JSCS Vol 66, No. 11-12

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J.Serb.Chem.Soc 66 (11-12)731-733(2001)
UDC 929 Dragutin M Drazic

Professor Dragutin M. Drazic
On the occasion of his 70th birthday

Professor Dragutin Drazic was born on May 5, 1930, in Belgrade. His father, Milan Drazic, was a professor at the Faculty of Civil Engineering of the University of Belgrade, while his mother, Zorka, was also a civil engineer working for the City of Belgrade. These facts, as well as the entire intellectual entourage in the “Professors’ Colony” in Belgrade, predetermined his orientation to natural sciences and engineering. Thus, after finishing elementary school before WWII and secondary school by 1949, he entered the Faculty of Science and Mathematics (Department of Chemistry) of the University of Belgrade. After his first year of study, he changed the school, enlisting in the faculty of Chemical Engineering (“Faculty of Technology”) of the same University. He graduated from the Department of Chemical Technology with the highest grade in 1956.
After graduation, he joined the teaching staff of the same school, in the Department of Physical Chemistry and Electrochemistry, in which he spent his entire career, commencing as an assistant lecturer and becoming a full professor. His affinity for science was supported by his wife Vera (b. Kuharic) who was in the same profession and also became a university professor in physical chemistry. The family tradition continued with their two sons, Milan and Dusan, who also joined the academic world, becoming capable mathematician and computer scientists.
Profesor Drazic taught very successfully a variety of subjects, such as Electrode Kinetics, Corrosion, Electrochemical Double Layer and Adsorption (postgraduate) and finally, Physical Chemistry – a General Course. At the height of his professional career he was the Head of the Chair and Department of Physical Chemistry and Electrochemistry for several years.
In July 1959 he went to the USA, to join the Electrochemistry Laboratory of the University of Pennsylvania in Philadelphia, led by Professor John O’Mara Bockris, which at the time was the leading electrochemistry research center of the Western World. In 1970 he returned to that Laboratory by invitation of Professor Bockris, to spend another year there as a group leader in several subject areas within electrochemistry.
As a parallel occupation, he joined the Electrochemistry Department of the Institute of Chemistry, Technology and Metallurgy (ICTM) at the time of its formation in 1961, as the research base of the Faculty of Technology and Metallurgy. He was an active project- and group leader through all the years till his retirement in 2001, being the Director of that institution as it changed to the Institute of Electrochemistry ICTM.
During his entire career until the present day, Professor Drazic was actively engaged in social activities. Among numerous engagements it should be noted that he was very active in the Serbian Chemical Society performing the duties of Bursar, Secretary, Vice-President and finally President of the Society. In 1985 he was elected as a life Honorary President of the Society. At present he is the Editor of the Journal of the Serbian Chemical Society. In the succession of editors of the Journal, he was the first to succeed in achieving its international recognition by ensuring its regular monthly appearance in the English language. On the international scene, he was a National Secretary of the International Society of Electrochemistry, a Vice-President of that Society (1992–1994), a member of the Commission on Electrochemistry of IUPAC and of the Working Group on Electrochemistry of the European Federation of Chemical Engineers.
In recognition of his achievements, in 1983 he was elected a Member correspondent and in 1991 a full Member of the Serbian Academy of Sciences and Arts. In 1995 he was awarded the Medal of the Serbian Chemical Society for Exceptional Contribution to Science.
The scientific work of Professor Drazic resulted in 2 books, 3 chapters in international series of monographs, 160 papers published in scientific journals and 41 paper published in collections of works presented at different professional meetings, 28 professional studies and 7 patents. His work has been cited in the scientific literature by other authors 1460 times until the present.
The main scientific interests of Professor Drazic can be grouped into three lines of research: a) new electrochemical power sources, b) measuring methods and new technological systems and c) electrochemical processes of deposition, dissolution and corrosion of metals.
In the first group, most of the published work is related to hydrogen–air fuel cells and metal–air systems, aluminium–air cells in particular. He was one of the initiators of research into these systems, which, according to some estimates (Nature, 287 (1980)), represents one of the most promising power sources of the future. Papers and patents which resulted from that work contained numerous original ideas which caught the attention of scientists working in the field throughout the World. The results which showed that aluminium can be turned from a stable construction material into a potent source of energy by low-alloying with some elements have far-reaching implications.
Professor Drazic successfully worked on new measuring techniques and technologies. Thus, he developed a new technique for measuring the adsorption of organic compounds on metal surfaces immersed in electrolytic solutions, a method for measuring the rates of corrosion of metals by recording the amounts of evolved hydrogen, a method for observing microscopically in situ, with magnification of up to 500, crystal growth during electrocrystallisation, etc. Especially important is his original method for determining the rates of corrosion from polarization measurements. He also investigated new three-dimensional electrochemical reactors with fluidized metal particles, which are specially suitable for processing dilute electrolytes, such are those encountered during elution of metal ores with very low metal contents, in waste water treatment and other similar systems.
In the third group are his investigations of the electrochemistry of iron and zinc. Aside from the papers which deal with problems of electrocrystallization of these metals, of particular importance, in view of the interpretation of corrosion phenomena, is his work on explaining the phenomena of the so-called “chemical dissolution” of metals and the mechanism of anodic dissolution.
Finally, the most important fundamental contribution of Professor Drazic is that of elucidating the mechanism of anodic dissolution of iron. He showed that the dissolution of this metals is a stepwise process involving an intermediate state of an adsorbed subferrohydroxide species in which iron is in the form of a univalent ion. This mechanism is now generally accepted and widely cited in numerous textbooks and monographies.
In conclusion, it is possible to state that Professor Drazic through his work became one of the leading figures in contemporary electrochemistry who, with his numerous followers, played a key role in forming what is known today as the Belgrade Electrochemistry School.
Aleksandar Despic

