downwards, absorbance increases until the reduction is completed at
−1.30 V. Absorbance does not decrease in the backward scan, indicating
that an irreversible reduction of GO has taken place under these
experimental conditions. The derivative voltabsorptogram at 300 nm
(Fig. 3B) exhibits a full correlation with the cyclic voltammogram
indicating that the two signals are related to the same process.
Moreover, the same experiment was performed using an electrode
without GO deposited on the surface. In this case, a reduction peak
was also observed at −0.88 V. However, there is no change in the
spectra during the experiment because no GO is deposited on the
electrode, demonstrating that spectroelectrochemistry provides unambiguous
information on the process taking place at the electrode.
In situ Ramanmonitoring of the process is very useful since the same
area of the electrode surface is sampled during the electrochemical