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Research is presented describing the electrochemical behavior of polynuclear ruthenium(II) bipyridine-type complexes with bridging ligands of 2,5-bis(2-pyridyl)pyrazine (2,5-dpp) and 2,3-bis(2-pyridyl)pyrazine, in highly purified N, N-dimethylformamide solution.

This work presents a study of a hard chromium plating process using low concentration H2CrO4 baths. In particular, the effect of different values of CrO3/H2SO4 ratio on coating properties such as adhesion, hardness, surface roughness, apparent density and microstructure were considered. To increase the solution conductivity, avoiding long deposition times and low throwing power typical of dilute solutions, the behaviour of various inorganic compounds was investigated. Specifically, the compounds suitable for obtaining brighter coatings with lower surface roughness values than those obtained using Fink’s solutions were Na2SO4 and Al2(SO4)3 × 18H2O. A bath composition was identified, with a limited use of Cr(VI) in a solution able to produce coatings with a better surface roughness than those of conventional industrial baths. [ABSTRACT FROM AUTHOR]

A gold surface is functionalized by chemisorption of the enantiopure N,N′-bis-[2,2′;5′,2″]tert-thiophene-5-yl methylcyclohexane-1,2-diamine (2T3N), a chiral oligothiophene derivative, via overnight incubation in a 2T3N ethanol solution. The Au|2T3N interface is characterized by x-ray photoelectron circular dichroism and comparing x-ray photoemission spectroscopy and electro-desorption results. Charge transmission at the Au|2T3N| solution interface is characterized by recording the cyclic voltammetry of the Fe(III)/Fe(II) reversible redox couple, finding a charge transfer rate constant, k°, variation from 1 × 10−1 to 3.3 × 10−2 cm s−1, when comparing the bare Au and the Au|2T3N interfaces, respectively. The "anomalous" high value of k° found for the chiral Au|2T3N interface can be rationalized on the basis of the chiral-induced spin selectivity effect, as further proved by magnetic–conductive atomic force microscopy measurements at room temperature. A spin polarization of about 30% is found. [ABSTRACT FROM AUTHOR]

Oxygen Reduction Reaction (ORR) is the bottle-neck strategic reaction ruling the fuel cell efficiency process. The slow kinetics of the reaction require highly effective electrocatalysts for proper boosting. In this field, composite catalysts formed by carbon nanotubes functionalized with palladium(II) complexes showed surprising catalytic activity comparable to those of a commercial Pt electrode, but the catalytic mechanisms of these materials still remain open to discussion. In this paper, we propose the combination of experimental and theoretical results to unfold the elementary reaction steps underlying the ORR catalysis. [ABSTRACT FROM AUTHOR]

Oxygen Reduction Reaction (ORR) catalysts, from waste automobile tyres obtained from Microwave assisted pyrolysis (MAP), were enriched with Co and Cu using the simple treatments sonochemical and electrochemical deposition. Catalytic activity was evaluated through onset potential and number of exchanged electrons measurements. Electrochemical data demonstrate an improvement in catalytic activity of the electrochemical modified char with Co. Char electrodes enriched with Co show a maximum positive shift of 40 mV with respect to raw char electrodes with a number of exchanged electrons per O2 molecule close to 4 (as for Pt) for the best sample. This corresponds to a reduction of the production of unwanted oxygen peroxide from 23% for raw char to 1%. Sample structure evolution before and after electrochemical deposition and electro-catalysis was investigated by scanning transmission electron microscopy and XPS. Such electrochemical treatments open new possibilities of refining waste chars and finding an economic alternative to noble metals-based catalysts for alkaline fuel cells. [ABSTRACT FROM AUTHOR]

Results are presented concerning the influence on the water splitting process of enantiopure tartaric acid present in bulk solution. Stainless steel and electrodeposited nickel are used as working electrode (WE) surface. The latter is obtained by electrodeposition on the two poles of a magnet. The influence and role played by the chiral compound in solution has been assessed by comparing the current values, in cyclic voltammetry (CV) experiments, recorded in the potential range at which oxygen evolution reaction (OER) occurs. In the case of tartaric acid and nickel WE a spin polarization of about 4% is found. The use of the chiral environment (bulk solution) and ferromagnetic chiral Ni electrode allows for observing the OER at a more favorable potential: About 50 mV (i.e., a cathodic, less positive, shift of the potential at which the oxygen evolution is observed). [ABSTRACT FROM AUTHOR]