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J.Serb.Chem.Soc. 66(11–12)735–752(2001)
UDC 535.352/.353+537.567:543.51
JSCS–2900
Review paper

R E V I E W
Ion/surface collisions: An alternative to gas-phase collisional activation in mass spectrometry

TEODOR AST

Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, P. O. Box 494, YU-11001 Belgrade, Yugoslavia

(Received 3 September 2001)
1. Introduction
2. Instrumentation
3. Surface-induced dissociation
4. Solid surfaces
5. Isomeric ion distinction
6. Conclusion

Keywords: mass spectrometry, ion activation, ion fragmentation, ion/surface collisions, internal energy.
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J.Serb.Chem.Soc. 66(11–12)753–763(2001)
UDC 543.422.25:547.665
JSCS –2901
Original scientific paper
NMR Analysis of 2-(2’, 3’-dihydro-1’H-inden-1’-yl)-1H-indene

JOVAN JOVANOVIC, MICHAEL SPITELLER* and PETER SPITELLER**

Faculty of Technology and Metallurgy, University of Belgrade, P. O. Box 3503, YU-11120 Belgrade, Yugoslavia
*Institute for Environmental Research, University of Dortmund, Otto-Hahn-Str. 6, D-44221 Dortmund, Germany
**Department of Chemistry, University of Munich, Butenandtstr. 13, D-81377 Munich, Germany,

(Received 24 June 2001)
1H, 13C and two dimensional NMR analyses were applied to determine the NMR parameters of 2-(2’,3’-dihydro-1’H-inden-1’-yl)-1H-indene. The chemical shifts of all the H- and C-atoms, as well as the appropriate coupling constants were determined and the complete NMR resonance assignments of the molecule are given. The predicted patterns of the four different H atoms of the two methylene groups of the indane structural element coincided completely with the complex patterns in the NMR spectra.

