Copper Electrodeposition onto Palladium from a Deep Eutectic System Based on Choline Chloride

Recently, there has been an increasing interest in developing nonaqueous electrolytes which have been widely employed as an alternative media for a range of metals and metal alloys electrodepositions. A promising and new class of electrolytes among ionic liquids (Ils) are deep eutectic solvents (DESs)1 . The purpose of the copper deposition study from DESs is the application of copper coating and copper alloys in both, industry and fundamental research. In this work, the electrochemical deposition of copper onto palladium working substrate from ChCl/EG (1:2 ratio) DES electrolyte at 50°C was investigated. Additionally, the Cu(II) electroreduction process was studied by potentiodynamic measurements, cyclic voltammetry, chronoamperometry, in the electrolytes with different concentrations of Cu(II) ions ranging from 0.1 M to 0.5 M. The cyclic voltammetry results indicated that the bulk deposition of Cu(II) begins to occur at around –0.080 V vs. Cu. It was found that copper deposition onto the Pd cathode from ChCl:EG electrolyte under potentiostatic conditions is achievable. Data collected from X-ray diffraction (XRD) analysis proved that the cathodic deposits are composed of Cu and CuPd intermetallic. CuPd alloys with different Pd-Cu ratios were prepared by constant potential of –0.100 V vs. Cu from ChCl/EG containing 0.1 M and 0.5 M Cu(II). It is worth noting that the Xray data indicated that the composition of the produced Pd-Cu films could be varied by changing the concentration of Cu(II) ions in the electrolyte or changing the deposition mode

Influence of Morphology of Sn Dendrites as Sub-layer on Electrolcatalytic Performance of Sn-Pd Electrocatalysts

Sn-Pd electrocatalysts convenient for a possible application in direct ethanol fuel cell were produced by two electrochemical deposition method. In the first step, Sn dendrites of various degree of ramification were electrodeposited by potentiostatically on cathodic potentials of –1200, –1400, –1600 and –1800 mV vs. Ag/AgCl. Electrodeposition of tin was performed from 20 g/l SnCl2 × 2H2O in 250 g/l NaOH electrolyte [1] at the room temperature on Cu electrodes. In the second step, Pd was electrodeposited galvanostatically at a current density of –5 mA cm-2 on the electrodes with electrodeposited Sn dendrites. Electrodeposition of Pd was performed from 1 M NH4Cl and 0.01 M PdCl2 at the room temperature [2]. The processes of electrochemical deposition of Sn and Pd were performed with amounts of the electricity of 400 and 267 mC, giving an atomic ratio synthesized the electrocatalysts of 60 at.% Sn‒40 at.% Pd. Morpological and elemental analysis of the Sn-Pd electrocatalysts was performed by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The particle size distribution (PSD) was used to estimate a size of Sn dendrites. The electrocatalytic activity of synthesized Sn-Pd electrocatalysts towards ethanol oxidation reaction (EOR) was examined by cyclic voltammetry (CV) and chronoamperometry, using 1 M NaOH with 1 M ethanol solution. Depending on the applied cathodic potentials, the following shapes of dendrites were formed: the needle-like and the spear-like at –1200 mV, an individual fern-like dendrites at –1400 mV, and intertwined network of dendrites of the fern-like shape was formed at cathodic potentials of – 1600 and – 1800 mV vs. Ag/AgCl. The partial coverage of the Sn dendrites through a formation of compact islands of Pd was attained by electrodeposition of Pd on the electrodes with the Sn dendrites. It was shown that morphology of the Sn dendrites as sub-layer strongly correlates the electrocatalytic activity of the Sn-Pd electrocatalysts. The largest electrocatalytic activity showed the Sn- Pd electrocatalyst constructed from the individual fern-like Sn dendrites as sub-layer produced at a cathodic potential of –1400 mV vs. Ag/AgCl. This dendrite type showed more branchy morphology than those obtained at the other cathodic potentials. Formation of individual needle-like and spear-like dendrites at a cathodic potential of – 1200 mV vs. Ag/AgCl did not contribute significantly to the increase of the initial electrode surface area. On the other hand, due to a high nucleation rate, growth a dendrites from one nucleation centre in more directions, as well as the fact that Sn is very soft metal, morphological characteristics of intertwined Sn dendrites obtained at cathodic potentials of −1600 and −1800 mV vs. Ag/AgCl approached to those of compact massive Sn. The partial coverage of Sn dendrites by Pd can be attributed to the current density distribution effect, because Pd electrodeposition process preferentially perfomed at the higher parts of the surface area, i.e. on the dendrites, rather than on the flat part of the electrode surface area. Aside from an influence of degree of branchy of Sn dendrites as sub-layer on the electrocatalytic activity in ethanol oxidation, varios electrocatalytic performance of the Sn-Pd electrocatalysts can also be ascribed to the bifunctional effect

A Novel Two-Step Electrochemical Deposition Method for Sn-Pd Electrocatalyst Synthesis for a Potential Application in Direct Ethanol Fuel Cells

Sn-Pd electrocatalysts with a constant atomic ratio of 60 at.% Sn‒40 at.% Pd suitable for potential application in direct ethanol fuel cells were synthesized using a novel two-step electrodeposition method. First, Sn was electrodeposited in various forms of dendrites, from spear-like and needle-like to individual fern-like dendrites to a network of intertwined fern-like dendrites, by varying the cathodic potential and then performing electrodeposition of Pd at a constant current density in the second step. A morphological and elemental analysis of Sn and Sn-Pd electrocatalysts was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques, while the size of Sn dendrites was analyzed using the particle size distribution (PSD) method. Cyclic voltammetry (CV) and chronoamperometry were applied in order to study the catalytic behavior of Sn-Pd electrocatalysts in the ethanol oxidation reaction (EOR), while CO stripping was used to estimate the antipoisoning capability of the electrocatalysts. The Sn surface morphology of the sub-layer was highly correlated with the electrocatalytic activity of the examined Sn-Pd electrocatalysts. The high activity it presented towards the EOR showed the suitability of the Sn-Pd electrocatalyst constructed from individual fern-like Sn dendrites as a sub-layer. Compared to Pd alone, this Sn-Pd catalyst showed more than 3 times higher activity and improved EOR kinetics. This enhancement in the catalytic activity of the Sn-Pd electrocatalysts is attributed to both the morphological characteristics of Sn as a sub-layer and the bifunctional effect

