describes other electrochemical aspects. While ionic liquidswith
discrete anions show signicant potential for the elec-trodeposition
of electronegative metals such as aluminium
, issues such as toxicity and availability will limit
theirpractical use for larger scale applications of other
Type 2 Y = MClx yH2OType 3 Y = RZ, Z = CONH2, COOH, OH
The electrochemistry, physical properties and
speciationoccurring in Types 1 and 2 ionic liquids has been
reportedfor a variety of metals . Considerably fewer
* Corresponding author. Fax: +44 116 252 3789.E-mail address:
[email protected] (A.P. Abbott).
Journal of Electroanalytical Chemis
Journal ofIonic liquids are classed as salts that are liquid at
below100 C . They have been extensively studied primarily
forsynthetic and electrochemical applications . The major-ity of
investigations have concentrated on imidazoliumcations with
discrete anions such as BF4 ; PF
(F3CSO2)2N. These ionic liquids have large potential win-
dows and exhibit relatively high conductivities and low
vis-cosities. Two recent reviews by Endres [3,4] cover allaspects
of electrodeposition from these liquids, Comptonand coworkers 
have reviewed fundamental aspects ofelectrochemistry in ionic
liquids and a book by Ohno 
An alternative approach to making ionic liquids is to startwith
a simple quaternary ammonium halide and decreasethe freezing point
by complexing the anion to eectivelydelocalise the charge. These
eutectic-based ionic liquidscan be described by the general
R1R2R3R4NX: z Y
and we have characterised these materials into three
typesdepending on the complexing agent Y;
Type 1 Y = MClx, M = Zn, Sn, Fe, Al, GeHere we describe the
electrolytic deposition of Zn, Sn and Zn/Sn alloys from a solution
of the metal chloride salts separately in ureaand ethylene
glycol/choline chloride based ionic liquids. We show that the
deposition kinetics and thermodynamics dier from the aque-ous
processes and that qualitatively dierent phases, compositions and
morphologies are obtained for the metal coatings in the
dierentionic liquid systems. We have quantied the electrochemical
stripping responses using cyclic voltammetry together with
compositionalanalysis using SEM/EDAX and X-ray diraction. The
dierences in electrochemical responses are rationalised in terms of
the speciationof both Zn and Sn chlorides in the ionic liquids that
have been identied using FAB mass spectrometry. Also we demonstrate
that com-posite metal coatings, e.g. containing Al2O3 particles,
can be obtained from these liquid systems by virtue of the stable
liquid suspensions.This novel feature of these liquids is a
function of their relatively high viscosity. 2006 Elsevier B.V. All
Keywords: Electrodeposition; Zinc; Alloy; Ionic liquid;
EutecticElectrodeposition of zinctin albased on cho
Andrew P. Abbott *, Glen Capper
Chemistry Department, University
Received 18 November 2005; received in reviAvailable onl
Dedicated to0022-0728/$ - see front matter 2006 Elsevier B.V.
All rights reserved.doi:10.1016/j.jelechem.2006.04.024ys from deep
eutectic solventsine chloride
aty J. McKenzie, Karl S. Ryder
eicester, Leicester LE1 7RH, UK
form 24 March 2006; accepted 3 April 200621 June 2006
try 599 (2007) 288294
analhave been carried out using Type 3 based liquids, which
usehydrogen bond donors as the complexing agents [11,12].The use of
simple amides, acids and alcohols as complexingagents makes the
liquids very versatile and to distinguishthem from other ionic
liquids the term deep eutectic sol-vents (DES) has been coined.
DESs have been used forelectropolishing , polymer synthesis
 and metaloxide processing . Most of our previous studies
haveconcentrated on choline chloride as the quaternary ammo-nium
salt as it is non-toxic, biodegradable and is alreadyused as a
common component to numerous householdand industrial products.
Hence it can be applied economi-cally to large-scale processes. In
the current work we showhow DESs formed with choline chloride and
either urea orethylene glycol can be used for the electrodeposition
ofzinc, tin, and zinctin alloys. We also show that the choiceof
hydrogen bond donor aects the type of alloy and theelectrochemistry
of the components in solution.
