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The effect of the molecular structure of indotricarbocyanine dyes on their luminescence spectral and redox properties was studied. The introduction of a chlorine-substituted bridge into the polymethine chain leads to a significant hypsochromic shift of the absorption and fluorescence spectra, whereas change in the structure of substituents at the indolenine terminal groups only has a weak effect on the spectra. The electrochemical properties of the polymethine dyes were studied by cyclic voltammetry. The oxidation and reduction potentials of the dyes were determined, and the corresponding energies of the highest occupied and lowest unoccupied molecular orbitals were calculated. Reduction of the molecules of the dye is an irreversible process, whereas the reversibility of the oxidation process depends on the structure of the polymethine chain and the nature of the counterion. Introduction of a chlorine–orthophenylene bridge into the polymethine chain leads to a significant increase in the reversibility of the oxidation reaction of the dyes on account of increase in the stability of the dication-radicals. It was shown that oxidation of the bromide ions occurs at lower potentials compared with oxidation of the dyes with a substituted polymethine chain, which probably leads to decrease in the reversibility of electrochemical oxidation of the dyes when bromide ions are present in solution.

Плотные и мезопористые пленки диоксида титана получены на титановых подложках методами термического окисления, гидролиза полибутилтитаната, нанесения золя диоксида титана, ультразвуковой обработки и анодного окисления и охарактеризованы с помощью сканирующей электронной микроскопии, просвечивающей электронной микроскопии и спектроскопии комбинационного рассеяния света. Электрохимическая активность диоксидтитановых пленок, исходных и модифицированных наночастицами золота, в реакции восстановления кислорода в щелочной среде исследована методом циклической вольтамперометрии. Показано, что эффективность протекания реакции восстановления кислорода на плотных и мезопористых диоксидтитановых пленках определяется их морфологией, структурой, а также степенью упорядоченности пор. Модифицирование пленок диоксида титана наночастицами золота приводит к снижению перенапряжения реакции электровосстановления кислорода. Установлено, что электроды, состоящие из высокоупорядоченных слоев нанотрубок диоксида титана с нанесенными наночастицами золота, демонстрируют существенно большую электрокаталитическую активность в реакции восстановления по сравнению с TiO2/Au-системами на основе плотных пленок и мезопористых пленок с неупорядоченной структурой пор. Свойства электрохимического поведения системы TiO2/Au (нанотрубки/наночастицы) объясняются особенностями транспорта электронов к поверхности электродов и структурой области пространственного заряда в мезопористой пленке оксида.

Epoxy based composites filled with RhB-loaded TiO2 containers were prepared. SEM, EDX mapping, and Raman spectroscopy showed a uniform distribution of the TiO2 particles in the polymeric matrix. The sensitivity of the composites to UV irradiation was studied. Efficiency of the composite decolorization was found to depend on the amount of RhB-loaded TiO2 containers incorporated into the coating. Accelerated decomposition of Rhodamine B in the composite under UV irradiation takes place due to photocatalytic activity of the TiO2 particles. The prepared composites can be used as UV-sensor material.

The peculiarities of morphology, crystalline structure and chemical composition of TiO 2 nanotubular layers (TNT) and TiO 2 nanoparticulate (NP) layers obtained by fluoride-mediated transformation of TNT have been described in the present paper. The annealing of amorphous TNT in a confined space under limited air access conditions leads to TNT-to-NP transformation accompanied by fluorine doping of the titania matrix as supported by X-ray photoelectron spectroscopy investigations. The collapse of tubular structure as well as the formation of nanoparticles was confirmed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. Electrocatalytic activity of both TNT and NP electrodes toward oxygen reduction reaction (ORR) has been examined by cyclic voltammetry (CV). The positive shift of ORR wave of the NP layers in comparison with TNT makes the NP-based electrodes more suitable for oxygen reduction. The improved activity of the NP electrodes is attributed to the increased concentration of redox active Ti 3+ species owing to fluorine doping of TiO 2 which plays a crucial role in electroreduction of oxygen molecules.

