Experimental and theoretical studies on carbon surface modification by reduction of in situ generated diazonium salt

The electrochemically induced functionalization of glassy carbon electrode by aryl groups was achieved by reduction of in situ generated diazonium cations in aqueous media. Surface modification experiments were performed by cyclic voltammetry (CV) scanning from +0.5 to −1.1 V. The barrier properties of the grafted layers were evaluated by cyclic voltammetry in the presence of Fe ( CN ) 6 3 - / 4 - electroactive redox probe. The modified electrodes showed very slow electron transfer compared to that unmodified surface. Once the monolayer is switched ON, it supports rapid electron exchange with the redox system but not with dopamine, which requires adsorption to the electrode surfaces. Ab initio density functional theory calculations allow determining HOMO–LUMO gap distance.