Reduction of Au3+ ions by activated surface atoms of platinum

In this work it is demonstrated that Pt electrodes can be activated by cathodic polarisation in the hydrogen evolution region which makes it prone to oxidation at potentials below that of bulk oxide formation. When an activated Pt electrode is placed in an aqueous HAuCl4 solution the electroless deposition of Au onto the surface of the electrode is observed and confirmed by cyclic voltammetry and XPS measurements. It is demonstrated that the oxidation of active Pt surface atoms provides the driving force for the spontaneous reduction of Au3+ ions into metallic Au to generate a Pt/Au surface which is highly active for the electro-oxidation of ethanol.

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► Active sites on platinum can be electrochemically generated by cathodic polarisation.
► Platinum active sites can be chemically oxidised by HAuCl4.
► The electroless deposition process produces a partially covered Pt electrode with Au.
► The Pt/Au electrode shows enhanced electrocatalytic performance for ethanol oxidation over Pt.