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Gold nanoparticles (AuNPs) have been deposited on titania nanotubular layers (TNT) via photocatalytic deposition, and the activity of the obtained AuNPs-TNT systems toward oxygen electroreduction reaction (ORR) in an alkaline medium has been studied and compared with the activity of AuNPs-TNT composites prepared from Au colloidal solutions. Two photodeposition methods were utilized for anchoring of AuNPs: direct UV-irradiation of a TNT electrode immersed into a HAuCl4 containing solution (TNT-Au1 composites) and initial adsorption of AuCl4- ions on TNT followed by UV-irradiation (TNT-Au2 composites). The size, spatial distribution, structure and surface of AuNPs deposited on TNT layers were studied via scanning and transmission electron microscopy, optical spectroscopy and underpotential deposition of lead ad-atoms on gold. It was found that these parameters depend on the photodeposition method. The TNT-Au2 composites have smaller size, higher surface concentration and more uniform distribution of AuNPs in the TNT layers as compared with the TNT-Au1 systems. The electrocatalytic efficiency of Au-TNT electrodes in ORR was found to depend on various factors such as doping level of TNT support (governed by annealing temperature), AuNPs size and their loading amount. The electroreduction of oxygen was observed at less negative potentials when Au nanoparticles were grown on the TNT surface by photoreduction in comparison with the TNT electrodes modified with AuNPs from sols. The enhanced activity of the photocatalytically prepared AuNPs-TNT composites can be explained by the consolidation of the interface between gold nanoparticles and TiO2 support and the absence of ligands on the AuNPs surface.

Encapsulated metal nanostructures were prepared using the powerful pulsed discharge method. Metal nanorods were obtained in porous titania and alumina matrix by direct electrodeposition from 1-ethyl-3-methylimidazolium chloride-based ionic liquids. The deposition process was characterized by cyclic voltammetry. Morphology of the encapsulated structures was studied by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) for morphological and elemental analysis. It was found that the most efficient method for electrodeposition of pure aluminum into titania nanotubes is the potential cycling method, while for deposition of the Al-Ti alloy in alumina pores a pulsed method with three different steps is preferable. Closing the titania nanotubes was found to be possible both with empty and metal-filled pores, whereas in alumina matrix this procedure can be performed only when pores are filled with a conductive material. The obtained results throw light on the mechanism of porous film encapsulation under high-voltage pulses and allow preparing encapsulated nanostructures in the oxide films.

We introduce a simple concept of a light induced pH change, followed by high amplitude manipulation of the mechanical properties of an adjacent polymer film. Irradiation of a titania surface is known to cause water splitting, and this can be used to reduce the environmental pH to pH 4. The mechanical modulus of an adjacent pH sensitive polymer film can thus be changed by more than an order of magnitude. The changes can be localized, maintained for hours and repeated without material destruction.

Seebeck coefficient values measured for textured polycrystalline Bi films have been compared with numerically computed ones. The proposed computation procedure requires crystallographic texture mapping and values of single-crystalline transport coefficients as input data. The comparison of computed and measured Seebeck coefficients allowed determining the factors affecting films' transport properties except of crystalline texture. Two particular cases are considered: when the film properties are affected only by texture and when they depend on texture and grain size simultaneously.

Thin oxide films were prepared electrochemically on the aluminum surface using the high-voltage discharge and potentiostatic methods in deionized water as an electrolyte. The growth of continuous films occurred only at potentials lower than the breakdown potential. The films obtained by the discharge method are more uniform and can grow to a higher thickness in comparison to those formed by the potentiostatic mode, as demonstrated by electrochemical impedance spectroscopy (EIS), transmission electron microscopy (TEM), and scanning Kelvin probe force microscopy (SKPFM). The data herein obtained can be used as a reference to understand better the properties of the films produced in conventional electrolytes where apart from water other species are present. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. All rights reserved.