Keywords: NMR spectroscopy, structure elucidation; dimers of indene.
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J.Serb.Chem.Soc. 66(11–12)765–784(2001)
UDC 628.316.12:547.562.1:66.087.3
JSCS–2902
Original scientific paper

Auto-inhibition effects in anodic oxidation of phenols for electrochemical waste-water purification

H. AL-MAZNAI and B. E. CONWAY

Department of Chemistry, University of Ottawa, 10 Marie Curie Street, Ottawa, ON. K1N 6N5 Canada

(Received 27 August 2001)
Removal or modification of noxious organic impurities in waste-waters is a major challenge for environmental science. Pollutants such as phenols and their derivatives, as well as PCBs, have attracted special attention. In recent years, the possibilities of effecting direct electrocatalytic oxidations at high-area electrodes such as supported Pt or RuO2 have been investigated. However, in a number of cases, especially with phenolic impurities, application of anodic oxidation fails to lead to continuous Faradaic oxidation currents owing to the electrode surfaces becoming blocked with polymeric oxidation products leading to auto-inhibition (“passivation”) of the desired electrode process. Examples of such effects with phenols and related compounds are examined comparatively in the present paper by means of cyclic volatammetry and chronoamperometry.
Keywords: phenol, waste-water purification, electro-oxidation, auto-inhibition.
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J.Serb.Chem.Soc. 66(11–12)785–797(2001)
UDC 66.087.3:546.262.3–31+546.92
JSCS –2903
Original scientific paper

Electrochemical oxidation of carbon monoxide: from platinum single crystals to low temperature fuel cells catalysts.
Part I: Carbon monoxide oxidation onto low index platinum single crystals

BRANIMIR N. GRGUR, NENAD M. MARKOVIC*, CHRISS A. LUCAS** and PHILIP N. ROSS JR**

Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, YU-11001 Belgrade, Yugoslavia,
*Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 2-100, Berkeley, CA 94720, USA, and
**Oliver Lodge Laboratory, Department of Physics, University of Liverpool, Liverpool L69 7ZE, UK

(Received 16 July 2001)
The electrochemical oxidation of carbon monoxide and the interfacial structure of the CO adlayer (COads) on platinum low index single crystals, Pt(111), Pt(100) and two reconstruction of Pt(110), were examined using the rotation disk electrode method in combination with the in situ surface X-ray diffraction scattering technique. The mechanism of CO oxidation is discussed on the basis of the findings that, depending on the potential, two energetic states of COads exist on the platinum surfaces. Thus, at lower potentials, weakly bonded states (COads,w) and at higher potentials strongly bonded states (COads,s) are formed. The mechanism of the oxidation of hydrogen-carbon monoxide mixtures is also proposed.
Keywords: platinum single crystals, carbon monoxide, electrooxidation, hydrogen, mechanism.
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J.Serb.Chem.Soc. 66(11–12)799–809(2001)
UDC 620.197.5:54611+541.18
JSCS–2904
Original scientific paper

The effect of organic molecules adsorption on hydrogen absorption in relation to the hydrogen evolution reaction

LJILJANA VRACAR

Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, P. O. Box 35-03, YU-11120, Belgrade, Yugoslavia, E-mail: ljvracar@elab.tmf.bg.ac.yu

(Received 11 July, revised 28 August 2001)
The competitive adsorption of organic molecules (2,7-naphthalenedisulfonic acid) and adsorbed H is of interest in relation to its influence on H absorption into a Pd-Ni electrodeposited alloy. The experimental results, in acid solution, show an enhancement of the coverage of the electrode surface with adosrbed H due to the competitive adsorption of organic molecules that interfere with H atoms, through lateral attractive interactions between the adsorbed species and communal electronic effects, leading supposedly to a decreased probability of H entry into the alloy. Chemisorbed H is, on the other hand, an intermediate in the HER, so the enhancement of the electrode coverage in the presence of co-adsorbed organic molecules promotes the hydrogen evolution reaction.
Keywords: hydrogen adsorption, absorption, hydrogen evolution, lateral interactions.
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J.Serb.Chem.Soc. 66(11–12)811–823(2001)
UDC 531.3:546.11+541.18+546.47:549.3
JSCS –2905
Original scientific paper

