839498.fig.004a
(a)
839498.fig.004b
(b)
Figure 4: Cyclic voltammograms of  M MG in aqueous solution at different scan rates (I: 0.01 and VI: 0.50 Vs−1): (a) the GCE was polished prior to each measurements; (b) the subsequent measurements without further polishing of GCE.