bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) High Rate Energy Storage Based on Pseudocapacitance in Oxide Materials
Authors: Dunn Bruce 
Published: February 2020

The growing interest in using pseudocapacitor-based materials for electrochemical energy storage is that the energy density associated with faradaic reactions is much greater, by at least an order of magnitude, than the electrical double layer capacitance of carbon electrodes. The reversible redox reactions that characterize pseudocapacitance occur at or near the surface of an electrode material and are fast enough so that the device's electrochemical features are similar to those of a carbon-based capacitor, but with significantly higher energy density. This paper will review recent research directed at identifying various electrochemical and structural characteristics which provide insight regarding pseudocapacitive materials and properties. One key feature associated with pseudocapacitance is that the rate of charge storage is determined by surface-like kinetics rather than semi-infinite diffusion as occurs with battery materials. In this regard, the presence of two-dimensional pathways in the structure of the oxide material seems to be favorable for obtaining a pseudocapacitive response. Another important consideration with this mechanism is that the structure does not undergo a first-order phase transition upon Li+ insertion. However, even with materials that exhibit such phase transitions, nanostructuring the material can effectively suppress the structural change and lead to attractive properties. In the case of nanoscale MoO2, we showed that pseudocapacitive properties are developed which enable the material to operate at high charge/discharge rates without decreasing the level of charge storage. Morphology is another parameter that can be used to develop pseudocapacitive properties in oxides. Mesoporous materials, which possess an interconnected pore network that provides electrolyte access to thin (<15 nm) redox-active walls, lead to a pseudocapacitive response while two-dimensional nanosheets of transition metal oxides exhibit surface-controlled kinetics indicative of pseudocapacitive behavior. The ensemble of these results suggests that we can expect an increasing number of materials to be developed that retain high energy density at charge/discharge rates which are well above those of battery materials.
Microsomal Bioelectrodes Modified with Nanostructures for Rapid Drug Metabolism and Inhibition Assays and Cost-Effective Green Synthesis
Authors: Krishnan Sadagopan , Walgama Charuksha , Nerimetla Rajasekhara 
Published: February 2020

Purification of membrane-bound enzymes in general and drug metabolizing human liver cytochrome P450 heme enzymes (CYPs)[1] in particular has been a major bottleneck in advancing the field of enzyme electrocatalysis. The ability to use unpurified enzymes and additionally mimic in vivo drug metabolic pathways would accelerate current drug development processes by enabling cost-effective rapid electrochemical drug screening and stereoselective drug metabolite synthesis. For new drug development, human liver microsomes (HLMs) are being used as in vitro systems to study drug metabolism, inhibition, and drug-drug interactions and to identify the specific isoforms of CYPs involved in these processes.[2] Application of liver microsomes or genetically engineered versions of microsomes containing CYPs and CYP-reductase in the development of new biosensing and electrocatalytic systems is an emerging research area.[3] Recently, our laboratory examined the influences of various carbon electrode materials in the direct electron transfer and electrocatalytic properties of immobilized HLMs.[4] We found that electrode roughness and hydrophilic nature offered greater electrocatalytic currents and microsomal film stability on electrodes. As a next step, our goal is to achieve highly enhanced electrocatalytic metabolite production with sufficient electrocatalytic stability and reusability features. For this, we are exploring various nanotechnology strategies to immobilize microsomes in biologically active form. Results from our preliminary findings in this objective utilizing carbon and metal oxide nanomaterials will be discussed.

[1] P. R. Ortiz de Montellano, Future Med. Chem. 2013, 5, 213-228.
[2] L. C. Wienkers, and T. G. Heath, Nat. Rev. Drug Discov. 2005, 4, 825-833.
[3] S. Krishnan, J. B. Schenkman, and J. F. Rusling, J. Phys. Chem. B 2011, 115, 8371-8380.
[4] C. Walgama, R. Nerimetla, N. F. Materer, D. Schildkraut, J. F. Elman, and S. Krishnan, Anal. Chem.