On the kinetics of the hydrogen evolution reaction on zinc in sulfate solutions

T. TRISOVIC, LJ. GAJIC-KRSTAJIC, N. KRSTAJIC* and M. VOJNOVIC*

Institute of Technical Science, SASA, Kneza Mihajla 35, YU-11000 Belgrade and
*Department of Physical Chemistry and Electrochemistry, Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4. YU-11000 Belgrade, Yugoslavia

(Received 12 July, revised 29 August 2001)
The kinetics and mechanism of the hydrogen evolution reaction (her) were studied on zinc in 1.0 mol dm-3 Na2SO4 at 298 K, in the pH range 4.4 – 10. It was found that a combination of classical potentiostatic steady-state voltammetry (PSV) and electrochemical impedance spectroscopy (EIS) can help to elucidate dilemmas concerning the mechanism of this reaction. Thus, over the whole potential region, the reaction path of the her on zinc cannot be presented by the classical Volmer -Tafel-Heyrovsky route. It was found that the very complex S-shape of the polarization curves could be explained by two parallel reaction mechanisms for the her. The first reaction mechanism is a consecutive combination of three steps, in which the surface zinc oxide plays an active role in the her, and second reaction mechanism is a consecutive combination of a Volmer step, followed by a Heyrovsky step. The second mechanism is dominant in the more negative potential region where the active sites for the her are metallic zinc.
Keywords: hydrogen evolution reaction, zinc electrode, sulfate solution, spectroscopy of electrochemical impedance, mechanism, NLS fitting, rate constants.
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J.Serb.Chem.Soc. 66(11–12)825–833(2001)
UDC 542.943+532.7:620.:123.91
JSCS –2906
Original scientific paper

A time effect in the early stages of a surface oxidation of a Pt(111) plane in alkaline solution

A. V. TRIPKOVIC, K. Dj. POPOVIC and J. D. LOVIC

Institute of Chemistry, Technology and Metallurgy, Department of Electrochemistry, Njegoseva 12, P. O. Box 815, YU-11001 Belgrade, Yugoslavia

(Received 5 July 2001)
A time effect in the early stages of surface oxidation of a Pt(111) plane in 0.1 M NaOH solution was studied by examining the reduction parts of the j/E profile recorded after holding the potential for various times at several values at the end of anodic-going sweeps. The processes associated with the two peaks, which appear in the anodic part of the voltammogram, are assigned to the early stages of a surface oxidation. Two OHad states are suggested based on the existence of reversibly or weakly bound OHad species and irreversibly or strongly bound OHad species. The reversibly bound OHad species are involved in the “normal” structure of the butterfly peak, while the irreversibly adsorbed OHad species can be obtained only by the slow diffusion of a part of the initially electrosorbed OH species from sites with low to sites with higher binding energies. The irreversibly reduced OHad species cannot be completely removed from the surface causing, therefore, some permanent transformation of the initial state of the surface. This kind of species was not detected in the area of the second oxidation peak. The phenomena observed in the reduction part of the j/E profile induced by a time effect in the second peak could be associated with a place-exchange mechanism between oxygen containing species, whatever they are, and the platinum surface.
Keywords: Pt(111) surface oxidation, reversible OHad species, irreversible OHad species, j/E profile, time effect.
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J.Serb.Chem.Soc. 66(11–12)835–845(2001)
UDC 586.815+621.3.032.22:621.357.0:667.63
JSCS –2907
Original scientific paper

Lead dioxide electrodes for high potential anodic processes

ROSSANO AMADELLI and A. B. VELICHENKO*

Centro di studio su Fotoreattività e Catalisi (CNR) - Dipartimento di Chimica (Università di Ferrara), via Borsari 46, 44100 Ferrara, Italy and *Department of *Physical Chemistry, Ukrainian State Chemical Technology University, Gagarin Ave., Dnepropetrovsk, 320005, Ukraine