Prospective of the LDI MS to characterization the corrosion products of silver-copper alloys on an example of the Ag-Cu-X (X- Zn, Pd, In) system

This work presents the perspective of applying the laser desorption/ionization mass spectrometry (LDI MS) for characterization the anode film of the Ag60Cu26Zn14, Ag58.5Cu31.5Pd10, and Ag63Cu27In10 alloys (at high concentrations of chloride ions in solutions). The reference LDI mass spectra of anode films of pure Ag and Cu have been used for the identification of product corrosion. Knowing the clusters detected in the reference spectra lead to the facilitating identification of the LDI mass spectrum of the sample and reduces the analysis time. The LDI MS analysis of these alloys revealed that the predominant corrosion product are AgCl (from AgnCln+1−/+, n = 1–3), and CuCl (from “superhalogen” CumCln− clusters, m = 1–2, n = 2–6); it also revealed Cu2(OH)3Cl (from Cu2(OH)(H2O)2+) and Cu2O (from Cu(H2O)+, Cu2O doped with chlorine). These results are in accordance with the X-ray diffraction and Raman analysis. The LDI MS spectra of alloys contain the additional peaks formed due to the mutual influences of different metals in the alloys (AgCuCl3− (AgCl-CuCl2−), AgCu2Cl4− (AgCl-CuCl-CuCl2−), and Ag2CuCl4− (AgCl-AgCl-CuCl−), which is consistent with the identified corrosion products. It should be noted that the LDI MS suggest the presence of CuCl2, which can be interpreted as the corrosion products retained in the porous films of alloys, and not detected by the other methods due to a small amount. The future theoretical and experimental studies of metal clusters, significant for metallurgy, can contribute that the LDI MS is becoming a powerful analytical tool for characterization the metal surfaces

Electrochemical investigation of 2-thiohydantoin derivatives as corrosion inhibitors for mild steel in acidic medium

Four 2-thiohydantoin derivatives were synthesized and their corrosion inhibition properties on mild steel (MS) in 0.5M HCl solution was evaluated using usual gravimetric and electrochemical methods (weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Morphology of the metal surface was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The study has shown that these compounds provide good protection for mild steel against corrosion in the acidic medium

Copper Electrodeposition onto Palladium from a Deep Eutectic System Based on Choline Chloride

In this work, the electrochemical deposition of copper onto palladium working substrate from ChCl/EG (1:2 ratio) DES electrolyte at 50°C was investigated. Additionally, the Cu(II) electroreduction process was studied by potentiodynamic measurements, cyclic voltammetry, chronoamperometry, in the electrolytes with different concentrations of Cu(II) ions ranging from 0.1 M to 0.5 M

Zn/Au alloys formation by Zn electrodeposition from a deep eutectic system

The electrochemical deposition of Zn onto Au from a choline chloride/ethylene glycol deep eutectic system containing different ZnCl2 concentrations has been investigated. The voltammetric results demonstrated that Zn electrodeposition commences in the zinc underpotential deposition (UPD) and proceeds through to the zinc overpotential deposition (OPD) region. The results of X-ray diffraction analysis revealed that the deposit prepared at a relatively low Zn overpotential of – 0.050 V vs. Zn was composed of cubic AuZn alloy. The morphology of the deposit has been characterized by means of a scanning electron microscope and displays a relatively compact and dendrite-free Zn/Au alloy deposit formed

Syntesis and characterization of a gilding bath based on gold complex with mercaptotriazole