Mesoporous ZnO materials have been synthesized through chemical deposition of different precursors from aqueous or water-ethanol solutions followed by their thermal decomposition at 400°C in air. The microstructure and morphology of the precursors and obtained ZnO powders were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and nitrogen adsorption-desorption (BET) methods. The structure of the precursor and physico-chemical properties of final zinc oxide powders were shown to be considerably influenced by the presence of Cl– ions and ethanol in solution. In water-ethanol solutions, Zn5(OH)8Cl2∙H2O or Zn5(OH)8(NO3)2∙(H2O)2 precursors are formed, while ZnO particles are directly deposited from aqueous solution. The photocatalytic activity of the synthesized ZnO materials was evaluated by the decolorization of Rhodamine B (RhB) upon UV irradiation. The ZnO powders have demonstrated high photocatalytic efficiency, enabling decomposition of 81.4-97.4 % RhB within 3 hours. The increased photocatalytic efficiency of ZnO prepared by annealing of Zn5(OH)8Cl2∙H2O precursor or deposited directly from aqueous chloride-containing solutions can be originated from the presence of Cl-containing compounds remaining after thermal treatment of simonkolleite as well as from introduction of Cl-dopant in ZnO.

Cadmium sulfide nanoparticle (NP) deposition by the successive ionic layer adsorption and reaction (SILAR) method on the surface of mesoporous ZnO micro-platelets with a large specific surface area (110 ± 10 m2g− 1) results in the formation of ZnO/CdS heterostructures exhibiting a high incident photon-to-current conversion efficiency (Y) not only within the region of CdS fundamental absorption (Ymax = 90%; 0.1 M Na2S + 0.1 M Na2SO3), but also in the sub-band-gap (SBG) range (Ymax = 25%). The onset potentials of SBG photoelectrochemical processes are more positive than the band-gap (BG) onset potential by up to 100 mV. A maximum incident photon-to-current conversion efficiency value for SBG processes is observed at larger amount of deposited CdS in comparison with the case of BG ones. The Urbach energy (EU) of CdS NPs determined from the photocurrent spectra reaches a maximal value on an early deposition stage (EU = 93 mV at SILAR cycle number N = 5), then lowers somewhat (EU = 73 mV at N = 10) and remains steady in the range of N from 20 to 300 (EU = 67 ± 1 mV). High efficiency of the photoelectrochemical SBG processes are interpreted in terms of light scattering in the ZnO/CdS heterostructures.

Grain structure and the temperature dependences of resistivity, magnetoresistance, Hall and Seebeck coefficients measured in the range from 4 to 300 K were investigated for polycrystalline bismuth films obtained by the melt spinning (MS) and electrochemical deposition (ECD) methods. Charge-carrier concentration and mobilities were calculated assuming the carrier scattering on acoustic deformation potential as the dominant scattering mechanism, parabolicity of holes dispersion law, implying the Lax model for L-band electrons and neglecting the influence of L-band holes on conductivity. The experimental results and calculations have demonstrated that the electrical properties of the Bi films studied are strongly affected by the grain-boundary density.

This work focuses on spectral sensitization of mesoporous TiO 2 films and Nb-doped TiO 2 films with polydisperse PbSe nanoparticles (TiO 2 /PbSe). For this, PbSe was electrochemically deposited from aqueous solution containing Pb 2+ cations and SeO 2 . Chemical amount of electrodeposited PbSe was controlled by deposition time and impacted on the magnitude of sensitized photocurrents. The efficacy of different ions (S n 2− ; I 3 − ; H 2 PO 4 − ; N 2 H 5 + ; SO 3 2− ; SCN − , SeSO 3 2− ) as hole scavengers for TiO 2 /PbSe photoanodes was assessed by dynamics of photocurrent in polarization measurements. Electrolyte of Na 2 SO 3 and Na 2 SeSO 3 is reported as an effective one to attain stable photocurrent. Photoelectrochemical cells with TiO 2 /PbSe photoanodes show solar to electricity conversion efficiency of 0.09%, in spectral region up to 700 nm for undoped TiO 2 . Enhancement of the photoresponse was achieved by different level of Nb doping into mesoporous TiO 2 film. Extension of spectral response up to 800 nm and photocurrent conversion efficiency of 0.24% is observed for TiO 2 /PbSe photoanodes with 2.5 at% Nb-doped TiO 2 . Doping with Nb results in positive shift on electrochemical scale of conduction band of TiO 2 . It favors the collection of photoelectrons from PbSe nanoparticles that have light absorption in wider spectral region.