Zinctin alloys have been deposited from a variety ofaqueous
baths including sulphate , gluconate  andpyrophosphate
baths . The alloys are found to havebetter corrosion resistance
than pure zinc, particularly inhigh humidity conditions and are
also reported to be supe-rior to cadmium deposits in marine
Choline chloride HOC2H4NCH33 Cl (ChCl)(Aldrich 99%) was
recrystallised from absolute ethanol, l-tered and dried under
vacuum. Urea (Aldrich > 99%) wasdried under vacuum prior to use.
Ethylene glycol (EG)(Aldrich 99+%), tin chloride (Aldrich) and zinc
chloride(BDH) were used as received. The eutectic mixtures
wereformed by stirring the two components together, in the sta-ted
proportions, at 100 C until a homogeneous, colourlessliquid formed.
Voltammetry was carried out using anAutolab PGSTAT12 potentiostat
controlled with GPESsoftware. A three-electrode system consisting
of a platinummicroelectrode (0.5 mm diameter) (made in-house) a
plati-num counter electrode and a silver wire reference
electrodewere used. The working electrode was polished with 0.3
lmalumina paste, rinsed and dried prior to all measurements.All
voltammograms were performed at 40 C and a scanrate of 20 mV s1.
Stainless steel Hull cell panels were pre-pared by washing with
deionised water and dried, thendegreased by placing in
dichloromethane (DCM) for2 min, then removed and allowed to dry.
The panel wasplaced in the Hull Cell with a nickel cathode (also
rinsedwith water and DCM prior to use). The cell was lled
with1ChCl:2urea ionic liquid containing 0.5 M Zn:0.05 M Snand 3 wt%
Al2O3. The panel was plated at 10 V for30 min, rinsed with
deionised water and allowed to dry.The current density at dierent
positions across the Hullcell was calibrated using a Ni strip 5 mm
wide. Surfaceanalysis was carried out using scanning electron
A.P. Abbott et al. / Journal of Electrocopy (Philips XL30 ESEM)
and energy dispersive analysisby X-rays (EDAX). Powder X-ray
diraction was carriedout using a Philips model PW 1730 X-ray
generator, witha PW 1716 diractometer and PW 1050/25 detector.
Thetube was a long ne focus Cu anode, Ni ltered Ka radia-tion. The
normal current operating conditions are 40 kV30 mA. Scans are run
from 15 to 110 2h with a step sizeof 0.02 2h, at a speed of 1/min.
Angle calibration is by asynthetic Si sintered standard.
3. Results and discussion
As with all non-aqueous electrochemistry, the denitionof a
reference potential is dicult due to the unknownliquid junction
potential. Most studies in ionic liquids haveused either ferrocene
as an internal standard or a silver wirequasi-reference electrode.
With the DESs based on urea andethylene glycol the latter approach
is used for two reasons.Firstly: ferrocene along with many of its
functionalisedderivatives is largely insoluble in the ionic
liquids. Second,the reference potential of the silver wire in both
IL environ-ments is likely to be dominated by the activity of
chlorideion. In all the experiments described here the
concentrationof chloride ion is very much larger than that of any
otherspecies in solution. The potential window of the urea:
cho-line chloride eutectic mixture is relatively small on a
plati-num electrode (1.2 V to +1.25 V vs. Ag) . However,metals
can be deposited with high current eciencies (videinfra) because
the reduction kinetics of the eutectic are con-siderably slower on
other metal surfaces e.g. on Zn no sig-nicant decomposition of the
eutectic occurs above 2 V.
Fig. 1A and B show the voltammetry of ZnCl2 and SnCl2in
ChClmixtures with urea and ethylene glycol, respectively.The peak
reduction potentials for tin are very similar in boththe urea and
glycol based liquids (0.38 V and 0.35 V,respectively) suggesting
rstly that the silver wire does actas a stable reference electrode
and secondly that the hydro-gen bond donor does not signicantly
aect the mechanismof tin ion reduction (where this is a combination
of thermo-dynamic and kinetic eects). The reduction potentials
forzinc are dierent in the urea and glycol based liquids(1.00 V
and0.85 V, respectively) suggesting that the zinccomplexes present
in solution may dier in the two liquids.In aqueous solutions the
dierence between the standardreduction potentials for the two
metals is 0.62 V. The dier-ence in the metal reduction potentials
in the urea-basedliquid is exactly the same as that in water, 0.62
V, while thatin the ethylene glycol based liquid is only 0.50 V.
