title: Robust Electrografting on Self-Organized 3D Graphene Electrodes.
abstract: Improving graphene-based electrode fabrication processes and developing robust methods for its functionalization are two key research routes to develop new high-performance electrodes for electrochemical applications. Here, a self-organized three-dimensional (3D) graphene electrode processed by pulsed laser deposition with thermal annealing is reported. This substrate shows great performance in electron transfer kinetics regarding ferrocene redox probes in solution. A robust electrografting strategy for covalently attaching a redox probe onto these graphene electrodes is also reported. The modification protocol consists of a combination of diazonium salt electrografting and click chemistry. An alkyne-terminated phenyl ring is first electrografted onto the self-organized 3D graphene electrode by in situ electrochemical reduction of 4-ethynylphenyl diazonium. Then the ethynylphenyl-modified surface efficiently reacts with the redox probe bearing a terminal azide moiety (2-azidoethyl ferrocene) by means of Cu(I)-catalyzed alkyne-azide cycloaddition. Our modification strategy applied to 3D graphene electrodes was analyzed by means of atomic force microscopy, scanning electron microscopy, Raman spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy (XPS). For XPS chemical surface analysis, special attention was paid to the distribution and chemical state of iron and nitrogen in order to highlight the functionalization of the graphene-based substrate by electrochemically grafting a ferrocene derivative. Dense grafting was observed, offering 4.9 × 10(-10) mol cm(-2) surface coverage and showing a stable signal over 22 days. The electrografting was performed in the form of multilayers, which offers higher ferrocene loading than a dense monolayer on a flat surface. This work opens highly promising perspectives for the development of self-organized 3D graphene electrodes with various sensing functionalities.
authors.affiliation: Institut des Sciences Analytiques, UMR 5280, CNRS, Université de Lyon 1 , 5 rue de la Doua, 69100 Villeurbanne, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Fortgang
authors.affiliation: Université de Lyon , F-69003, Lyon, France.|Université de Saint-Étienne , Laboratoire Hubert Curien (UMR 5516 CNRS), 42000 Saint-Étienne, France.
authors.forename: Teddy
authors.initials: T
authors.lastname: Tite
authors.affiliation: Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines , 42023 Saint-Etienne, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Barnier
authors.affiliation: Institut des Sciences Analytiques, UMR 5280, CNRS, Université de Lyon 1 , 5 rue de la Doua, 69100 Villeurbanne, France.
authors.forename: Nedjla
authors.initials: N
authors.lastname: Zehani
authors.affiliation: Université de Lyon , F-69003, Lyon, France.|Université de Saint-Étienne , Laboratoire Hubert Curien (UMR 5516 CNRS), 42000 Saint-Étienne, France.
authors.forename: Chiranjeevi
authors.initials: C
authors.lastname: Maddi
authors.affiliation: Institut des Sciences Analytiques, UMR 5280, CNRS, Université de Lyon 1 , 5 rue de la Doua, 69100 Villeurbanne, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Lagarde
authors.affiliation: Université de Lyon , F-69003, Lyon, France.|Université de Saint-Étienne , Laboratoire Hubert Curien (UMR 5516 CNRS), 42000 Saint-Étienne, France.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Loir
authors.affiliation: Institut des Sciences Analytiques, UMR 5280, CNRS, Université de Lyon 1 , 5 rue de la Doua, 69100 Villeurbanne, France.
authors.forename: Nicole
authors.initials: N
authors.lastname: Jaffrezic-Renault
authors.affiliation: Université de Lyon , F-69003, Lyon, France.|Université de Saint-Étienne , Laboratoire Hubert Curien (UMR 5516 CNRS), 42000 Saint-Étienne, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Donnet
authors.affiliation: Université de Lyon , F-69003, Lyon, France.|Université de Saint-Étienne , Laboratoire Hubert Curien (UMR 5516 CNRS), 42000 Saint-Étienne, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Garrelie
authors.affiliation: Institut des Sciences Analytiques, UMR 5280, CNRS, Université de Lyon 1 , 5 rue de la Doua, 69100 Villeurbanne, France.
authors.forename: Carole
authors.initials: C
authors.lastname: Chaix
keywords: X-ray photoelectron spectroscopy; click chemistry; diazonium electrografting; ferrocene; self-organized 3D graphene