Elektrolit na bazi kompleksa zlata sa merkaptotriazolom sintetizovan je u širokoj oblasti pH vrednosti od kisele do alkalne (pH=2-12). Nakon sinteze elektrolita urađena je detaljna karakterizacija kompleksa u tečnom i čvrstom stanju u celom opsegu stabilnosti kompleksa. Fizičko-hemijska karakterizacija elektrolita urađena je najpre primenom Ultraljubičaste- Vidljive (UV-vis) spektroskopije i Atomske Emisione Spektrometrije sa indukovano spregnutom plazmom (AAS- ICP). UV-vis spektri elektrolita na pH vrednostima dva i sedam pokazali su pikove na talasnim dužinama koje su vrlo bliske talasnim dužinama pikova za merkaptotriazol, što može ukazati na to da su na ovim pH vrednostima veze Au-MT elektrolitu uspostavljene u najmanjoj meri. UV - vis spektrometrija Au-MT elektrolita na pH 9 pokazala je pik na 272,0 nm što može da ukaže na to da je jedino na ovoj pH vrednosti uspostavljena veza između Au i MT. Pojava pika pri vrednost od 272,0 nm koja je bliska vrednostima koje se mogu naći u literaturi za druge necijanidne elektrolite (sulfiti, tiosulfati i tiousulfati-sulfiti) može da ukaže na to da je veza između Au i MT ostvarena preko atoma sumpora. AAS - ICP analiza je potvrdila predviđene koncentracije zlata u elektrolitu uz maksimalno odstupanje od 0,01 g/dm3. Uporedna toksikološka ispitivanja elektrolita na bazi kompleksa zlata sa merkaptotriazolom (pH=2, 4, 7, 9 i 12) i klasičnog cijanidnog elektrolita (pH=9), urađena metodom "in vitro" na kulturi ćelija humane leukemije K562 su pokazala da je toksičnost organskog kompleksa zlata pri pH vrednostima od: pH=4, 7 i 12 manja u odnosu na alkalni cijanidni elektrolit a nešto veća na pH=2, dok su na pH=9 ove vrednosti približno iste. Elektrohemijska karakterizacija kompleksa zlata sa merkaptotriazolom urađena je merenjem potencijala otvorenog kola, metodom ciklične voltametrije i snimanjem polarizacionih krivih uz praćenje pH vrednosti i provodljivosti elektrolta pre i posle elektrohemijskih eksperimenta. Ova ispitivanja su vršena u periodu od 12 meseci pri različitim pH vrednostima 2, 4, 7, 9 i 12 i optimalnoj koncentraciji zlata u elektrolitu od 2,5 g/dm3 i u periodu od četiri meseca pri optimalnoj pH vrednosti od 9 i koncentracijama zlata u elektrolitu od 1,5; 2,0; 2,5; 3,0 i 3,5 g/dm3. Na elektrolitima čija je pH=4, 7 i 12 prvi vidljivi znakovi raspadanja kompleksa su se pojavili nakon tri meseca od sinteze. Elektrohemijske karakteristike kompleksa zlata sa merkaptotriazolom čija je pH vrednost dva i devet su ostale nepromenjene u periodu od godinu dana. Na ovim elektrolitima nisu zapažene nikakve vizuelne promene u periodu od 12 meseci. Ispitivanje uticaja organskog kompleksa zlata sa merkaptotriazolom na fotoosetljive slojeve koji se koriste pri izradi štampanih ploča urađeno je na prethodno pripremljenim štampanim pločama sa razvijenom mrežom i sa ivicama - linijama na koje je nanešen lak. Fotoosetljivi slojevi na pločicama otporni su na dejstvo elektrolita pri pH vrednostima od 2, 7 i 9. Pri pH=4 prve vizuelne promene se zapažaju nakon 150 s dok se na pH=12 prve promene pojavljuju već nakon 30 s. Sa mikrofotografija površina pločica se takođe može videti da su fotoosetljivi slojevi pločica najotporniji na dejstvo elektrolita na pH=2 i pH=9. Pri pH=9 fotoosetljivi slojevi na pločicama otporni su na dejstvo elektrolita pri svim koncentracijama zlata u opsegu od 1,5 do 3,5 g/dm3. Sintetizovani rastvori kompleksa zlata sa merkaptotriazolom uparavani su na sobnoj temperaturi do suva u cilju dobijanja i karakterizacije nagrađenog jedinjenja u kristalnom obliku. Optička mikroskopija ovih kristala, pokazala je da se kristali dobijeni pri različitim pH vrednostima međusobno razlikuju po boji, krupnoći i homogenosti. Najhomogeniji (po boji i krupnoći) i najsitniji kristali su dobijeni iz elektrolita na pH=9. Najvažnije otkriće IC/Raman spektroskopije je da je Raman spektroskopija obezbedila definitivnu potvrdu o uspostavljenoj vezi jona metala i atoma sumpora. Takođe, ove tehnike su ukazale na to da atom azota u prstenu nagrađenog jedinjenja Au-MT, ostaje protonovan, što ne ide u prilog prvobitnoj pretpostavci proistekloj iz analize UVspektara, da je na pH=9 moguća koordinacija ne samo atoma sumpora, već i atoma azota sa zlatom. Metoda masene spektrometrije ukazala je na prisustvo molekula velikih masa koji mogu da odgovaraju kombinacijama Au-2MT, Au-2MT-Gly, pa se čak ni kombinacija Au- 2MT-2Gly ne može u potpunosti isključiti u konačnoj formulaciji strukture nastalog jedinjenja. Takođe su zapaženi pikovi koji ukazuju na prisustvo trovalentnog zlata. Međutim, maseni spektar čvrstog uzorka otkriva i pojavu pika na m/z koji odgovara masi atoma zlata, to jest može da ukaže na prisustvo jednovalentnog zlata. Ipak, ovaj pik je mnogo slabijeg intenziteta. Jedan od dominantnih pikova kod svih masenih spektara dobijenih za uzorke na pH=2, 4 i 7, je pik na m/z 201, koji može da potiče od dva molekula merkaptotriazola (2MT), što dodatno sugeriše mogućnost formiranja disulfidnog mosta između ova dva molekula. X-ray difraktogram za kristale kompleksa zlata sa merkaptotriazolom dobijene iz elektrolita na pH=9, ne pokazuje poklapanje sa karticama nijednog poznatog jedinjenja zlata, što takođe potvrđuje pretpostavke da je sintetizovano novo jedinjenje. Uporedna karakterizacija elektrohemijski staloženih dekorativnih prevlaka zlata dobijenih iz sveže sintetisnog elektrolita, iz elektrolita nakon stajanja od godinu dana, kao i prevlaka dobijenih iz elektolita dobijenog rastvaranjem kristala zlatomerkaptotriazola (spoljni izgled, debljina, hrapavost, mikrotvrdoća po Knoopu i elektronska mikroskopija - SEM sa EDS-om) pokazala je da su prevlake dobijene iz sva tri elektrolita sjajne sa dobrom adhezijom. Najmanja hrapavost je izmerena za prevlaku dobijenu iz svežeg elektrolita a najveća za prevlaku dobijenu iz elektrolta dobijenog rastvaranjem kristala. U pogledu mikrotvrdoće ne postoje značajne razlike.An electrolyte based on gold complex with mercaptotriazole was synthesized in a wide pH range from acid to alkaline (pH=2-12). After synthesis of the electrolyte, detailed