Electrochemical surface nanopatterning by selective reductive desorption from mixed metal surfaces

Abstract

a b s t r a c t We report on a novel strategy to the functionalisation of electrode surfaces based on the preparation and patterning of mixed metal electrodes using metal selective electrodesorption of a sacrificial alkanethiol. Plain palladium (Pd) and plain polycrystalline gold (poly-Au) electrodes were used initially to determinemetal specific potential windows within which electrodesorption of the short alkanethiol mercaptoethanol could be achieved.We found that stripping of mercaptoethanol from gold was achieved at potentials lower than −0.800V, whilst stripping from palladiumwas achieved at more positive potentials i.e. around−0.650 V. Mixedmetal electrodeswere prepared by electroplating for short period of times palladium onto poly-Au electrodes. The resulting surfaceswere characterised electrochemically in 1MH2SO4 and clearly exhibited reduction peaks for both gold and palladium oxide formation. The mixed metal electrodes were coated with mercaptoethanol, which was further selectively removed from Pd by cyclic voltammetry in NaOH in the Pd-specific potential window. The presence of bare Pd domains revealed following electrodesorption was confirmed by subsequently adsorbing the electroactive alkanethiol 6- ferrocenylhexanethiol onto the freshly revealed Pd. Cyclic voltamogramms exhibited sharp redox peaks that could only be attributed to the successful immobilisation of 6-ferrocenylhexanethiol onto fresh Pd domains. Control surfaces, i.e. MCE fully coated Pd/Poly-Au electrode, exposed to 6-ferrocenylhexanethiol did not exhibit significant voltammetric features, attesting to the efficient patterning of the mixed metal electrode byemployingmetal specific reductive desorption of short alkanethiols. The possibility to pattern electrode surfaces in such way will find application in the field of diagnostics, and also