(Received 22 August 2001)
Doping of PbO2 by cations (Fe3+, Co2+ and Ni2+), by F- and by cations and F- simultaneously is discussed as a way of improving the stability and electrochemical activity in processes occurring at high potentials. Doping allows the control of the amount of structural water in an oxide. Radiotracer experiments showed that high electrodeposition current densities favour the segregation of incorporated tritium (protons) at the surface. On the other hand, fluorine doping results in a marked decrease in the amount of surface oxygen species. The influence of doping with metal cations strongly depends on the nature of the metal. Iron behaves like fluorine, while nickel causes an accumulation of surface oxygen species. Doped PbO2 electrodes have quite good activities for the electrogeneration of ozone. In particular, Fe and Co doped PbO2 showed a current efficiency of 15–20 % for this process. This result is relevant to our recent studies on “cathodic oxidation”, i.e., an ozone mediated electrochemical method in which an O2 stream is used to sweep the O2/O3 gas mixture produced at a PbO2 anode into the cathodic compartment of the same electrochemical cell containing polluting species.
Keywords: lead dioxide anodes, doping, ozone electrogeneration.
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J.Serb.Chem.Soc. 66(11–12)847–857(2001)
UDC 546.82+546.96+621.3.032.22:541.182.6:541.13
JSCS –2908
Original scientific paper

The effect of the composition of the dispersing medium of oxide sols on the electrocatalytic activity of sol-gel obtained RuO2-TiO2/Ti anodes

DEJAN MITROVIC, VLADIMIR PANIC, ALEKSANDAR DEKANSKI*, SLOBODAN MILONJIC**, RADOSLAV ATANASOSKI* and BRANISLAV NIKOLIC

Faculty of Technology and Metallurgy, Karnegijeva 4, YU-11120 Belgrade,
*ICTM - Center for Electrochemistry, Njegoseva 12, YU-11000 Belgrade and
**Vinca Institute of Nuclear Sciences, P. O. Box 552, YU-11001 Belgrade, Yugoslavia

(Received 18 June, revised 28 August 2001)
The influence of the addition of methanol, ethanol, 1-propanol and 2-propanol to the dispersing medium of a mixture of RuO2 and TiO2 sols on the electrochemically active surface area for proton exchange, as well as on the electrocatalytic activity for the chlorine evolution reaction (CER) of RuO2-TiO2/Ti electrode obtained by sol-gel procedure was investigated. The electrochemically active surface area was examined by cyclic voltammetry, while the analysis of the activity for the CER was performed by polarization measurements. The stability of the obtained anode coatings was also checked by an accelerated stability test. The anode properties depend on the number of C atoms in the alcohol molecule, as well as on the elapsed time between the preparation of the sols/alcohol mixture and its application onto the titanium support. The addition of alcohol increased the activity of the anodes for the CER, compared to those prepared without the addition, but their stability was smaller.
Keywords: activated titanium anodes, RuO2 sol, TiO2 sol, sol-gel procedure, dispersing media, chlorine evolution reaction.
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J.Serb.Chem.Soc. 66(11–12)859–870(2001)
UDC 547.448:541.183:548.75
JSCS – 2909
Original scientific paper

Layer formation by 1,7-diphosphono-heptane

P. PÓCZIK, I. FELHÕSI, J. TELEGDI, M. KALAJI* and E. KÁLMÁN

IC CRC HAS, Pusztaszeri út 59-67, 1025 Budapest, Hungary and
*Department of Chemistry, University of Wales, Bangor, Gwynedd, LL57 2UW, UK

(Received  20 July 2001)
Surface modification of polycrystalline ARMCO iron and an Fe(110) single crystal was performed using a solution of 1,7-diphosphono-heptane (DPH). The changes of the surface properties were studied by subtractively normalised interfacial Fourier transform infrared spectroscopy (SNIFTIRS), scanning tunneling microscopy (STM) and electrochemical impedance spectroscopy (EIS). The immersion of the surfaces into DPH solution resulted in a build up of an ordered thin multimolecular layer after a few hours of continuous adsorption. The orientation of the DPH molecules was influenced by the supporting electrolyte and the electrode potential. The treatment in the absence of oxygen resulted in a lower corrosion protection effect compared to diphosphonate layer formation in an atmospheric environment.
Keywords: adsorption, diphosphonate, EIS, self-assembling molecules, SNIFTRIS, STM.
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J.Serb.Chem.Soc. 66(11–12)871–880(2001)
UDC
JSCS – 2810
Original acientific paper

