Electro-reduction of Nitrobenzene at Titanium Cathode in SDS Aqueous Micellar Solution

摘要

Electro-catalytic reduction of nitrobenzene has been studied from a number of perspective.~(1-23)However, there are very few known studies so far in literature related to reduction of nitrobenzene at titanium electrode in aqueous media. Previously we have studied the electrochemical reduction of nitrate at titanium electrode.~(24)This work relates to electro-reduction of nitrobenzene at titanium cathode, 0.05 cm~2, in the presence of miceller aqueous solution of sodium dodecyl sulphate, using titanium etching and cyclic voltammetric methods in a three-electrode system. Nitrobenzene gives single reduction peak corresponding to the irreversible electrochemical reduction shown in Fig. 1. However at higher concentrations and lower sweep rates single peak splits into two cathodic peaks at more negative potentials. These peaks correspond to reaction mechanisms as per literature for neutral, acidic and alkaline solutions~(1-16) involving four-electron over-all reduction; consisting of a first step, with one-electron transfer to form anion radical (peak I) same electron transfer observed in aqueous micellar media17'20. While the second step involves protonation of anion radical followed by a three electron-addition (peak II) leading to the formation of phenylhydroxylamine. Furthermore the linear relationship of graph, plotted as square root of sweep rate versus cathodic peak current demonstrates that the process is diffusion controlled.