A stable anthraquinone-derivative cathode to develop sodium metal batteries: the role of ammoniates as electrolytes

Rechargeable sodium metal batteries constitute a cost-effective option for energy storage although sodium shows some drawbacks in terms of reactivity with organic solvents and dendritic growth. Here we demonstrate that an organic dye, indanthrone blue, behaves as an efficient cathode material for the development of secondary sodium metal batteries when combined with novel inorganic electrolytes. These electrolytes are ammonia solvates, known as liquid ammoniates, which can be formulated as NaI·3.3NH3 and NaBF4·2.5NH3. They impart excellent stability to sodium metal, and they favor sodium non-dendritic growth linked to their exceedingly high sodium ion concentration. This advantage is complemented by a high specific conductivity. The battery described here can last hundreds of cycles at 10 C while keeping a Coulombic efficiency of 99% from the first cycle. Because of the high capacity of the cathode and the superior physicochemical properties of the electrolytes, the battery can reach a specific energy value as high as 210 Wh kg−1IB, and a high specific power of 2.2 kW kg−1IB, even at below room temperature (4 °C). Importantly, the battery is based on abundant and cost-effective materials, bearing promise for its application in large-scale energy storage.This work has been developed in the context of project RTI2018–102061–B–I00 financed by FEDER/Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación. The Generalitat Valenciana through project PROMETEO/2020/089 is also gratefully acknowledged

Spectroelectrochemical Study of the Photoinduced Catalytic Formation of 4,4′-Dimercaptoazobenzene from 4-Aminobenzenethiol Adsorbed on Nanostructured Copper

Surface-enhanced raman scattering (SERS) spectra of self-assembled monolayers of 4-aminobenzenethiol (4-ABT) on copper (Cu) and silver (Ag) surfaces decorated with Cu and Ag nanostructures, respectively, have been obtained with lasers at 532, 632.8, 785, and 1064 nm. Density functional theory (DFT) has been used to obtain calculated vibrational frequencies of the 4-ABT and 4,4′-dimercaptoazobenzene (4,4′-DMAB) molecules adsorbed on model Cu surfaces. The features of the SERS spectra depend on the electrode potential and the type and power density of the laser. SERS spectra showed the formation of the 4,4′-DMAB on the nanostructured Cu surface independently of the laser employed. For the sake of comparison SERS spectra of a self-assembled monolayer of the 4-ABT on Ag surfaces decorated with Ag nanostructures have been also obtained with the same four lasers. When using the 532 and 632.8 nm lasers, the 4,4′-DMAB is formed on Cu surface at electrode potentials as low as −1.0 V (AgCl/Ag) showing a different behavior with respect to Ag (and others metals such as Au and Pt). On the other hand, the surface-enhanced infrared reflection absorption (SEIRA) spectra showed that in the absence of the laser excitation the 4,4′-DMAB is not produced from the adsorbed 4-ABT on nanostructured Cu in the whole range of potentials studied. These results point out the prevalence of the role of electron–hole pairs through surface plasmon activity to explain the obtained SERS spectra.Financial support from Ministerio de Economía y Competitividad (Projects CTQ2013-48280-C3-3-R and CTQ2013-44083-P), Fondos Feder, and the University of Alicante are greatly acknowledged

Hydroxyurea electrooxidation at gold electrodes. In situ infrared spectroelectrochemical and DFT characterization of adsorbed intermediates

The oxidation of hydroxyurea (H2NCONHOH, HU) at Au(100), Au(111) and Au(111)–25 nm thin film electrodes is studied spectroelectrochemically in perchloric acid solutions. HU, which in agreement with DFT results interacts weakly with the gold surfaces, oxidizes irreversibly at gold electrodes irrespective of the surface orientation. The in situ infrared external reflection spectra prove the formation of dissolved carbon dioxide and adsorbed cyanate as products of the HU electrooxidation reaction. A band at ca. 2230 cm−1 can be related both to dissolved isocyanic acid coming from the protonation of adsorbed cyanate or to nitrous oxide coming from the oxidation of hydroxylamine, which is formed (together with adsorbed cyanate) upon the chemical decomposition of hydroxyurea. ATR-SEIRAS experiments allow the observation of other adsorbate bands that can be tentatively ascribed to reaction intermediates that conserve the NCN skeleton and are bonded to the metal by the nitrogen atoms at near on-top positions. Bonding to the surface can be either unidentate or bidentate, involving covalent-type bonds or dative bonding through the lone pairs of the N atoms. Some of the signals of the experimental spectra, in particular those appearing around 1800 cm−1, can be assigned to the CO stretch of adsorbed intermediates having a nitrosyl group formed by oxidation of the NOH moiety (namely, adsorbed nitrosoformamide or its deprotonated form). The bands observed around 1650 cm−1 can correspond either to the NO stretching mode of the former species or to the CO stretching modes of adspecies conserving the NOH group.The authors acknowledge the funding by Ministerio de Economía y Competitividad through projectsCTQ2016-76221-P (AIE/FEDER, UE) and CTQ2016-76231-C2-2-R (AEI/FEDER, UE) and by the University of Alicante (VIGROB-263). William Cheuquepán is grateful for the award of a F.P.I. grant associated to project CTQ2009-13142

