the current was dominated by the rate of the electron cross exchange (Re) between the Pt redox sites and MB molecules. According to the method described in the literature [29], the rate of electron exchange (Re) between the electrode surface and MB molecules was calculated as per the following equation:
where, Ic is the catalytic current in the presence of MB+, Id is the diffusion limited current in absence of MB+ and t the time. The inset of Fig. 7 shows the Ic/Id versus t1/2 curve in the −0.7 V. From the slope, the value of Re was determined to be 8.3 × 107 L mol−1 s−1. Based on all experimental data, a scheme of bleaching of MB molecules has been proposed in Scheme 1.