independent dual potentiostat. Each anode and cathode is a 30 cm x 30 cm carbon fabric electrode, and the counter electrode is a 30 cm x 30 cm x 1 cm graphite felt electrode. Dual potentiostats are connected to a computer using a data acquisition system to record anodic and cathodic current during enrichment. After reaching steady state current, each MFC is connected to a power management system that stores the harvested energy in a supercapacitor. The supercapacitors are discharged intermittently to power small air pumps used to aerate the cathodes.
(Invited) Mechanistic Details of Protonic Solar Cells Formed Via Covalent Modification of Passive Ion-Exchange Membranes with Photoacid Dye Molecules
Authors: White William , Sanborn Christopher D. , Schwartz Eric , Luo Simon , Fabian David M. , Renna Lawrence A. , Ardo Shane 
Published: February 2020

Many electrochemical technologies require ion-conducting polymer electrolytes. These polymers are passive in that electric bias across them drives ion migration in the thermodynamically favored direction.1 Recently, my group engineered two important features into ion-selective polymer membranes to introduce the active function of photovoltaic action and demonstration of an ionic solar cell. These features were covalent bonding of photoacid dyes to the polymers such that absorption of visible light liberated protons, and polymers with charge-selective contacts to facilitate separation and collection of H+ and OH–.2,3 The most effective designs join a monopolar cation-selective polymer to a monopolar anion-selective polymer to form a bipolar membrane whose electrostatics and thermodynamics mimic those of a rectifying semiconductor pn-junction diode. Illumination from either side of a photoacid-modified bipolar membrane resulted in photoinduced deprotonation of photoacids followed by charge separation in a direction dictated by the built-in electrostatic asymmetry in the polymers.
Performance optimization is underway to increase the state-of-the-art voltage to beyond 120 mV and state-of-the-art current to beyond 100 μA/cm2. The aim of these efforts is to gain a strong fundamental understanding of dye and material function using a variety of techniques. These include electrochemical impedance spectroscopy to quantify properties of capacitive space-charge regions; pulsed-laser spectroscopy to elucidate light-driven mechanisms of ion transfer and transport; finite-element numerical modeling to understand photoacid dye kinetics and drift–diffusion generation–recombination membrane physics; and optical, electron, and ion microscopies to elucidate materials morphology and function.
Collectively, these photo-responsive polymers represent a new class of materials that use light to trigger changes in local pH and/or electrostatic potential. These local changes can be used to affect macroscopic processes such as direct solar desalination of salt water or triggering redox chemistry or chemical catalysis.
Acknowledgment: This work is supported by a Moore Inventor Fellowship from the Gordon & Betty Moore Foundation, under Grant #5641.
References:

Reiter, R. S.; White, W.; Ardo, S. Journal of The Electrochemical Society, 2016, 163, H3132.

White, W.; Sanborn, C. D.; Reiter, R. S.; Fabian, D. M.; Ardo, S. Journal of the American Chemical Society, 2017, 139, 11726.

White, W.; Sanborn, C. D.; Fabian, D. M.; Ardo, S. Joule, 2017, Accepted Manuscript, DOI: 10.1016/j.joule.2017.10.015.