Electronic structure and experimental benchmarking of aluminum spinels for solar water splitting

A computational methodology for screening aluminum-based spinel oxides for photoelectrochemical water splitting has been developed by combining HSE06 and PBE + U calculations. The method, which can be extended to other ternary oxides, provides values for formation energies, band gaps, band edge positions, and carrier effective masses. The formation energies indicate that the Al spinels of Mg, Co, Ni, and Zn (successfully synthesized using a sol-gel method) are among the most stable in the series. Except for the Mg and Zn cases, the electronic structures of the spinels are rather similar, with band gaps separating occupied and empty 3 d metal states. The charge-transfer band gap values are found to be above 3 eV, limiting the use of these materials in solar water splitting, although an estimate of the band edge positions indicates that, in general, both conduction band electrons and valence band holes can promote water reduction and oxidation, respectively. The effective masses of the charge carriers suggests that the spinels are n-type semiconductors as experimentally demonstrated. Importantly, both the UV–vis spectra and the photoelectrochemical results qualitatively agree with the theoretical electronic structure. In general vein, this work demonstrates the potential of theoretical screening for the development and selection of new photoelectrode materials based on ternary oxides for their application in solar water splitting.The authors gratefully acknowledge funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no. 760930 (FotoH2 project). This research was also partially funded by the Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación/Fondos FEDER through project PID2021-128876OB-I00 and by the Generalitat Valenciana through project PROMETEO/2020/089. F.J.P. also acknowledges the Spanish Ministry of Education for the award of an FPU grant

On the electrochemical behavior of formamidine disulfide on gold electrodes in acid media

The adsorption and reactivity of formamidine disulfide (FDS) were studied at gold single crystal and thin film electrodes in perchloric acid solutions and the results of cyclic voltammetry and in situ infrared spectroscopy (SNIFTIR and ATR-SEIRAS) experiments compared with those previously obtained with thiourea (TU). In addition, optimized geometries and theoretical harmonic vibrational frequencies were obtained for adsorbed FDS, TU and thioureate from plane-wave DFT calculations using periodic surface models. These results were compared in the case of TU and thioureate to those previously obtained with a model Au cluster surface with (111) orientation. In the case of FDS, weak adsorption takes place with the S–S bond essentially parallel to the metal surface. No specific bands for adsorbed FDS can be identified in the experimental ATR-SEIRA spectra. These latter spectra suggest that adsorbed thioureate species are spontaneously formed upon dissociative adsorption of FDS when dosing this molecule at open circuit. Some of the adsorbed thioureate species undergo reductive protonation giving rise to a mixed adlayer formed by adsorbed thioureate and thiourea in a surface process which is faster when a controlled potential of 0.70 V is applied. In agreement with the observations reported when dosing TU, the ratio between TU and thioureate adsorbates is found to depend on the electrode potential, being higher for potentials close to the hydrogen evolution limit and decreasing for higher potential values.The authors acknowledge the finance by Ministerio de Economía y Competitividad (project CTQ2013-44083-P) and the University of Alicante. William Cheuquepán is grateful for the award of a F.P.I. grant associated to project CTQ2009-13142

Towards higher current and voltage LCLs

LCLs are widely used devices for power control and distribution in satellites. Traditionally, P-type MOSFETs have been used due to their simplicity from the control perspective. Actual ESA standard defines LCLs up to class 10 (10A) and 50V. However, 100V bus voltage is common in high power platforms and the current trend is to increase even more this value, around 300V. In this new scenario, the classic concept of LCL design needs to be revised, and this work proposes a simple alternative for P-type MOSFETs that operates at high voltage and can be easily scaled up in curren

