"The oxide gold anodically grown on the confined aqueous layer bounded by the water/ anisol interface"

JORGE ZERBINO; ALBERTO MALTZ; ARIEL G. MEYRA; CLAUDIO DELLA VOLPE

Buenos Aires

Workshop; Structure and Dynamics of Glassy, Supercooled and Nanoconfined Fluids; 2012

IMQUIMAE-UBA

Preliminary work for the captive drop of an organic liquid immersed in the aqueous environment onthe gold surface, shows that the contact angle is very close to 0o. The surface of gold electrodes inthe double layer and in the gold oxide regions are investigated at pH 7 in confined phosphatebuffer aqueous solutions and in 0.5 M HClO4 using Contact Angle (CA), Voltammetry, andElectrochemical Impedance Spectroscopy (EIS) techniques. Different experiments are performedusing Benzene, Toluene, Anisol, Hexane, m-Xylene, Choroform and Butylacetate [1] developingdifferent external water/solvent interfaces. The EIS results for the electrode in contact with solventsare similar to that observed in the absence of solvent. The capacity value is similar in the doublelayer region and at 1.7 V vs SHE for the first minutes of the oxide monolayer growth. For longertimes at 1.7 V a second time constant rises at lower frequencies showing the effect of the differentsolvents on the oxide layer aging. Particularly an increase of the contact angle is also noticed incontact with anisol. These effects point to an increase of the surface heterogenity induced byeither the oxide growth and aging or the lifting of the surface reconstruction in the water doublelayer region similar to that reported for Au(100): hex  (1x1). The capacity measured aresimilar to that observed in the gold/electrolyte interface, showing that several layers of waterremain on the cycled gold electrode after the addition of the organic solvent.