Journal of Solid State Electrochemistry

Pyun, Su-Il

doi: 10.1007/s10008-020-04780-2pmid: N/A

In this report, we conceptually distinguish direct electron transfer (DET) from mediator-involved (mediated) electron transfer (MET) in a glucose/oxygen-based fuel cell (FC) using an electrode potential/Fermi energy diagram. The anodic and cathodic overvoltages deviating from the equilibrium potential (the Fermi energy of redox electrons) were taken into account for the organic/inorganic redox couple and the mental experiments were performed during the trip of redox electrons through the interface between the anodic/cathodic organic/inorganic active mass and electrodes to propose electron transfer pathway. The proposed schema (inequality (MET) and equality in Fermi energy (DET)) should be experimentally corroborated by measurement of the electromotive force (emf). The MET is of technological significance in the presence of an electron mediator of the redox couple, despite a slightly narrower emf estimated between two electrodes by roughly 1 to 2 mV at most than the DET, in view of the thermodynamic and electro-kinetic viewpoints.

Petiti, Chiara; Gulotta, Davide; Mariani, Bruna; Toniolo, Lucia; Goidanich, Sara

doi: 10.1007/s10008-020-04822-9pmid: N/A

Electrochemical techniques have been successfully applied in the past as non-destructive techniques to the cultural heritage field. In particular, linear polarisation resistance (LPR) and electrochemical impedance spectroscopy (EIS) have been employed for the onsite monitoring of corrosion on metallic works of art, providing valuable results. Such techniques have been successfully adapted from the industrial field for this particular kind of application, but a systematic evaluation of the influence of all experimental settings on the obtained results is still lacking: several factors and parameters can affect the results, and it is important to properly consider their influence for a reliable interpretation of data. Therefore, in this work, the influence of a series of experimental parameters was evaluated in order to obtain a reliable and time-effective setup by performing a series of tests on a bronze artefact. Several variables were considered, with particular attention to those affecting the reproducibility and reliability of the measurements, as well as the duration of each single acquisition. It was demonstrated, in fact, that an optimised experimental setup from the point of view of the duration could improve also reproducibility and reliability of the measurements. The optimised protocol was then adopted in the framework of a diagnostic campaign of the Monumento ai Caduti (War Memorial) of Lecco (IT)

von Aspern, Natascha; Wölke, Christian; Börner, Markus; Winter, Martin; Cekic-Laskovic, Isidora

doi: 10.1007/s10008-020-04781-1pmid: N/A

Two functional high-voltage additives, namely 2-(2,2,3,3,3-pentafluoropropoxy)-1,3,2-dioxaphospholane (PFPOEPi) and 1-methyl-3,5-bis(trifluoromethyl)-1H-pyrazole (MBTFMP) were combined as functional additive mixture in organic carbonate–based electrolyte formulation for high-voltage lithium battery application. Their impact on the overall performance in NMC111 cathode-based cells was compared with the single-additive–containing electrolyte counterpart. The obtained results point to similar cycling performance of the additive mixture containing electrolyte formulation compared with the MBTFMP-containing cells, whereas the single PFPOEPi-containing cells displayed the best cycling performance in NMC111||graphite cells. With regard to the cathode electrolyte interphase (CEI), characterized and analyzed by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), both the MBTFMP and the PFPOEPi functional additives decompose on the NMC111 surface in single-additive–containing electrolyte formulations. However, the thickness of the CEI formed in the additive mixture–containing electrolyte formulation is determined by the MBTFMP additive, whereas the PFPOEPi additive impacts a change in the composition of the CEI. Furthermore, the MBTFMP additive decomposes prior to the PFPOEPi and, therefore, dominates the cycling performance of NMC111||graphite cells containing functional additive mixture–based electrolyte. This systematic approach allows us to understand the synergistic impact of each functional additive in an electrolyte formulation containing an additive mixture and helps to identify the right additive combination for advanced electrolyte formulation as well as to elucidate whether the single-additive or the additive mixture approach is more effective for the development of advanced functional electrolytes for lithium-based cell chemistries.Graphical abstract[graphic not available: see fulltext]

da Costa Soares, Izabelle Cristina; da Silva, Ámison Rick Lopes; de Moura Santos, Elaine Cristina Martins; dos Santos, Elisama Vieira; da Silva, Djalma Ribeiro; Martínez-Huitle, Carlos A.

doi: 10.1007/s10008-020-04813-wpmid: N/A

Anodic oxidation (AO) approach proceeds via direct and indirect electrochemical pathways and their subsequent reactions. The interest to elucidate the mechanisms for removing dyes from water contributes to the understanding of more complex reactions involving organic pollutants towards anode surfaces. The present study was motivated by the reports that promote the use of AO for removing different organic compounds but no considerations about the influence of different functional groups in their structure have been discussed. Therefore, we have evaluated the influence of different functional groups in the dye structure (Reactive Orange 16, Reactive Violet 4, Reactive Red 228, and Reactive Black 5) by potentiodynamic measurements and by computational analyzes using density functional theory (DFT). The computational studies have allowed to carry out morphological studies on the frontier orbitals where the electrons are more energetic and then, the electron-transfer to electrode surface is achieved, which was associated to the electrochemical measurements (current-potential profiles). Also, the theoretical studies were used to understand the bulk electrolysis, in terms of mineralization. The results clearly demonstrate that organic molecules can be degraded in different way and level due to the oxidants electrochemically generated as well as the interaction of dyes with anode surface by adsorbed/non-adsorbed intermediates. Conversely, the decolorization mechanisms, which are related to the fragmentation of chromophore group, are associated to the direct AO approach, favoring different order of elimination, as already reported in our previous work. The results were discussed in light of the existing literature.

Dominguez-Flores, Fabiola; Santos, Elizabeth; Schmickler, Wolfgang; Juarez, Fernanda

doi: 10.1007/s10008-020-04802-zpmid: N/A

The interaction between two Cl− ions separated by the wall of a narrow carbon nanotube has been investigated by density functional theory (DFT) and by DFT-based tight binding (DFTB+). The direct Coulomb interaction between the ions is screened by the nanotube, no matter if the latter is conducting or semiconducting. The presence of the ions induces changes in the electronic density of states of the nanotube, which results in an effective attraction between the ions of the order of 0.2–0.3 eV. The interaction of the outside ions with the tube has a covalent component, when the two ions are near there is even a direct chemical attraction between the ions. In contrast to the effective attraction between two Li+ ions reported before (Juarez et al., Phys Chem Chem Phys 22:10,603, 2020), the effect cannot be explained in terms of physical concepts alone. DFTB+ performs well when compared with DFT, and lends itself to fast calculations for large systems.