Band 83, Heft 2

The electrochemical community in the southeastern part of Europe has been renowned worldwide for more than 50 years. The contributions to electrochemical science, involving publications, scientific meetings, or, generally speaking, electrochemical research, development, education, and applications are recognized to a wider extent than expected, bearing in mind this relatively small geographic area. The tradition connected with 16 biannual Yugoslav Symposia on Electrochemistry, followed by a few Croatian Electrochemical Symposia and Electrochemical Symposia of Serbia and Montenegro merged into a Regional Symposium. Actually, the mutual idea was born in Belgrade, Serbia and Zagreb, Croatia. Going toward the European Union, nine chemical societies from southeast European organized the 2nd Symposium (the Serbian Chemical Society was the local organizer), held in Belgrade, Serbia, 6-10 June 2010 http://www.rse-see.net. The 1st Symposium, with the Croatian Society of Chemical Engineers as the local organizer, was held in Rovinj, Croatia in 2008. The 2nd Symposium was attended by more than 200 participants, including young scientists (such as university students participating in the Satellite Student Symposium with 19 contributions) from more than 30 countries. Eminent invited plenary and keynote speakers delivered 9 and 18 lectures, respectively, and 46 oral and 118 poster presentations were contributed, promoting thereby contemporary electrochemical knowledge even outside the region. Topics such as fundamental aspects of electrochemistry, energy conversion, materials, corrosion, environmental electrochemistry, and bio-electrochemistry, among others, lead to the conclusion that this was a very successful meeting. The selected papers published herein give a representative view of the Symposium, considering electrochemical thermodynamics, the fundamentals of electrochemical kinetics, the structure of electrode materials, and some basic electrochemical reactions and applications of electrochemical and materials science principles as biomedical implants, in analytical chemistry and corrosion. The 3rd Regional Symposium on Electrochemistry of Southeast Europe is scheduled for 2012. The local organizer is the Romanian Chemical Society, and the venue will be Bucharest, Romania. Branislav Nikolić Conference Editor

The electrochemical noise verification of the Gibbs fluctuation theory shows that the Gibbs ergodic idea works perfectly with respect to the pair correlations of the electrode charge thermal fluctuations. At the same time, the Gibbs formulae for the triple- and higher-order correlations of the electrode charge thermal fluctuations are outside of the ergodic hypothesis. This failure of the Gibbs ergodic idea suggests that the noise version of the electrochemical charge-transfer theory should be developed. In the context of nano-electrochemistry, the second- and higher-order correlations of the electrochemical noise processes may be considered as the quantities suitable for the nano-electrochemical characterization of both the electrode processes and electrochemical devices.

Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and zero-charge-potential measurements have been performed for the title systems. The results of the Rh(111)/aqueous HCl solutions demonstrate that in solutions of binary electrolytes with adsorbing anions the interfacial impedance is a single, indivisible element, even if its frequency dependence implies a four-element circuit. The measurements on Au(111) in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF 6 ) reveal that double-layer formation and rearrangement in ionic liquids are very slow processes manifesting themselves as a parallel combination of a capacitance and a constant phase element (CPE).

Polycrystalline smooth and platinized platinum electrodes have been extensively employed in electrochemistry. It is of utmost importance to gain a deeper insight into the processes occurring during their electrochemical transformations. Piezoelectric nanogravimetry by using electrochemical quartz crystal nanobalance (EQCN) is one of the most powerful tools for obtaining information on the events occurring at the electrode surface. This method has been exploited to monitor the surface mass changes as a function of the electrode potential varying the experimental conditions (time scale, solution composition, temperature), which allows one to draw conclusions in respect of the formation and removal of adsorbed and deposited species as well as changes in the electrochemical double layer. Furthermore, platinum dissolution processes, which are of importance (e.g., regarding the long-term stability of proton exchange fuel cells), are also discussed.

A rational understanding of what occurs during electrocrystallization, defined at a nanolevel, is developed to control electrodeposition processes. The electrokinetic behavior of the elements in solutions and the electrodeposits structure resulting from the electron exchange reaction at the cathodic surface are taken into consideration and compared. Transient electrokinetic parameters are measured with the secondary current pulse (SCP) technique, where a square galvanostatic pulse of a few ms duration is superimposed on the cathode while electrodeposition is running. Two parameters are obtained, the transient Tafel slope and the adsorption pseudo-capacitance; whilst a third parameter, the diffusive time constant, must be introduced if the overvoltage does not arrive to a steady state during the short pulse period. These parameters are related to the growth of different structures and permit a good control of the process. Control of the growth with nanodefinition is key to the development of innovative processes to keep pace with more and more demanding applications and environmental challenges. Examples are given to stress the relevance of the theoretical framework and to show possible implications for electrodeposition technology and its applications.

The aim of this work was the production and characterization of composite Ni matrix electrodeposits. Pure Ni, micro- and nano-SiC Ni matrix composite deposits have been produced from a Watts’s-type electroplating bath under both direct (DC) and pulse current (PC) conditions. The obtained deposits have been characterized regarding their microstructure by scanning electron microscopy (SEM) observations on both top surface and cross-section and their SiC content by energy-dispersive X-ray spectrometry (EDXS) and glow discharge optical emission spectrometry (GDOES) analyses. The resistance to localized corrosion has been evaluated by exposing the samples in a salt spray cabinet and performing visual observation as well as electrochemical impedance spectroscopy (EIS) measurements every five days. Both the use of PC and the codeposition of the nanoparticles lead to a grain refinement of the Ni matrix. The use of the PC did not influence in a significant way the resistance of the pure Ni deposits to the localized corrosion. The incorporation of micro-SiC led to a decrease of the corrosion resistance for the deposits produced under DC, while the microcomposites produced under PC presented a corrosion resistance comparable to the pure Ni deposits. The nanocomposites presented the highest corrosion resistance due to the more compact and fine-grained microstructure. EIS revealed the presence of a localized corrosion attack earlier than the visual observation, giving useful information about the failure mechanism.

