To this end, GCE first was immersed into a
deoxygenated solution of 0.5 M H2SO4 in the presence
of 0.1 mM HAuCl4 and 0.1 mM KI for a few seconds.
Then, a step potential from 1.1 to 0.0 V was applied to
the GC electrode for 45 s in three successive steps
(15 + 15 + 15 s).