Electrografting of in situ generated pyrrole derivative diazonium salt for the surface modification of nickel

tThis work reports for the first time on the modification of nickel surfaces by cathodic electrografting of in situ generated diazonium. An original diazonium salt (the 4-pyrrolylphenyldiazonium called Py-PD hereafter) was electrografted on nickel after its generation from 4-(1H-pyrrol-1-yl)aniline (Py-A) inpresence of three acidic conditions (1, 2 and 10 equiv. of HClO4/Py-A) has been investigated by UV-visspectroscopy. Results show that the potentiostatic electrografting of Py-PD is concomitant with nickeland proton reduction. This electrografting leads to the formation of multilayered films in each of thestudied in situ generation conditions. The use of 1 equiv. of HClO4/Py-A for the in situ generation resultsin the formation of inhomogeneous and irreproducible coatings while 2 and 10 equiv. lead to the forma-tion of highly covering, homogeneous and reproducible films. These films present good electrochemicalbarrier properties toward the ferri/ferrocyanide couple. The use of gentle stoichiometric acidic conditionsfor in situ diazonium generation widens the application field of this one-step procedure to the surfacemodification of oxidizable materials presenting an unstable oxide layer.