2015
, 87
, 4712-4718.
Quasireversible Is Irreversible Dressed up
Authors: Harrington David A. 
Published: February 2020

Diffusion and convection to an electrode with an irreversible reaction is allegedly a much simpler mass-transport problem than the same problem for a quasireversible reaction. This seems self-evident, since in the quasireversible case the mass transport of the product species has to be included, not just the reactant species. This leads to a coupled mass transport problem, and that has to be harder, right? Well, not necessarily. Under the common assumption that the diffusivities are equal, the quasireversible concentration profiles and current density can be trivially derived from the irreversible ones. One just replaces the forward rate constant by the sum of the forward and backward rate constants, scales the result and adds a constant. What could be simpler than that?
I show that this works under most of the convective diffusion situations encountered in electrochemistry. Of course there are some restrictions. On the other hand, for some cases the condition of equal diffusivities can be relaxed. I give some examples of where this is more than just a curiosity in relating known results in classic electrochemistry. In particular, it can lead to more efficient numerical analysis schemes.
[1] D.A. Harrington, Electrochim. Acta., 308, 152 (2015).
Dye-Sensitized Solar Cells in Humidity Environment: A Suitable Fabrication Procedure and Outdoor Test of Cell Stability
Authors: Nguyen Hoang Thai , Tran Linh Thi Phuong , Le Nghiem Van , Vo Long , Nguyen Thoa Thi Phuong 
Published: February 2020

The performance of dye-sensitized solar cells (DSCs) fabricated by conventional procedure in humid environment have rapidly declined in outdoor testing. This fact may be caused due to the uptake of water into cells during the process of dye soaking (around 20 - 24 hours) and electrolyte filling under ambient air. In this work a new fabrication procedure, that proved to prevent the water uptake, was established for DSC assembling in high humidity environment. In the procedure, the sandwich cell, assembled from preparative FTO/TiO2 and FTO/Pt electrodes was filled with N719 (10 mM)/DMF solution for the dye adsorption on TiO2film in 4 hours. The dye adsorbing, electrolyte filling and cell sealing have been carried out in inert gas atmosphere using a glove box.
By new fabrication procedure the energy conversion efficiency (η) of DSCs was improved on 10%. In addition, DSCs fabricated by new procedure were more stable under outdoor testing, the efficiency was even increased 9% at 14-day-outdoor-exposure. From 30thday of outdoor test the cell efficiency began slightly decrease, and reached the initial value after 100-day-exposure.
The effect of co-adsorption with chenodeoxycholic acid (CDA) on DSC performance based on new fabrication procedure was investigated. By addition of 100 mM CDA the short circuit photocurrent has significantly increased, the open circuit voltage slightly increased, and the overall power conversion efficiency of as-prepared DSCs was improved by 8%. However the effect of CDA on cell performance was diminished during outdoor exposure.
The change of DSC characteristics was discussed based on analysis of electrochemical impedance spectroscopy (EIS) data. The enhancement of photocurrent caused by the photo-activation of the cathode interface during first weeks of outdoors exposure, as well was the effect of co-adsorbate, were interpreted from impedance spectra.
Effect of Morphology Controlled Synthesis of BiOCl Photocathode By Chemical Vapor Deposition for Solar Water Reduction
Authors: Myung Yoon , Banerjee Sriya , Banerjee Parag 
Published: February 2020

Bismuth oxychloride has emerged as an important material for photoelectrochemical, photocatalysis and photovoltaic application. Its unique crystal structure of alternating sheets of [BiO2]2+ and two Cl-1 along the c-axis, leads to the formation of an internal electrical dipole, facilitating faster electron-hole separation. It has a p-type conductivity with a bandgap of ~3.4 eV and its band edge position is suitable for photelectrochemical water reduction.
In this study, BiOCl films with 3 different morphologies are synthesized by the chemical vapor deposition process and the effect of sample morphology on the photoelectrochemical behavior is studied. BiOCl is deposited on transparent electrodes by thermal vapor transport of BiCl3 precursors. Figure 1(a-c) shows the as deposited microwall, micropore and microflower morphologies of BiOCl, obtained by finely controlling the deposition conditions
The photoelectrochemical cells fabricated using the as grown micropore morphology showed the highest photocurrent. The micropore structure allows solution penetration into the pores thus providing faster charge transport pathways. Structural investigation will be presented using SEM, XRD and Raman spectroscopy. This work demonstrates that tailoring the BiOCl surface morphology can lead to efficient photoelectrochemical water reduction.