Electrochemical properties and thermal stability of epoxy coatings electrodeposited on aluminium and modified aluminium surfaces

VESNA B. MISKOVIC-STANKOVIC, ZORICA Z. LAZAREVIC and ZORICA M. KACAREVIC-POPOVIC*

Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, P. O. Box 3503, YU-11120 Beograde and
*Vinca Institute of Nuclear Sciences, P. O. Box 522, YU-11001 Belgrade, Yugoslavia

(Received 5 June, revised 27 August 2001)
The corrosion behaviour of epoxy coatings electrodeposited on aluminium, as well as on electrochemically and chemically modified aluminium were investigated during exposure to 3 % NaCl. Electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA) were used for the determination of the protective properties of epoxy coatings on aluminium, anodized aluminium, phosphatized and chromatized-phosphatized aluminium. The protective properties of epoxy coatings on anodized and chromatized-phosphatized aluminium are significantly improved with respect to the same epoxy coatings on aluminium and phosphatized aluminium: higher values of the pore resitance and charge-transfer resistance, lower values of the coating capacitance, double-layer capacitance and relative permittivity (from EIS) smaller amount of absorbed water inside the coating (From TGA). On the other hand, the lower values of the ipdt temperature indicate a lower thermal stability of the epoxy coatings on anodized and chromatized-phosphatized aluminium.
Keywords: electrodeposition, epoxy coatings, aluminium, anodized aluminium, phosphatized and chromatized- phosphatized aluminium, corrosion, EIS.
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J.Serb.Chem.Soc. 66(11–12)881–886(2001)
UDC 621.373.1:541.135.5–669.1:547.368
JSCS –2911
Original scientific paper

Current oscillations of iron in p-toluenesulfonic acid

HAITAO CUI*, SHENHAO CHEN*,**, SHIYONG ZHAO* and CHAO WANG*,**

*Department of Chemistry, Shandong University, Jinan 250100, P. R. China and
**State Key Laboratory for Corrosion and Protection, Shenyang 110015, P. R. China

(Received 10 May 2001)
The periodic current oscillations of an iron electrode in p-toluenesulfonic acid (PTSA) solutions were investigated by cyclic volatammetry and potentiostatic polarization. The Fe/PTSA system is a new electrochemical oscillator and shows some interesting phenomena. The oscillations are ascribed to the alternate buildup and breakdown of Fe(OH)2 and Fe3O4 films.
Keywords: iron, electrodissolution, p-toluenesulfonic acid, current oscillation, pH dependence.
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J.Serb.Chem.Soc. 66(11–12)887–898(2001)
UDC 66.097:546.92:66.087.3
JSCS – 2912
Original scientific paper

New methods of controlled monolayer-to-multilayer deposition of Pt for designing electrocatalysts at an atomic level

S. R. BRANKOVIC, J. X. WANG and R. R. ADZIC

Materials Science and Technology Department, Brookhaven National Laboratory, Upton, New York, USA