characterization of the complex in liquid and solid state in the whole range of its stability was performed. Physico-chemical characterization of the electrolyte was performed, firstly by Ultraviolet-visible spectroscopy (UV-vis) and by atomic asorption spectroscopy with inductively coupled plasma (AAS-ICP). UV- spectra of Au-MT electrolyte at pH=2 and 7 show absorbtion peaks at wavelenghts which are very close to the wavelenght of apsorption peak of mercaptotriazole, which may indicate that in these solutions, chemical bonds Au-MT was the weakest. UV- spectra of Au-MT electrolyte at pH=9 shows an absorption peak at 272.0 nm, which may suggest that the bond between MT and Au has only realised in this particular case. The appearance of the peak as the value of 272.0 nm is close to the literature data for the other non-cyanide electrolytes (sulphite, thiosulphate and thiosulphate-sulphite), it may be assumed that the coordination of Au to MT at pH 9 is realized through the sulphur atom. AAS-ICP analysis confirmed the projected gold concentrations in the electrolyte with a maximum deviation of 0.01 g/dm3. For a comparative toxicity study of electrolyte based on the mercaptotriazole gold complex (pH=2, 4, 7, 9 and 12) and the classic alkaline cyanide electrolyte (pH=9), "in vitro" method was applied. For cytotoxicity testing, the culture of K562 cells of human leukemia was used. Results show that the toxicity of organic complex of gold at pH values of 4, 7 and 12 is lower than alkaline cyanide electrolyte but higher at pH=2, while at pH=9 the relative cell viability is almost equal. Electrochemical characterization of gold complex based on mercaptotriazole was performed by: the open circuit potential measurment, cycling voltametry method and recording the polarization curves, with pH values and conductivity of the electrolyte measurment before and after each electrochemical experiment. These tests were performed for a period of 12 months at different pH values: 2, 4, 7, 9 and 12 at optimal concentration of gold in the electrolyte of 2,5 g/dm3 and in the period of four mounths at optimal pH value of 9 and at the concentrations of gold in the electrolyte of 1,5; 2,0; 2,5; 3,0 and 3,5 g/dm3. For electrolytes with pH= 4, 7 and 12 the first visible signs of decomposition of the complex appeared three months after synthesis. Electrochemical characteristics of gold complex with mercaptotriazole at pH value of two and nine remained unchanged for a period of one year. In that period any visual changes on these electrolytes did not appear too these electrolytes. Study of the effect of organic gold complex with mercaptotriazole on photoresist layers used in the manufacture of printed circuit boards, was performed on previously prepared PCB with developed net and lacquered edges - lines. The photoresist layers on the boards are resistant to the effects of electrolyte at pH values of 2, 7 and 9. At pH=4 the first visual changes are observed after 150 s while at pH=12 the first changes appeared after only 30 seconds. From tiles surfaces micrographs it can also be seen that the photoresist layers of tiles most resistant to the effects of electrolyte pH=2 and pH=9. At pH=9 photoresist layers of tiles are resistant to the influence of electrolyte at all concentrations of gold in the range of 1.5 to 3.5 g/dm3. Synthesized solutions of gold complex based on mercaptotriazole are vaporized at room temperature to dry in order to obtain and characterize Au-MT in the crystalline form. Optical microscopy showed that the crystals obtained from solutions of different pH values are different in color, size and homogeneity. The most homogeneous (according to size and color) and the smallest crystals were obtained from the electrolyte with pH=9. The most important finding of IC/Raman spectroscopy analysis is that the Raman spectroscopy has provided a definitive confirmation of bond established between metal ion and sulphur atom. Also, both techniques indicated that the nitrogen atom in the ring of obtained Au-MT compound, remains protonated at pH = 9, which does not support an assumption formulated from the analysis of UV-spectra, that MT molekules at this pH may interact with the metal ion not only through the sulphur, but also through the nitrogen atom. Mass spectrometry indicated the presence of high weight molecule that can match combinations of Au-2MT and 2MT-Au-Gly. Even the combination of 2MT-Au-2Gly could not be completely excluded in the final formulation of the structure of the resulting compound. The peaks indicating the presence of Au (III) were also noticed. Additionally, the mass spectra of solid sample reveal a peak at m/z corresponding to the mass of a gold atom, which may indicate the presence of Au (I). However, this peak is of very weak intensity. One of the major peaks in all mass spectra obtained for the samples at pH = 2, 4 and 7, is the peak at m/z 201, which may originate from a fragment corresponding to the mass of two molecules of mercaptotriazole (2MT); this further suggests the possibility of formation of a disulfide „bridge“ between these two molecules. In available data bases no compound was found that match with the X-ray difractogram of crystals of the gold mercaptotriazole complex obtained from the electrolyte of pH = 9. It confirms the assumption that a new compound was synthesized. Comparative characterization of electrochemically deposited gold decorative coatings obtained from the freshly synthesized electrolyte, then from the electrolyte after a year, and coatings obtained from the electrolyte obtained by dissolving crystals of goldmercaptotriazole (external appearance, thickness, surface roughness, the Knoop microhardness and electron microscopy - SEM with EDS) showed that the coatings obtained from all the three electrolytes are bright and with good adhesion. The smallest roughness was measured for the coatings obtained from fresh electrolyte and the greatest for the coatings obtained from electrolyte obtained by dissolving crystals. In terms of hardness there are no significant differences