Energy transfer reactions are the key for living open systems, biological chemical networking and development of life inspired nanoscale machineries. It is a challenge to find simple reliable synthetic chemical networks providing a localization of the time dependent flux of matter. In this paper we introduce a reliable, minimal reagent consuming, stable inorganic light promoted proton pump. Localized illumination was applied to a TiO2 surface in solution for reversible spatially controlled “inorganic photoproton” isometric cycling, the lateral separation of water splitting reactions. The proton flux is pumped during irradiation of the surface of TiO2 and dynamically maintained at the irradiated surface area in the absence of any membrane or predetermined material structure. Moreover we spatially predetermine a transient acidic pH on the TiO2 surface in the irradiated area with feedback-driven generation of a base as deactivator. Importantly we describe, how to effectively monitor the spatial localization of the process by in situ scanning ion selective electrode technique (SIET) measurements for pH and scanning vibrating electrode technique (SVET) for local photoelectrochemical studies. This work shows the great potential for time- and space-resolved water splitting reactions for following investigation of pH stimulated processes in open systems with their flexible localization on a surface. published

Mesoporous TiO 2 powder with large surface area and high porosity was prepared via template-free method of heat-stimulated oxidizing destruction of TiC by HNO 3. Anatase crystalline phase of as-prepared and annealed at 200−400 °C titania was confirmed by XRD technique. Surface nitrate-nitro groups responsible for high adsorption capacity of the TiO 2 powders were studied by FTIR spectroscopy. The annealing temperature can be used as a factor for regulation of titania morphology and structural properties. The rise in the annealing temperature higher than the temperature of nitrate-nitro groups decomposition induces the growth of TiO 2 crystallites, decreasing porosity and surface area, the drop of adsorption capacity, and improving photocatalytic activity under UV irradiation.

We obtained optically transparent n-type semiconductor films of lead zirconate titanate Pb(ZrxTi1–x)O3 by reaction of individual sols of hydrated titanium dioxide and zirconium dioxide with lead ions, followed by heat treatment at 500–800°C. We established that these films, when in contact with an aqueous electrolyte, can generate a photopotential and a photocurrent when exposed to UV radiation (250–400 nm). The average values of the bandgap energy from optical absorption and photocurrent spectroscopy data are slightly dependent on the composition of the lead zirconate titanate solid solution (they increase by 0.07–0.12 eV on going from Pb(Zr0.2Ti0.8)O3 to Pb(Zr0.52Ti0.48)O3), which may be connected with features of the band structure in these materials.

Effi cient and homogeneous surface-enhanced Raman scattering (SERS) substrates are usually prepared using lithographic approaches, physical evaporation, or in situ chemical reduction. However, these approaches are time-consuming, expensive, and very diffi cult to upscale. Alternatively, template-assisted approaches using colloidal suspensions of preformed nanoparticles have become more popular because of their low cost, fast production, and ability to be scaled up easily. One of the limitations of these methods is the dimensions of the structured surfaces. In this context, a new method for designing low-cost, up-scalable surface patterns that match building block dimensionality based on anodization of aluminum, enabling a hierarchical organization of anisotropic nanoparticles, is presented. The proposed new technology starts with anodized aluminum oxide with regular parallel linear periodicities. To produce a highly effi cient plasmonic surface, gold nanorods are assembled into parallel lines where the long axes of the Au rods are also oriented along the substrate lines, thus inducing reproducible tip-to-tip plasmonic coupling with the corresponding generation of highly active hotspots. Additionally, this advanced material presents an inherent hydrophobicity that can be exploited as a method for concentration of analytes on the surface. SERS detection is demonstrated with benzenethiol and 2-naphtoic acid.

Properties of CdS nanoparticles (NPs) grown by successive ionic layer adsorption and reaction (SILAR) method on the surface of electrodeposited ZnO films were studied by Raman, photocurrent and UV–Vis absorption spectroscopies. The CdS nanoparticles deposited at a SILAR cycle number ( N ) from 5 to 10 exhibit a broadening of the band gap ( E g ) by 0.17–0.31 eV as compared with that of the CdS particles grown at N = 30. The size quantization of the interband transition energy in CdS nanoparticles is in accordance with the Raman spectroscopic data demonstrating a considerable increase in the LO peak intensity with increasing the N from 5 to 10 as a result of transition to resonant light scattering. The spectral width of the LO peak decreases from 50 to 15 cm − 1 as the N increases from 5 to 30 reflecting a less pronounced effect of the nanoparticle surface on the phonon scattering. A large spectral width of the Raman peaks is assumed to originate from a complex structure of the CdS nanoparticles comprising crystallinity domains that can affect the phonon confinement. The photocurrent spectroscopy of ZnO/CdS heterostructures showed that the band gap of CdS NPs deposited at N > 20 is smaller by ~ 0.08 eV than that of bulk cadmium sulfide. It was concluded that this effect is not associated with photoexcitation of structural defects but rather reflects intrinsic electronic properties of SILAR-deposited CdS nanoparticles.