Fig. 1Balso illustrates the dierence in deposition kinetics for
Znand Sn, as the charges associated with deposition and strip-ping
of the metal are approximately equal despite a 10-folddierence in
the concentration of the two metal salts.
It is also evident from Fig. 1 that the currents for reduc-tion
and oxidation of zinc are signicantly dierentbetween the two
liquids despite the concentrations beingsimilar. For example the
ratio of the cathodic peak cur-rents, ip(EG)/ip(urea), observed
during Zn deposition,
ytical Chemistry 599 (2007) 288294 289Fig. 1, shows a ratio of
approximately 15. The magnitudeof this ratio can be explained, in
the most part, by the
naldierence in viscosity, g, of the two liquids (gurea = 1072
[email protected] 20 C; gEG = 50 cP @ 20 C) [11,13]. These viscositiesare related
to the diusion coecients, D, of reacting spe-cies by Waldens Rule
(below) , where the subscripts 1and 2 denote the viscosities
and diusion coecients of areacting species in two diering
D g D g
Fig. 1. (A) Voltammograms (scan rate 20 mV s1) for a Pt
microdiscelectrode (0.5 mm diameter) immersed in 1ChCl:2urea
containing 0.05 MSnCl2 (solid line) and in 1ChCl:2urea containing
0.5 M ZnCl2 (dottedline). (B) Voltammograms (scan rate 20 mV s1)
for a Pt microdiscelectrode (0.5 mm diameter) immersed in 1ChCl:2EG
containing 0.05 MSnCl2 (solid line) and in 1ChCl:2EG containing 0.5
M ZnCl2 (dotted line).
290 A.P. Abbott et al. / Journal of Electroa1 1 2 2
It can easily be shown for a diusion-controlled process ina
linear sweep voltammogram that the corresponding ratioof peak
currents for Zn ion reduction in the two media isgiven by the
Inserting the ratio of diusion coecients derived from
theviscosity values (Waldens Rule) into this expression gives
avalue for the ratio ip(EG)/ip(urea) of 5. This indicates
thatviscosity eects only account for approximately one-thirdof the
observed dierences, and the remaining discrepancycould be accounted
for by variations in surface area of theelectrode together with
dierences in the deposition kinet-ics (since the deposition peaks
have qualitatively dierentshapes).
SnCl2 is considerably less soluble in the ChCl:urea sys-tems and
at the concentration shown in Fig. 1 produces aslightly turbid
yellow solution suggesting that the solutionis actually beyond its
saturation limit for tin chloride. Thismay account, in part, for
the smaller voltammetricresponse of SnCl2 (in relation to ZnCl2)
observed for theurea system (see Fig. 1).
