Electrochemical quantification of the electro-active surface area of Au nanoparticles supported onto an ITO electrode by means of Cu upd

• Au nanoparticles, AuNPs, were chemically synthesized and supported onto ITO.
• Cu upd was carried out on the AuNPs-modified ITO electrode from H2SO4.
• Cu upd electric charge, q, was evaluated from cycle voltammetry and chronoamperometry.
• AuNPs’s electroactive surface area was evaluated from the recorded q values.
• AuNPs-ITO electrode remains unaltered after this surface quantification process.

The active surface area, Asa, of gold nanoparticles, AuNPs, chemically synthesized and supported onto an ITO electrode (0.126 ± 0.006 cm2) was electrochemically quantified. To do this, a copper monolayer is formed onto AuNPs, due to Cu upd, when the AuNPs-modified ITO electrode is immersed in an aqueous solution containing Cu(II) ions. From both cyclic voltammetry and potentiostatic current transients recorded in the Cu upd region, corresponding to a full monolayer, it was possible to calculate the associated electric charge. From these values and those related with the charge density corresponding to a full monolayer of Cu ions onto the Au surface, the Asa of the AuNPs-modified ITO electrode was estimated. Regardless of the electrochemical method used, the Asa was practically the same, namely: (0.285 ± 0.046) cm2 and (0.265 ± 0.043) cm2 from potentiostatic and potentiodynamic experiments, respectively. After Asa evaluation the AuNPs-modified ITO remains free from Cu atoms. AFM measurements of Asa indicated that the values were comparable with those obtained by electrochemical means.

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