Prior to modification, Au electrodes (polycrystalline gold rod,
99.99%, 2mm diameter) were polished using alumina slurries
with particle diameters 0.3m and 0.05m, respectively, and
subsequently cleaned through ultrasonication in distilled water
and ethanol, each for 5min. Subsequently, the Au electrode was
immersed in piranha solution (a bath of 7 parts H2SO4 to 3
parts 30% H2O2) for 20 min.