To elucidate the cause for the dierent voltammetricresponses FAB
mass spectra were run of both ChCl:2ureaand ChCl:2EG each
containing ZnCl2, then SnCl2 andnally a mixture of the two metals
in a 10:1 ratio. In thepositive ion analysis mode, peaks of m/z =
104 and 243were the only signals observed and these are known to
cor-respond to the species Choline+ and [2Choline Cl]+ andshows
that no signicant cationic metal-containing speciesare formed. The
negative ion spectra are considerably morecomplex due to the
isotope splitting of the metal chloridespecies. A signal at 174 is
common to all spectra [Choline2Cl]. The signals at m/z = 95 and 97
were also observedcorresponding to [Cl. urea] and [Cl. EG]. Where
justtin is present the only species identied in both liquids
iscentred at m/z = 225 [SnCl3]
. We have previously studiedeutectic mixtures between just SnCl2
and ChCl and foundboth SnCl3 and Sn2Cl
5 , but none of the di-tin species
were detected in either the urea or EG case.For the zinc
containing liquids a signicant dierence is
observed between the urea and EG systems. In urea theonly zinc
containing species is ZnCl3 whereas in EGZnCl3 ; Zn2Cl
5 and Zn3Cl
7 were detected. The most
probable explanation for the observed dierences betweenzinc
chloride in these two liquids is the ligand propertiesof the two
complexing agents. Urea will act as a far stron-ger ligand for
ZnCl3 than ethylene glycol. Its absence fromthe FAB-MS spectrum is
not unexpected as it is rarely seenas a metal complex with this
technique. No mixed metalcomplexes (e.g. ZnSnCl5 were observed in
either the ureaor EG liquids, which is in contrast to what was
found in theZnCl2/SnCl2/ChCl eutectic where it was the dominant
spe-cies . Eutectic mixtures between ChCl and ZnCl2 arereported
to contain ZnCl3 ; Zn2Cl
5 and Zn3Cl
7 . The rela-
tive proportions of each species have been quantied
usingpotentiometry . It was found that Zn2Cl
5 was the pre-
dominant species. The observation that no Zn2Cl5 was
observed in the urea based liquid suggests that urea actsas a
better complexing agent than ZnCl2 for ZnCl
The dierence in the species present will certainly resultin a
change in reduction potential of the metal. Fig. 1 sug-gests that
the mixed zinc species present in 1ChCl:2EG areeasier to reduce
than ZnCl3 in urea lending further weightto the idea that the urea
is involved in the coordinationsphere. There is a signicant
dierence between the voltam-metric behaviour of the two liquids
containing both tin andzinc chlorides. Fig. 2 shows the response
for a solution con-taining 0.5 M ZnCl2 and 0.05 M SnCl2. In the
ethylene gly-col based ionic liquid separate deposition and
strippingsignals are observed for tin and zinc. Stopping the
reduc-tive scan at 0.5 V the deposition of only tin is observedwith
QC = QA. Extending the scan potential down to1.5 V results in a
separate reduction signal for zinc. Thezinc deposition response is
not as sharp as that observedin Fig. 1 for pure zinc, but this
would be expected as thedeposition of zinc is now occurring on a
fresh tin surfacerather than platinum. The two stripping potentials
occur-ring on the anodic sweep occur at approximately the
samepotentials as the individual metals shown in Fig. 1B sug-
ytical Chemistry 599 (2007) 288294gesting that this is stripping
of the pure metals and that thisis a two-phase alloy i.e. discrete
zinc and tin phases. It is
-1.250 -0.750 -0.250 0.250 0.750 1.250-4
E / V
i / A
Fig. 3. Voltammograms (scan rate 20 mV s1) for a Pt microdisc
electrode(0.5 mm diameter) immersed in a 1:2ChCl:urea DES
containing 0.05 MSnCl2 and 0.5 M ZnCl2.
analytical Chemistry 599 (2007) 288294 291only when the
reductive limit is extended to more negativepotentials that a third
stripping peak is observed at+50 mV and this could be due to a
third phase consistingof predominantly tin with some zinc. The
relative areasunder the oxidation peaks vary with the lower
reductionlimit. Comparing these data to the 2ZnCl2/ChCl
eutecticwith 3 wt% SnCl2 described previously  it is
interestingto note that the voltammetry is very similar to that
shownin Fig. 1B. However, the dierence between the
reductionpotentials of the two metals in the 2ZnCl2/ChCl eutecticis
only 0.341 V which is less than that observed in eitherof the two
solvents seen here and less than the standardaqueous reduction
potentials (0.62 V). Interestingly, thiscould be due to the
presence of mixed metal complexesi.e. ZnSnCl5 which are known to
exist in the Type 1 sys-tems .
Guaus and Torrent-Burgues  studied the depositionof tinzinc
alloys from aqueous sulphategluconate bathsand found a considerably
more complex voltammetricresponse than that shown in Fig. 2. It was
shown thatthe four reduction peaks observed were due to dierentzinc
and tin containing species. The response observed onthe anodic
sweep is comparable with that observed with
-1.500 -1.000 -0.500 0 0.500 1.000 1.500-4
E / V
i / A
Fig. 2. Voltammograms (scan rate 20 mV s1) for a Pt microdisc
electrode(0.5 mm diameter) immersed in a 1:2 ChCl:EG DES containing
0.05 MSnCl2 and 0.5 M ZnCl2.
A.P. Abbott et al. / Journal of ElectroChCl:2EG. The stripping
of pure zinc and pure tin areclearly discernable and the third
oxidative peak increasesits relative size depending on the lower
reductive limit, akinto that observed above.