Figure 1
Electrochemistry of Co(TPTZ)2 Complex on a Carbon Paste Electrode Modified with TiO2 Nanoparticles
Authors: Ortaboy Sinem , Atun Gülten 
Published: February 2020

Nowadays, the cobalt based complexes have attracted considerable interest in dye sensitized solar cells (DSSC). They have been widely used as a redox electrolyte [1], sensitizing agent [2] and the component of counter electrode (CE) material [3]. Therefore, their electron-proton transfer behavior should be taken into account to achieve success in efficient DSSC [4].
In the present study, electrochemical behavior of cobalt (II) complex with the N-donor ligand 2,2’-bipyridyl-1,3,5-tripyridyl-s-triazine (TPTZ) on the TiO2 modified carbon paste (T/CPE) was compared with the bare carbon paste electrode (CPE). The electrochemical response of the complex was studied by means of square-wave voltammetry (SWV) technique in a conventional one compartment cell using a saturated Ag/AgCl and a platinum wire as the reference and counter electrode, respectively. The effect of TiO2/graphite ratio of T/CPE on the voltammetric response of the Co(TPTZ)2 complex was examined and the best result was obtained for 60 % (w/w). The ligand/metal ratio and stability constant of the complex as well as the mechanisms of the electrode processes were elucidated by examining the effects of pH, ligand concentration and frequency on the voltammograms. The optimum pH was selected as 7.5 for comparison of the T/CPE and CPE electrodes. The electrochemical impedance spectroscopy (EIS) results obtained in the phosphate buffer indicated that T/CPE had higher charge transfer resistance and electroactivity than those of the bare electrode. It was concluded from the Bode-phase diagrams that nano-TiO2 structure increases the conductivity between electrode and electrolyte interface due to the good penetration of the Co(TPTZ)2 complex into the electrode surface trough the nano-TiO2 pores. All the electrochemical results were found to be consistent with the surface morphology of the working electrodes obtained using atomic force microscopy (AFM).

References:

[1] T.W. Hamann, Dalton Transactions 41 (2012) 3111–3115.
[2] N. Goswami, P. K. Gogoi, M. K. Bhattacharyya, D. Saikia, International Journal Of Innovative Research & Development 1 (7) (2012) 92-103
[3] S.Y. Chae, Y.J. Hwang, J.H. Choi, O.S. Joo, Electrochimica Acta 114 (2013) 745– 749.
[4]S. Ortaboy, G. Atun, Materials Chemistry and Physics 156 (2015) 129-140

Acknowledgements

This work was supported by Scientific Research Projects Coordination Unit of Istanbul University. Project Number: 3757-Doctoral Thesis Project. It was also supported by the Scientific and Technological Research Council of Turkey (TUBITAK) 2219- International Postdoctoral Research Fellowship Program (App. No: 1059B191401401).
Catalyzing Hydrogen Evolution Reaction By the Use of Earlier Transition Metal Nitrides
Authors: Abghoui Younes , Skulason Egill 
Published: February 2020

Today’s society is in pursuit of an alternative route for production of energy and chemicals due to scarcity of natural gases and fossil fuels. At the same time, strict environmental regulations push international scientific and industrial community towards more sustainable ways to meet the increasing demands of our energy-intensive society resulted in development of energy conversion technologies. As of now, hydrogen is accepted as an integral ingredient for renewably synthesis of e.g. ammonia and methanol. It is also the cleanest fuel and one of the most promising sources of energy [1]. The electrochemical hydrogen evolution reaction (HER) is a very interesting CO2-free approach effectively catalyzed by the Pt group metals. But Pt is scarce and therefore expensive. In order to meet the increasing need for hydrogen and energy, new catalysts should be explored that are active for HER as good as or nearing that of Pt fulfills. If that achieves, precious Pt can be replaced by cheaper and more abundant material holding great promise for clean energy technologies.
In this study, we used density functional theory calculations to screen for highly stable and active catalysts amongst a range of transition metal nitride surfaces [2]. The free energy of all intermediates was calculated with density functional theory (DFT). For the candidates promising for HER, activation energies for H2 formation were calculated at varying applied potentials [3]. The free energy of adsorption of H nominates a few nitrides capable of catalyzing HER at low overpotentials of around 0.0 to +0.35 V vs. SHE. We are currently examining these extremely promising HER catalysts in more detailed theory and experiment and the preliminary observations and measurements are indicative of the validity of our model as the proposed overpotentials for HER agree with the experimental polarization curves.
References
1) Crabtree, G. W., Dresselhaus, M. S. and Buchanan, M. V. Phys. Today, 2004, 57, 39−44
2) Y. Abghoui, A. L. Garden, V. F. Hlynsson, S. Björgvinsdóttir, H. Ólafsdóttir, and E. Skúlason, Phys. Chem. Chem. Phys., 2015, 17, 4909–4918.
3) Y. Abghoui and E. Skúlason, in preparation (2015)

