Gold cleaning methods for electrochemical detection applications

This work investigates methods for obtaining reliably clean gold film surfaces. Nine gold cleaning methods are investigated here: UV ozone photoreactor; potassium hydroxide-hydrogen peroxide; potassium hydroxide potential sweep; sulfuric acid hydrogen peroxide; sulfuric acid potential cycling; hydrochloric acid potential cycling; dimethylamine borane reducing agent solutions at 25 and 65^oC; and a dilute form of Aqua Regia. Peak-current potential-differences obtained from cyclic voltammetry and charge transfer resistance obtained from electrochemical impedance spectroscopy, as well as X-ray photo-electron spectroscopy are used to characterize surface cleanliness. A low peak-current potential-difference and charge transfer resistance indicates a cleaner surface, as does a higher percentage of elemental gold on the electrode surface. The potassium hydroxide potential sweep method is found to leave the gold surface the cleanest overall.