(Received 15 June 2001)
Two new methods for monolayer-to-multileyer Pt deposition are presented. One involves Pt deposition by the replacement of an UPD metal monolayer on an electrode surface and the other the spontaneous deposition of Pt on Ru. The first method, exemplified by the replacement of a Cu monolayer on a Au(111) surface, occurs as a spontaneous irreversible redox reaction in which the Cu monolayer is oxidized by Pt cations, which are reduced and simultaneously deposited. The second method is illustrated by the deposition of Pt on a Ru(0001) surface and on carbon-supported Ru nanoparticles. This deposition takes place upon immersion of a UHV-prepared Ru(0001) crystal or Ru nanoparticles, reduced in H2, in a solution containing PtCl62- ions. The oxidation of Ru to RuOH by a local cell mechanism appears to be coupled with Pt deposition. This method facilitates the design of active Pt-Ru catalysts with ultimately low Pt loadings. Only a quarter of a monolayer of Pt on Ru nanoparticles yields an electrocatalyst with higher activity and CO tolerance for H2/CO oxidation than commercial Pt-Ru alloy electrocatalysts with considerably higher Pt loadings.
Keywords: electrocatalysis, H2 electrooxidation, Pt, Ru, catalytic poisons.
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J.Serb.Chem.Soc. 66(11–12)899–912(2001)
UDC 669.24'27:621.357.7:620.193
JSCS – 2913
Original scientific paper

Characterization and corrosion properties of electrodeposited Ni-W alloys

M. OBRADOVIC, J. STEVANOVIC, A. DESPIC, R. STEVANOVIC and J. STOCH*

ICTM - Institute of Electrochemistry, Njegoseva 12, P. O. Box 473, YU-11001 Belgrade, Yugoslavia and
*Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 1 30-239 Krakow, Poland

(Received 30 July, revised 8 August 2001)
Ni-W alloys electrodeposited from citrate solution consist of three different phases, which are all present in high W-content alloys: a solid solution of W in a Ni matrix; an intermetallic compound Ni4W, as well as another solid solution of W in Ni with a W content higher than 20 mol. %. XPS analysis revealed that the alloys were covered with a surface layer of complex structure containing the pure metals Ni and W, Ni(OH)2 and WO3, on the very surface as well as some partially reduced oxide WO2.72 (most probably a solid solution of WO2.72 in Ni) and tungsten carbide in the layer underneath. It is highly likely that some of the oxide species in the layer act as intermediates in the cathodic deposition process. Identifying these species should be the clue to a more detailed understanding of the mechanism of induced deposition of W than has been achieved so far. Corrosion of Ni-W alloys in sulfuric acid solution at OCP, occurs by the preferential dissolution of nickel from the surface layer. The longer the corrosion process lasts, the more the surface behaves like pure W. The lowest initial corrosion rates were recorded with alloys rich in W, but after aging at OCP the lowest corrosion c.d. was found for the Ni-W alloy with the most homogenous phase structure, consisting of the solid solution only.
Keywords: nickel-tungsten, induced codeposition, phase structure, corrosion.
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J.Serb.Chem.Soc. 66(11–12)913–921(2001)
UDC 66.067.9+541.135:546.682
JSCS – 2914
Original scientific paper

A study of the morphological aspects of the indium electrorefining process

SVETOMIR HADZI JORDANOV, ALEKSANDAR DIMITROV, PERICA PAUNOVIC and DRAGAN SLAVKOV

Faculty of Technology and Metallurgy, University “Sts Cyril and Methodius”, P. O. Box 580, Skopje, Macedonia, e-mail: shj@ereb.mf.ukim.edu.mk

(Received 20 June 2001)
The cathodic deposition of In was performed under conditions suitable for electrorefining purposes. The main goal of the study was: i) to determine the possibilities for In ultrapurification through multiple electrorefining with controlled parameters and ii) to study the regularities of the morphology of the In deposit as influenced by the electrodeposition conditions. Without application of special high purity techniques, it was possible to obtain an In purity level of 99.997 %, by repeating the refining procedure in a set of modular electrolysis cells with forced electrolyte circulation and applying modified current regimes. Irregular (non planparallel) migration of indium from the anode to the cathode and vice versa, as well as dendrite formation at the edges of the electrode prevented further repetition necessary for the achievment of higher purification levels. This provoked the need to study the morphology of the In-deposits. The phenomena and some regularities of In nucleation and grain growth, as influenced by the applied overpotential and quantity of current passed through the cell, were studied. Electrodeposition was performed onto a stationary Pt-electrode from a mixed sulfate–chloride solution. SEM with magnification up to 1000 × was used to identify the morphology of the deposits. Granular grains were dominant at overpotentials of 85 and 110 mV, while at 160 and 185 mV, needle-like and nonbranched dendrites were visible. The deposit became less compact as its thickness advanced. The apparent thickness of the In layer increased from 20–25 to 320–380 mm when the amount of charge was increased from 1 to 10 mA h cm-2.
Keywords: In, electrorefining, ultrapurification, SEM, morphology, dendrites.
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J.Serb.Chem.Soc. 66(11–12)923–933(2001)
UDC 539.24+531.755+543:669–492.2/.3+669.3
JSCS –2915
Original scientific paper