Effect of electrochemically injected magnesium ions on the process in which carbonate deposits are formed on a corrodible surface of low-carbon steel in water of heat-and-water supply systems was studied. It was found that the anticorrosion efficiency of the deposit, evaluated by the polarization-resistance method and voltammetry, is approximately 1.5 times that of natural deposits formed in the absence of injected magnesium ions. X-ray diffraction analysis with grazing beam incidence, scanning electron microscopy, and energy-dispersive analysis demonstrated that mostly dense polycrystalline calcium carbonate deposits with a structure of aragonite are formed in the presence of magnesium ions. The mechanism by which a protective CaCO3 layer grows on the corrodible surface of low-carbon steel is discussed.

Mesoporous titania as powders and thin films on ITO were prepared using gelatin as an available and non-expensive pore-forming agent. The mesoporous TiO2 manifested a much higher photocatalytic activity in the gas-phase air oxidation of ethanol and acetaldehyde than the commercial nanocrystalline TiO2 P25 (Degussa Corp.). The mesoporous ITO/TiO2 films exhibited 12-14% efficiency of photocurrent generation in aqueous Na2S electrolyte when illuminated by UV light. Deposition of CdS and PbS nanoparticles onto the surface of ITO/TiO2 further increases the photocurrent yields and expands the light sensitivity range of the films to 500-520 nm (CdS) and to 650-700 nm (PbS).

We introduce a simple concept of a light induced pH change, followed by high amplitude manipulation of the mechanical properties of an adjacent polymer film. Irradiation of a titania surface is known to cause water splitting, and this can be used to reduce the environmental pH to pH 4. The mechanical modulus of an adjacent pH sensitive polymer film can thus be changed by more than an order of magnitude. The changes can be localized, maintained for hours and repeated without material destruction.

A new effective method of photocatalytic deposition of hydroxyapatite (HA) onto semiconductor substrates is proposed. A highly ordered nanotubular TiO2 (TNT) layer formed on titanium via its anodization is chosen as the photoactive substrate. The method is based on photodecomposition of the phosphate anion precursor, triethylphosphate (TEP), on the semiconductor surface with the following reaction of formed phosphate anions with calcium cations presented in the solution. HA can be deposited only on irradiated areas, providing the possibility of photoresist-free HA patterning. It is shown that HA deposition can be controlled via pH, light intensity, and duration of the process. Energy-dispersive X-ray spectroscopy profile analysis and glow discharge optical emission spectroscopy of HA-modified TNT prove that HA deposits over the entire TNT depth. High biocompatibility of the surfaces is proven by protein adsorption and pre-osteoblast cell growth.

Electrocatalytic activity of both bare high-ordered TiO2 nanotubes (TNTs) and gold nanoparticles (Au NPs) loaded TNTs toward oxygen reduction reaction (ORR) has been examined by cyclic voltammetry (CV). Cyclic voltammograms for Au NPs-TNT electrodes are characterized by an additional wave observed at less negative potentials which is responsible for oxygen electroreduction on the surface of gold NPs. The overpotential for O-2 reduction on the Au surface grows with increasing the temperature of TNT annealing and the Au NPs size. The nature of the effects observed was explained by peculiarities of the electron transport through Schottky barrier formed at the Au NPs - TiO2 interface. The width of the Schottky barrier, determined by semiconductor doping level and Au NPs size, plays a key role in the mechanism of electron transport through the space charge region. (C) 2016 Elsevier Ltd. All rights reserved.

