1,721,147 research outputs found
Adsorption behavior of I3(-) and I(-) ions at a nanoporous NiO/acetonitrile interface studied by X-ray photoelectron spectroscopy
No full textThe adsorption of I- and I3 - anions, i.e., the two species constituting the most common redox couple of dye-sensitized solar cells (DSCs), onto the surface of screen-printed nanoporous NiO was studied by means of X-ray photoelectron spectroscopy (XPS). Nanoporous NiO films were deposited on transparent metallic fluorine-doped tin oxide (FTO) and polarized as working electrodes in a three-electrode cell with differently concentrated I-/I3 - electrolytes to simulate the different conditions experienced by the NiO cathodes during the lifecycle of a p-type DSC (p-DSC) at those atomic sites not passivated by the dye. Bare NiO films were tested also as photocathodes of nonsensitized p-DSCs. The ex situ XPS analysis of I 4d ionization region of both reference and electrochemically treated NiO films showed that the presence of native and electrochemically generated Ni3+ and Ni4+ centers induces fast adsorption/desorption of I- ions and catalyzes their oxidation to I3 - ions. The adsorption phenomena generated by I- and I3 - species on nanoporous NiO electrodes can also induce an effect of electrochemical passivation toward a fraction of charged Ni sites. Such an effect would render these sites inactive for the further realization of those photoelectrochemical processes at the basis of the operation of a p-DSC. © 2016 American Chemical Society
Is binge drinking in adolescence related to specific impairments in well-being? New insights from a pilot survey of high school students
No full textHeavy episodic alcohol consumption or binge drinking (BD) is highly prevalent among adolescents in Europe. Young BD is associated with a range of negative health and social outcomes and its causes could be referred to greater positive alcohol expectancies or low self-efficacy and personality characteristics. Moreover, it is likely that some adolescents drink because they want to reduce negative emotions or deal with stress. Little is known on the relationship between BD and specific well-being impairments, whereas it seems that meaning in life, a concept similar to psychological well-being, do not characterize such population. We recruited 679 consecutive students who completed the Psychosocial Index and the Alcohol Use Disorder Identification Test (AUDIT). Among the recruited students, 337 consume alcohol and 161 report BD. Significant differences have been highlighted among three groups (no drinkers, drinkers and bingers) concerning stress and environmental mastery. Both higher scores of stress and lower levels of environmental mastery are associated with BD. These preliminary data show that BD is highly represented and the novelty of this study refers to the evaluation of binge drinking phenomenon in adolescents, through validated and reliable methods in the field of clinimetrics
Study of the influence of the I-Based electrolyte composition on the photoconversion properties of p-Type Dye-sensitized solar cells
No full textIn the framework of the research on dye-sensitized solar cells of p-type (p-DSCs) the definition and optimization of the electrolyte have been a crucial aspect for the reach of the recent records of photo-conversion for these devices. At the basis of this progress there was the replacement of the redox shuttle of reference I-3(-)/I- with opportune redox mediators which deliver higher photocurrents and produce larger open circuit photovoltages. In the present study we intend to optimize the composition of the iodine-based electrolyte for p-DSCs employing variable concentrations of redox shuttle. Beside the general conditioning of the overall performance, the analysis of the influence of p-DSC electrolytes has concerned the aspects of the extent of optical parasitic absorption of the electrolyte, of the chemical aggressiveness of the redox species and of the control of the phenomena of electronic back-donation by the photoreduction product. Non-obvious correlations have been found between the main cell parameters (eta, J(SC), V-OC, FF) and the electrolyte conductivity. In the present work, a photocurrent density higher than 4.0 mA*cm(-2) is reported when I-based electrolyte (LiI 1.0 M and I-2 1.0 M in ACN) was employed. EIS experiments proved that this outstanding photocurrent was due to the lowering of recombination phenomena. (C) 2018 The Electrochemical Societ
Nanostructured p-type semiconductor electrodes and photoelectrochemistry of their reduction processes