Syntesis and characterization of a gilding bath based on gold complex with mercaptotriazole

Elektrolit na bazi kompleksa zlata sa merkaptotriazolom sintetizovan je u širokoj oblasti pH vrednosti od kisele do alkalne (pH=2-12). Nakon sinteze elektrolita urađena je detaljna karakterizacija kompleksa u tečnom i čvrstom stanju u celom opsegu stabilnosti kompleksa. Fizičko-hemijska karakterizacija elektrolita urađena je najpre primenom Ultraljubičaste- Vidljive (UV-vis) spektroskopije i Atomske Emisione Spektrometrije sa indukovano spregnutom plazmom (AAS- ICP). UV-vis spektri elektrolita na pH vrednostima dva i sedam pokazali su pikove na talasnim dužinama koje su vrlo bliske talasnim dužinama pikova za merkaptotriazol, što može ukazati na to da su na ovim pH vrednostima veze Au-MT elektrolitu uspostavljene u najmanjoj meri. UV - vis spektrometrija Au-MT elektrolita na pH 9 pokazala je pik na 272,0 nm što može da ukaže na to da je jedino na ovoj pH vrednosti uspostavljena veza između Au i MT. Pojava pika pri vrednost od 272,0 nm koja je bliska vrednostima koje se mogu naći u literaturi za druge necijanidne elektrolite (sulfiti, tiosulfati i tiousulfati-sulfiti) može da ukaže na to da je veza između Au i MT ostvarena preko atoma sumpora. AAS - ICP analiza je potvrdila predviđene koncentracije zlata u elektrolitu uz maksimalno odstupanje od 0,01 g/dm3. Uporedna toksikološka ispitivanja elektrolita na bazi kompleksa zlata sa merkaptotriazolom (pH=2, 4, 7, 9 i 12) i klasičnog cijanidnog elektrolita (pH=9), urađena metodom "in vitro" na kulturi ćelija humane leukemije K562 su pokazala da je toksičnost organskog kompleksa zlata pri pH vrednostima od: pH=4, 7 i 12 manja u odnosu na alkalni cijanidni elektrolit a nešto veća na pH=2, dok su na pH=9 ove vrednosti približno iste. Elektrohemijska karakterizacija kompleksa zlata sa merkaptotriazolom urađena je merenjem potencijala otvorenog kola, metodom ciklične voltametrije i snimanjem polarizacionih krivih uz praćenje pH vrednosti i provodljivosti elektrolta pre i posle elektrohemijskih eksperimenta. Ova ispitivanja su vršena u periodu od 12 meseci pri različitim pH vrednostima 2, 4, 7, 9 i 12 i optimalnoj koncentraciji zlata u elektrolitu od 2,5 g/dm3 i u periodu od četiri meseca pri optimalnoj pH vrednosti od 9 i koncentracijama zlata u elektrolitu od 1,5; 2,0; 2,5; 3,0 i 3,5 g/dm3. Na elektrolitima čija je pH=4, 7 i 12 prvi vidljivi znakovi raspadanja kompleksa su se pojavili nakon tri meseca od sinteze. Elektrohemijske karakteristike kompleksa zlata sa merkaptotriazolom čija je pH vrednost dva i devet su ostale nepromenjene u periodu od godinu dana. Na ovim elektrolitima nisu zapažene nikakve vizuelne promene u periodu od 12 meseci. Ispitivanje uticaja organskog kompleksa zlata sa merkaptotriazolom na fotoosetljive slojeve koji se koriste pri izradi štampanih ploča urađeno je na prethodno pripremljenim štampanim pločama sa razvijenom mrežom i sa ivicama - linijama na koje je nanešen lak. Fotoosetljivi slojevi na pločicama otporni su na dejstvo elektrolita pri pH vrednostima od 2, 7 i 9. Pri pH=4 prve vizuelne promene se zapažaju nakon 150 s dok se na pH=12 prve promene pojavljuju već nakon 30 s. Sa mikrofotografija površina pločica se takođe može videti da su fotoosetljivi slojevi pločica najotporniji na dejstvo elektrolita na pH=2 i pH=9. Pri pH=9 fotoosetljivi slojevi na pločicama otporni su na dejstvo elektrolita pri svim koncentracijama zlata u opsegu od 1,5 do 3,5 g/dm3. Sintetizovani rastvori kompleksa zlata sa merkaptotriazolom uparavani su na sobnoj temperaturi do suva u cilju dobijanja i karakterizacije nagrađenog jedinjenja u kristalnom obliku. Optička mikroskopija ovih kristala, pokazala je da se kristali dobijeni pri različitim pH vrednostima međusobno razlikuju po boji, krupnoći i homogenosti. Najhomogeniji (po boji i krupnoći) i najsitniji kristali su dobijeni iz elektrolita na pH=9. Najvažnije otkriće IC/Raman spektroskopije je da je Raman spektroskopija obezbedila definitivnu potvrdu o uspostavljenoj vezi jona metala i atoma sumpora. Takođe, ove tehnike su ukazale na to da atom azota u prstenu nagrađenog jedinjenja Au-MT, ostaje protonovan, što ne ide u prilog prvobitnoj pretpostavci proistekloj iz analize UVspektara, da je na pH=9 moguća koordinacija ne samo atoma sumpora, već i atoma azota sa zlatom. Metoda masene spektrometrije ukazala je na prisustvo molekula velikih masa koji mogu da odgovaraju kombinacijama Au-2MT, Au-2MT-Gly, pa se čak ni kombinacija Au- 2MT-2Gly ne može u potpunosti isključiti u konačnoj formulaciji strukture nastalog jedinjenja. Takođe su zapaženi pikovi koji ukazuju na prisustvo trovalentnog zlata. Međutim, maseni spektar čvrstog uzorka otkriva i pojavu pika na m/z koji odgovara masi atoma zlata, to jest može da ukaže na prisustvo jednovalentnog zlata. Ipak, ovaj pik je mnogo slabijeg intenziteta. Jedan od dominantnih pikova kod svih masenih spektara dobijenih za uzorke na pH=2, 4 i 7, je pik na m/z 201, koji može da potiče od dva molekula merkaptotriazola (2MT), što dodatno sugeriše mogućnost formiranja disulfidnog mosta između ova dva molekula. X-ray difraktogram za kristale kompleksa zlata sa merkaptotriazolom dobijene iz elektrolita na pH=9, ne pokazuje poklapanje sa karticama nijednog poznatog jedinjenja zlata, što takođe potvrđuje pretpostavke da je sintetizovano novo jedinjenje. Uporedna karakterizacija elektrohemijski staloženih dekorativnih prevlaka zlata dobijenih iz sveže sintetisnog elektrolita, iz elektrolita nakon stajanja od godinu dana, kao i prevlaka dobijenih iz elektolita dobijenog rastvaranjem kristala zlatomerkaptotriazola (spoljni izgled, debljina, hrapavost, mikrotvrdoća po Knoopu i elektronska mikroskopija - SEM sa EDS-om) pokazala je da su prevlake dobijene iz sva tri elektrolita sjajne sa dobrom adhezijom. Najmanja hrapavost je izmerena za prevlaku dobijenu iz svežeg elektrolita a najveća za prevlaku dobijenu iz elektrolta dobijenog rastvaranjem kristala. U pogledu mikrotvrdoće ne postoje značajne razlike.An electrolyte based on gold complex with mercaptotriazole was synthesized in a wide pH range from acid to alkaline (pH=2-12). After