Prolongation of the average life expectancy and an active lifestyle in old age are related to the constant increase in the number of joint diseases that eventually require a surgical procedure. The diseased joint is replaced with a joint prosthesis, the functionality of the joint is recovered, and pain is reduced. In the last decade, the number of joint replacement operations has increased several times over and is expected to increase further. In order to enable patients to have a painless and active lifestyle, it is necessary to develop materials that are long-lasting in vivo. Metallic biomaterials must exhibit high corrosion and wear resistance. In vitro research on materials under simulated physiological conditions is presented. These experiments are complemented by examples from clinical practice performed in collaboration with orthopedic surgeons. Morphological and chemical changes in the material during the course of in vivo performance are related to processes of wear and corrosion. The local and systemic consequences of these processes in the human body are presented.

Zeolite-modified electrodes (ZMEs) have been widely investigated because of their chemical, physical, and structural characteristics (shape, size, and charge selectivities; physical and chemical stabilities; high ion-exchange capacity; hydrophilic character; etc.), which make them of high interest in the design of electroanalytical systems. The paper presents recent literature data about fundamental and practical aspects related to the obtaining and applications of ZMEs. Some new ZMEs based on carbon paste incorporating soluble pheno-thiazinic dyes adsorbed on X-type zeolites are assessed comparatively, and the influence of some experimental parameters on the electrochemical response of these electrodes was investigated. The kinetic parameters for the heterogeneous electron-transfer process corresponding to the surface-immobilized mediators were determined, and all observed differences were used as evidence of the influence of the mediator structure and of the zeolite nature on the electrochemical activity of the new electrodes and on their electrocatalytic properties toward β-nicotinamide adenine dinucleotide (NADH) or ascorbic acid (AA) electro-oxidation and H 2 O 2 electroreduction.

Layer-by-layer (LbL) deposition is a convenient technique for the formation of ultra-thin nanocomposite layers containing metallic nanoparticles (NPs) and conducting polymers (CPs). The advantages of this approach for producing composite layers suitable for electroanalytical applications are discussed. Examples of electroanalytical applications of LbL-deposited composites are presented. Composite layers consisting of polyaniline (PANI) and Pd NPs are used for hydrazine oxidation. The PANI–Au NPs system is applied for dopamine (DA) and uric acid (UA) oxidation.

The biennial review of atomic-weight determinations and other cognate data has resulted in changes for the standard atomic weights of 11 elements. Many atomic weights are not constants of nature, but depend upon the physical, chemical, and nuclear history of the material. The standard atomic weights of 10 elements having two or more stable isotopes have been changed to reflect this variability of atomic-weight values in natural terrestrial materials. To emphasize the fact that these standard atomic weights are not constants of nature, each atomic-weight value is expressed as an interval. The interval is used together with the symbol [ a ; b ] to denote the set of atomic-weight values, A r (E), of element E in normal materials for which a ≤ A r (E) ≤ b . The symbols a and b denote the bounds of the interval [ a ; b ]. The revised atomic weight of hydrogen, A r (H), is [1.007 84; 1.008 11] from 1.007 94(7); lithium, A r (Li), is [6.938; 6.997] from 6.941(2); boron, A r (B), is [10.806; 10.821] from 10.811(7); carbon, A r (C), is [12.0096; 12.0116] from 12.0107(8); nitrogen, A r (N), is [14.006 43; 14.007 28] from 14.0067(2); oxygen, A r (O), is [15.999 03; 15.999 77] from 15.9994(3); silicon, A r (Si), is [28.084; 28.086] from 28.0855(3); sulfur, A r (S), is [32.059; 32.076] from 32.065(2); chlorine, A r (Cl), is [35.446; 35.457] from 35.453(2); and thallium, A r (Tl), is [204.382; 204.385] from 204.3833(2). This fundamental change in the presentation of the atomic weights represents an important advance in our knowledge of the natural world and underscores the significance and contributions of chemistry to the well-being of humankind in the International Year of Chemistry 2011. The standard atomic weight of germanium, A r (Ge), was also changed to 72.63(1) from 72.64(1).

The Commission on Isotopic Abundances and Atomic Weights (CIAAW) of the International Union of Pure and Applied Chemistry (IUPAC) completed its last update of the isotopic compositions of the elements as determined by isotope-ratio mass spectrometry in 2009. That update involved a critical evaluation of the published literature and forms the basis of the table of the isotopic compositions of the elements (TICE) presented here. For each element, TICE includes evaluated data from the “best measurement” of the isotope abundances in a single sample, along with a set of representative isotope abundances and uncertainties that accommodate known variations in normal terrestrial materials. The representative isotope abundances and uncertainties generally are consistent with the standard atomic weight of the element A r (E) and its uncertainty U [ A r (E)] recommended by CIAAW in 2007.