A porous hydroxyapatite (HA)-incorporated TiO2 coating has been deposited on the titanium substrate using a plasma electrolytic oxidation coupled with electrophoretic deposition (PEO-EPD). Potassium titanium(IV) oxalate is decomposed by micro arcs generated on the anode producing TiO2 while HA particles have been simultaneously deposited on anode during EPD process. Hydroxyapatite and TiO2 particles have been coagulated into roundish conglomerates with the average diameter in a range of 200-600 nm. The microstructure, as well as elemental and phase composition of the coatings have been examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES), fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). XRD has showed that the coatings are composed mainly of HA, rutile and anatase phases. The composition and surface morphologies are not strongly dependent on the applied voltages. The amount of HA deposited into the coating increases with increasing the applied voltage. The wear resistance of PEO-EPD coatings has been assessed using tribological tests. The bioactivity of the obtained coatings has been investigated in a simulated blood fluid.

The effect of spectral sensitization of photoelectrochemical processes on the surfaces of mesoporous TiO2 modified by electrochemically deposited PbSe nanoparticles has been observed.

The present work reports the synthesis of layered double hydroxides (LDHs) nanocontainers loaded with different corrosion inhibitors (vanadate, phosphate, and 2-mercaptobenzothiazolate) and the characterization of the resulting pigments by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The anticorrosion activity of these nanocontainers with respect to aluminum alloy AA2024 was investigated by electrochemical impedance spectroscopy (EIS). The bare metallic substrates were immersed in dispersions of nanocontainers in sodium chloride solution and tested to understand the inhibition mechanisms and efficiency. The nanocontainers were also incorporated into commercial coatings used for aeronautical applications to study the active corrosion protection properties in systems of industrial relevance. The results show that an enhancement of the active protection effect can be reached when nanocontainers loaded with different inhibitors are combined in the same protective coating system.

Ni–B alloy coatings with different boron content ranging from 4 to approximately 28 at.% were prepared by electrodeposition in a nickel-plating bath containing sodium decahydroclovodecaborate as a boron source. The influence of the boron concentration in the coatings on their structure, morphology, electrochemical and corrosion behavior, physico-mechanical and electrical properties was investigated using X-ray diffractometry (XRD), scanning electron microscopy (SEM), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and other methods. It was found that the electrodeposited Ni–B coatings with relatively low boron content (≤8 at.%) are nanocrystalline and comprise a solid solution of boron in f.c.c. Ni lattice having a mixed substituted-interstitial type. Further increase in the boron content (up to 10–15 at.%) leads to the appearance of heterogeneous amorphous-nanocrystalline structure, and the coatings with a high boron content (20 at.% and above) are X-ray amorphous. Polarization measurements in neutral NaCl solutions showed that the Ni–B coatings with relatively low boron content demonstrate a potential region of low anodic currents associated with the passive film formation at the alloy surface. The anodic current in this potential region increases significantly with increasing the boron content above 10 at.%, suggesting the non-protective nature of the anodic film formed on the amorphous Ni–B alloys. Immersion tests monitored by EIS measurements revealed a significantly better corrosion performance of the Ni–B coatings with low boron content (4 at.%) in comparison with that of the amorphous coatings. The microhardness and wear resistance of the Ni–B coatings essentially increases with increasing the boron content. Maximum microhardness and wear resistance were found for the coatings containing 8 at.% B.

Titania-containing organic–inorganic hybrid sol–gel films have been developed as an alternative to chromate-based coatings for surface pretreatment of aluminium alloys. Stable hybrid sols were prepared by hydrolysis of 3-glycidoxypropyltrimethoxysilane and different titanium organic compounds in 2-propanol solution in the presence of small amounts of acidified water. Different diketones were used as complexing agents in this synthesis for controllable hydrolysis of titanium organics. The properties of the obtained coatings were compared with those of zirconia-containing films. Electrochemical impedance spectroscopy (EIS) measurements and standard salt spray tests were performed to investigate the corrosion protection performance of the hybrid coatings. It was revealed that their protective properties depend significantly on the nature of metalorganic precursors and complexing agents used in the process of sol preparation. The best anticorrosive protection of AA2024 in chloride solutions is provided by the titania-containing sol–gel films prepared with titanium(IV) tetrapropoxide and acetylacetone as starting materials. In the case of zirconia-containing films, better protective properties were found when applying ethylacetoacetate as a complexing agent.