synthesis of the electrolyte, detailed characterization of the complex in liquid and solid state in the whole range of its stability was performed. Physico-chemical characterization of the electrolyte was performed, firstly by Ultraviolet-visible spectroscopy (UV-vis) and by atomic asorption spectroscopy with inductively coupled plasma (AAS-ICP). UV- spectra of Au-MT electrolyte at pH=2 and 7 show absorbtion peaks at wavelenghts which are very close to the wavelenght of apsorption peak of mercaptotriazole, which may indicate that in these solutions, chemical bonds Au-MT was the weakest. UV- spectra of Au-MT electrolyte at pH=9 shows an absorption peak at 272.0 nm, which may suggest that the bond between MT and Au has only realised in this particular case. The appearance of the peak as the value of 272.0 nm is close to the literature data for the other non-cyanide electrolytes (sulphite, thiosulphate and thiosulphate-sulphite), it may be assumed that the coordination of Au to MT at pH 9 is realized through the sulphur atom. AAS-ICP analysis confirmed the projected gold concentrations in the electrolyte with a maximum deviation of 0.01 g/dm3. For a comparative toxicity study of electrolyte based on the mercaptotriazole gold complex (pH=2, 4, 7, 9 and 12) and the classic alkaline cyanide electrolyte (pH=9), "in vitro" method was applied. For cytotoxicity testing, the culture of K562 cells of human leukemia was used. Results show that the toxicity of organic complex of gold at pH values of 4, 7 and 12 is lower than alkaline cyanide electrolyte but higher at pH=2, while at pH=9 the relative cell viability is almost equal. Electrochemical characterization of gold complex based on mercaptotriazole was performed by: the open circuit potential measurment, cycling voltametry method and recording the polarization curves, with pH values and conductivity of the electrolyte measurment before and after each electrochemical experiment. These tests were performed for a period of 12 months at different pH values: 2, 4, 7, 9 and 12 at optimal concentration of gold in the electrolyte of 2,5 g/dm3 and in the period of four mounths at optimal pH value of 9 and at the concentrations of gold in the electrolyte of 1,5; 2,0; 2,5; 3,0 and 3,5 g/dm3. For electrolytes with pH= 4, 7 and 12 the first visible signs of decomposition of the complex appeared three months after synthesis. Electrochemical characteristics of gold complex with mercaptotriazole at pH value of two and nine remained unchanged for a period of one year. In that period any visual changes on these electrolytes did not appear too these electrolytes. Study of the effect of organic gold complex with mercaptotriazole on photoresist layers used in the manufacture of printed circuit boards, was performed on previously prepared PCB with developed net and lacquered edges - lines. The photoresist layers on the boards are resistant to the effects of electrolyte at pH values of 2, 7 and 9. At pH=4 the first visual changes are observed after 150 s while at pH=12 the first changes appeared after only 30 seconds. From tiles surfaces micrographs it can also be seen that the photoresist layers of tiles most resistant to the effects of electrolyte pH=2 and pH=9. At pH=9 photoresist layers of tiles are resistant to the influence of electrolyte at all concentrations of gold in the range of 1.5 to 3.5 g/dm3. Synthesized solutions of gold complex based on mercaptotriazole are vaporized at room temperature to dry in order to obtain and characterize Au-MT in the crystalline form. Optical microscopy showed that the crystals obtained from solutions of different pH values are different in color, size and homogeneity. The most homogeneous (according to size and color) and the smallest crystals were obtained from the electrolyte with pH=9. The most important finding of IC/Raman spectroscopy analysis is that the Raman spectroscopy has provided a definitive confirmation of bond established between metal ion and sulphur atom. Also, both techniques indicated that the nitrogen atom in the ring of obtained Au-MT compound, remains protonated at pH = 9, which does not support an assumption formulated from the analysis of UV-spectra, that MT molekules at this pH may interact with the metal ion not only through the sulphur, but also through the nitrogen atom. Mass spectrometry indicated the presence of high weight molecule that can match combinations of Au-2MT and 2MT-Au-Gly. Even the combination of 2MT-Au-2Gly could not be completely excluded in the final formulation of the structure of the resulting compound. The peaks indicating the presence of Au (III) were also noticed. Additionally, the mass spectra of solid sample reveal a peak at m/z corresponding to the mass of a gold atom, which may indicate the presence of Au (I). However, this peak is of very weak intensity. One of the major peaks in all mass spectra obtained for the samples at pH = 2, 4 and 7, is the peak at m/z 201, which may originate from a fragment corresponding to the mass of two molecules of mercaptotriazole (2MT); this further suggests the possibility of formation of a disulfide „bridge“ between these two molecules. In available data bases no compound was found that match with the X-ray difractogram of crystals of the gold mercaptotriazole complex obtained from the electrolyte of pH = 9. It confirms the assumption that a new compound was synthesized. Comparative characterization of electrochemically deposited gold decorative coatings obtained from the freshly synthesized electrolyte, then from the electrolyte after a year, and coatings obtained from the electrolyte obtained by dissolving crystals of goldmercaptotriazole (external appearance, thickness, surface roughness, the Knoop microhardness and electron microscopy - SEM with EDS) showed that the coatings obtained from all the three electrolytes are bright and with good adhesion. The smallest roughness was measured for the coatings obtained from fresh electrolyte and the greatest for the coatings obtained from electrolyte obtained by dissolving crystals. In terms of hardness there are no significant differences