Fig. 3 shows an analogous voltammogram to thatshown in Fig. 2
but using urea as the hydrogen bond donorin place of EG. The
electrochemical response in the twoionic liquids is clearly dierent
and signicantly theresponse is also dierent to the response of the
two individ-ual component voltammograms for SnCl2 and ZnCl2.
Thereductive potentials for tin and zinc are shifted to
morepositive potentials compared to those in Fig. 2. A shift
inreference potential is not likely to be a large
contributoryfactor because the reference electrode appears to
remainstable (vide supra) as can be seen by comparing Figs. 1and 2.
The single anodic process occurs at a voltage thatis in between
those for the zinc and tin processes shownin Fig. 1. Even taking
the shift in reference potential intoaccount the dierence between
the main onset of reduction(0.88 V) and the oxidation peak
potential (0.55 V) isnevertheless greater than that shown in Fig.
1. Interestinglyno stripping of a tin rich phase is observed. It is
probabletherefore, that the use of urea in the ionic liquid tends
tolead to less of the separate zinc and tin phases and
insteadyields a zinc rich phase.
Bulk deposition of zinc from both EG and urea basedliquids leads
to zinc deposits with small crystallites thathave negligible
residual chloride. The deposits are dulland silver coloured in all
cases. Fig. 4 shows an SEM imageof a zinc lm grown in 1ChCl:2EG
containing 0.5 MZnCl2:0.05 M SnCl2 at a current density of 10 mA
for 1 h. This was typical of the morphology in both theEG and
urea based liquids and was relatively unaectedby the current
density. We have previously shown that zinccan be deposited as a
crack free lm with high current e-ciency from a 1ChCl:2ZnCl2 liquid
. These lms arewhite in appearance and are made up of
crystallites thatare slightly larger than those shown in Fig. 4
(c.a. 1025 lm) . The morphology is also similar to thatobtained
from deposition from the 2ZnCl2/ChCl eutecticFig. 4. Scanning
electron micrograph obtained by the electrolysis of 0.5 MZnCl2/0.05
M SnCl2 in 1ChCl:2EG at a current density of 10 mA cm
2 for1 h.
with 3 wt% SnCl2 . The issue associated with the use ofthese
Type 1 zinc eutectics is the low conductivity(36 lS cm1 at 40 C)
whereas the two Type 3 eutectic mix-tures used in this work have
much higher conductivities(ChCl:2urea = 1.8 mS cm1 and ChCl:2EG =
11 mS cm1
both at 40 C) [11,13].Alternatively the deposition of tin,
reported here, pro-
duced more dendritic clusters. The dendrites are built upof
simple cubic crystals as can be seen from Fig. 5. Thedeposition of
whisker-like deposits, which is common forthe deposition of tin
from aqueous solutions, was notobserved in either ionic liquid when
the current densityapplied was 10 mA cm2.
Electrolysis of the mixed SnCl2/ZnCl2 solutions pro-duced
deposits with dierent morphologies depending onthe hydrogen bond
donor used. With urea based liquidsthe deposit was made up of cubic
crystallites, which looksimilar to those found in Fig. 4 (not
shown). Energy Dis-persive Analysis by X-rays (EDAX) showed that
they arepredominantly zinc (ca. 89%) with the remainder being
Fig. 7. Scanning electron micrograph of a deposit grown from
thesolution shown in Fig. 3 at a current density of 10 mA cm2 for
60 min(A + 1.0 V in situ anodic etch was performed in the solution
for 1 minbefore deposition commenced).
20 40 60 80 1000
2 / degrees
Fig. 8. X-ray diraction (XRD) analysis of the samples shown in
Figs. 6and 7.
Fig. 9. Scanning electron micrograph of an alloy deposit grown
from thesolution of 0.5 M Zn:0.05 M Sn in 1ChCl:2urea containing 3
292 A.P. Abbott et al. / Journal of Electroanalytical Chemistry
599 (2007) 288294Fig. 5. Scanning electron micrograph obtained by
the electrolysis of0.05 M SnCl2 in 1ChCl:2urea, plated onto copper
substrate at a currentdensity of 10 mA cm2 for 30 min.