An original hybrid, organic/inorganic, composite material with a unique shape nanostructures (NSs) are prepared and characterized. Nanopetals of nickel oxide (NiO-NPs) substrate is used to grow polyaniline (PANI) via electrochemical polymerization, allowing to obtain a quite peculiar nanohemispheres morphology (PANI-NHs). A unique combination of different hydrothermal and electrochemical techniques are used to grow these complex architectures at nanoscale. Electron microscopies (SEM and TEM) are used for the morphology analysis. XPS, PMIRRAS and Raman measurements were used for surface characterization. Along the experimental study, IR spectra are calculated for oligomers of leucoemeraldine and pernigraniline. By the present combination of chemical and physical characteristics at the nanoscale, the overall surface area of our hybrid composite material is greatly increased, thus enhancing the electrochemical activity of the single constituent's composition. Note that, the specific capacitance of the present NiO-NPs/PANI-NHs composite material is ~545 F/g, which is higher than that of the individual starting materials. Thus, a dramatic improvement is obtained in the performance of energy storage with respect to the parental materials, as a nanoscale effect. • Supercapacitors play a fundamental role in energy storage. • A peculiar hybrid "NiO".|"PANI" composite is here synthesized and characterized • Remarkably high value, about 560 F/g, capacitance per mass performance is obtained. • The hydrothermal growt, of the substrate allows for long term in-operando stability. [ABSTRACT FROM AUTHOR]

To understand the electrical and charge transport phenomena in either single or large‐scale molecular junctions, direct current (DC) measurements are mainly utilized. The current–voltage data obtained from DC measurements on molecular junctions (MJs) are employed to infer charge transport parameters, including barrier height, contact resistance, attenuation factor (β), and underlying transport mechanisms. However, DC measurements can not separate the individual electrical components, as it produces a total current that flows in the molecular junctions. Contact resistance obtained from the DC measurements by extrapolating plot of resistance versus chain length can not make exact value. In addition, defected SAMs‐based MJs or junctions having a protective layer, DC measurements alone can predict neither proper electrical values nor the correct transport mechanisms and it lacks frequency response. Electrical impedance spectroscopy (EIS) along with the circuit model enables the identification of individual electrical components of the molecular junctions and faultless contact resistance values that facilitate the model of actual transport mechanisms. In this Review, the working principle of electrical impedance spectroscopy and circuit modeling to digitize the experimental results on various molecular junctions, is discussed. Overall, the EIS technique can serve as an excellent analytical tool for the proper electrical characterization that is highly desirable for molecular electronics. [ABSTRACT FROM AUTHOR]

Our society largely relies on inorganic semiconductor devices which are, so far, fabricated using expensive and complex processes requiring ultra‐high vacuum equipment. Here we report on the possibility of growing a p–n junction taking advantage of electrochemical processes based on the use of aqueous solutions. The growth of the junction has been carried out using the Electrochemical Atomic Layer Deposition (E‐ALD) technique, which allowed to sequentially deposit two different semiconductors, CdS and Cu2S, on an Ag(111) substrate, in a single procedure. The growth process was monitored in situ by Surface X‐Ray Diffraction (SXRD) and resulted in the fabrication of a thin double‐layer structure with a high degree of crystallographic order and a well‐defined interface. The high‐performance electrical characteristics of the device were analysed ex‐situ and show the characteristic feature of a diode. [ABSTRACT FROM AUTHOR]

Charge transfer (CT) crystals exhibit unique electronic and magnetic properties with interesting applications. We present a rational and easy guide which allows to foresee the effective charge transfer co‐crystal production and that is based on the comparison of the frontier molecular orbital (MO) energies of a donor and acceptor couple. For the sake of comparison, theoretical calculations have been carried out by using the cheap and fast PM6 semiempirical Hamiltonian and pure HF/cc‐pVTZ level of the theory. The results are then compared with experimental results obtained both by chemical (bromine and iodine were used as the acceptor) and electrochemical doping (exploiting an original experimental set‐up by this laboratory: the electrochemical transistor). Infra‐red vibrational experimental results and theoretically calculated spectra are compared to assess both the effective donor‐acceptor (D/A) charge‐transfer and transport mechanism (giant IRAV polaron signature). XPS spectra have been collected (carbon (1 s) and iodine (3d5/2)) signals, yielding further evidence of the effective formation of the CT anthracene:iodine complex. [ABSTRACT FROM AUTHOR]

