Spontaneous adsorption and electrochemical behaviour of safranine O at electrochemically activated glassy carbon electrode

Abstract

The adsorption behaviour of safranine O (SO) at electrochemically pretreated glassy carbon electrodes has been studied. It was found that SO adsorption depended on the properties of the electrode surface, as determined by the nature and duration of the activation step. It was noticed that SO was adsorbed spontaneously and strongly on the surface of anodically pretreated electrode. The electrochemical behaviour of the modified electrode was investigated in H 2SO 4 (0.25 M) using cyclic voltammetry (CV). A reversible two electron, two proton wave was observed at −180 mV vs. SCE and the formal potential was found to be decreasing upon increasing the solution pH (−56.8 mV pH −1). The modified electrode exhibited good stability on repeated scanning between −500 and 200 mV vs. SCE, causing only 5% decrease in the peak height after 100 cycles at a scan rate of 20 mV s −1. The surface coverage was calculated to be 0.812 nmol cm −2 and the electron transfer rate constant ( k s 0 = 1.45 s − 1 ) and transfer coefficient ( α = 0.43) for the adsorbed SO were evaluated using the Laviron method. The modified electrode clearly showed good electrocatalytic ability for oxygen reduction to H 2O 2.