power supply is connected.

For the comparative study of various peaks positions, Raman spectra of neutral and chemically reduced form of EV(ClO$_4$)$_2$ has been carried out to verify spectra obtain from electrode E$_1$ and E$_2$ under different bias conditions (Fig. 5(c)). To identify and verify\[33\] the changes in EV$^{2+}$, EV$^{\newmoon +  }$ and EV$^{o}$ concentration Raman peaks of chemically reduced state of EV were studied. The solid EV(ClO$_4$)$_2$ powder was reduced using an aqueous solution of sodium borohydride (NaBH$_4$). Raman spectrum from this reduced state of EV(ClO$_4$)$_2$ is shown in Fig S3 in SI and it was observed that the EV powder turns dark-bluish immediately after mixing with NaBH$_4$ due to reduction of EV. This change of colour is due to variation in absorption spectrum. The same solution turns back into transparent due to oxidation of EV$^{\newmoon +  }$ to EV$^{2+}$ as higher oxidation state is the more stable state in the ambient conditions. Raman spectrum from chemically reduced form of EV(ClO$_4$)$_2$ shows peaks at 1028 and 1528 cm$^{-1}$ which are signatures of EV$^{\newmoon +  }$ species.(These peaks are marked by stars in figure S4). It is now safe to conclude that the blue color observed in Fig. 2 as 