The behavior of dense ceramic anodes made of perovskite-type $$ {\text{La}}_{{1 - x - y}} {\text{Sr}}_{x} {\text{Co}}_{{1 - z}} {\text{Al}}_{z} {\text{O}}_{{3 - \delta }} $$ (x = 0.30–0.70; y = 0–0.05; z = 0–0.20) and K2NiF4-type $$ {\text{La}}_{2} {\text{Ni}}_{{1 - x}} {\text{Me}}_{x} {\text{O}}_{{4 + \delta }} $$ (Me = Co, Cu; x = 0–0.20) indicates significant influence of metal hydroxide formation at the electrode surface on the oxygen evolution reaction (OER) kinetics in alkaline solutions. The overpotential of cobaltite electrodes was found to decrease with time, while cyclic voltammetry shows the appearance of redox peaks characteristic of Co(OH)2/CoOOH. This is accompanied with increasing effective capacitance estimated from the impedance spectroscopy data, because of roughening of the ceramic surface. The steady-state polarization curves of $$ {\left( {{\text{La}},{\text{Sr}}} \right)}{\text{CoO}}_{{{\text{3}} - \delta }} $$ in the OER range, including the Tafel slope, are very similar to those of model Co(OH)2–La(OH)3 composite films where the introduction of lanthanum hydroxide leads to decreasing electrochemical activity. La2NiO4-based anodes exhibit a low electrochemical performance and poor stability. The effects of oxygen nonstoichiometry of the perovskite-related phases are rather negligible at high overpotentials but become significant when the polarization decreases, a result of increasing role of oxygen intercalation processes. The maximum electrocatalytic activity to OER was observed for A-site-deficient $$ {\left( {{\text{La}}_{{0.3}} {\text{Sr}}_{{0.7}} } \right)}_{{0.97}} {\text{CoO}}_{{3 - \delta }} $$ , where the lanthanum content is relatively low and the Co4+ concentration determined by thermogravimetric analysis is highest compared to other cobaltites. Applying microporous layers made of template-synthesized nanocrystalline $$ {\left( {{\text{La}}_{{0.3}} {\text{Sr}}_{{0.7}} } \right)}_{{0.97}} {\text{CoO}}_{{3 - \delta }} $$ leads to an improved anode performance, although the effects of microstructure and thickness are modest, suggesting a narrow electrochemical reaction zone. Further enhancement of the OER kinetics can be achieved by electrodeposition of cobalt hydroxide- and nickel hydroxide-based films.

Electrochemical studies of thiol-capped semiconductor nanocrystals have demonstrated several distinct oxidation and reduction peaks in the voltammograms with the peak positions being nanocrystal size dependent. It is demonstrated that the method is very sensitive to the nanocrystal surface states, providing complimentary information for better understanding the optical properties of semiconductor nanocrystals.

Active corrosion protection of AA2024-T3 alloy has been provided by an environmental-friendly, well adhering pre-treatment system consisting of an inhibitor-loaded titanium oxide porous layer and a sol–gel based thin hybrid film. A novel approach aimed at developing a nanoporous reservoir for storing of corrosion inhibitors on the metal/coating interface has been proposed. The nanostructured porous TiO 2 interlayer was prepared on the aluminium alloy surface by controllable hydrolysis of titanium alkoxide in the presence of template agent. The morphology and the structure of the TiO 2 film were characterized with TEM, EDS, SEM, and AFM techniques. Different ways of loading of the inhibitor in the pre-treatment coating were discussed. In contrast to direct embedding of the inhibitors into the sol–gel matrix, the use of the porous reservoir eliminates the negative effect of the inhibitor on the stability of the hybrid sol–gel matrix. TiO 2 /inhibitor/sol–gel systems show enhanced corrosion protection and self-healing ability confirmed by EIS and SVET measurements.

Underpotential deposition (UPD) of Cd adatoms onto the surface of Te and CdTe films in Cd 2+ -containing solutions has been studied using electrochemical methods and AFM. The electrochemical deposition of Cd adatoms on Te and CdTe begins at potentials 400 mV more positive than the reversible potential of Cd 2+ /Cd couple and proceeds irreversibly. A strong chemical interaction of Cd adatoms with the surface Te atoms is the driving force of the UPD process. The deposition of Cd adatoms on the tellurium surface is accompanied by their stepwise interaction with tellurium to give CdTe nanophase.

