Browsing by Author "Quaresma, S."
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- Alternative baths for the gold electrodeposition based on 1-butyl-1-methyl-pyrrolidinium dicyanamide ionic liquidPublication . Sá, A.I. De; Quaresma, S.; Eugénio, S.; Rangel, C. M.; Vilar, R.
- Gold deposition from 1-butyl-1-methyl-pyrrolidinium dicyanamide ionic liquid at open-circuit and under potentiostatic controlPublication . Sá, A.I. De; Eugénio, S.; Quaresma, S.; Rangel, C. M.; Vilar, R.In this work, the deposition of gold on copper substrates from solutions of HAuCl4.3H2O in 1-butyl-1-methylpyrrolidinium dicyanamide was studied. Deposition was carried out in open-circuit and under potentiostatic control at temperatures from 293 to 353 K, in normal atmosphere, with deposition conditions allowing water from atmospheric absorption up to 0.8 wt.%. Films of gold were obtained by both methods. Deposition at open-circuit occurs by galvanic displacement mechanism. Involvement of Cu+ species in the electrodeposition process was suggested by cyclic voltammetry. Furthermore, copper incorporation in the gold films was confirmed by X-ray diffraction. SEM observation and XRD analysis show that films are nanocrystalline with a globular morphology except for the films formed under potentiostatic control at 353 K, which show a dendritic structure. The size of the crystallites determined by Scherrer's equation varies in the range from 6 to 25 nm.
- Gold electrodeposition from ionic liquids: an alternative to conventional aqueous bathsPublication . Sá, A.I. De; Rangel, C. M.; Quaresma, S.; Eugénio, S.; Vilar, R.
- Towards an electroless deposition of gold on metallic substrates using ionic liquids as electrolytesPublication . Sá, A.I. De; Quaresma, S.; Eugénio, S.; Rangel, C. M.; Vilar, RuiRecent research has suggested a number of applications for gold in fuel cells and related hydrogen fuel processing, which include light weight corrosion resistance bipolar plates and the incorporation of gold as catalyst to provide improvements in electrode conductivity, among others. This paper reports on the electroless deposition of gold on copper substrates from a HAuCl4.3H2O solution in 1-butyl-1- methylpyrrolidinium dicyanamide (BMP-DCA), in laboratory atmospheric conditions. The electrochemical behaviour of the plating solution was studied by potential sweep techniques. Results suggest that gold ions are reduced and deposited on copper without the aid of external polarization, probably by displacement deposition involving copper dissolution, since no other oxidation reaction was identified. Preliminary studies using SEM/EDX showed that compact gold thin films, deposited on copper substrates at 333 K, present a granular nanostructured morphology.
- Towards an electroless deposition of gold on metallic substrates using ionic liquids as electrolytesPublication . Sá, A.I. De; Eugénio, S.; Quaresma, S.; Rangel, C. M.; Vilar, RuiRecent research has suggested a number of applications for gold in fuel cells and related hydrogen fuel processing, which include coatings for light weight corrosion resistance bipolar plates and the incorporation of gold as catalyst to provide improvements in electrode conductivity, among others. This paper reports on the electroless deposition of gold on copper substrates from a HAuCl4.3H2O solution in 1-butyl-1-methylpyrrolidinium dicyanamide (BMP-DCA), in normal atmospheric conditions. The electrochemical behaviour of the plating solution was studied by potential sweep techniques. Results indicate that gold ions are deposited on copper without the aid of external polarization. The deposition process probably involves a displacement reaction involving copper dissolution, since no other oxidation reaction was identified. Preliminary studies using SEM/EDX showed that gold thin films, deposited on copper substrates at 333 K, present a granular nanostructured morphology, typical of electrodeposited films from DCA containing ionic liquids.