Syntesis and characterization of a gilding bath based on gold complex with mercaptotriazole

Elektrolit na bazi kompleksa zlata sa merkaptotriazolom sintetizovan je u širokoj oblasti pH vrednosti od kisele do alkalne (pH=2-12). Nakon sinteze elektrolita urađena je detaljna karakterizacija kompleksa u tečnom i čvrstom stanju u celom opsegu stabilnosti kompleksa. Fizičko-hemijska karakterizacija elektrolita urađena je najpre primenom Ultraljubičaste- Vidljive (UV-vis) spektroskopije i Atomske Emisione Spektrometrije sa indukovano spregnutom plazmom (AAS- ICP). UV-vis spektri elektrolita na pH vrednostima dva i sedam pokazali su pikove na talasnim dužinama koje su vrlo bliske talasnim dužinama pikova za merkaptotriazol, što može ukazati na to da su na ovim pH vrednostima veze Au-MT elektrolitu uspostavljene u najmanjoj meri. UV - vis spektrometrija Au-MT elektrolita na pH 9 pokazala je pik na 272,0 nm što može da ukaže na to da je jedino na ovoj pH vrednosti uspostavljena veza između Au i MT. Pojava pika pri vrednost od 272,0 nm koja je bliska vrednostima koje se mogu naći u literaturi za druge necijanidne elektrolite (sulfiti, tiosulfati i tiousulfati-sulfiti) može da ukaže na to da je veza između Au i MT ostvarena preko atoma sumpora. AAS - ICP analiza je potvrdila predviđene koncentracije zlata u elektrolitu uz maksimalno odstupanje od 0,01 g/dm3. Uporedna toksikološka ispitivanja elektrolita na bazi kompleksa zlata sa merkaptotriazolom (pH=2, 4, 7, 9 i 12) i klasičnog cijanidnog elektrolita (pH=9), urađena metodom "in vitro" na kulturi ćelija humane leukemije K562 su pokazala da je toksičnost organskog kompleksa zlata pri pH vrednostima od: pH=4, 7 i 12 manja u odnosu na alkalni cijanidni elektrolit a nešto veća na pH=2, dok su na pH=9 ove vrednosti približno iste. Elektrohemijska karakterizacija kompleksa zlata sa merkaptotriazolom urađena je merenjem potencijala otvorenog kola, metodom ciklične voltametrije i snimanjem polarizacionih krivih uz praćenje pH vrednosti i provodljivosti elektrolta pre i posle elektrohemijskih eksperimenta. Ova ispitivanja su vršena u periodu od 12 meseci pri različitim pH vrednostima 2, 4, 7, 9 i 12 i optimalnoj koncentraciji zlata u elektrolitu od 2,5 g/dm3 i u periodu od četiri meseca pri optimalnoj pH vrednosti od 9 i koncentracijama zlata u elektrolitu od 1,5; 2,0; 2,5; 3,0 i 3,5 g/dm3. Na elektrolitima čija je pH=4, 7 i 12 prvi vidljivi znakovi raspadanja kompleksa su se pojavili nakon tri meseca od sinteze. Elektrohemijske karakteristike kompleksa zlata sa merkaptotriazolom čija je pH vrednost dva i devet su ostale nepromenjene u periodu od godinu dana. Na ovim elektrolitima nisu zapažene nikakve vizuelne promene u periodu od 12 meseci. Ispitivanje uticaja organskog kompleksa zlata sa merkaptotriazolom na fotoosetljive slojeve koji se koriste pri izradi štampanih ploča urađeno je na prethodno pripremljenim štampanim pločama sa razvijenom mrežom i sa ivicama - linijama na koje je nanešen lak. Fotoosetljivi slojevi na pločicama otporni su na dejstvo elektrolita pri pH vrednostima od 2, 7 i 9. Pri pH=4 prve vizuelne promene se zapažaju nakon 150 s dok se na pH=12 prve promene pojavljuju već nakon 30 s. Sa mikrofotografija površina pločica se takođe može videti da su fotoosetljivi slojevi pločica najotporniji na dejstvo elektrolita na pH=2 i pH=9. Pri pH=9 fotoosetljivi slojevi na pločicama otporni su na dejstvo elektrolita pri svim koncentracijama zlata u opsegu od 1,5 do 3,5 g/dm3. Sintetizovani rastvori kompleksa zlata sa merkaptotriazolom uparavani su na sobnoj temperaturi do suva u cilju dobijanja i karakterizacije nagrađenog jedinjenja u kristalnom obliku. Optička mikroskopija ovih kristala, pokazala je da se kristali dobijeni pri različitim pH vrednostima međusobno razlikuju po boji, krupnoći i homogenosti. Najhomogeniji (po boji i krupnoći) i najsitniji kristali su dobijeni iz elektrolita na pH=9. Najvažnije otkriće IC/Raman spektroskopije je da je Raman spektroskopija obezbedila definitivnu potvrdu o uspostavljenoj vezi jona metala i atoma sumpora. Takođe, ove tehnike su ukazale na to da atom azota u prstenu nagrađenog jedinjenja Au-MT, ostaje protonovan, što ne ide u prilog prvobitnoj pretpostavci proistekloj iz analize UVspektara, da je na pH=9 moguća koordinacija ne samo atoma sumpora, već i atoma azota sa zlatom. Metoda masene spektrometrije ukazala je na prisustvo molekula velikih masa koji mogu da odgovaraju kombinacijama Au-2MT, Au-2MT-Gly, pa se čak ni kombinacija Au- 2MT-2Gly ne može u potpunosti isključiti u konačnoj formulaciji strukture nastalog jedinjenja. Takođe su zapaženi pikovi koji ukazuju na prisustvo trovalentnog zlata. Međutim, maseni spektar čvrstog uzorka otkriva i pojavu pika na m/z koji odgovara masi atoma zlata, to jest može da ukaže na prisustvo jednovalentnog zlata. Ipak, ovaj pik je mnogo slabijeg intenziteta. Jedan od dominantnih pikova kod svih masenih spektara dobijenih za uzorke na pH=2, 4 i 7, je pik na m/z 201, koji može da potiče od dva molekula merkaptotriazola (2MT), što dodatno sugeriše mogućnost formiranja disulfidnog mosta između ova dva molekula. X-ray difraktogram za kristale kompleksa zlata sa merkaptotriazolom dobijene iz elektrolita na pH=9, ne pokazuje poklapanje sa karticama nijednog poznatog jedinjenja zlata, što takođe potvrđuje pretpostavke da je sintetizovano novo jedinjenje. Uporedna karakterizacija elektrohemijski staloženih dekorativnih prevlaka zlata dobijenih iz sveže sintetisnog elektrolita, iz elektrolita nakon stajanja od godinu dana, kao i prevlaka dobijenih iz elektolita dobijenog rastvaranjem kristala zlatomerkaptotriazola (spoljni izgled, debljina, hrapavost, mikrotvrdoća po Knoopu i elektronska mikroskopija - SEM sa EDS-om) pokazala je da su prevlake dobijene iz sva tri elektrolita sjajne sa dobrom adhezijom. Najmanja hrapavost je izmerena za prevlaku dobijenu iz svežeg elektrolita a najveća za prevlaku dobijenu iz elektrolta dobijenog rastvaranjem kristala. U pogledu mikrotvrdoće ne postoje značajne razlike.An electrolyte based on gold complex with mercaptotriazole was synthesized in a wide pH range from acid to alkaline (pH=2-12). After