Spectroelectrochemical detection of specifically adsorbed cyanurate anions at gold electrodes with (111) orientation in contact with cyanate and cyanuric acid neutral solutions

The adsorption and reactivity of cyanate at Au(111) single crystal and Au(111)-25 nm thin film electrodes is studied spectroelectrochemically in sodium perchlorate solutions and compared to those of cyanuric acid (C3N3O3H3). From the Surface Enhanced Infrared Reflection Absorption spectra obtained under Attenuated Total Reflection conditions (ATR-SEIRAS) it can be concluded that adsorbed cyanate species predominate at the electrode surface for low cyanate concentrations. However, for cyanate concentrations above 1 mM, the similarity of the ATR-SEIRA spectra with those obtained in cyanuric acid containing solutions indicates that some species coming from cyanuric acid is formed and adsorbed at the (111) gold surface sites as the result of an electroless trimerization reaction. Taking into account the results of Density Functional Theory (DFT) calculations, the experimental voltammetric and ATR-SEIRAS results agree with the formation of adlayers of specifically adsorbed triketo-monocyanurate species that adsorb perpendicular to the electrode surface.The authors acknowledge the funding by Ministerio de Economía y Competitividad (projects CTQ2016-76221-P and CTQ2016-76231-C2-2-R) and the University of Alicante (VIGROB-044 and VIGROB-263). William Cheuquepán is grateful for the award of a F.P.I. grant associated to project CTQ2009-13142

DFT and spectroelectrochemical study of cyanate adsorption on gold single crystal electrodes in neutral medium

The adsorption of cyanate anions at Au(111) and Au(100) single crystal electrodes has been studied spectroelectrochemically in neutral solutions. Potential-dependent in situ InfraRed Reflection Absorption spectra obtained below the onset of cyanate oxidation were compared with previously published data and analyzed on the basis of periodical Density Functional Theory (DFT) calculations. The calculated adsorption energies for cyanate and related species suggest that cyanic and isocyanic acid adsorb weakly at the studied gold surfaces and, thus, seems not to be at the origin of any of the adsorbate bands in the experimental infrared spectra collected in the cyanate-containing solutions. The latter features can be clearly ascribed to the asymmetric OCN stretching of N-bonded cyanate species. The observation of absorption bands in a wide spectral region, including features above 2200 cm− 1, agrees with the coexistence of N-bonded cyanate species with different adsorption sites and tilting angles. DFT calculations have revealed that although these adspecies can have significantly different frequencies, their adsorption energies are rather close. In addition, the existence of collective in-phase vibrations at relatively high cyanate coverages also contributes to the widening of the absorption bands.The authors acknowledge the funding by the Ministerio de Economía y Competitividad (project CTQ2013-44083-P) and the University of Alicante (VIGROB-263). William Cheuquepán is grateful for the award of a F.P.I. grant associated to project CTQ2009-13142

Formation of cyanuric acid from cyanate adsorbed at gold electrodes

We report the formation of cyanuric acid species at Au(111) electrodes in cyanate-containing solutions, due to the electroless trimerization of isocyanic acid. Similar experimental bands in the range between 1300 and 1900 cm− 1 are observed in Surface Enhanced Infrared Reflection Spectroscopy experiments under Attenuated Total Reflection conditions (ATR-SEIRAS) with solutions containing either cyanate anions at high concentration or cyanuric acid. The experimental frequencies agree well with those obtained from Density Functional Theory (DFT) calculations for the adsorbed cyanurate anion, bonded to the metal in a tridentate configuration, with its molecular plane perpendicular to the metal surface.The authors acknowledge funding by Ministerio de Economía y Competitividad (project CTQ2013-44083-P) and University of Alicante (VIGROB-263).William Cheuquepán is grateful for the award of a F.P.I. grant associated to project CTQ2009-13142

Turning Emergency Plans into Executable Artifacts

ISBN: 978-0-692-21194-6 Available under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0) LicenseInternational audienceOn the way to the improvement of Emergency Plans, we show how a structured specification of the response procedures allows transforming static plans into dynamic, executable entities that can drive the way different actors participate in crisis responses. Additionally, the execution of plans requires the definition of information access mechanisms allowing execution engines to provide an actor with all the information resources he or she needs to accomplish a response task. We describe work in progress to improve the SAGA's Plan definition Module and Plan Execution Engine to support information-rich plan execution