Full text linkThis review reports the properties of p-type semiconductors with nanostructured features employed as photocathodes in photoelectrochemical cells (PECs). Light absorption is crucial for the activation of the reduction processes occurring at the p-type electrode either in the pristine or in a modified/sensitized state. Beside thermodynamics, the kinetics of the electron transfer (et) process from photocathode to a redox shuttle in the oxidized form is also crucial since the flow of electrons will take place correctly if the et rate will overcome that one of recombination and trapping events which impede the charge separation produced by the absorption of light. Depending on the nature of the chromophore, i.e. if the semiconductor itself or the chemisorbed dye-sensitizer, different energy levels will be involved in the cathodic et process. An analysis of the general properties and requirements of electrodic materials of p-type for being efficient photoelectrocatalysts of reduction processes in dye-sensitized solar cells (DSC) will be given. The working principle of p-type DSCs will be described and extended to other p-type PECs conceived and developed for the conversion of the solar radiation into chemical products of energetic/chemical interest like non fossil fuels or derivatives of carbon dioxide
Assessing the Structure of Protic Ionic Liquids Based on Triethylammonium and Organic Acid Anions
Full text linkWe present a computational analysis of the short-range structure of three protic ionic liquids based on strong organic acids: trifluoracetate, methanesulfonate, and triflate of triethylammonium. Accurate ab initio computations carried out on the gas-phase dimers show that the protonation of triethylamine is spontaneous. We have identified the anion-cation binding motif that is due to the presence of a strong hydrogen bond and to electrostatic interactions. The strength of the hydrogen bond and the magnitude of the binding energy decrease in the order trifluoroacetate ≳ methanesulfonate > triflate. The corresponding simulations of the bulk phases, obtained using a semiempirical evaluation of the interatomic forces, reveal that on short timescales, the state of the three liquids remains highly ionized and that the gas-phase cation-/anion-binding motif is preserved while no other peculiar structural features seem to emerge
Gestational diabetes in multiple pregnancies
No full textrelazioni reciproche fra diabete gestazionale e gravidanza gemellare
On the impact of electrolyte temperature on contact glow discharge electrolysis
No full textThis study aims at disclosing the effect of small temperature drops (10–15 °C) of the electrolyte on Contact Glow Discharge Electrolysis (CGDE). In our experiments, we measure the temperature change of electrolyte and electrode as well as the change in current following on from the addition of, first, frozen and, second, boiling KOH aqueous solution (0.1 M). Quite surprisingly, only the addition of frozen KOH aqueous solution has a significant impact on current (+130%), caused by the decrease in electrolyte temperature (-11 °C). In contrast, the addition of boiling KOH aqueous solution has a negligible effect on current. A very similar behavior is recorded when frozen or boiling type III deionized water is used: the addition of ice has an even stronger impact on current (+145 %) and on electrolyte temperature (-14 °C), while adding boiling water has no measurable effect. Thus, we here demonstrated that electrolyte temperature is critical for managing the responsiveness of the CGDE system. Our results pave the way toward temperature controlled CGDE, a powerful tool for a greener and a more efficient environmental chemistry
Turning Pd-catalysed direct C–H arylation of thiophene derivatives into green : industrial wastewater as an effective reaction medium
Full text linkThe Pd-catalysed direct C-H arylation of thiophene derivatives, appealing for technological application, is performed under green conditions using water as the sole reaction medium. The reaction is independent of the grade of the water, thus enabling the virtuous repurposing of low-purity grade industrial wastewater, allowing one to bring the process to the gram scale and improve its green metrics
Editorial: polymer materials for energy storage and harvesting, and other sustainable applications
No full textOxidative dissolution of NiO in aqueous electrolyte: an impedance study
Full text linkThe present contribution reports on the analysis of the electrochemical properties of screen-printed nickel oxide (NiO) in aqueous electrolyte when NiO is in the configuration of thin film (thickness, l ≤ 7 μm). This type of NiO samples presents mesoscopic morphology. The latter characteristic combined to the intrinsic electroactivity of the oxide leads to the observation of proportionality between NiO thickness and current density. In particular, NiO undergoes two distinct processes of oxidation with reversible features in aqueous media. These redox processes occur in the solid state and, as such, involve mass/charge transfer between the NiO electrode and the electrolyte. On the other hand, the electrochemical oxidation of NiO is accompanied by the progressive chemical dissolution of the oxide when the latter is in the oxidized state. This is a consequence of the elevated content of stored charge on NiO surface when it interfaces a high polarity solvent like water. In the present work we have considered electrochemical impedance spectroscopy (EIS) for the investigation of the charge transfer/transport properties of NiO during the simultaneous occurrence of chemical and electrochemical processes. The study proposes models of electrical circuits for analyzing the interfacial phenomena involved in the aqueous oxidation of NiO. © 201
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