synthesis of the electrolyte, detailed characterization of the complex in liquid and solid state in the whole range of its stability was performed. Physico-chemical characterization of the electrolyte was performed, firstly by Ultraviolet-visible spectroscopy (UV-vis) and by atomic asorption spectroscopy with inductively coupled plasma (AAS-ICP). UV- spectra of Au-MT electrolyte at pH=2 and 7 show absorbtion peaks at wavelenghts which are very close to the wavelenght of apsorption peak of mercaptotriazole, which may indicate that in these solutions, chemical bonds Au-MT was the weakest. UV- spectra of Au-MT electrolyte at pH=9 shows an absorption peak at 272.0 nm, which may suggest that the bond between MT and Au has only realised in this particular case. The appearance of the peak as the value of 272.0 nm is close to the literature data for the other non-cyanide electrolytes (sulphite, thiosulphate and thiosulphate-sulphite), it may be assumed that the coordination of Au to MT at pH 9 is realized through the sulphur atom. AAS-ICP analysis confirmed the projected gold concentrations in the electrolyte with a maximum deviation of 0.01 g/dm3. For a comparative toxicity study of electrolyte based on the mercaptotriazole gold complex (pH=2, 4, 7, 9 and 12) and the classic alkaline cyanide electrolyte (pH=9), "in vitro" method was applied. For cytotoxicity testing, the culture of K562 cells of human leukemia was used. Results show that the toxicity of organic complex of gold at pH values of 4, 7 and 12 is lower than alkaline cyanide electrolyte but higher at pH=2, while at pH=9 the relative cell viability is almost equal. Electrochemical characterization of gold complex based on mercaptotriazole was performed by: the open circuit potential measurment, cycling voltametry method and recording the polarization curves, with pH values and conductivity of the electrolyte measurment before and after each electrochemical experiment. These tests were performed for a period of 12 months at different pH values: 2, 4, 7, 9 and 12 at optimal concentration of gold in the electrolyte of 2,5 g/dm3 and in the period of four mounths at optimal pH value of 9 and at the concentrations of gold in the electrolyte of 1,5; 2,0; 2,5; 3,0 and 3,5 g/dm3. For electrolytes with pH= 4, 7 and 12 the first visible signs of decomposition of the complex appeared three months after synthesis. Electrochemical characteristics of gold complex with mercaptotriazole at pH value of two and nine remained unchanged for a period of one year. In that period any visual changes on these electrolytes did not appear too these electrolytes. Study of the effect of organic gold complex with mercaptotriazole on photoresist layers used in the manufacture of printed circuit boards, was performed on previously prepared PCB with developed net and lacquered edges - lines. The photoresist layers on the boards are resistant to the effects of electrolyte at pH values of 2, 7 and 9. At pH=4 the first visual changes are observed after 150 s while at pH=12 the first changes appeared after only 30 seconds. From tiles surfaces micrographs it can also be seen that the photoresist layers of tiles most resistant to the effects of electrolyte pH=2 and pH=9. At pH=9 photoresist layers of tiles are resistant to the influence of electrolyte at all concentrations of gold in the range of 1.5 to 3.5 g/dm3. Synthesized solutions of gold complex based on mercaptotriazole are vaporized at room temperature to dry in order to obtain and characterize Au-MT in the crystalline form. Optical microscopy showed that the crystals obtained from solutions of different pH values are different in color, size and homogeneity. The most homogeneous (according to size and color) and the smallest crystals were obtained from the electrolyte with pH=9. The most important finding of IC/Raman spectroscopy analysis is that the Raman spectroscopy has provided a definitive confirmation of bond established between metal ion and sulphur atom. Also, both techniques indicated that the nitrogen atom in the ring of obtained Au-MT compound, remains protonated at pH = 9, which does not support an assumption formulated from the analysis of UV-spectra, that MT molekules at this pH may interact with the metal ion not only through the sulphur, but also through the nitrogen atom. Mass spectrometry indicated the presence of high weight molecule that can match combinations of Au-2MT and 2MT-Au-Gly. Even the combination of 2MT-Au-2Gly could not be completely excluded in the final formulation of the structure of the resulting compound. The peaks indicating the presence of Au (III) were also noticed. Additionally, the mass spectra of solid sample reveal a peak at m/z corresponding to the mass of a gold atom, which may indicate the presence of Au (I). However, this peak is of very weak intensity. One of the major peaks in all mass spectra obtained for the samples at pH = 2, 4 and 7, is the peak at m/z 201, which may originate from a fragment corresponding to the mass of two molecules of mercaptotriazole (2MT); this further suggests the possibility of formation of a disulfide „bridge“ between these two molecules. In available data bases no compound was found that match with the X-ray difractogram of crystals of the gold mercaptotriazole complex obtained from the electrolyte of pH = 9. It confirms the assumption that a new compound was synthesized. Comparative characterization of electrochemically deposited gold decorative coatings obtained from the freshly synthesized electrolyte, then from the electrolyte after a year, and coatings obtained from the electrolyte obtained by dissolving crystals of goldmercaptotriazole (external appearance, thickness, surface roughness, the Knoop microhardness and electron microscopy - SEM with EDS) showed that the coatings obtained from all the three electrolytes are bright and with good adhesion. The smallest roughness was measured for the coatings obtained from fresh electrolyte and the greatest for the coatings obtained from electrolyte obtained by dissolving crystals. In terms of hardness there are no significant differences