Electrochemical studies of thiol-capped ZnSe nanocrystals in aqueous solution have demonstrated several distinct oxidation and reduction peaks in the voltammograms, with the peak positions being dependent on the size of the nanocrystals and their photoluminescence quantum efficiency. The evolution of the specific features in the cyclic voltammetric curves of ZnSe NCs as a function of their photochemical treatment is studied. The interpretation of the results based on the approaches previously developed for CdTe NCs is found to be in good correlation with the proposed mechanism of the ZnSe NCs phototreatment, i.e., the formation of a sulfur-enriched surface shell. By this, cyclic voltammetry has been demonstrated to be a powerful method for probing surface states of semiconductor NCs as well as for monitoring the evolution of these states during photochemical processing.

In this study, the interaction of phosphomolybdic acid (H3PMo12O40) with poly[2-metoxy-5-(3′,7′-dimethyloctyloxy)-p-phenylene vinylene] (MDMO-PPV) has been investigated by the methods of optical absorbance and luminescence spectroscopy, electrochemical, EPR and chemical analysis. It is shown that the interaction between MDMO-PPV and H3PMo12O40 leads to the formation of charge-transfer complex, which involves one heteropolyanion per four monomer units of the polymer chain. We have demonstrated that this interaction causes reversible changes in the electronic structure of the polymer as well as the appearance of an additional line in a long-wavelength region of optical absorbance spectra, a sharp decrease of the efficiency of luminescence and the emergence of pronounced EPR signal.

Dense ceramic anodes of perovskite-type La1-x-ySrxCo1-zAlzO3-δ ( x = 0.45-0.70; y = 0- 0.05; z = 0-0.20) and K2NiF4-type La2Ni1-xMexO4+δ (Me = Co, Cu; x = 0-0.20), synthesized by the glycine-nitrate technique, were assessed for oxygen evolution in alkaline media. The lowest overpotentials are observed for (La0.3Sr0.7)0.97CoO3-δ, which exhibits a significant oxygen deficiency in combination with high conductivity associated with the A-site cation nonstoichiometry compensation mechanism via Co4+ formation. Perovskite-type cobaltite anodes are essentially stable in alkaline solutions, whilst La2NiO4-based electrodes exhibit degradation at the potentials where the oxygen evolution occurs, probably due to the electrochemical oxygen intercalation in the lattice.

Several alkaline baths based on different complexing agents were examined for iron electroplating. The resultant films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was shown that adherent and smooth iron coatings with uniform microstructure can be obtained using alkaline Fe (II) baths containing pyrophosphate and tartrate ions as complexing agents. The average grain size can be substantially decreased by glycine additions in the pyrophosphate bath. The faradaic efficiency in these electrolytes may achieve up to 40-50%. The tartrate-containing baths are characterized with a higher throwing power and an increased buffer capacity with respect to the pyrophosphate-based electrolytes. The resultant Fe coatings are single-phase, whilst substantial broadening of the XRD peaks indicates nano-scale grain size. The alkaline baths based on EDTA complexes of iron (III) give black dull iron deposits and are characterized by rather low cathodic current efficiencies, especially at low current densities.

The 1,2,4-triazole, 3-amino-1,2,4-triazole, benzotriazole and 2-mercaptobenzothiazole were evaluated in the present work as corrosion inhibitors for protection of the 2024 aluminium alloy in neutral chloride solutions. The corrosion protection performance was investigated by means of DC polarization and electrochemical impedance spectroscopy (EIS). Scanning Kelvin probe force microscopy (SKPFM) and atomic force microscopy (AFM) were used to study the evolution of the Volta potential distribution and the surface topography during corrosion tests. The results show that all inhibitors under study confer corrosion protection to the AA2024 alloy forming a thin organic layer on the substrate surface. Benzotriazole and 2-mercaptobenzothiazole offer better corrosion protection in comparison with the other two. The inhibitors studied act decreasing the rate of both the anodic and cathodic processes. In the latter case the dealloying of the copper-reach particles is hindered, slowing down the oxygen reduction.