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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article click here (134 KB pdf file)
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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End of Volume 66
Copyright & copy; SHD 2001.
Updated
January 22, 2002.
For
more information contact: SHD@elab.tmf.bg.ac.yu