Electroactive self-assembled monolayers (SAMs) bearing a ferrocene (Fc) redox couple were chemically assembled on H-terminated semiconducting degenerate-doped n-type Si(111) substrate. This allows to create a Si(111)|organic-spacer|Fc hybrid interface, where the ferrocene moiety is covalently immobilized on the silicon, via two alkyl molecular spacers of different length. Organic monolayer formation was probed by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) and X-ray photoelectron spectroscopy (XPS) measurements, which were also used to estimate thickness and surface assembled monolayer (SAM) surface coverage. Atomic force microscopy (AFM) measurements allowed to ascertain surface morphology and roughness. The single electron transfer process, between the ferrocene redox probe and the Si electrode surface, was probed by cyclic voltammetry (CV) measurements. CVs recorded at different scan rates, in the 10 to 500 mV s−1 range, allowed to determine peak-to-peak separation, half-wave potential, and charge-transfer rate constant (KET). The experimental findings suggest that the electron transfer is a one electron quasi-reversible process. The present demonstration of surface engineering of functional redox-active organometallic molecule can be efficient in the field of molecular electronics, surface-base redox chemistry, opto-electronic applications. [ABSTRACT FROM AUTHOR]

This Letter reports an original spin valve device that is based on a chiral templated nickel material. Chirality in Ni is induced by exploiting co-electrodeposition of an organic chiral template. In this specific case, the chiral templating is enantiopure tartaric acid (TA). Facile electrodeposition (co-deposition) in ambient conditions produces a nickel chiral-templated material. Z-shaped magnetoresistance curves, switching sign as a function of TA handedness, prove the peculiar ferromagnetic character induced by the presence of a chiral compound. Synchrotron measurements using circular polarized light, x-ray natural circular dichroism, confirm the chirality of the Ni in the TA/Ni composite. Density functional theory calculation proves the existence of a strong electronic delocalization involving the tartaric acid and Ni. The significant finding of this Letter is that chiral templated Ni paves the way for future spin valve, which will be able to control the spin without an external magnetic field (as indeed foreseen within the chiral induced spin selectivity-effect framework). [ABSTRACT FROM AUTHOR]

This research investigates the difference between products obtained through two hydrothermal carbonization treatments. Our aim is to synthesize metal-free, carbon-based catalysts for the oxygen reduction reaction (ORR) to serve as efficient and cost-effective alternatives to platinum-based catalysts. Catalysts synthesized using the traditional hydrothermal approach exhibit a higher electrocatalytic activity for ORR in alkaline media, despite their more energy-intensive production process. The superior performance is attributed to differences in the particle morphology and the chemical composition of the particle surfaces. The presence of functional groups on the surfaces of catalysts obtained via a traditional approach significantly enhances ORR activity by facilitating deprotonation reactions in an alkaline environment. Our research aims to provide a reference for future investigations, shifting the focus to the fine-tuning of surface chemical compositions and morphologies of metal-free catalysts to enhance ORR activity. [ABSTRACT FROM AUTHOR]

In this paper it is experimentally demonstrated that the electron‐spin/molecular‐handedness interaction plays a fundamental role in the chiral recognition process. This conclusion is inferred comparing current versus potential (I–V) curves recorded using chiral electrode surfaces, which are obtained via chemisorption of an enantiopure thiophene derivative: 3,3′‐bibenzothiophene core functionalized with 2,2′‐bithiophene wings (BT2T4). The chiral recognition capability of these chiral‐electrodes is probed via cyclic voltammetry measurements, where, Ag nanoparticles (AgNPs) capped with enantiopure BT2T4 (BT2T4@AgNP) are used as the chiral redox probe. Then, the interface handedness is explored by recording spin‐polarized I–V curves in spin‐dependent electrochemistry (SDE) and magnetic‐conductive atomic force microscopy (mc‐AFM) experiments. The quality of the interfaces is thoroughly cross‐checked using X‐ray photoemission spectroscopy, Raman, electrodesorption measurements, which further substantiate the metal(electrode)‐sulfur(thiophene) central role in the chemisorption process. Spin‐polarization values of about 15% and 30% are obtained in the case of SDE and mc‐AFM experiments, respectively. [ABSTRACT FROM AUTHOR]