Fig. 6. Scanning electron micrograph of a ca. 12 mm deposit
a solution of 0.5 M ZnCl2/0.05 M SnCl2 in 1ChCl:2urea + 3 wt%
aluminaat a current density of 10 mA cm2 for 120 min.
(shown in Fig. 3) at a current density of 10 mA cm2 for 30 min.
Brightareas show high Al2O3 content.
largely tin with only traces of chloride. The two metalsseemed
evenly distributed throughout the deposit. Thickdeposits (>1 mm)
showed unusual morphologies. Fig. 6shows a ca. 12 mm deposit grown
from a solution of0.5 M ZnCl2:0.05 M SnCl2 in 1ChCl:2urea, at a
currentdensity of 10 mA cm2 for 120 min. Regular macroscopicpores
of approximately 150 lm diameter are observed witha regular
crystalline architecture surrounding them.
Electrolysis of the ethylene glycol based liquid used inFig. 2
at 10 mA cm2 gave a deposit with similar underly-ing morphology to
that shown in Fig. 7 but with dendriticgrowths on the top. These
dendritic areas showed higher Sncontent than the bulk and we assume
that the dendrites arepure tin. The overall Sn composition of the
underlyingmetal is higher in tin than that found using urea based
liq-uids (ca. 4045% Sn and 5055% Zn). Hence it can be seenthat
changes in ionic liquid composition can aect the ther-modynamics of
metal deposition by changing metalspeciation.
X-ray diraction (XRD) analysis was carried out on thesamples
shown in Figs. 6 and 7 and the results are shown inFig. 8. The XRD
spectra are notably dierent with the dis-tinct tin signals at 2h =
30, 64 and 74 being absent fromthe sample deposited from the urea
based liquid. Signals at2h = 34 and 36 are largely absent from the
sample pre-pared in the EG based liquid and from those
depositedfrom aqueous solutions  and could be due to a
homoge-neous Zn based alloy.
The relatively high viscosity of these solvents allowsimproved
stability of suspensions. Colloidal dispersionsof 1 lm Al2O3
require over 3 h to settle and this is possiblyaided by the high
ionic strength of the liquids. A dispersionof 3 wt% Al2O3 was made
in the mixture whose voltamme-try is shown in Fig. 2. Mild
agitation was sucient toretain the alumina as a homogeneous
80 100 120 140
Current density / mA cm-2
Zn Sn O Al Cl
Fig. 10. Plot of elemental composition as a function of current
density forthe deposits shown in Fig. 11 (data obtained from the
hull cell panelshown in Fig. 11).
A.P. Abbott et al. / Journal of Electroanalytical Chemistry 599
(2007) 288294 293Fig. 11. Scanning electron micrograph showing
dierent regions of a hull ceZn:0.05 M Sn in 1ChCl:2urea containing
3 wt% Al2O3 (shown in Fig. 3) atD = 148.ll panel coated with an
alloy deposit grown from the solution of 0.5 M
various current densities for 30 min. A = 85 mA cm2; B = 97; C =
voltammetry of the dispersion showed negligible dierencefrom
that shown in Fig. 2.
Fig. 9 shows an SEM image of the Zn/Sn alloy depos-ited from the
EG based liquid using a current density of10 mA cm2 for 30 min.
EDAX analysis conrms theinclusion of Al2O3 in the lms and these can
be seen asbright areas in Fig. 9. The size of the Al2O3
inclusionsappears to suggest that the particles do not aggregate
insolution or upon deposition in the lm but rather remainas
discrete entities. The Al concentration in the lm isapproximately 1
wt% which is similar to that in the liquidsuggesting that the
material is just dragged onto the surface
for the deposition of coatings with improved wearresistance.
The authors acknowledge the EU under the FP6 pro-gramme for
funding this work through the IONMETProject.
