Electroless synthesis of multibranched gold nanostructures encapsulated by poly(o-phenylenediamine) in Nafion

Electrodeposited gold nanostructures at Nafion–poly(o-phenylenediamine) modified electrode and its electrocatalytic application

“…2B) and the plot of redox potential of PPD versus pH showed a slope value of 65 mV/pH. The pH dependence of redox potential of PPD indicates that the redox reaction involves two electron and two proton transfer [19,39]. Also, the reduction peak of Au shifted cathodically when the pH was varied systematically.…”

“…The GC/Nf electrode was immersed in a deaerated 0.1 M oPD monomer solution for 10 min. The electrostatic attraction between the sulfonate groups of Nf and the protonated amine groups of oPD [19] led the formation of Nf-oPD film on the electrode (GC/Nf-oPD). At this modified electrode, Au nanostructures were electrodeposited at an applied potential of À0.2 V for 300 s by dipping the electrode in an electrolyte solution containing 3 mM HAuCl 4 and 0.5 M H 2 SO 4 .…”

“…When the Nf/oPD film was dipped in HAuCl 4 solution, oPD was oxidized by Au 3+ and the oxidized oPD monomer underwent polymerization leading to the formation of PPD at the Nf film. During the oxidative polymerization, a radical cation of oPD monomer initially forms and followed by polymerization leading to the formation of phenazine ring [19,37]. Schematic illustration of fabrication of GC/Nf-PPD/ Au electrode is shown in scheme 1.…”

“…The EASA was calculated using the reported procedure and the value of 390 lC was used as a calibration factor for Au modified electrodes [33,41]. Previously, our group has successfully fabricated the Nf-PPD/Au electrode through an electroless synthesis [19]. It is understood that the reduction of HAuCl 4 occurs in the oPD layer and the oPD monomers get oxidized through oxidative polymerization to form PPD/Au in Nf film.…”

“…The PPD/Au film was used as a novel biocompatible interface for the immobilization of antibody to detect antigen [18]. Recently, our group has reported the preparation of multi-branched cactus like Au nanostructures encapsulated in Nf-PPD composite film through an electroless synthetic route [19].…”