Figure 1
Effects of Composition and Structure on Performance and Durability of Pt-Ni Extended Surface Catalysts
Authors: Pylypenko Svitlana , Ngo Chilan , Shulda Sarah , Alia Shaun M , Pivovar Bryan S 
Published: February 2020

Reduction of electrocatalyst costs is crucial to the commercialization of proton exchange membrane fuel cells (PEMFCs). Platinum nanoparticles on high surface area carbon (Pt/HSC) substantially increase the Pt surface area and thus decrease the required amount of Pt, but suffer from loss of activity from various degradation processes. Extended Pt nanostructures are promising candidates to replace traditional electrocatalysts, as they have been shown to improve specific activity and durability; however, these materials have typically exhibited limited surface areas.
In this work, extended surface Pt-nickel (Ni) nanowires with 7 and 17 wt% Pt have been synthesized via spontaneous galvanic displacement and achieved exceptionally high surface areas (up to >90m2/g Pt). Various post-processing treatments have been applied to modify the composition and structure of these nanowires, with the goal of further improving their activity and durability. Extensive spectroscopy and microscopy studies were carried out to elucidate relationships between electrochemical performance and material composition, morphology, and structure both in bulk and at the surface.
Annealing the Pt-Ni nanowires in hydrogen continuously increased the specific activity with a peak in mass activity at 250°C. X-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) show that this activity increase is a result of Pt-Ni alloying. An additional cause of the increased activity is likely the formation of a more homogeneous Pt layer, which was induced by hydrogen annealing and clearly visible in elemental maps aquired with energy dispersive x-ray spectroscopy (EDS) via transmission electron microscopy (TEM). Further modification of the hydrogen annealed samples discussed in this work include oxygen annealing, acid leaching, and combinations of acid leaching with further heat treatments. XPS, TEM and EDS were used to investigate changes in the nanowires resulting from different strengths of acid treatments, which were utilized to remove undesired Ni species while maintaining high activity and durability.
[1]. S.M. Alia, Y. Yan, B.S. Pivovar, “Galvanic Displacement as a Route to Highly Active and Durable, Extended Surface Electrocatalysts” Catalysis Science and Technology, 2014, 4 (10), 3589 - 3600. DOI: 10.1039/C4CY00736KG.
Figure 1. EDS maps of Pt-Ni nanowire annealed in hydrogen at 250°C.

Figure 1
Tuning Pt-Skin or M-Rich Surface on Bimetallic Nanoparticles (Pt3Ni, PtBi, Pt3Co) for Enhanced Electrocatalytic Activities
Authors: Jiang Yan-Xia , Zhang Bin-Wei , Zhen Chun-Hua , Sun Shi-Gang 
Published: February 2020

Controlling surface composition of bimetallic catalysts is of significance in energy conversion and storage. We synthesized a series of bimetallic catalysts of different surface composition on porous graphitic carbon (PtBi/PC, Pt3Ni/PC, Pt3Co/PC: figures A, C, E, G) with average diameter < 4 nm by controlled thermal treatment method.
Formic acid oxidation on Pt/C is performed via the poisoning path (figure B), whereas oxidation of formic acid to form CO2 is done via the non-poisoning path on the PtBi/PC (figure D). The value of the peak current density is 4.6 times of that of the Pt/C catalysts. Pt3Ni catalyst with Pt-skin surface showed over 300% increase in mass activity compared with Pt/C for the oxygen reduction reaction (figure F). When we tuned the surface composition to Ni-rich, it showed 300% increasein mass activity when compared with Pt/C towards oxidizing of HCOOH. Ethanol oxidation on Pt3Co/PC with Pt-skin surface showed 2.5 times on mass activity than that of Pt/C. In addition, we proposed a new method to characterize Pt-skin or M-rich structure by using formic acid oxidation as probe reaction with the characterization of cyclic voltammetry and electrochemical in situFTIRs.
Our approach to control surface composition can be used to design nanocatalysts for different reaction and enhance their catalytic performances. and The method is simple and clean that is effective and promotional to be industrialized.

