Hydroxynaphthoquinone ultrathin films obtained by diazonium electroreduction: toward design of biosensitive electroactive interfaces.
Electroactive 2-(phenylsulfanyl)-8-hydroxy-1,4-naphthoquinone has been electrodeposited via the reduction of the corresponding diazonium salt on Au electrodes. Surface characterizations by X-ray photoelectron spectroscopy (XPS) and infrared reflection-absorption spectroscopy (IRRAS) reveal that the mechanism of film deposition follows an aryl radical formation and its immobilization on the electrode surface. Electrochemical study shows that the surface coverage can be finely tuned (thickness between one and four layers) by adjusting the potential and the deposition time. By managing the potential applied when reducing diazonium in potentiostatic mode, the formed layer could mediate or not charge transfer. This is the first time that the films obtained by diazonium process are demonstrated to act as mediators in the growth process. Hence, with potentials higher than the formal potential of quinone group, very thin and homogeneous layers are obtained, whereas thicker films are formed when more cathodic potentials than that of quinone are applied. The possibility to manage the charge-transfer kinetics, the thickness, and the homogeneity of electroactive deposits is interesting in the scope of designing electrochemical transducers.
March
Gregory
G
Laboratoire ITODYS (Interfaces, Traitements, Organisation et Dynamique des Systèmes), UMR 7086, Université Denis Diderot-Paris 7, Paris Cedex 13, France.
Reisberg
Steeve
S
Piro
Benoit
B
Pham
Minh-Chau
MC
Fave
Claire
C
Noel
Vincent
V
D003979:Diazonium Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D006859:Hydrogen / Q000737:chemistry; D015394:Molecular Structure; D009285:Naphthoquinones / Q000737:chemistry*; D010084:Oxidation-Reduction; D013499:Surface Properties
D003979:Diazonium Compounds; D009285:Naphthoquinones; D006859:Hydrogen