294 A.P. Abbott et al. / Journal of Electroanalytical Chemistry
599 (2007) 288294as the metal deposits.A Hull cell test was also
carried out to determine the
eect of current density on the Zn, Sn and Al2O3 composi-tion of
the lm (determined by EDAX). Fig. 10 shows thepercentage of each
component as a function of current den-sity and it can be seen that
this is largely unaected over thecurrent density range studied. It
was however found thatthe morphology of the surface layer was
dependent onthe current density. At I = 85 mA cm2 a
homogenousdeposit is formed as shown in Fig. 11A. Increasing the
cur-rent density yields a similar underlying deposit with
anamorphous surface coating (Fig. 11B) that is tin rich(42% Sn and
38% Zn). At higher current densities(Fig. 11C: I = 110 mA cm2) oral
shaped tin depositsare found on the surface and these aggregate at
even highercurrent densities (Fig. 11D: I = 148 mA cm2) these
coa-lesce to give nodular deposits.
This work shows that ionic liquids based on eutecticmixtures of
choline chloride and hydrogen bond donorssuch as ethylene glycol or
urea can be used as electrochem-ical solvents. It is shown that
zinc and tin can be electrode-posited from these liquids both
individually and as alloys.It is shown for the rst time that the
alloy morphologyand composition can be changed by judicious choice
ofthe ionic liquid. It is proposed that metal speciation is acause
of metal reduction thermodynamics. It is also dem-onstrated that
composite materials can be deposited andAl2O3 is used as an
example. This could open a new avenue T. Welton, Chem. Rev. 99
(1999) 2071. P. Wasserscheid, T. Welton, Ionic Liquids in
Verlag, Weinheim, Germany, 2003. F. Endres, ChemPhysChem 3
(2002) 144. F. Endres, Z. Phys. Chem. 218 (2004) 255. M.C.
Buzzeo, R.G. Evans, R.G. Compton, ChemPhysChem 5 (2004)
1106. H. Ohno (Ed.), Electrochemical Aspects of Ionic
Liquids, John Wiley
& Sons, New York, 2005. A.P. Abbott, G. Capper, D.L.
Davies, H.L. Munro, R.K. Rasheed,
V. Tambyrajah, Chem. Commun. (2001) 2010. A.P. Abbott, G.
Capper, D.L. Davies, R.K. Rasheed, Inorg. Chem.
43 (2004) 3447. A.P. Abbott, G. Capper, D.L. Davies, R.K.
Rasheed, Chem. Eur. J.
10 (2004) 3769. A.P. Abbott, G. Capper, D.L. Davies, R.K.
Rasheed, V. Tambyra-
jah, T. Inst. Met. Fin. 79 (2001) 204. A.P. Abbott, G.
Capper, D.L. Davies, R.K. Rasheed, V. Tambyra-
jah, Chem. Commun. (2003) 70. A.P. Abbott, D. Boothby, G.
Capper, D.L. Davies, R.K. Rasheed, J.
Am. Chem. Soc. 126 (2004) 9142. A.P. Abbott, G. Capper, B.G.
Swain, D.A. Wheeler, T. Inst. Met.
Fin. 83 (2005) 51. J.H. Liao, P.C. Wu, Y.H. Bai, Inorg.
Chem. Commun. 8 (2005)
390. A.P. Abbott, G. Capper, D.L. Davies, R. Rasheed, P.
Inorg. Chem. 44 (2005) 6497. St. Vitkova, V. Ivanova, G.
Raichevsky, Surf. Coat. Technol. 82
(1996) 226. E. Guaus, J. Torrent-Burgues, J. Electroanal.
Chem. 549 (2003) 25. V.S. Vasantha, M. Pushpavanam, V.S.
Muralidharan, Met. Finish.
(1996) 60. A.J. Bard, L.R. Falkner, Electrochemical Methods;
and Applications, Wiley, Chichester, 1980. A.P. Abbott, G.C.
Capper, D.L. Davies, H. Munro, R. Rasheed, V.
Tambyrajah, Ionic Liquids as Green Solvents: Progress and
Pros-pects, in: R.D. Rogers, K.R. Seddon (Eds.), ACS Symposium
Series,American Chemical Society, 2003, p. 439.
Electrodeposition of zinc-tin alloys from deep eutectic solvents
based on choline chlorideIntroductionExperimentalResults and