 The effect of particle structure on apparent density of electrolytic copper powder

M. G. PAVLOVIC, LJ. J. PAVLOVIC, E. R. IVANOVIC*, V. RADMILOVIC** and K. I. POPOV**

ICTM - Department of Electochemistry, Njegoseva 12, YU-11000 Belgrade,
*Faculty of Agriculture, University of Belgrade, Nemanjina 6, YU-11080 Zemun - Belgrade and
**Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, YU-11000 Belgrade, Yugoslavia

(Received 6 June, revised 30 August 2001)
The quantitative microstructural analysis and the sieve analysis of copper powder as well as the scanning electron microscopy analysis of the copper powders particles were performed. It was found that the structure of the copper powder particles determines the apparent density of copper powder. The powder particles from the same fractions of different powders occupy approximately the same volume, but the structure of metallic copper is very different. This causes the difference in apparent densities of copper powder obtained under different conditions. The more dendritic is the structure of powder particles the smaller is the apparent density of copper powder.
Keywords: particle structure, apparent density, electrolytic copper powder, galvanostatic deposition.
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J.Serb.Chem.Soc. 66(11–12)935–952(2001)
UDC 621.357.7+669.3:541.183+546.33'131
JSCS – 2916
Original scientific paper

Copper electrodeposition from a copper acid baths in the presence of PEG and NaCl

V. D. JOVIC and B. M. JOVIC

Materials Engineering Department, Drexel University, Philadelphia, PA 19104, USA

(Received 7 June 2001)
Copper electrodeposition from copper acid solutions containing PEG and NaCl has been investigated onto Cu(111), Cu(100) and polycrystalline copper electrodes using polarization and EIS measurements. The adsorption of sulphate and chloride anions, and PEG molecules, was investigated onto Cu(111) and Cu(100) by cyclic voltammetry and differential capacitance measurements. Differential capacitance vs. potential curves recorded onto Cu(100) in solutions containing 0.1 M H2SO4, 0.1 M H2SO4 + 10-3 M PEG and 0.1 M H2SO4 + 10-3 M PEG + 10-3 M NaCl confirm that “specific adsorption” of PEG molecules occurs in the absence of NaCl in the solution, in the potential region of copper electrodeposition, e.g., between –1.0 V and –0.5 V vs. SSE. In the presence of chloride ions, the adsorption of PEG molecules is suppressed and there is no evidence of adsorption of neutral PEG molecules. It is shown that hysteresis, appearing on the polarization curves of copper electrodeposition, is not a consequence of competition between inhibition provided by the Cl-PEG/Cu2+/Cu+/Cu interface and the catalytic effects of Cl-MPSA/Cu2+/Cu+/Cu interaction, because hysteresis is present in the solution containing only PEG and NaCl, e.g., in the absence of MPSA. EIS measurements confirm the simultaneous occurrence of two processes during copper electrodeposition: deposition of copper by discharge of Cu2+ ions and “specific adsorption” and discharge of some heavily charged species, most probably containing Cu, PEG and Cl.
Keywords: copper, electrodeposition, PEG, chloride, complexes, Cu(111), Cu(100), adsorption, differential capacitance.
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J.Serb.Chem.Soc. 66(11–12)953–958(2001)
Contents of Volume 66
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J.Serb.Chem.Soc. 66(11–12)959–961(2001)
Subject Index
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J.Serb.Chem.Soc. 66(11–12)963–966(2001)
Author Index
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