Figure 1
PdCu/C Catalysts for the Electrochemical Oxidation of Renewable Polyalcohols
Authors: Haan John , Muneeb Omar , Estrada Jose , Flores Jennifer , Nguyen Kelly 
Published: February 2020

The development of the alkaline anion exchange membrane (AEM) for the direct liquid fuel cell opened up opportunities for the use of new fuels (that oxidized inefficiently in PEM fuel cells) and new catalysts (that corroded easily in PEM fuel cells). The first fuel studied in depth was ethanol because it oxidizes much more efficiently in alkaline media than acidic media. However, the same palladium catalyst that oxidizes ethanol in alkaline media can also be used to oxidize several other alcohol fuels including polyalcohols such as ethylene glycol (EG), propylene glycol (PG), and glycerol (G). Therefore, we recently demonstrated a flexible fuel direct liquid fuel cell that operated on alcohols such as ethanol, EG, PG, and G. However, these fuels all oxidize more slowly then ethanol, requiring significant kinetic improvement to be used practically.
We tested various combinations of Pd:Cu and compared them in each polyalcohol fuel, EG, PG, and G. We observed that any quantity of Cu added to the Pd produced an increase in oxidation rate compared with pure Pd for all three polyalcohol fuels. We also observed a down-shift in d-band center as observed by XPS. We hypothesize that the addition of Cu to the Pd results in a combination of the electronic and bifunctional effects. The electronic effect is caused by perturbations in the electronic structure of Pd, the primary catalyst, induced by the Cu. The bifunctional effect is caused by the co-catalysis of Pd and Cu directly on the surface of the catalyst.
Electrochemical Approaches to Synthesis Different (di)Phenylphosphine Oxide Derivatives
Authors: Khrizanforova Vera , Khrizanforov Mikhail , Gryaznova Tatyana , Budnikova Yulia 
Published: February 2020

Phosphine oxides are successfully used as building blocks, specifically, for the synthesis of substituted vitamin D3 analogs. Tertiary phosphine oxides are key targets in the chemistry of organophosphorus compounds. They are widely used as ligands for metal complex catalysts, special solvents for stabilization of nanosystems in the synthesis of semiconductors, extractants for noble, rare-earth, and transuranium elements, fire-retardants, and photochromic and lumines-cent materials.1-4

Of particular interest are functionalized tertiary phosphine oxides; however, their synthesis involves some difficulties. A convenient synthetic approach to such compounds is based on the addition of secondary phosphine oxides to functionally substituted alkynes at high temperature by using equivalent amounts of oxidant and catalyst.1-4

In our work the synthesis of different (di)phenilphosphine oxide derivatives in electrocatalytic conditions have been performed. Our approach provides an efficient way to construct different phosphorus-containing products, including bisphosphonates, benzo[b]phosphole oxides, alkynyl(diaryl)phosphine oxides with high yield at room temperature in oxidant-free media. The mechanism includes forming cobalt and silver complexes with diphenylphosphine oxide, their electrochemical reduction/oxidation leads to binding with acetylene and obtaining target products.

Acknowledgements

This work was supported by the Russian Science Foundation no. 14-23-00016.

References

1 Wang, T.; Chen,S.; Shao, A.; Gao, M.; Huang, Y.; Lei, A. Org.Lett. 2015, 17, 118.
2 Chen, Y.-R.; Duan, W.-L. J. Am. Chem. Soc. 2013, 135, 16754.
3 Dvorko, M. Yu.; Glotova, T. E.; Ushakov, I. A.; Gusarova, N. K. Russ. J. Org. Chem. 2010, 45, 485.
4 Srinivas, V.; Balaraman, E.; Sajna, K.V.; Kumara Swamy, K.C. Eur. J. Org.
Chem.

2011, 4222–4230.

Figure 1
Activity Trends of Co3O4 on Metallic Interlayers Supported on Porous Carbon Support
Authors: Kishor Koshal , Saha Sulay , Pala Raj Ganesh , Sivakumar Sri 
Published: February 2020

We explore the design of support for Co-based water oxidation electrocatalysts. While earth abundant metals (EAM) have adequate conductivity, they lack the porosity provided by carbon support. To alleviate this problem and make the electrode more three dimensional, we demonstrate the utility of electrodeposited metal interlayers that not only offers parallel electron conduction pathways, but also due to variation of exposed surface during electrodeposition and electronic structure which promotes electrocatalytic activity of Co3O4. To see the effect of parallel metal interlayer, a range of non-noble earth abundant metals are explored. Maximum OER activity is found to be with Cu-modified metal support which is attributed to its higher electrical conductivity with enhancement of OER activity about 6 times in similar condition with respect to unmodified porous carbon support. The OER activity of electrodeposited Co3O4 is found to have a linear relationship with electrical conductivity with electron donor metals and electron acceptor metals individually. The above understanding can be useful in increasing OER activity of the same electrocatalyst by tuning support-catalyst interaction.